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Project Help and Ideas » High Power Motor Controller

February 29, 2012
by meltbox360
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I started looking at large electric motors and using them on bikes or even go carts and I have decided to go with a 500W motor @24v for my project. The mosfet I picked out to drive this thing is the PHP/PHB191NQ06LT digikey part number 568-5756-ND. I was hoping to use a few in parallel as I doubt a single one would handle stall current too well. The motor being driven is the my1020 500W 24v version. I'm thinking I should only need 3 of these mosfets to drive it safely even when stalled. I however am mostly worried about being able to directly drive these mosfets from the atmega168. I'm not sure I completely understand how a pin in pwm mode functions and what voltage is the voltage that switched that mosfet on. From reading the datasheet I gather that anything above 2v means its on? Does pwm send a low signal or 0v to turn the mosfet off.

Sorry I have a lot of questions but I'm just jumping into the world of figure it out yourself and I can't quite interpret or find everything I need to know to do this correctly.

March 01, 2012
by meltbox360
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I have changed my chosen mosfet to BUK6E3R2-55C,127 and added the following heatsink 576802B04000G made by Aavid Thermalloy and I believe it should give me 26.8 amps per mosfet @40C no air flow before they melt. I will probably add in a fan but all calculations I will do from this point on will be based on the no airflow numbers. My only issue at this point is finding someone who knows the resistance of the my1020 24v 500w motor. From there I can figure out the stall current and be on my merry way towards building a controller that will not explode.

One question to anyone who has done PCB work. Is it practical for me to etch a pcb for this. I'm not sure how wide the traces would have to be and the parts I'm picking are through hole mount. I was actually planning on improvising and doing it on wood with connections done with a lot of solder and somewhat thick wire. I feel like that may not work though. I can switch to surface mount easily so it would be nice to know before I order parts.

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