Linear actuator current simulation model

Hello,

I am trying to model a linear actuator in simscape matlab but have been quite unsuccessful. The way I want the model to work is to apply a load at the end of the lead screw and set a speed at which the motor runs and from that information measure a current that is drawn by the motor.

My main issue is that I am unable to make the BLDC (https://uk.mathworks.com/help/sps/ref/bldc.html) drive my gears. I am using a BLDC current controller with PWM generation to power the gates of a converter that should then power the BLDC. I have attached the part of the circuit I think is the problem but honestly I don't really know if that is the problem. What I think the problem is that the converter is not getting the correct pulse to drive which is most likely cause by the way i have set up my BLDC controller. I will also attach the whole circuit.

Many thanks in advance.

Answer 1

[Sabin]

The problem is most likely in the control algorithm or parameterization. I have copy and paste your mechanical system into the existing BLDC Position Control example (I have removed the outer position loop and set reference to 2400 rpm) and it all works fine.

Few issues I have noticed in your model is that you pass Direction=0 in the BLDC Current Controller with PWM Generation, that’s not correct, for positive speed that input should be 1. Also, there might be a sample time issue with the PWM Generator because the control algorithm has 1e-4, Timer period is 1e-3 and fundamental is 1e-4.

I suggest starting with the BLDC Position Control example and build incrementally:

Step 1: remove position loop

Step 2: Update parameterization to match your requirements

Step 3: Add mechanical subsystem as per your requirements

[Beniamin]

Hi Sabin,

Thank you for your response. I have been able to succefully control the motor now. Thank you for the guidance on this.