Larger views of the MOSFET "bricks"

In the bottom picture you can see the four MOSFET "bricks" all bolted together more easily than in the top picture. Each row of MOSFETs on each "brick" is one branch of the H bridge and can (in theory) handle 560 amps. Each MOSFET can handle 140amps continuously and can survive instantaneous spikes in excess of this (up to 270amps so says the data sheet).

I have connected a separate 2.5mm CSA wire to each MOSFET, and at the other end used spade terminals, which I have bolted together. Doing this has two advantages. Firstly, I can ensure that each MOSFET has an independent power feed and will therefore ensure that as near as practicable, each will carry and equal share of the current being supplied to the motors. Secondly, if a MOSFET does blow, then it is easier to remove it from the brick without disturbing the others. The setup may look a bit cluttered with spade terminals, but I can isolate each part, and I know that each branch is getting its fair share of the supply and load.

On the left of the "bricks" there are some large capacitors. These smooth out the power feeds, and also provide some power storage as the MOSFETs turn on and off. I have mounted them as close to the MOSFETs as I can, so as to provide the best smoothing possible.