Author Topic: Wanting to use a PWM signal to control throttle speed for VEC200 motor controlle  (Read 3103 times)

Offline FusionJuggler

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I currently have a VEC200 series motor controller, controlling a 3kw brushless motor both from golden motors.
 
I’m able to get the motor controller to control the brushless motor fine by using the throttle stick. The signal going into the throttle ranges from 0.8v to about 3.4v. I believe that my throttle stick is a potentiometer stick it's made by WUXING and has a code "HT417/2". I believe that it's a potentiometer because in the PI-800 program, I use to program the motor controller it worked when I set it to potentiometer.

I'm currently working on a project where I'm supposed to be able to control the motor speed using a microcontroller and normally I would use a PWM signal to do so. I'd ideally do this by adjusting the signal's duty cycle to adjust the throttle signal speed. I've been experimenting with trying to get it to work by using a signal generator to test the PWM signal. I've tested 500Hz, 1kHz, 10kHz, 50kHz, and 60kHz, each at various duty cycles. None of those frequencies has gotten me the same control I've been able to get with the throttle stick. I've noticed that frequencies above 10kHz just don't cause the motor to spin at all but for frequencies 1kHz and below, I do get motion in the motor. Though the motion is inconsistent e.g. it will stutter a bit for like a minute and then go full speed without warning.

The circuit diagram is attached.

If I'm honest I don't really know where to begin with getting the PWM signal to work so if anyone can provide me with some recourses that explain how to do so that would be appreciated. I have quite a lot of experience with using PWM in other projects that required speed control but this is my first time using golden motors equipment. I would also love links to where I can get documentation on this motor controller, and not the guide because the guide doesn't seem to have a lot of information.

Thank you for your time, and if you need more information please highlight what specifically so I can provide it, I may have simply overlooked something.

Offline FusionJuggler

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SOLVED:

Hello, it took too long for anyone to respond to my query and after a while, I just figured out how to do it.
I believe it's a matter of making sure that the maximum voltage and minimum voltage of your PWM signal is within the range you programed your motor controller to operate at. So for example I programmed the motor controller to have a minimum allowable voltage of about 0.8v and a maximum allowable voltage of 3.4v. So if you just feed it a PWM signal that switches between 0v and 5v it obviously wouldn't work. So I used a function generator to experiment a bit a little and I managed to get a PWM signal working.

Here are the specifications,
use a square waveform
run at 10kHz
amplitude 500mVpp
offset 2.15Vdc
phase 0

This will give you a square wave whose maximum voltage is 2.4v and the minimum voltage is 1.9v
Now this itself doesn't give me the full range of control, I'm still screwing around with the signal, I just need to keep playing around with the offset and the vpp and I'll probably be able to get it in the right ballpark. Also, it should go without saying that the duty cycle is what I'm using to adjust the variable voltage within the range, so for example if I want to achieve a voltage of about 2.15v I would set the duty cycle to 50%, and if I want 2.1v I'd set it to 37%.