Transcript TI Spins Motors…Smarter, Safer, Greener.

2014 Texas Instruments Motor Control Training Series
To schedule a motor control
seminar for your company, or in
your area, please contact me at
[email protected]
www.kappaiq.com
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.
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
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 http://www.ipes.ethz.ch
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
Lab Exercise 3: Axis Decoupling
1/Ld
1/Lq
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
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.
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
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 “Daxis 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.
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
Lab Exercise 3: Axis Decoupling
Double-click on the “Decoupling” block located between the
d and q axis current regulators to open it. Then Doubleclick 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?
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
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?
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
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:
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
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?
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
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
360o to find the torque as a function of id and iq.
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?
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.
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?
Dave Wilson
TI Spins Motors…Smarter, Safer, Greener.