MPII Internal Controller Burnt Out

[Ceylanm]

Hi all,
We are working on a electric vehicle which has two MPII motor.
While we are testing the car, we realized one of the motors are not working.
Then removed the shell of the motor and saw some of resistors and capacitors are burnt.
I attached the picture of burnt motor driver.
What could be the reason for this situation, could anybody inform us not to repeat it again 
Thanks

[N43122]

Hard to say because the pic is not clear but the circled area on the right appears to be transistors or voltage regulators. Transistors, voltage regulators and capacitors usually fail by reverse polarity, excessive voltage or excessive heat.  A resistor does not usually fail unless current through it is excessive. The popped cap in combination with the burnt voltage reg tell me it's possible it was powered reverse polarity

[Ceylanm]

We have programmed motor mode as unimmed mode
This could be the reason?
While going forward, backward command struggled the motor controller?

[Bikemad]

I have attached a close up showing the components in that area of the controller board.

I have no idea as to what has actually caused it, but I managed to blow the same capacitor, along with the three other smaller ones (see attachments below) when I connected two controllers in parallel, and the battery supply was definitely not reversed. Although the second controller blew, the original one was completely undamaged.
 
Incidentally, that capacitor is only rated for 25V max, so I'm guessing it's used either for smoothing the +5V supply, or perhaps for another low voltage supply (<20V) that's used for gate switching on the MOSFETs.

Regarding the "unimmed" reverse setting, do both of your wheel turn in the same direction, or are they on opposite sides of the vehicle?

Were the driving wheels on the ground or raised during testing?

Alan
 

[Ceylanm]

They were on the ground and both of them was turning in same direction

[Bikemad]

Are they both connected to a single throttle, if they are, you will need to disconnect one of the +5V supplies so they are not joined together.

This may account for my controller failure, as I've just spotted that I connected the +5v regulated power supplies on both controllers together, which is not recommended.
I wish I'd noticed that before I tested them.

Alan
 

[Ceylanm]

=)
We have a DSP to control motors separately.
Two analog outputs are connected to drivers.
White cables (analog signal to motors) are being used and red ones (5V source) are open, not connected to anywhere.