2014 Texas Instruments Motor Control Training Series Dave Wilson To schedule a motor control seminar for your company, or in your area, please contact me at

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 1: Field Oriented Speed Control In the “Lab Exercises” folder, open the file “03 FOC Speed Control”, and follow the directions in the file. This exercise lets you build a field oriented speed loop by connecting together “Lego” style control blocks. If connected correctly, the speed and current plots should look like the pictures shown in the file. (If you get stuck, you can always open the file “03a FOC Speed Control” for a hint. But try not to do this unless you absolutely have to. ) After you have obtained a working simulation, play around with some of the system parameters (e.g., ADC resolution, sampling frequency, and encoder resolution) to see what effects they have on the performance of the speed loop.

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 2: Space Vector Modulation In the “Lab Exercises” folder, open the file “SVM Switching.html”. Depending on your browser settings, you may get a message saying that content is blocked. Follow the steps for your browser to allow Java scripts to run. You should then see a Space Vector Diag. Click on the tip of the red arrow and drag it around the complex plane. Note the level of the three bars. What do they represent? Drag the red bar in the bottom diagram horizontally across the PWM waveforms. What is the correlation with the bar position and the switch diagram in the upper right? Source: Interactive Power Electronics Seminar (iPES), Prof. Johann W. Kolar, ETH Zurich

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 3: Axis Decoupling 1/L d 1/L q

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 3: Axis Decoupling Using the stator circuit block diagram on the previous page, define the cross-coupled distortion voltage into the d axis from the q axis. Write the expression in terms of Isq. Using the above expression, design a Feed-forward compensator for the d-axis current regulator that exactly cancels this distortion. Do the same thing for the q-axis current regulator.

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 3: Axis Decoupling In the “Lab Exercises” folder, open the file “01 FOC with Encoder.vsm”, and run the simulation. Scroll to the right and then down to locate the “D- axis Current” and Q-axis Current” plots. Note the amplitude of the noise spikes on the d-axis current which correlate to transitions in q-axis current.

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 3: Axis Decoupling Double-click on the “Decoupling” block located between the d and q axis current regulators to open it. Then Double- click on the “PMSM Decoupling” block inside of that. Using the input variables on the left, build your decoupling structures that you just designed; one for the d-axis, and one for the q-axis. The outputs Vd and Vq will be directly added to the current regulator outputs. When you are finished, right-click until you are once again at the top hierarchical level of the simulation. Rerun the simulation and again scroll over to the plots of Id and Iq. Is your decoupling network effective in mitigating the cross-coupling between the two axes?

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 4: Field Weakening In the “Lab Exercises” folder, open the file “01a FOC with Encoder.vsm”. Click the green “Play” arrow to start the simulation. Scroll off-screen to the right to watch the speed plot. The commanded speed is 5000 RPM. What is the steady-state actual speed? Why can’t it reach 5000 RPM? Scroll down to the “Q-Axis Voltage Headroom” plot. What is the voltage headroom between the q-axis back EMF voltage and the q-axis voltage limit during the steady-state high-speed region? How does this affect the ability of the q-axis current regulator to create current?

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 4: Field Weakening Scroll to the left until you locate the “Motor/Load Selector Block”. Double-click to open. You should see a panel like this:

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 4: Field Weakening In the upper right corner, change the “Auto Field Weakening” entry from a “0” to a “1”. This activates a field weakening algorithm which applies negative d-axis current based on the q-axis voltage level. Rerun the simulation. Scroll to the far right to see the speed plot. What is the steady-state motor speed now? Scroll down to the “Q-Axis Voltage Headroom” plot. What is the voltage headroom now compared to when no field weakening was applied? Scroll up to the very top plot (rotor flux). Did the rotor flux change?

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 5: MTPA on Toyota Prius Motor In the “Lab Exercises” folder, open the file “Prius Motor Current Vector Sweep.vsm”. This file simulates a Prius motor with a locked rotor, and the current vector is swept 360 o to find the torque as a function of i d and i q. Run the simulation. How do the estimates for Id and Iq from the MTPA estimator compare to the actual values (which are found below the estimated values)? Reduce the motor current to a very low value by changing the value of “Imag” from 200 amps to 5 amps. Run the simulation again. What is the angle for peak torque? Which toque (reactance or reluctance) is dominant?

TI Spins Motors…Smarter, Safer, Greener. Dave Wilson Lab Exercise 5: MTPA on Toyota Prius Motor Increase the motor current to a very high value by changing the value of “Imag” from 5 amps to 2000 amps. Run the simulation again. Now what is the angle for peak torque? Which torque is dominant? What can you conclude from this experiment? Change the value of “Imag” back to its nominal value of 200 amps, and rerun the simulation. Again, note the Id and Iq values. Assume you want negative (braking torque) out of the Prius. Right click on the “Max Torque” switch feeding the MTPA Estimator to change it to “Min Torque”. Run the simulation again. What change did this cause in the Isd and Isq estimates?