ENGR7812 Power Electronics Project
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ENGR7812
Power Electronics
Project
1 Introduction
Four different Simulink projects are defined for the power electronics course project. Each student is required to submit a single report. Simulation may be performed in MATLAB Simulink environment. This project includes the performance evaluation of different converters as follows:
1.1 Aim
The aim of this project is to learn the simulation of the power electronics converters. This practical helps students to engage with the related blocks of the MATLAB Simulink.
1.2 Equipment Required
This project will be conducted in MATLAB Simulink.
1.3 General Instructions
The theoretical results should be derived from the information provided in the course notes. It is probably best to generate your theoretical expected results using MATLAB.
For each test do the following:
• The reports should have the following format: title, abstract, introduction, main body (methodology, results, critical analysis and discussion), conclusions and references.
• Record observed voltage waveforms in your report.
• Explain the operation of the circuit.
• Comment on the significance of the results and any significant discrepancies between expected/calculated and observed values.
• Show the required wave forms and explain them in details.
• Show how you derived the calculated values (e . g. show derivations and/or submit MATLAB code).
• Present results in tabular form as given the manual.
2 Task 1: 3-phase Diode Rectifier with LC filter
Figure 1. 3-phase Diode Rectifier with LC filter
2.1 Circuit parameters:
VL-L (rms) = 208V at 50 HZ
Ls = 0.1 mH
Rs = 1 mΩ
Ld = 0.5 mH
Rd = 5 mΩ
Cd = 500uf
Rload = 16.5Ω
2.2 Questions:
(1) Obtain Va , ia , Vab , Vd and id wave form:
(2) By means of Fourier analysis of ia, calculate its harmonic components as a ratio of ia1:
(3) Find Ia, Ia1, Idis, %THD in the input current, input displacement power factor and input power factor. How the result does compare with the 1 phase diode bridge rectifier.
(4) Calculate Icap (the rms current through the filter capacitor) as a ratio of the average load current Iload.
(5) Investigate the influence of Ld on the input displacement power factor, the input power factor and the average dc voltage Vd. Suggested range of Ld is between 0.1 mH to 10 mH.
3 Task 2: DC – DC converter
Figure 2. DC-DC converter
1- In the steady state, obtain the following waveforms:
a) VL and iL waveforms.
b) Vo, iload and iC waveforms.
2- Increase the load resistance to 10 Ω . Obtain and observe the VL and iL waveforms. Check
if the results agree with the following equation:
=
Vd
ILB,max =
3- Obtain the peak to peak ripple in the output voltage and check to see if the results agree
with the analytical calculations.
4- Calculate the rms value of the current through the output capacitor as a ratio of the
average load current Io. The rms value of the current equal to 14.75µA and the average load current equal to 12A. This curve is the load current Io.
5- Calculate the peak to peak ripple in the output voltage in the presence of the output
capacitor equivalent series resistance (ESR) (Suggested ESR=100mΩ). Plot the ripple across C, ESR and the total ripple in Vo.
4 Delta-Connected 3-phase AC-AC converter
Figure 3. Delta connected converter
A three-phase full wave Delta-connected converter has been shown in Figure 3. Assume that the supply line to line voltage is equal to 400 volts. And R value in each branch is 10 Ω . Simulate the converter in Simulink and test its performance in 30- and 60-degrees firing angle.
(1) Calculate the following parameters for each firing angle and compare them with the simulation results:
- Output voltage
- Output current
- Input and output power
- Power factor
(2) In the simulation, calculate the THD, 1st, 3rd, and 5th harmonics of the input line current for each firing angle.
(3) Change the resistive load to a RL load with 10 Ω resistance and 20 mH inductance. And measure the following:
- Output voltage
- Output current
- Input and output power
- Power factor
(4) In the RL load condition, measure the THD, 1st, 3rd, and 5th harmonics of the input line current for each firing angle.
(5) Compare the results your simulation in both resistive and resistive-inductive load. What is your expectation? How the RL load affects the power factor and harmonics? What is the source of the difference between the results of the inductive and resistive load?
5 12 pulses rectifiers
5.1 12 pulses diode rectifier
Figure 4. 12 pulses diode rectifier
A three-phase 12 pulses diode rectifier has been shown in Figure 4. Assume that the supply line to line voltage is equal to 400 volts rms. And R and L values of the load are 10 Ω, and 50mH, respectively. Simulate the converter in MATLAB/Simulink and test its performance. The transformer section is a three-phase transformer with three sets of windings. The input side is a delta connected with 30 degrees lagging. The second sets of windings connected to the upper three phase rectifier has a star connection. Also, the third sets of windings are connected in delta connection to produce 30 degrees leading. The nominal power of the transformer is 25kW which operates at 50Hz frequency. The core resistance (Rm) and inductance (Lm) are equal to 500 pu. The windings characteristics are as follow:
- Input winding: V1ph-ph =400 volts, R1 = 0.002 pu, and L1 = 0.08 pu.
- Output winding2: V2ph-ph =100 volts, R2 = 0.002 pu, and L2 = 0.08 pu.
- Output winding3: V3ph-ph =400 volts, R3 = 0.002 pu, and L3 = 0.08 pu.
(1) Show the output voltage of the upper and lower rectifiers separately and explain their differences. Measure their average and ripple.
(2) Show the output voltage and current. Measure their average and ripple.
(3) Plot the input voltage and current. Measure the THD of the input current for each phase.
(4) Measure the input power factor.
(5) Check the power factor and THD of the input current by increasing the value of the load inductance from 50mH to 200mH.
5.2 12 pulses-controlled rectifier:
Figure 5. 12 pulses controlled-rectifier
A three-phase 12 pulses-controlled rectifier has been shown in Figure 5. Assume that the supply line to line voltage is equal to 400 volts rms. And R and L values of the load are 10 Ω, and 50mH, respectively. Simulate the converter in MATLAB/Simulink and test its performance. The transformer section is a three-phase transformer with three sets of windings. The input side is a delta connected with 30 degrees lagging. The second sets of windings connected to the upper three phase rectifier has a star connection. Also, the third sets of windings are connected in delta connection to produce 30 degrees leading. The nominal power of the transformer is 25kW which operates at 50Hz frequency. The core resistance (Rm) and inductance (Lm) are equal to 500 pu. The windings characteristics are as follow:
- Input winding: V1ph-ph =400 volts, R1 = 0.002 pu, and L1 = 0.08 pu.
- Output winding2: V2ph-ph =100 volts, R2 = 0.002 pu, and L2 = 0.08 pu.
- Output winding3: V3ph-ph =400 volts, R3 = 0.002 pu, and L3 = 0.08 pu.
Calculate the following parameters for 30 degrees firing angle.
(6) Show the output voltage of the upper and lower rectifiers separately and explain their differences. Measure their average and ripple.
(7) Show the output voltage and current. Measure their average and ripple.
(8) Plot the input voltage and current. Measure the THD of the input current for each phase.
(9) Measure the input power factor.
(10) Check the power factor and THD of the input current by increasing the value of the load inductance from 50mH to 200mH.
2022-11-02