[Kasmodean]

Hello everyone,

First before I start I want to say awesome job to everyone involved with open revolt, especially you Paul.

I was trying to learn how to make a small dc motor controller for a robot I am building and came across the idea of PWM. I then figured after I made my robot to work, I could use the same principle to make a controller for my car. ( I have previously looked at doing a electric car conversion but controller cost has held me back.) The problem was it was one thing to make a robot controller with no safety features and making the same type for my car. It is then that I came across this forum. I have read up to page 150/370+, and I am still reading but I have a few questions on something that everyone seems to take for granted that are probably really simple, but I don't understand.

1) Every controller circuit I have looked at either has a capacitor connected to the motor's + & - terminals, or no capacitor, or capacitors around the + & - terminals and from + terminal to ground. In your schematic you have lots of capacitors from Batt + /Motor + to ground. How does that control the voltage spikes hitting the diodes from the motor - terminal while the mosfets are off? Or if that is not the purpose of them, what it?

2) Everything I have heard about diodes say they shouldn't be placed in parallel, especially if no equalizing resistor is attached. But your circuit has a bunch of diodes in parallel. How do they equalize and not have the best performer take more current then it can handle? This is also important because I was thinking of using IGBTs instead of mosfets and those aren't suppose to be in parallel either but everyone is saying you can do it.

EDIT: I just found on the diodes spec sheet that the forward voltage drop inceases as current increases. It is because of this that they balance, right?