# Dc motor controller



## major (Apr 4, 2008)

DORADITYA said:


> RELATED TO DC MOTOR CONTROLLER (EV VEHICLES)
> 1: Need for large number of capacitors in the power circuit (store the charge and dissipate to which part of the component mosfet or diodes ??) ?
> 2: what are diodes parallel to the mosfets for ? ( other than preventing the back emf coming from the motor ) and is it have anything to do with firing angle ?
> 3:advantage of using many mosfets in parallel than using a single mosfet and on what basis must that mosfet chosen?
> ...


Hi,

Welcome to the forum. I suggest you study the buck converter and mosfet application notes. Along with the general topic of power electronics, your questions can make more sense. There are also websites with tutorials on the subject of DC motor control. And then you can utilize the forum search tool to find threads and posts for specific items or detail. Like read through the threads which appear when you type in_"free wheeling diode"_ to the search box. 

Regards,

major


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## domosher (Jul 10, 2011)

The large number of capacitors is to bypass and filter the batteries to provide a lower impedance to drive the motor with higher peak current and higher peak voltage to the motor when the mosfets turn on. The diodes commutate the the inductive current from the energy stored in the series inductance in the motor without them you will fry the mosfets with excessive voltage. The reason for the large number of mosfets in parallel is first they do not make ones big enough to handle the current as well as the peak dissipation necessary to control these larger motors.


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## DORADITYA (Dec 22, 2013)

that was very helpful, thank you @tesseract @domasher


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