Hi,
This is my first post in the forum, and I need help on debugging the setup I have.
The motor driver used is # Pololu G2 High-Power Motor Driver 24v13.
The PWM frequency is set at 10kHz.
The VREF is 3.3V.
The supply power voltage to the motor (VIN) is 24V from a maxwell DC DC converter.
nSleep is set to HIGH.
There is a 470uF 63V cap added to the driver.
There is also a 36k resistor added between VREF and GND for current limiting.
The driver works perfectly without problem when in manual control mode. However, when we tried to control the motor with a pid loop, it died. Will changing PWM or switching DIR kill the board? I was so confused and don’t know what could be the potential cause of this.
This is the second boards get destroyed under this condition.
When a DC motor is commanded to go from full speed forward to full speed reverse it can draw up to twice its stall current. With a PID loop, it is possible that kind of action was done, especially when first tuning it. How was the motor moving right before the driver broke? Could you post the specifications for your motor? What is the current limit of your supply? Could you post a link to its specifications as well?
Thanks for your reply.
The power supply to the motor has a 10A fast blow fuse in place, which wasn’t blow out when the failure happened. The motor was first set to move to one direction. And after it reached the target position we set it to move to opposite direction. And the failure happened after a fraction of second after the second command. The motor only moved a little bit and then stopped. The motor was 120W and under 24V the rated current is 5.6Amp.
Do you have an external capacitor soldered to the board? Even though there is a fuse on the input, it would still be helpful to know more about your supply. A large spike in current demand from the motor (like when reversing) could result in a large voltage spike on VIN. Wall power supplies often protect themselves from current flowing back into their outputs, which exacerbates the voltage spike which could then damage the driver. If that is what happened, a capacitor should help, and if you already have one installed, one of our shunt regulators would provide extra protection.
