ECE 5041 Electric Machine
_____Submit one single pdf file to include all results. Submit all simulation files too.
_____SUBMIT ALL FILES INDIVIDUALLY. NO ZIP FILES WILL BE ACCEPTED.
_____All simulation plots need to use data stored in “ToWorkSpace”. No credits will be given to screenshots of scopes.
A 3-phase IPM machine used on a hybrid electric vehicle has the following parameters. You will use these machine parameters for your simulations in this homework.
Number of poles: 8
Peak value of maximum phase current Ipeak : 500 A
Peak value of maximum phase voltage V peak : 115 V
Phase winding dc resistance rs : 0.02 Ω
d-axis inductance Ld : 0.18 mH
q-axis inductance Lq : 0.25 mH
Flux linkage of permanent magnet λm : 0.05 V-s
Problem 1. (40’) IPM machine simulation using adc/ac power converter
1.1 (6’) Watch the Matlab tutorial video on using open-loop voltage control for anIPM machine driven by adc/ac converter and build your own IPM machine model following the tutorial.
Take a screenshot of your simulation model and include in the homework submission. Include the screenshots of subsystems too.
1.2 (7’) Set the dc bus voltage of the dc/ac converter to be 500 V. When sine-triangle PWM algorithm is used to generate the switching signals for three phases, the reference sinusoidal voltages are compared to a high frequency triangle carrier wave. Set the switching frequency to be 5 kHz,i.e., the frequency for the carrier triangle wave.
In your simulation, use p.u. values for both the reference voltage and carrier wave. The peak value for the triangle carrier wave is -1 and +1 p.u. If mis used to represent the peak value of the reference voltage in p.u., the actual phase output voltage can be calculated using the following equation.
where miscalled modulation index, Vdc is the voltage of the dc bus. The range of modulation index is also between -1 and +1 p.u.
Based on the above information, answer the following questions:
a) (3’) If modulation index is 0.5, what is the actual peak value of the output phase voltage?
b) (4’) If the desired actual peak value of the output phase voltage is 100 V, what should be the reference voltage value in p.u. for the simulation? What equation do you use to convert the desired actual output phase voltage to the reference voltage value in p.u.? (You will need to use this equation in your simulation)
1.3 (27’) Use the model you have built in 1.1 to make the machine run at 3000 rpm and produce
50 Nm. The operating point should be on the maximum torque per amp curve.
a) (3’) Comment on how to select the simulation step size for your simulation.
b) (3’) Calculate the requiredid and iq to produce 50 Nm at 3000 rpm.
c) (3’) Calculate the required Vd and Vq and apply these to your simulation.
(The Vd and Vq values I used in my simulation are for a different torque. You need to calculate what Vd and Vq are needed!)
d) (12’) Plot the following waveforms over two fundamental cycles when your simulation gets to steady state:
figure (1)
subplot(411) rotor electrical angle vs time
subplot(412) three-phase currents vs time
subplot(413) machined-axis and q-axis currents vs time
subplot(414) d-axis voltage reference,q-axis voltage reference, and 3-phase reference voltages vs time (actual value, not p.u.)
figure (2)
subplot(411) rotor electrical angle vs time
subplot(412) phase A reference voltage in p.u. and carrier wave vs time
subplot(413) switching signal for top switch of phase A vs time
subplot(414) the actual d-axis voltage and q-axis voltage of the machine vs time
e) (3’) Explain why the three-phase currents and dq axis currents have ripples, which didn’t exist in the simulation in Homework 5.
f) (3’) Explain why the actual machined-axis and q-axis voltages are pulse voltages instead of dc voltages like what you saw in Homework 5.
Problem 2. (40’) IPM machine simulation using current feedback control
2.1 (6’) Watch theMatlab tutorial videoon current closed-loop control of anIPM machine simulation and buildup your own simulation model following the tutorial. Set Kp to be 10 and Ki to be 5 for both current controllers. Set the speed to be 3000 rpm.