M1 Driver Fault

General discussion of using Roboclaw motor controllers
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Basicmicro Support
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Joined: Thu Feb 26, 2015 9:45 pm
Re: M1 Driver Fault

Post by Basicmicro Support »

You can not just use a switching power supply with motors. Motors act like generators when slowing down. The PC power supply in almost all cases can not handle this generated return power. In your case either your power supply is now fried(sounds likely given your monitor was also getting glitched) or just the roboclaw has been damaged because when it couldnt push the regenerated energy back to the power supply its voltage would have shot through the roof(well over the rated voltage of the board) which is what damaged the mosfet(and probably the mosfet drivers).

1. I'd be very careful about using that PC power supply again. It may appear to work under no load but its possible internal components may have been damaged.

2. You will have to send the roboclaw in for repair. Please send the board to our main address(see contact us on our website). Include your return address and your phone number and a copy of this post inside the package. You will most likely just be charged for the return shipping. It will depend on just how badly the board was damaged. Significant overvoltage could have damaged the main regulator which would have cascaded down through all the components on the board.

3. If you have no choice but to use a power supply you must provide a way of dealing with the regenerated voltage. You can set the roboclaws maximum voltage to 1v or 2v above the power supply voltage(some switching supplied are sensitive enough that even 1v or 2v is too high though). This will cause the roboclaw to set braking mode whenever the voltage jumps up(which will dissipate the energy but will also stop the motors at the same time very quickly). Alternatively you will need to add a regen voltage clamp/power disipation circuit. This consists of an appropriate power mosfet(logic level) and a large wattage resistor and optionally a large capacitor(rated at least 50v). A third option is to add a battery(at the same voltage as the power supply) in parallel with the power supply. Then the battery will act as a buffer for the regen power.

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