Designing of H-bridge

dave226

Hi, I am designing a small EV and I am looking forward to some guidlines regarding designing of H-bridge torque controller for controlling somewhat in between 6-8 permanent magnet brush DC motors , the overall power required from these motors is between 70 to 250 W, where 70 W is for normal purpose and 250 W for peak requirements.

Could you please suggest me the cheapest controlling design for such operation like
a) which type(with particular specs) of the bunch of small pmdc motors best fit for such operation (here the torque requirement is around 20 N-m) and i want to run all motors (say parallel combination) with a constant speed and controlled torque(preferable).
b) How to design and what is the best and the cheapest torque controlling method of these motors using H-bridge (like providing a common reference or say separate torque control of each motor and providing those with a common reference), the type of Mosfets and the heat sinks. Keeping in mind the availability in the market and the price factor too.

If you have any questions regarding this please ask me. All suggestions and ideas are welcome. Any help would be of great help!!!

Thanks!!!
Dave

dave226

PS: I am planning to operate these bunch of pmdc brush motors with a 12V supply