How do I implement PID with PWM for 3 phase inverter for induction motor feedback control

I am doing a three phase inverter for induction motor control for a graduate class project. For this, PID is going to be used in a closed loop with a PWM generation unit. Moreover, I will take the error between the reference speed of the motor and the actual speed of motor. But I am unsure on how to design a PID with six pulse PWM generation for a three phase inverter. Can anyone help me? I have attached my screenshot of my partially built model of the circuitry using simpowersystems blocks which includes battery, universal bridge for three phase inverter, general induction motor model, PID controller block, and PWM generator. I have also attached the simulink model for this partially completed model as well.

Dan

Answer 1

[Arkadiy Turevskiy]

Take a look here .

[dkuang]

The material in this link does not give any information on implementing PID with PWM generation system in simulink.

[Arkadiy Turevskiy]

Not true. For instance, this example is pretty much what you are trying to do.

[dkuang]

But that is not the right information. I am planning take the rotational speed of the induction motor and subtract the reference speed from the actual motor speed to obtain the error for the PID feedback loop. The output from the PID controller block is will be converted to PWM to drive the inverter which I do not know how to do.

[ABDULLA ZULFIKHAR]

I am dong my project now on this

[Arkadiy Turevskiy]

Ok, so I think what you need to do is this: in your "PWM Generator" block dialog, uncheck the option "Internal generation of modulating signals". This will make the block use external signal for specifying modulating signal. In other words, the block will now have an inport, and you can connect your PID Controller output to that inport.

You will still need to fix other issues with the model after that, for example Asynchronous Machine Si Units block outputs a vector of signals, so you need to select the correct signal from that vector, before you subtract it from the reference.

If you read documentation for blocks you are using, you should be able to figure it out.

[dkuang]

Can you connect the PID controller block output directly to the PWM generator, or does the output from the PID controller need to be first converted to the reference sine wave signal required for the PWM generator to control the inverter for the induction motor speed control. In my case, the speed measurement is taken in units of radians per second.

[Giorgos]

I also am stuck on this question regarding my project, did you finally figure it out?

[dkuang]

I figured it out using different approach using field oriented control. You can look at an example by typing in power_acdrive in the matlab command if you have simpowersystems. For more details, go to the page http://www.mathworks.com/help/physmod/sps/powersys/ug/building-your-own-drive.html