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Power Electronics Lab Manual Version 1.0 – 11 November 2014 Preliminary Content – This document may not include the latest updates and may contain errors.

Power Electronics Lab Manual This introductory lab series was created in collaboration with Dr. Afshin Izadian of the Indiana University – Purdue University Indianapolis. It introduces students to basic power electronics circuits and the analysis techniques used to characterize them.

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Copyright Under the copyright laws, this publication may not be reproduced or transmitted in any form, electronic or mechanical, including photocopying, recording, storing in an information retrieval system, or translating, in whole or in part, without the prior written consent of National Instruments Corporation. National Instruments respects the intellectual property of others, and we ask our users to do the same. NI software is protected by copyright and other intellectual property laws. Where NI software may be used to reproduce software or other materials belonging to others, you may use NI software only to reproduce materials that you may reproduce in accordance with the terms of any applicable license or other legal restriction. Trademarks LabVIEW, National Instruments, NI, ni.com, and NI-DAQ are trademarks of National Instruments. Refer to the Terms of Use section on ni.com/legal for more information about National Instruments trademarks. Other product and company names mentioned herein are trademarks or trade names of their respective companies Patents For patents covering National Instruments products, refer to ni.com/patents. Some portions of this product are protected under United States Patent No. 6,560,572. WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS (1) NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT INJURY TO A HUMAN. (2) IN ANY APPLICATION, INCLUDING THE ABOVE, RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE IMPAIRED BY ADVERSE FACTORS, INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY, COMPUTER HARDWARE MALFUNCTIONS, COMPUTER OPERATING SYSTEM SOFTWARE FITNESS, FITNESS OF COMPILERS AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION, INSTALLATION ERRORS, SOFTWARE AND HARDWARE COMPATIBILITY PROBLEMS, MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL DEVICES, TRANSIENT FAILURES OF ELECTRONIC SYSTEMS (HARDWARE AND/OR SOFTWARE), UNANTICIPATED USES OR MISUSES, OR ERRORS ON THE PART OF THE USER OR APPLICATIONS DESIGNER (ADVERSE FACTORS SUCH AS THESE ARE HEREAFTER COLLECTIVELY TERMED “SYSTEM FAILURES”). ANY APPLICATION WHERE A SYSTEM FAILURE WOULD CREATE A RISK OF HARM TO PROPERTY OR PERSONS (INCLUDING THE RISK OF BODILY INJURY AND DEATH) SHOULD NOT BE RELIANT SOLELY UPON ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM FAILURE. TO AVOID DAMAGE, INJURY, OR DEATH, THE USER OR APPLICATION DESIGNER MUST TAKE REASONABLY PRUDENT STEPS TO PROTECT AGAINST SYSTEM FAILURES, INCLUDING BUT NOT LIMITED TO BACK-UP OR SHUT DOWN MECHANISMS. BECAUSE EACH END-USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS' TESTING PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY NATIONAL INSTRUMENTS, THE USER OR APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER NATIONAL INSTRUMENTS PRODUCTS ARE INCORPORATED IN A SYSTEM OR APPLICATION, INCLUDING, WITHOUT LIMITATION, THE APPROPRIATE DESIGN, PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION.

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Contents Lab at a Glance.................................................................................................................... 7 What You Will Do ................................................................................................................ 7 Time Required..................................................................................................................... 7 Background Knowledge ....................................................................................................... 8

Gate Driver Lab........................................................................................................................ 9 1.1 Goal .............................................................................................................................10 1.2 Objectives ....................................................................................................................10 1.3 Pre-Lab Activities ..........................................................................................................10 1.3a Get to Know the Topics ........................................................................................................................ 10 1.3b Pre-Assessment Quiz ............................................................................................................................ 11 1.4 Lab Procedure............................................................................................................... 12 1.4a Design the Circuit in Multisim .............................................................................................................. 12 1.4b Perform an Oscilloscope Analysis .........................................................................................................13 1.4c Simulate a Power Transistor with Gate Drive ....................................................................................... 14 1.4d Build the Gate Driver Circuit on a myProto Breadboard ....................................................................... 16 1.5 Create a Lab Report ....................................................................................................... 17 1.6 Final Observations ........................................................................................................ 17

Buck Converter Lab ................................................................................................................. 19 2.1 Goal .............................................................................................................................20 2.2 Objectives ....................................................................................................................20 2.3 Pre-Lab Activities ..........................................................................................................20 2.3a Get to Know the Topics........................................................................................................................ 20 2.3b Pre-Assessment Quiz........................................................................................................................... 21 2.4 Lab Procedure............................................................................................................... 21 2.4a Design the Circuit in Multisim .............................................................................................................. 21 2.4b Perform a Transient Analysis ............................................................................................................... 22 2.4c Perform a Parameter Sweep (Resistive Load) ...................................................................................... 24 2.4d Perform a Parameter Sweep (Corner Frequency) ................................................................................ 26 2.4e Perform a Parameter Sweep (Inductive Load) ......................................................................................27 2.4f Build and Explore the Buck Converter on a myProto Breadboard ..........................................................27

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2.5 Create a Lab Report ...................................................................................................... 29 2.6 Final Observations ....................................................................................................... 29

Boost Converter Lab ............................................................................................................... 31 3.1 Goal ............................................................................................................................. 32 3.2 Objectives .................................................................................................................... 32 3.3 Pre-Lab Activities .......................................................................................................... 32 3.3a Get to Know the Topics ........................................................................................................................ 32 3.3b Pre-Assessment Quiz ............................................................................................................................33 3.4 Lab Procedure............................................................................................................... 33 3.4a Design the Circuit in Multisim ...............................................................................................................33 3.4b Perform a Transient Analysis ............................................................................................................... 34 3.4c Perform a Parameter Sweep (Resistive Load) ...................................................................................... 36 3.4d Perform a Parameter Sweep (Corner Frequency)................................................................................. 38 3.4e Perform a Parameter Sweep (Inductive Load) ..................................................................................... 39 3.4f Build and Explore the Boost Converter on a myProto Breadboard........................................................ 39 3.5 Create a Lab Report ...................................................................................................... 40 3.6 Final Observations ........................................................................................................41

Buck Boost Converter Lab ....................................................................................................... 43 4.1 Goal ............................................................................................................................ 44 4.2 Objectives ................................................................................................................... 44 4.3 Pre-Lab Activities ......................................................................................................... 44 4.3a Get to Know the Topics........................................................................................................................ 44 4.3b Pre-Assessment Quiz........................................................................................................................... 45 4.4 Lab Procedure...............................................................................................................45 4.4a Design the Circuit in Multisim .............................................................................................................. 45 4.4b Perform a Transient Analysis ............................................................................................................... 46 4.4c Perform a Parameter Sweep (Resistive Load) ...................................................................................... 48 4.4d Perform a Parameter Sweep (Corner Frequency) ................................................................................ 50 4.4e Perform a Parameter Sweep (Inductive Load) ......................................................................................51 4.4f Build and Explore the Buck Boost Converter on a myProto Breadboard ................................................51 4.5 Create a Lab Report ....................................................................................................... 52 4.6 Final Observations ........................................................................................................ 53

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Full Bridge Inverter Lab .......................................................................................................... 55 5.1 Goal .............................................................................................................................56 5.2 Objectives ....................................................................................................................56 5.3 Pre-Lab Activities ..........................................................................................................56 5.3a Get to Know the Topics ........................................................................................................................ 56 5.3b Pre-Assessment Quiz ............................................................................................................................57 5.4 Lab Procedures ............................................................................................................ 58 5.4a Design a Multisim Circuit ..................................................................................................................... 58 5.4b Perform a Transient Analysis ............................................................................................................... 59 5.4c Perform a Parameter Sweep ................................................................................................................ 61 5.4d Build the Full Bridge Inverter on a myProto Breadboard ...................................................................... 62 5.5 Lab Report ....................................................................................................................63 5.6 Final Observations ........................................................................................................63

Rectifier Lab ........................................................................................................................... 65 6.1 Goal ............................................................................................................................ 66 6.2 Objectives ................................................................................................................... 66 6.3 Pre-Lab Activities ......................................................................................................... 66 6.3a Get to Know the Topics........................................................................................................................ 66 6.3b Pre-Assessment Quiz........................................................................................................................... 67 6.4 Lab Procedure Part 1: Half and Full Wave Uncontrolled Rectifiers ......................................67 6.4a Design the Circuit in Multisim .............................................................................................................. 67 6.4b Perform a Transient Analysis ............................................................................................................... 68 6.4c Perform a Parameter Sweep (Half Wave Rectifier) ...............................................................................70 6.4d Perform a Parameter Sweep (Full Wave Rectifier) ................................................................................72 6.4e Build and Explore the Uncontrolled Rectifier on a myProto Breadboard............................................... 73 6.5 Lab Procedure Part 2: Phase Controlled Full Bridge Rectifier .............................................74 6.5a Multisim SCR Simulation ..................................................................................................................... 74 6.5b SCR Transient analysis .........................................................................................................................75 6.6 Create a Lab Report ...................................................................................................... 75 6.7 Final Observations ........................................................................................................76

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Lab at a Glance Lab Gate Driver

Overview Discover power transistors and the importance of the gate driver circuit

Buck Converter

Simulate, build and experiment with a DC-DC step down converter

Boost Converter

Simulate, build and experiment with a DC-DC step up converter

Buck Boost Converter

Simulate, build and experiment with a DC-DC step up and step down converter

Full Bridge Inverter

Simulate, build and experiment with a DC – AC converter

Rectifier

Simulate, build and experiment with a Half, Full bridge and controlled rectifier

What You Will Do Throughout these labs you will use NI myDAQ and LabVIEW and Multisim to simulate and test basic Power Electronics circuits. These labs will allow students to quickly see the differences between ideal and real circuits. Students will learn the importance of the additional circuitry needed to drive power transistors as well as how to test various component values on these circuits to decide how to optimize the output.

Time Required The labs should take around three (2-3) hours, but this can vary depending on your prior knowledge and rate of learning.

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Background Knowledge It is recommended that you have some exposure to LabVIEW, but it is not required. The instructions for the exercises cover all necessary steps to complete the task. Note that you are expected to learn basic tasks as you progress, and the instructions become less detailed and require that you retain some of the knowledge. You are expected to be familiar with using a computer, mouse, and keyboard.

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Gate Driver Lab One Hour

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1.1 Goal To understand the importance of using a gate driver when controlling power transistors and to become familiar with National Instruments hardware

1.2 Objectives In this lab you will:   

Simulate a circuit in Multisim software. Build and interact with a gate driver circuit. You will design the circuit to sweep various frequencies of square waves to output to an insulated Gate Bipolar Transistor (IGBT). Create a lab report to present your data, observations, and conclusions.

1.3 Pre-Lab Activities 1.3a Get to Know the Topics Review the following resources to familiarize yourself with the topics listed before you begin the lab:

Textbook References: Hart, Daniel W. Power Electronics. New York, NY: McGraw-Hill, 2011. Section: 10. Mohan, Ned, Undeland, Tore M, Robbins, William P. Power Electronics: Converters Applications and Design. Danvers, MA: John Wiley and Sons, 2003. Sections: 28.1 – 28.3 myDAQ References: Get Started Using NI myDAQ with LabVIEW for Education https://www.youtube.com/watch?v=RsD2tHbuAF4 DAQ Lesson 1 https://decibel.ni.com/content/docs/DOC-11624

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1.3b Pre-Assessment Quiz Complete the following quiz to check your understanding of the relevant topics before you begin the lab. a. What is meant when a circuit is Unipolar or Bipolar? List the benefits of each. b. Draw a MOSFET front view and label each of the following parts: a) Gate – Metal b) Gate – Oxide c) Drain d) Source e) Body b. Explain how the MOS capacitor contributes to the need for gate drive circuitry in 3-5 sentences. Include information on charging and discharging capacitors and suggest different ways to charge and discharge at different rates. c. Draw and label a transistor with a gate drive circuit. Draw the path for current to and from the gate when the control circuit produces a high and another when the control circuit produces a low. d. List the different regions of operation for a BJT and MOSFET. Using the data sheet for your Insulated Gate Bipolar Transistor (IGBT), list the voltages needed to put the transistor into its different regions. e. What are the voltage and current specifications of the analog output channels of the myDAQ? What region of operation do you estimate the myDAQ can drive the IGBT into without a drive circuit?

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1.4 Lab Procedure 1.4a Design the Circuit in Multisim Designing the circuit in Multisim allows you to gain an understanding of the circuit you will prototype on a breadboard later. Simulate a Power Transistor with No Gate Drive Step 1: Design the following circuit in Multisim

Figure 1 Transistor Circuit with No Gate Drive Finding Components in Multisim V1/V2 – DC voltage sources, V2 is being used as a reference voltage for the PWM signal being generated while V1 is the voltage source of the switching circuit. Found in Group: Sources; Family: Power_Sources. U1 – PWM function used to generate the square wave signal for the transistor, found in Group: Power; Family: Power_Controllers. IRF520 – Power transistor used to switch the DC supply based on the square wave signal from the PWM function. Found in Group: Transistors; Family: Power_Mos_N.

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XSC1 – Oscilloscope used to monitor runtime signals from the circuit. You can use wires or on-page connectors to wire up the circuit. For more information about working in Multisim, visit: https://www.youtube.com/user/ntspress/search?query=multisim.

1.4b Perform an Oscilloscope Analysis An oscilloscope allows you to probe different portions of your circuit and gain an understanding of the inputs and outputs of your circuit during simulation runtime. You will observe the output of an IGBT as you apply higher frequency square waves to the input. Step 2: Double click on the PWM function and enter the following configuration settings: Reference signal frequency: 250 kHz Reference Signal minimum voltage: 0V Reference Signal maximum voltage: 1V Output voltage amplitude: 5V Output rise/fall time: 1ns This will allow the PWM function to output a signal based on the comparison between the input voltage provided by “V2” and the sawtooth wave used as a reference. The function will output a high when the input voltage is higher than the reference and a low when it is lower. Since the input is a constant, the output signal will maintain a constant ratio between time spent high and low. The input voltage is set to 0.5 which makes it so that it is high higher than the reference sawtooth voltage (set to 1V) for half the time. This ratio will remain the same even as the frequency of the sawtooth reference signal is changed. Click “Ok” to accept the settings you entered. Step 3: Double Click on the Oscilloscope function to open the graph panel as seen in Figure 2. Click on the green arrow in the main Multisim window to let the simulation run for a few seconds, and then stop it by pressing on the red stop square in the main Multisim window. On the Oscilloscope panel, increase the Timebase: Scale field to 100ns/Div and use the scroll bar to move to a point on the graph where there is a rising edge for Signal A.

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Note: You will need to change the Scale of channel A and B in order to see all of the signals you are simulating.

Figure 2 Oscilloscope graph panel Step 4: Move cursor T2, using the left and right arrow buttons, to the point on signal A that is approximately 90% of signal A’s maximum amplitude. Move cursor T1 to approximately the 10% point. Record the time for T2-T1 as “Rise Time” and take a screen shot of the graph for your lab report. Note: The cursor controls are right below the scroll bar on the oscilloscope panel. Step 5: Using the scroll bar again, move to a location where there is a falling edge of signal A and repeat the process you followed from step 4, this time with T2 being the 10% point and T1 being the 90% point. Record the time for T2-T1 as “Fall Time” and take a screen shot for your lab report. Step 6: Change the Timebase: Scale in order to see multiple periods of signal A. Take a screen shot of this for your lab report and record the maximum amplitude of signal A.

1.4c Simulate a Power Transistor with Gate Drive Step 7: Modify your current circuit to match the following.

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The additional components can be found in Group: Transistors: Family: BJT_NPN and BJT_PNP. You can search for them by the model numbers listed in the figure. The additional power supply provides a higher voltage and current signal that can be switched by the control signal.

Figure 3 Create Measurement Expression Step 8: Repeat steps 3-6 on the new circuit to accumulate information to use for comparison between the power transistor output with and without the gate driver.

Challenge Question 1: Explain in detail why the output rise and fall times are so different between the two circuits. Challenge Question 2: Go back and calculate the power dissipated in the transistor in both cases. Explain why there is a difference between the two and reference the regions that the transistor is in.

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1.4d Build the Gate Driver Circuit on a myProto Breadboard The circuit you built in Multisim utilized power transistors in its design, these will be replaced with Insulated Gate Bipolar Transistors in the breadboard design, and two integrated chips will be used to provide isolation and gate drive. Step 9: Using the schematic provided in Figure 4, build the gate driver circuit on a myProto and wire the appropriate lines from the circuit to the breakout bank of the myProto. Connect the myProto to the myDAQ, and plug the myDAQ into your computer using the USB connector.

Figure 4 Isolation and gate drive integrated chips

Step 10: Open the Gate Driver Lab.vi, select the appropriate myDAQ from the “Devices” drop down, and run the VI. Observe the output waveform and comment on the amplitude and rise and fall times of the signal. Vary the frequency of the output square wave and observe the change in the output waveform. Step 11 (Optional): Directly connect the myDAQ control signal to the gate of the IGBT and rerun the Gate Driver Lab.vi. Vary the signal frequency and examine the output waveform for any changes. Comment on the influence of the gate driver in your lab report.

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1.5 Create a Lab Report Complete a 3-5 page report which includes all pictures, observations and answers to questions presented in the lab. Label all pictures with descriptive captions that relate them back to content in your lab report. Include an introduction, conclusion and 3-5 sentences that talk about the effects of a gate driver on a power circuit. Discuss how the circuit can be improved to allow for less power dissipation and suggest ways to maintain performance at even higher frequencies.

1.6 Final Observations Record other thoughts and observations you made throughout the lab and connect them to something you have observed or experienced in the real world.

Challenge: Explore PCB Design Attached are schematics for the gate driver circuit. These can either be used to add to the lab experience with an additional PCB design section or help reduce prototyping time for students if boards are created before the lab by lab assistants.

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Boost Converter Lab

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Buck Converter Lab One Hour

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2.1 Goal To understand the basics of a buck converter circuit, common transistors used in power electronics, and National Instruments hardware

2.2 Objectives In this lab you will:  



Simulate a buck converter circuit in Multisim software. Build and interact with a step down, DC to DC converter circuit, commonly known as a buck converter. You will design the circuit to output a switch DC voltage that varies according to switch frequency and duty cycle. Create a lab report to present your data, observations, and conclusions.

2.3 Pre-Lab Activities 2.3a Get to Know the Topics Review the following resources to familiarize yourself with the topics listed before you begin the lab. Textbook References: Hart, Daniel W. Power Electronics. New York, NY: McGraw-Hill 2011. Print Sections: 1.4, 8.1-8.4 Mohan, Ned, Undeland, Tore M, Robbins, William P. Power Electronics: Converters Applications and Design. Danvers, MA: John Wiley and Sons 2003 Sections: 2.1-2.8, 7.2-7.4 myDAQ References: Get Started Using NI myDAQ with LabVIEW for Education https://www.youtube.com/watch?v=RsD2tHbuAF4 DAQ Lesson 1 https://decibel.ni.com/content/docs/DOC-11624

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2.3b Pre-Assessment Quiz Complete the following quiz to check your understanding of the relevant topics before you begin the lab. a. Create a table that compares at least four transistors and provides a ranking of the transistors based on power capability and switching speed. b. Describe at least one method for reducing power loss in your circuit. Explain how the method can be implemented in a practical application. c. Draw the two modes of operation for the buck converter. Label the flow of current for each mode. Write the expression for duty ratio and comment on what makes the duty ratio so important d. Write the equation for output voltage ripple for a buck converter. Comment on what this equation implies about switching frequency and the corner frequency of the low pass filter in the buck converter. e. List all the steps and I/O lines needed to generate a continuous pulse train from the myDAQ using the on-board counter.

2.4 Lab Procedure 2.4a Design the Circuit in Multisim Designing the circuit in Multisim allows you to gain an understanding of the circuit you will prototype on the breadboard later. Note that MOSFET Power transistors are used in the simulation instead of the IGBTs used in prototyping, and the gate driver circuit from Lab 0 Gate Driver has been purposely removed in order to emphasize the buck converter configuration. Design the following circuit in Multisim.

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Figure 5 Buck (Step Down) Converter Circuit

Finding Components in Multisim DC_Source – DC voltage source found in Group: Sources; Family: Power_Sources. PWM_Generator – PWM function used to generate the buck converter control signal, found in Group: Power; Family: Power_Controllers. DC_PWM_Controller – DC signal used as a reference for the PWM generation. See DC_Source for location. VCVS– Voltage Controlled Voltage Source used to provide a constant voltage regardless of the current requirements of the load, in this case the MOSFET. Found in Group: Sources; Family: Controlled_Voltage_Sources. Power_MOSFET Q1– Power transistor used to switch the DC supply in order to provide an alternating signal for the buck converter. Found in Group: Transistors; Family: Power_Mos_N. For more information about working in Multisim, visit: https://www.youtube.com/user/ntspress/search?query=multisim

2.4b Perform a Transient Analysis A transient analysis gives you an idea of how your circuit will respond over a set period of time. It allows you to apply some input and observe an output through simulation. Boost Converter Lab

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Step 2: Label the wire at the top of the resister branch by right clicking on it and choosing “Properties”. Then under the “Net name” tab, update “Preferred net name” with a descriptive name of your choice, and click “Ok”.

Figure 6 Wire Properties Step 3: Click “Simulate” on the top toolbar and navigate to Analyses>>Transient Analysis. In the pop up configuration window, choose the “Analysis parameters” tab and set the following parameters: Initial Conditions: Set to zero Start time (TSTART): 0 End time (TSTOP): 0.05s Step 4: Navigate to the “Output” tab, click on the descriptive name you just made to select that node to monitor from the “Variables in circuit” field and click “Add”. Select anything that may be in the “Selected variable for analysis” field that you are not monitoring and click “Remove”.

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Figure 7 Create Measurement Expression

Step 5: Click “Simulate” to run the transient analysis. Take a screen shot of your results to include in your lab report.

2.4c Perform a Parameter Sweep (Resistive Load) A parameter sweep gives you an idea of how your circuit would respond with different values for components such as resistors and capacitors. This sweep can be fine-tuned to allow you to find the optimum point of operation for you circuit, so when you prototype your circuit with real components you can have an idea of the range of component values you can use to achieve a satisfactory output. In this lab you will perform parameter sweeps on the control signal’s duty cycle, the buck converter capacitance, inductance, and load inductance.

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Step 6: Click “Simulate” on the top toolbar and navigate to Analyses>> Parameter Sweep. In the pop up configuration window, navigate to the “Analysis parameters” tab and set the following parameters: Sweep Parameter: Device Parameter Device Type: Vsource Name: vdc_pwm_controller (the name of the PWM_controller on your schematic) Parameter: dc Start: 100 mV Stop: 950 mV Number of points: 6 Analysis to sweep: Transient Analysis Verify on the “Output” tab that the “Selected variables for analysis” field shows the resistor load branch as selected for analysis, the same that was chosen for your transient analysis step. Click “Simulate” to run the parameter sweep. This will create six instances of your buck converter output, which correspond to the six different PWM duty cycles created from varying the PWM_Controller voltage. Take a screen shot of your results to include in your lab report. Find out what the PWM switching frequency is from the PWM generator function (done by double clicking on the function) and label the screenshot with the frequency where the analysis takes place. Step 7: Pick five different frequencies evenly spaced out in the range from 50Hz to 20 kHz. Change the PWM generator frequency to each of these values, and rerun your transient analysis from steps 2 and 3 for each frequency value. Take a screen shot of all of these trials for your lab report and comment on the effects you observed of changing the generator frequency.

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2.4d Perform a Parameter Sweep (Corner Frequency) The corner frequency of your LC (inductor capacitor) lowpass filter can be increased or decreased to change the high frequency content allowed through your buck converter. Next, you will explore how you can change the response of the filter and its effects on the buck converter DC output. Step 8: Navigate to the “Parameter Sweep” analysis and select the following parameters to perform a sweep of the inductance: Sweep Parameter: Device Parameter Device Type: Inductor Name: L1 Parameter: inductance Start: 1 mH Stop: 100 mH Number of points: 6 Analysis to sweep: Transient Analysis Step 9: Click “Simulate” to run the analysis. Take a screen shot of the output for your lab report and comment on the impact of the inductance in your buck converter. Include in your comment a theoretical explanation of the inductor and its response to change in voltage and current. Step 10: Navigate to the “Parameter Sweep” analysis and select the following parameters to perform a sweep of the capacitance: Sweep Parameter: Device Parameter Device Type: Capacitor Name: C1 Parameter: capacitance Start: 1 uF Stop: 200 uF Number of points: 12

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Analysis to sweep: Transient Analysis Step 11: Click “Simulate” to run the analysis. Take a screen shot of the output for your lab report and comment on the impact of the capacitance in your buck converter. Include in your comment a theoretical explanation of the capacitor and its response to change in voltage and current.

2.4e Perform a Parameter Sweep (Inductive Load) In most applications, your DC-DC converter will not be tied to just a resistor. Most hardware includes some form of capacitance and inductance. You will now explore the effects of having an inductive load in your circuit. Step 12: Modify the 1k ohm resistor in the load to 50ohms. Add a 10mH inductor to your circuit in series with your 500 ohm resistance (the resistor and inductor should still be in parallel with the capacitor in your circuit). Step 13: Click “Simulate” in the top toolbar and choose “Parameter sweep”. Use the same configuration you had from your previous run and click “Simulate”. Take a screen shot of your results for your lab report and comment on what changed in the resulting output and why.

Challenge Question 1: Voltage ripple relies heavily on the switching frequency and corner frequency of your LC lowpass filter. Calculate the corner frequency of this buck converter, determine a switching frequency that will increase V ripple, and modify the PWM generator with your new switching frequency value. This can be done by double clicking on the PWM function and changing the reference frequency. Rerun a transient analysis and comment on whether the change gives the expected results. Challenge Question 2: There is a significant amount of power lost in the buck converter diode. Explain why this is the case and suggest ways to improve the efficiency of your buck converter. For example, you might suggest additional circuitry.

2.4f Build and Explore the Buck Converter on a myProto Breadboard The circuit built in Multisim utilized power transistors in its design, these will be replaced with Insulated Gate Bipolar Transistors in the breadboard design and the gate driver from Lab 0 will be used to control the transistors. Comment on how this will influence the results of the breadboard circuit in your lab report. Also talk about the importance of the diodes placed across each transistor.

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Step 14: Build the Buck converter on your myProto protoboard using Insulated Gate Bipolar Transistors (IGBTs). The design should follow what you designed in Multisim, and you should build the gate driver from Lab 0 to properly control the IGBTs. Use values for the resistor, capacitor and inductor similar to that used in the initial Multisim design. The PWM generator will be replaced with the Analog output 0 line from the myDAQ. You may use the block diagram in Figure 5 to assist in building the buck converter circuit.

Figure 5 Buck Converter Block Diagram Step 15: Connect the myProto to your myDAQ and plug the myDAQ into your computer. Step 16: Open the myDAQBuckBoost.vi and modify the Frequency (Hz) and Duty Cycle (%) controls to 1000Hz and 10% respectively. Run the code and observe the instantaneous signals. Use the myDAQBuckBoost.vi to fill in the Table 1 (included at the end of the lab). Include this table along with a screenshot of the instantaneous signals from the VI front panel in your lab report. Step 17: Choose three other capacitor and three other inductor values to test in your circuit. The capacitor and inductor values should fall in the same range as those used in the parameter sweep with one value falling at the low end, the second at the high end, and the last in the middle of the range. Swap pairs of these components into your circuit and fill out a copy of Table 1 for each using the myDAQBuckBoost.vi. Include all of these tables as well as screenshots from the VI front panel of the instantaneous signals that correspond to each table in your lab report. (You do not need to have more than three tables for your lab report). Step 18: Explore the block diagram of the myDAQBuckBoost.vi and gain an understanding of how signals are generated and what form of analysis is being used.

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2.5 Create a Lab Report Complete a 3-5 page report that includes all pictures, tables, observations and answers to questions presented in the lab. Label all pictures with descriptive captions that relate them back to content in your lab report. Include an introduction, a results section, and a conclusion that also explains one practical application of a Buck Converter.

2.6 Final Observations Record other thoughts and observations you made throughout the lab and connect them to something you have observed or experienced in the real world.

Challenge: Explore the PCB Design Attached are schematics for the buck converter circuit. These can either be used to add to the lab experience with an additional PCB design section or help reduce prototyping time for students if boards are created before the lab by lab assistants.

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Switching

Duty Cycle(%)

Vout DC(V)

Vout RMS(V)

Iout DC(A)

Frequency(Hz)

Iout RMS (A)

DC Output Power (W)

Inductance(mH) Capacitance(uF) Table 1 Experimental Observations

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Boost Converter Lab One Hour

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3.1 Goal To understand the basics of a boost converter circuit, common transistors used in power electronics, and National Instruments hardware.

3.2 Objectives In this lab you will:  



Simulate a boost converter circuit in Multisim software. Build and interact with a step up, DC to DC converter circuit, commonly known as a boost converter. You will design the circuit to output a switch DC voltage that varies according to switch frequency and duty cycle. Create a lab report to present your data, observations, and conclusions.

3.3 Pre-Lab Activities 3.3a Get to Know the Topics Review the following resources to familiarize yourself with the topics listed before you begin the lab. Textbook References: Hart, Daniel W. Power Electronics. New York, NY: McGraw-Hill 2011. Print Sections: 1.4, 6.4 Mohan, Ned, Undeland, Tore M, Robbins, William P. Power Electronics: Converters Applications and Design. Danvers, MA: John Wiley and Sons 2003 Sections: 2.1-2.8, 7.4 myDAQ References: Get Started Using NI myDAQ with LabVIEW for Education https://www.youtube.com/watch?v=RsD2tHbuAF4 DAQ Lesson 1 https://decibel.ni.com/content/docs/DOC-11624

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3.3b Pre-Assessment Quiz Complete the following quiz to check your understanding of the relevant topics before you begin the lab. a. Explain the principles of voltage increment in a boost converter. b. How is the PWM signal generated and applied to a transistor? Explain the switching procedures in a turn-on and turn-off process. c. What are advantages and disadvantages of a boost converter?

3.4 Lab Procedure 3.4a Design the Circuit in Multisim Designing the circuit in Multisim allows you to gain an understanding of the circuit you will prototype on the breadboard later. Note that MOSFET Power transistors are used in the simulation instead of the IGBTs used in prototyping, and the gate driver circuit from Lab 0 Gate Driver has been purposely removed in order to emphasize the boost converter configuration. Design the following circuit in Multisim. Double click the PWM_Generator and set a Reference signal frequency of 5 kHz.

Figure 6 Boost (Step Up) Converter Circuit Finding Components in Multisim DC_Source – DC voltage source found in Group: Sources; Family: Power_Sources.

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PWM_Generator – PWM function used to generate the boost converter control signal, found in Group: Power; Family: Power_Controllers. DC_PWM_Controller – DC signal used as a reference for the PWM generation. See DC_Source for location. VCVS– Voltage Controlled Voltage Source used to provide a constant voltage regardless of the current requirements of the load, in this case the MOSFET. Found in Group: Sources; Family: Controlled_Voltage_Sources. Power_MOSFET– Power transistor used to switch the DC supply in order to provide an alternating signal for the boost converter. Found in Group: Transistors; Family: Power_Mos_N. For more information about working in Multisim, visit: https://www.youtube.com/user/ntspress/search?query=multisim

3.4b Perform a Transient Analysis A transient analysis gives you an idea of how your circuit will respond over a set period of time. It allows you to apply some input and observe an output through simulation. Step 2: Label the wire at the top of the resister branch by right clicking on it and choosing “Properties”. Then under the “Net name” tab, update “Preferred net name” with a descriptive name of your choice, and click “Ok”.

Figure 7 Wire Properties

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Step 3: Click “Simulate” on the top toolbar and navigate to Analyses>>Transient Analysis. In the pop up configuration window, choose the “Analysis parameters” tab and set the following parameters: Initial Conditions: Set to zero Start time (TSTART): 0 End time (TSTOP): 0.05s Step 4: Navigate to the “Output” tab, click on the descriptive name you just made to select that node to monitor from the “Variables in circuit” field and click “Add”. Select anything that may be in the “Selected variable for analysis” field that you are not monitoring and click “Remove”.

Figure 8 Create Measurement Expression

Step 5: Click “Simulate” to run the transient analysis. Take a screen shot of your results to include in your lab report. In this setup we have achieved a duty cycle ( ) of 40%, use the Boost Converter Lab

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following equation to calculate the expected output voltage then use the cursors in your transient analysis to measure what the average voltage of you output is. In your lab report document the calculated and simulated output voltages. Calculate the percent error of your data and comment on why you believe there to be an error.

Equation 1 Boost converter output voltage equation

3.4c Perform a Parameter Sweep (Resistive Load) A parameter sweep gives you an idea of how your circuit would respond with different values for components such as resistors and capacitors. This sweep can be fine-tuned to allow you to find the optimum point of operation for you circuit, so when you prototype your circuit with real components you can have an idea of the range of component values you can use to achieve a satisfactory output. In this lab you will perform parameter sweeps on the control signal’s duty cycle, the boost converter capacitance, inductance, and load inductance. Step 6: Click “Simulate” on the top toolbar and navigate to Analyses>> Parameter Sweep. In the pop up configuration window, navigate to the “Analysis parameters” tab and set the following parameters: Sweep Parameter: Device Parameter Device Type: Vsource Name: vdc_pwm_controller (the name of the PWM_controller on your schematic) Parameter: dc Start: 100 mV Stop: 950 mV Number of points: 6 Analysis to sweep: Transient Analysis Verify on the “Output” tab that the “Selected variables for analysis” field shows the resistor load branch as selected for analysis, the same that was chosen for your transient analysis step. Click “Simulate” to run the parameter sweep. This will create six instances of your boost converter output, which correspond to the six different PWM duty cycles created from varying the PWM_Controller voltage. Boost Converter Lab

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Take a screen shot of your results to include in your lab report. Find out what the PWM switching frequency is from the PWM generator function (done by double clicking on the function) and label the screenshot with the frequency where the analysis takes place. Step 7: Pick five different frequencies evenly spaced out in the range from 50Hz to 20 kHz. Change the PWM generator frequency to each of these values, and rerun your transient analysis from steps 2 and 3 for each frequency value. Take a screen shot of all of these trials for your lab report and comment on the effects you observed of changing the generator frequency.

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3.4d Perform a Parameter Sweep (Corner Frequency) The corner frequency of your LC (inductor capacitor) lowpass filter can be increased or decreased to change the high frequency content allowed through your boost converter. Next, you will explore how you can change the response of the filter and its effects on the boost converter DC output. Step 8: Navigate to the “Parameter Sweep” analysis and select the following parameters to perform a sweep of the inductance: Sweep Parameter: Device Parameter Device Type: Inductor Name: L1 Parameter: inductance Start: 1 mH Stop: 100 mH Number of points: 6 Analysis to sweep: Transient Analysis Step 9: Click “Simulate” to run the analysis. Take a screen shot of the output for your lab report and comment on the impact of the inductance in your boost converter. Include in your comment a theoretical explanation of the inductor and its response to change in voltage and current. Step 10: Navigate to the “Parameter Sweep” analysis and select the following parameters to perform a sweep of the capacitance: Sweep Parameter: Device Parameter Device Type: Capacitor Name: C1 Parameter: capacitance Start: 1 uF Stop: 200 uF Number of points: 12

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Analysis to sweep: Transient Analysis Step 11: Click “Simulate” to run the analysis. Take a screen shot of the output for your lab report and comment on the impact of the capacitance in your boost converter. Include in your comment a theoretical explanation of the capacitor and its response to change in voltage and current.

3.4e Perform a Parameter Sweep (Inductive Load) In most applications, your DC-DC converter will not be tied to just a resistor. Most hardware includes some form of capacitance and inductance. You will now explore the effects of having an inductive load in your circuit. Step 12: Modify the 1k ohm resistor in the load to 50ohms. Add a 10mH inductor to your circuit in series with your 500 ohm resistance (the resistor and inductor should still be in parallel with the capacitor in your circuit). Step 13: Click “Simulate” in the top toolbar and choose “Parameter sweep”. Use the same configuration you had from your previous run and click “Simulate”. Take a screen shot of your results for your lab report and comment on what changed in the resulting output and why.

Challenge Question 1: Explain the critical values of a boost converter. Describe how the frequency, inductance and capacitance values determine the operation modes. Challenge Question 2: Explain the discontinuous current mode and continuous current mode of operation. What differences are observed in each mode? Challenge Question 3: Describe a 1-quadrant, 2-quadrant and 4-quadrant converter.

3.4f Build and Explore the Boost Converter on a myProto Breadboard The circuit built in Multisim utilized power transistors in its design, these will be replaced with Insulated Gate Bipolar Transistors in the breadboard design and the gate driver from Lab 0 will be used to control the transistors. Comment on how this will influence the results of the breadboard circuit in your lab report. Also talk about the importance of the diodes placed across each transistor. Step 14: Build the Boost converter on your myProto protoboard using Insulated Gate Bipolar Transistors (IGBTs). The design should follow what you designed in Multisim, and you should build the gate driver from Lab 0 to properly control the IGBTs. Use values for the resistor, capacitor and inductor similar to that used in the initial Multisim design. The PWM generator will be replaced with Boost Converter Lab

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the Analog output 0 line from the myDAQ. You may use the block diagram in Figure 9 to assist in building the boost converter circuit.

Figure 9 Boost Converter Block Diagram Step 15: Connect the myProto to your myDAQ and plug the myDAQ into your computer. Step 16: Open the myDAQBuckBoost.vi and modify the Frequency (Hz) and Duty Cycle (%) controls to 1000Hz and 10% respectively. Run the code and observe the instantaneous signals. Use the myDAQBuckBoost.vi to fill in the Table 1 (included at the end of the lab). Include this table along with a screenshot of the instantaneous signals from the VI front panel in your lab report. Step 17: Choose three other capacitor and three other inductor values to test in your circuit. The capacitor and inductor values should fall in the same range as those used in the parameter sweep with one value falling at the low end, the second at the high end, and the last in the middle of the range. Swap pairs of these components into your circuit and fill out a copy of Table 1 for each using the myDAQBuckBoost.vi. Include all of these tables as well as screenshots from the VI front panel of the instantaneous signals that correspond to each table in your lab report. (You do not need to have more than three tables for your lab report). Step 18: Explore the block diagram of the myDAQBuckBoost.vi and gain an understanding of how signals are generated and what form of analysis is being used.

3.5 Create a Lab Report Complete a 3-5 page report that includes all pictures, tables, observations and answers to questions presented in the lab. Label all pictures with descriptive captions that relate them back to content in your lab report. Include an introduction, a results section, and a conclusion that also explains one practical application of a Boost Converter.

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3.6 Final Observations Record other thoughts and observations you made throughout the lab and connect them to something you have observed or experienced in the real world.

Challenge: Explore the PCB Design Attached are schematics for the boost converter circuit. These can either be used to add to the lab experience with an additional PCB design section or help reduce prototyping time for students if boards are created before the lab by lab assistants.

Switching

Duty Cycle(%)

Vout DC(V)

Vout RMS(V)

Iout DC(A)

Frequency(Hz)

Iout RMS (A)

DC Output Power (W)

Inductance(mH) Capacitance(uF) Table 1 Experimental Observations Boost Converter Lab

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L A B

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Buck Boost Converter Lab One Hour

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4.1 Goal To understand the basics of a buck boost converter circuit, common transistors used in power electronics, and National Instruments hardware

4.2 Objectives In this lab you will:  



Simulate a buck boost converter circuit in Multisim software. Build and interact with a step up step down, DC to DC converter circuit, commonly known as a buck boost converter. You will design the circuit to output a switch DC voltage that varies according to switch frequency and duty cycle. Create a lab report to present your data, observations, and conclusions.

4.3 Pre-Lab Activities 4.3a Get to Know the Topics Review the following resources to familiarize yourself with the topics listed before you begin the lab. Textbook References: Hart, Daniel W. Power Electronics. New York, NY: McGraw-Hill 2011. Print Sections: 1.4, 8.1-8.4 Mohan, Ned, Undeland, Tore M, Robbins, William P. Power Electronics: Converters Applications and Design. Danvers, MA: John Wiley and Sons 2003 Sections: 2.1-2.8, 7.2-7.4 myDAQ References: Get Started Using NI myDAQ with LabVIEW for Education https://www.youtube.com/watch?v=RsD2tHbuAF4 DAQ Lesson 1 https://decibel.ni.com/content/docs/DOC-11624

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4.3b Pre-Assessment Quiz Complete the following quiz to check your understanding of the relevant topics before you begin the lab. a) b)

Obtain the relation of the output voltage, input voltage and duty cycle in a buck-boost converter. Explain how the circuit operation reduces and boosts the voltage. Explain the advantages and disadvantages of a buck-boost converter.

4.4 Lab Procedure 4.4a Design the Circuit in Multisim Designing the circuit in Multisim allows you to gain an understanding of the circuit you will prototype on the breadboard later. Note that MOSFET Power transistors are used in the simulation instead of the IGBTs used in prototyping, and the gate driver circuit from Lab 0 Gate Driver has been purposely removed in order to emphasize the buck converter configuration. Design the following circuit in Multisim. Double click the PWM_Generator and set a Reference signal frequency of 5kHz.

Figure 10 Buck Boost Converter Circuit Finding Components in Multisim DC_Source – DC voltage source found in Group: Sources; Family: Power_Sources. Boost Converter Lab

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PWM_Generator – PWM function used to generate the buck converter control signal, found in Group: Power; Family: Power_Controllers. DC_PWM_Controller – DC signal used as a reference for the PWM generation. See DC_Source for location. VCVS– Voltage Controlled Voltage Source used to provide a constant voltage regardless of the current requirements of the load, in this case the MOSFET. Found in Group: Sources; Family: Controlled_Voltage_Sources. Power_MOSFET– Power transistor used to switch the DC supply in order to provide an alternating signal for the buck converter. Found in Group: Transistors; Family: Power_Mos_N. For more information about working in Multisim, visit: https://www.youtube.com/user/ntspress/search?query=multisim

4.4b Perform a Transient Analysis A transient analysis gives you an idea of how your circuit will respond over a set period of time. It allows you to apply some input and observe an output through simulation. Step 2: Label the wire at the top of the resister branch by right clicking on it and choosing “Properties”. Then under the “Net name” tab, update “Preferred net name” with a descriptive name of your choice, and click “Ok”.

Figure 11 Wire Properties

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Step 3: Click “Simulate” on the top toolbar and navigate to Analyses>>Transient Analysis. In the pop up configuration window, choose the “Analysis parameters” tab and set the following parameters: Initial Conditions: Set to zero Start time (TSTART): 0 End time (TSTOP): 0.05s Step 4: Navigate to the “Output” tab, click on the descriptive name you just made to select that node to monitor from the “Variables in circuit” field and click “Add”. Select anything that may be in the “Selected variable for analysis” field that you are not monitoring and click “Remove”.

Figure 12 Create Measurement Expression

Step 5: Click “Simulate” to run the transient analysis. Take a screen shot of your results to include in your lab report. In this setup we have achieved a duty cycle ( ) of 40%, use the Boost Converter Lab

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following equation to calculate the expected output voltage then use the cursors in your transient analysis to measure what the average voltage of you output is. In your lab report document the calculated and simulated output voltages. Calculate the percent error of your data and comment on why you believe there to be an error.

Equation 2 Buck Boost converter output voltage equation

4.4c Perform a Parameter Sweep (Resistive Load) A parameter sweep gives you an idea of how your circuit would respond with different values for components such as resistors and capacitors. This sweep can be fine-tuned to allow you to find the optimum point of operation for you circuit, so when you prototype your circuit with real components you can have an idea of the range of component values you can use to achieve a satisfactory output. In this lab you will perform parameter sweeps on the control signal’s duty cycle, the buck converter capacitance, inductance, and load inductance. Step 6: Click “Simulate” on the top toolbar and navigate to Analyses>> Parameter Sweep. In the pop up configuration window, navigate to the “Analysis parameters” tab and set the following parameters: Sweep Parameter: Device Parameter Device Type: Vsource Name: vdc_pwm_controller (the name of the PWM_controller on your schematic) Parameter: dc Start: 100 mV Stop: 950 mV Number of points: 6 Analysis to sweep: Transient Analysis Verify on the “Output” tab that the “Selected variables for analysis” field shows the resistor load branch as selected for analysis, the same that was chosen for your transient analysis step. Click “Simulate” to run the parameter sweep. This will create six instances of your buck boost converter output, which correspond to the six different PWM duty cycles created from varying the PWM_Controller voltage. Boost Converter Lab

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Take a screen shot of your results to include in your lab report. Find out what the PWM switching frequency is from the PWM generator function (done by double clicking on the function) and label the screenshot with the frequency where the analysis takes place. Step 7: Pick five different frequencies evenly spaced out in the range from 50Hz to 20kHz. Change the PWM generator frequency to each of these values, and rerun your transient analysis from steps 2 and 3 for each frequency value. Take a screen shot of all of these trials for your lab report and comment on the effects you observed of changing the generator frequency.

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4.4d Perform a Parameter Sweep (Corner Frequency) The corner frequency of your LC (inductor capacitor) lowpass filter can be increased or decreased to change the high frequency content allowed through your buck boost converter. Next, you will explore how you can change the response of the filter and its effects on the buck boost converter DC output. Step 8: Navigate to the “Parameter Sweep” analysis and select the following parameters to perform a sweep of the inductance: Sweep Parameter: Device Parameter Device Type: Inductor Name: L1 Parameter: inductance Start: 1 mH Stop: 100 mH Number of points: 6 Analysis to sweep: Transient Analysis Step 9: Click “Simulate” to run the analysis. Take a screen shot of the output for your lab report and comment on the impact of the inductance in your buck converter. Include in your comment a theoretical explanation of the inductor and its response to change in voltage and current. Step 10: Navigate to the “Parameter Sweep” analysis and select the following parameters to perform a sweep of the capacitance: Sweep Parameter: Device Parameter Device Type: Capacitor Name: C1 Parameter: capacitance Start: 1 uF Stop: 200 uF Number of points: 12

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Analysis to sweep: Transient Analysis Step 11: Click “Simulate” to run the analysis. Take a screen shot of the output for your lab report and comment on the impact of the capacitance in your buck boost converter. Include in your comment a theoretical explanation of the capacitor and its response to change in voltage and current.

4.4e Perform a Parameter Sweep (Inductive Load) In most applications, your DC-DC converter will not be tied to just a resistor. Most hardware includes some form of capacitance and inductance. You will now explore the effects of having an inductive load in your circuit. Step 12: Modify the 1k ohm resistor in the load to 50ohms. Add a 10mH inductor to your circuit in series with your 500 ohm resistance (the resistor and inductor should still be in parallel with the capacitor in your circuit). Step 13: Click “Simulate” in the top toolbar and choose “Parameter sweep”. Use the same configuration you had from your previous run and click “Simulate”. Take a screen shot of your results for your lab report and comment on what changed in the resulting output and why.

Challenge Question 1: Draw a non-inverting buck-boost circuit, and illustrate the circuit operation. Challenge Question 2: Explain the technical issues of a transistor using a voltage controlled voltage source.

4.4f Build and Explore the Buck Boost Converter on a myProto Breadboard The circuit built in Multisim utilized power transistors in its design, these will be replaced with Insulated Gate Bipolar Transistors in the breadboard design and the gate driver from Lab 0 will be used to control the transistors. Comment on how this will influence the results of the breadboard circuit in your lab report. Also talk about the importance of the diodes placed across each transistor. Step 14: Build the Buck converter on your myProto protoboard using Insulated Gate Bipolar Transistors (IGBTs). The design should follow what you designed in Multisim, and you should build the gate driver from Lab 0 to properly control the IGBTs. Use values for the resistor, capacitor and inductor similar to that used in the initial Multisim design. The PWM generator will be replaced with

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the Analog output 0 line from the myDAQ. You may use the block diagram in Figure 13 to assist in building the buck boost converter circuit.

Figure 13 Buck Converter Block Diagram Step 15: Connect the myProto to your myDAQ and plug the myDAQ into your computer. Step 16: Open the myDAQBuckBoost.vi and modify the Frequency (Hz) and Duty Cycle (%) controls to 1000Hz and 10% respectively. Run the code and observe the instantaneous signals. Use the myDAQBuckBoost.vi to fill in the Table 1 (included at the end of the lab). Include this table along with a screenshot of the instantaneous signals from the VI front panel in your lab report. Step 17: Choose three other capacitor and three other inductor values to test in your circuit. The capacitor and inductor values should fall in the same range as those used in the parameter sweep with one value falling at the low end, the second at the high end, and the last in the middle of the range. Swap pairs of these components into your circuit and fill out a copy of Table 1 for each using the myDAQBuckBoost.vi. Include all of these tables as well as screenshots from the VI front panel of the instantaneous signals that correspond to each table in your lab report. (You do not need to have more than three tables for your lab report). Step 18: Explore the block diagram of the myDAQBuckBoost.vi and gain an understanding of how signals are generated and what form of analysis is being used.

4.5 Create a Lab Report Complete a 3-5 page report that includes all pictures, tables, observations and answers to questions presented in the lab. Label all pictures with descriptive captions that relate them back to content in your lab report. Include an introduction, a results section, and a conclusion that also explains one practical application of a Buck Boost Converter.

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4.6 Final Observations Record other thoughts and observations you made throughout the lab and connect them to something you have observed or experienced in the real world.

Challenge: Explore the PCB Design Attached are schematics for the buck converter circuit. These can either be used to add to the lab experience with an additional PCB design section or help reduce prototyping time for students if boards are created before the lab by lab assistants.

Switching

Duty Cycle(%)

Vout DC(V)

Vout RMS(V)

Iout DC(A)

Frequency(Hz)

Iout RMS (A)

DC Output Power (W)

Inductance(mH) Capacitance(uF) Table 1 Experimental Observations Full Bridge Inverter

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Full Bridge Inverter

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L A B

5

Full Bridge Inverter Lab One Hour

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5.1 Goal To understand the basics of a full bridge inverter, common transistors used in power electronics, and National Instruments hardware.

5.2 Objectives In this lab you will:   

Simulate a full bridge inverter circuit in Multisim software. Build and interact with an inverter circuit on a myProto breadboard. You will design the circuit to output a sinusoidal voltage that you will then observe under different load conditions. Create a lab report to present your data, observations, and conclusions.

5.3 Pre-Lab Activities 5.3a Get to Know the Topics Review the following resources to familiarize yourself with the topics listed before you begin the lab.

Textbook References: Hart, Daniel W. Power Electronics. New York, NY: McGraw-Hill 2011. Print Sections: 1.4, 8.1-8.4 Mohan, Ned, Undeland, Tore M, Robbins, William P. Power Electronics: Converters Applications and Design. Danvers, MA: John Wiley and Sons 2003 Sections: 2.1-2.8, 8.1-8.3 myDAQ References: Get Started Using NI myDAQ with LabVIEW for Education https://www.youtube.com/watch?v=RsD2tHbuAF4 DAQ Lesson 1 https://decibel.ni.com/content/docs/DOC-11624

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5.3b Pre-Assessment Quiz Complete the following quiz to check your understanding of the relevant topics before you begin the lab. a. What are the desired characteristics of ideal controllable switches? a) Block arbitrarily large forward and reverse voltages with zero current flow when off. b) Conduct arbitrarily large currents with zero voltage drop when on. c) Instantaneously change between on and off state and vice versa. d) Negligible power required to control the switch b. List 3 controllable switches, draw and label their circuit symbol, and draw their i-v characteristics curve. a) Bipolar Junction Transistor b) Metal Oxide Semiconductor Field Effect Transistor c) Thyristor d) Isolated Gate Bipolar Transistor c. Draw a full bridge inverter circuit and label the path of current in the forward and reverse states. Discuss where the load should be as well as how the direction of current is changed during operation. d. Draw the timing diagram that can be used to achieve the PWM signal needed to control the full bridge inverter. Label the reference control signal and switching triangle signal then, using the switching scheme, draw the resulting PWM signal. e. List all the steps and I/O lines needed to acquire an analog signal and output that same signal using myDAQ and LabVIEW express VIs.

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5.4 Lab Procedures 5.4a Design a Multisim Circuit Designing a circuit in Multisim allows you to gain an understanding of the circuit you will prototype on a breadboard later. MOSFET power transistors are used in simulation instead of the IGBTs used in prototyping, and the gate driver circuit from Lab 0 has been purposely removed in order to place emphasis on the full bridge configuration. Build the following circuit in Multisim.

Figure 14 Full Bridge Inverter Circuit Finding Components in Multisim DC_Source – DC voltage source found in Group: Sources; Family: Power_Sources. PWM_GeneratorA/B – PWM function used to generate the inverter control signals found in Group: Power; Family: Power_Controllers. Control_Signal/Control_Signal_Delayed – Reference sinusoidal signal used to generate PWM control signals. The two are used in order to create control signals for the positive and negative peaks of the output sinusoid. They are found in Group: Sources; Family: Signal_Voltage_Sources.

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VCVS_A/B – Voltage Controlled Voltage Source used to provide a constant voltage regardless of the current requirements of the load, in this case the MOSFET. Found in Group: Sources; Family: Controlled_Voltage_Sources. Power_MOSFET_1-4 – Power transistor used to switch the DC supply in order to create an AC output signal. Found in Group: Transistors; Family: Power_Mos_N. You can use wires or on-page connectors to wire up the circuit. For more information about working with Multisim, visit: https://www.youtube.com/user/ntspress/search?query=multisim.

5.4b Perform a Transient Analysis A transient analysis gives you an idea of how your circuit will respond over a set period of time. It allows you to apply some input and observe an output through simulation. Step 2: Label the wire between your capacitor and inductor by right clicking on it and choosing “Properties”. Then under the Net name tab, update the “Preferred net name” field with a descriptive name of your choice and click “Ok”.

Figure 15 Wire Properties Step 3: Click on “Simulate” on the top toolbar and navigate to Analyses>>Transient Analysis. In the pop up configuration window choose the “Analysis parameters” tab and set the following parameters: Initial Conditions: Set to zero Start time (TSTART): 0 Full Bridge Inverter

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End time (TSTOP): 0.05s Navigate to the “Output” tab and click “Add expression”. In this configuration window, seen in Figure 16, you can add variables that are signals from the diagram then you can use a function step to carry out an operation. Double click on the signals to populate the Expression field. You are trying to differentially read the voltage across the capacitor, this means you want to take the voltage at the node between the capacitor and inductor and the node at the other end of the capacitor and subtract those two values. Once completed, press “Ok”; the expression should already be included in the “Selected Variables for analysis” window.

Figure 16 Create Measurement Expression Click “Simulate” to run the transient analysis. Take a screen shot of your results to include in your lab report.

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5.4c Perform a Parameter Sweep A parameter sweep gives you an idea of how your circuit will respond with different values for components such as resistors and capacitors. This sweep can be fine-tuned to allow you to find the optimum point of operation for you circuit, so when you prototype your circuit with real components you can have an idea of the range of component values you can use to achieve a satisfactory output. Step 4: Click on “Simulate” on the top toolbar and navigate to Analyses>> Parameter Sweep. In the Pop up window, navigate to the “Analysis parameters” tab and set the following parameters: Device Type: Capacitor Start: 1uF Stop: 100uf Number of points: 5 Analysis to sweep: Transient Analysis Verify on the “Output” tab that the “Selected variables for analysis” field shows the expression you created during your transient analysis step. Click “Simulate to run the parameter sweep. This will create five instances of your inverter output, which corresponds to the five different capacitance values tested during the sweep. Take a screen shot of your results to include in your lab report.

Challenge Question 1: The two sinusoidal reference signals, Control_Signal and Control_Signal_Delayed, are out of phase. Explain why this is important then experiment with different phase angles and see how the output changes. Include your explanation as well as any observations you make when changing the phase angle between the two signals. Challenge Question 2: The voltage controlled voltage sources in the inverter circuit are used to supply a voltage regardless of the loads current requirement in the ideal case. Describe another circuit that can be built as a voltage controlled voltage source. Include your explanation in your lab report.

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5.4d Build the Full Bridge Inverter on a myProto Breadboard The circuit built in Multisim utilized power transistors in its design. These will be replaced with Insulated Gate Bipolar Transistors in the breadboard design, and the gate driver from Lab 0 will be used to control the transistors. In your lab report, comment on how this will influence the results of the breadboard circuit. Also talk about the importance of the diodes placed across each transistor. Step 5: Build the Full Bridge Inverter on your myProto using Insulated Gate Bipolar Transistors (IGBTs). Follow the design you did in Multisim. The gate driver from Lab 0 should be built and replicated four times in order to be used to properly control the IGBTs. Use values for the resistor, capacitor, and inductor similar to that used in the initial Multisim design. The PWM generators will be replaced with the Analog output 0 and 1 lines from the myDAQ. You may use the block diagram in Figure 17 to assist in building the inverter circuit. Connect the myProto to your myDAQ and plug the myDAQ into your computer.

Figure 17 Full Bridge Inverter block diagram Step 6: Open and Run the Inverter Lab.vi and observe the output waveform. Comment on whether this waveform matches the simulation waveform. Are there any factors that would cause this signal to be different from the signal received in Multisim? Step 7: Choose 3 other capacitance values to test in your circuit. The capacitor values should fall in the same range as those used in the parameter sweep with one value falling at the low end, the second at the high end, and the last in the middle of the range. Swap these capacitors into your circuit, run the Inverter Lab.vi, and take screen shots of the results for your lab report. Rectifier Lab

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Step 8: Open and observe the PWM control signals.vi. The implementation purposely did not follow the theoretical solution for the PWM signals. Devise a means of realizing the theoretical solution in LabVIEW, implement it and run it without being connected to the inverter circuit. Take a screen shot of your generated signals for your lab report.

5.5 Lab Report Complete a 3-5 page report that includes all pictures, tables, observations and answers to questions presented in the lab. Label all pictures with descriptive captions that relate them back to content in your lab report. Include an introduction, a results section, and a conclusion that also explains one practical application of a Full Bridge Inverter.

5.6 Final Observations Record other thoughts and observations you made throughout the lab and connect them to something you have observed or experienced in the real world.

Challenge: Explore the PCB Design Attached are schematics for the buck converter circuit. These can either be used to add to the lab experience with an additional PCB design section or help reduce prototyping time for students if boards are created before the lab by lab assistants.

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L A B

6

Rectifier Lab One Hour

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6.1 Goal To understand the basics of an uncontrolled and controlled rectifier circuit, common transistors used in power electronics, and National Instruments hardware

6.2 Objectives In this lab you will:    

Simulate a half and full wave uncontrolled rectifier circuit in Multisim software. Simulate a full wave controlled rectifier circuit in Multisim software. Build and interact with a controlled rectifier circuit. You will reference the AC signal in the control mechanism to determine when to switch transistors. Create a lab report to present your data, observations, and conclusions.

6.3 Pre-Lab Activities 6.3a Get to Know the Topics Review the following resources to familiarize yourself with the topics listed before you begin the lab. Textbook References: Hart, Daniel W. Power Electronics. New York, NY: McGraw-Hill 2011. Print Sections: 1.4, Mohan, Ned, Undeland, Tore M, Robbins, William P. Power Electronics: Converters Applications and Design. Danvers, MA: John Wiley and Sons 2003 Sections: 2.1-2.8, 5.3-5.4, 6.2-6.3 myDAQ References: Get Started Using NI myDAQ with LabVIEW for Education https://www.youtube.com/watch?v=RsD2tHbuAF4 DAQ Lesson 1 https://decibel.ni.com/content/docs/DOC-11624

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6.3b Pre-Assessment Quiz Complete the following quiz to check your understanding of the relevant topics before you begin the lab. f. Explain the operation of a thyristor and its principle differences with a transistor and a diode. g. How does the line commutation stop the current in a thyristor? h. What happens if a highly inductive load is connected to a phase-controlled rectifier?

6.4 Lab Procedure Part 1: Half and Full Wave Uncontrolled Rectifiers 6.4a Design the Circuit in Multisim Designing the circuit in Multisim allows you to gain an understanding of the circuit you will prototype on the breadboard later. Note that MOSFET Power transistors are used in the simulation instead of the IGBTs used in prototyping, and the gate driver circuit from Lab 0 Gate Driver has been purposely removed in order to emphasize the boost converter configuration. Design the following half wave rectifier circuit in Multisim.

Figure 18 Boost (Step Up) Converter Circuit Finding Components in Multisim V1 – AC Power source found in Group: Sources; Family: Power_Sources.

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The diode resistor and capacitor are fundamental components that can be found at the top toolbar of Multisim. The two sections to look under are “Place Diode” and “Place Basic”.

6.4b Perform a Transient Analysis A transient analysis gives you an idea of how your circuit will respond over a set period of time. It allows you to apply some input and observe an output through simulation. Step 2: Label the wire at the top of the resister branch by right clicking on it and choosing “Properties”. Then under the “Net name” tab, update “Preferred net name” with a descriptive name of your choice, and click “Ok”.

Figure 19 Wire Properties Step 3: Click “Simulate” on the top toolbar and navigate to Analyses>>Transient Analysis. In the pop up configuration window, choose the “Analysis parameters” tab and set the following parameters: Initial Conditions: Set to zero Start time (TSTART): 0 End time (TSTOP): 0.5s Step 4: Navigate to the “Output” tab, click on the descriptive name you just made to select that node to monitor from the “Variables in circuit” field and click “Add”. Select anything that may be in the “Selected variable for analysis” field that you are not monitoring and click “Remove”.

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Figure 20 Selecting rectifier output Step 5: Click “Simulate” to run the transient analysis. Take a screen shot of your results to include in your lab report. Use the following equation to determine the ripple voltage of the current circuit configuration. Compare and comment on how close the simulated data is to the theoretical calculation. You can find the ripple voltage of your signal by using the cursors of the parameter sweep display and setting one to measure the lowest point of the voltage signal and one to measure the highest point then taking the difference. The cursors can be obtained by selecting Cursor>>Show Cursor from the top toolbar of the simulation window. You can then move the cursors on the graph to your desired points. Calculate the percent error of the theoretical versus simulated data.

Equation 3 Half wave rectifier ripple voltage equation

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6.4c Perform a Parameter Sweep (Half Wave Rectifier) A parameter sweep gives you an idea of how your circuit would respond with different values for components such as resistors and capacitors. This sweep can be fine-tuned to allow you to find the optimum point of operation for you circuit, so when you prototype your circuit with real components you can have an idea of the range of component values you can use to achieve a satisfactory output. Step 6: Click “Simulate” on the top toolbar and navigate to Analyses>> Parameter Sweep. In the pop up configuration window, navigate to the “Analysis parameters” tab and set the following parameters: Sweep Parameter: Device Parameter Device Type: Capacitor Name: C1 (the name of the discrete capacitor you placed on your schematic) Parameter: capacitance Start: 1 uF Stop: 10 uF Number of points: 5 Analysis to sweep: Transient Analysis Verify on the “Output” tab that the “Selected variables for analysis” field shows the resistor load branch as selected for analysis, the same that was chosen for your transient analysis step. Click “Simulate” to run the parameter sweep. This will create five instances of your rectifier output, which correspond to the five different capacitor values in your sweep. Take a screen shot of your results to include in your lab report. Make a prediction as to what the output will look like for the full wave rectifier state why you believe this will be the case. Step 7: Design the following full wave rectifier circuit in Multisim.

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Figure 21 Full Bridge Rectifier

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6.4d Perform a Parameter Sweep (Full Wave Rectifier) The full wave rectifier has a load between its two diode branches. We will conduct the same parameter sweep done in section 6.4 but now the output will be taken as the difference between the two points of the load instead of just with reference to ground. Step 8: Double click on the wires on either side of the capacitor and resistor as seen in Figure 22 and, in properties, give them each a descriptive name.

Figure 22 Rectifier load labeling Step 9: Navigate to the “Parameter Sweep” analysis and select the same parameters from the previous parameter sweep this time still choosing the capacitor as the component you will be sweeping. Step 10: Navigate to the “Output” tab and choose “Add Expression”. Double click on the name you gave to the wire branch on the left of the load, double click on the subtraction function then double click on the name you gave to the wire branch on the right of the load. Click “Ok” then click “Simulate” Step 11: Click “Simulate” to run the analysis. Take a screen shot of the output for your lab report. Use cursors on the signal with the largest swing, which corresponds to the 1uF capacitance test, and find the difference between the lowest and highest point in the signal. Comment on how this compares to the half wave rectifier ripple voltage. Comment on why this is the case making sure to provide equations to support your answer in your lab report.

Challenge Question 1: Draw the circuit for a three phase uncontrolled rectifier circuit and provide and explanation on how it works and its benefit. Challenge Question 2: Explain what would happen to the output signal if the frequency of the input signal were to increase while everything else stayed the same

6.4e Build and Explore the Uncontrolled Rectifier on a myProto Breadboard Step 12: Build the full bridge rectifier circuit following the design done in Multisim. You may follow the block diagram in Figure 23 for a reference on connecting to your myDAQ.

Figure 23 Rectifier Block Diagram Step 13: Connect the myProto to your myDAQ and plug the myDAQ into your computer. The NI ELVIS Instrument launcher should appear on your desktop letting you know your device has been detected. Step 14: Open the myDAQRectifier.vi, select your myDAQ device from the device drop down control and run the VI. Navigate to the “Uncontrolled Rectifier” tab to observe the input and output waveform. Comment on how this compares to the output signals from your simulation in your lab report. Step 15: Vary the input signal frequency and note how this influences the output signal. Comment on this in your lab report.

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6.5 Lab Procedure Part 2: Phase Controlled Full Bridge Rectifier 6.5a Multisim SCR Simulation Step 16: Design the following Silicon Controlled Rectifier (SCR) circuit in Multisim.

Figure 24 SCR circuit

Step 17: Double click on the pulsed voltage source V2 and set the following parameters: o

Initial Value: 0

o

Pulsed Value: 5

o

Delay Time: 5m

o

Pulse Width: 5m

o

Period: 20m

Step 18: Double click on the pulsed voltage source V3 and set the following parameters: o

Initial Value: -5

o

Pulsed Value: 0

o

Delay Time: 12m

o

Pulse Width: 8m

o

Period: 20m

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Setting these values for the two pulsed voltage sources creates two pulse trains, one for the positive half of the AC input and one for the negative half. These pulse trains will trigger the SCRs at specific times in order to control how much signal is transmitted to be filtered for the DC output.

6.5b SCR Transient analysis Step 19: Label the wire branches on both ends of the resistor load with descriptive names. This will be used to aid in creating an expression for these two branches.

Step 20: Click “Simulate” on the top toolbar and navigate to Analyses>>Transient Analysis. In the pop up configuration window, choose the “Analysis parameters” tab and set the following parameters: Initial Conditions: Set to zero Start time (TSTART): 0 End time (TSTOP): 0.5s Step 21: Using the same technique from steps 9 and 10, create an expression that will take the voltage at the load as the difference between the voltages at each end of the load. Step 22: Click “Simulate” to run the analysis, comment on what happens when the output signal has a zero crossing in your lab report. Also include how the output signal as seen here will influence the DC signal that will be derived from this. Explain how changing where you trigger the SCR affects the DC output. Include a picture of the output in your lab report. Step 23: Vary the delay time and pulse width of both signals making sure that they always add to 10ms for V2 and 20ms for V3. Run the transient analysis again with the new delay and pulse width times and take a picture of your new results to include in your lab report.

6.6 Create a Lab Report Complete a 5-10 page report that includes all pictures, tables, observations and answers to questions presented in the lab. Label all pictures with descriptive captions that relate them back to content in your lab report. Include an introduction, a results section, and a conclusion that also explains one practical application of a Boost Converter.

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6.7 Final Observations Record other thoughts and observations you made throughout the lab and connect them to something you have observed or experienced in the real world.

Challenge: Explore the PCB Design Attached are schematics for the uncontrolled and controlled full wave rectifier circuit. These can either be used to add to the lab experience with an additional PCB design section or help reduce prototyping time for students if boards are created before the lab by lab assistants.

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