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motor controller how to increase power can i just add MOSFETs

Discussion in 'Sensors and Actuators' started by onercboater, Mar 2, 2011.

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  1. onercboater


    Mar 1, 2011
    hello this is my 1st post here, what I am trying to do it create a more powerful reversible DC motor controller to drive a 12v-14.5v DC brushed motor. The motor in question is a minn kota trolling motor that at 14.5v draws 49-50A at full throttle. I intend to control the device either through servos moving the potentiometers (or preferably through actuation direct from a joystick and would be absolutely tickled if i could control it via radio control receiver however I must 1st come up with an inexpensive controller circuit to build 1st before working on fancy controls) the schematic I am intending to follow is here...
    located at the bottom of the page. I realize that asking this circuit to deliver 50A continuously in either forward or reverse would be a failure as the board it's self is unable to handle more than 5-10A even with the traces improved by layering solder on them. What I want to do is use this circuit in a modified form, I wish to triple or quadruple the MOSFETs by adding more in parallel, so instead of a total of 4 MOSFETs I am proposing that I use 16 which would give me 4x the capacity in ea direction. I also intend to use the circuit board only for the control portion and intended to fabricate my own separate board for the MOSFETs, which would allow me to use 4 gauge wire for the power in and power out of the driver portion of the circuit with a tap coming off of the heavy gauge connectors to feed the control portion of it. I realize I will need much greater heat sink capacity and am considering either very large fan cooled heat sinks or water cooled heat sinks. I have been warned of capacitance issues when adding additional MOSFETs and I am not sure if this will be a problem or not, if it is a problem how would I work around this. If someone has a better circuit design for me to follow that will not require programming I would be more than happy to follow it.

    It has been over 20yrs since my last electronics class in HS, and I can still easily follow a schematic for assembly or bread boarding, I vaguely remember my electronics theory mostly just the basics needed for radio control toys such as wattage calculation.

    Thank you very much.

    PS wow i didnt expect 1st post to be so long ... :D
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