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Topic: controlling speed and direction of a 24V 20A motor (Read 886 times) previous topic - next topic

carbondudeoxide

hello ive seen previusly a pot talking about how to drive a 12V 9A motor using 2 p channel mosfets and 2 n channel mosfets, here is the image of the almost finshed circuit diagram that they came up with:   original post:http://arduino.cc/forum/index.php/topic,16654.msg121293.html#msg121293

how would i modify this to work with controlling a 24V 20A motor? or is there a better way of controlling them?

also another question regarding the mosfets, can they be put in parralel to share the current over them or would this not work?

johnwasser

At a minimum you will need a different driver chip.  The TC442x series only goes up to 18V.

The Fairchild NDP6060L is good for 48A, 60V so that's fine.

The Fairchild FQP47P06 is good for -47A, -60V so that's fine.

I think all you need to change is the driver chip.
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Magician

Pay attention to reply #9 in other thread.
MOSFET should works well in parallel, to increase current.
Pololu has some variety: http://www.pololu.com/catalog/category/10

MarkT

#3
Dec 19, 2012, 08:51 pm Last Edit: Dec 19, 2012, 08:54 pm by MarkT Reason: 1
That circuit diagram is crazy - the 1uF caps on the MOSFET gates are really bad news - where is this circuit from?

Even without the caps on the gates it has potential for large current shoot-through spikes which is very bad news
usually - unless the gate voltage changes very rapidly there wil be significant time with both high and low
switches hard on.

It cannot scale to 24V because it's using p-channel and n-channel with common gates, so 10 or 12V is what will
work, or 5V if logic-level FETs are used.

For large H-bridges the usual approach is an H-bridge driver that controls 4 n-channel MOSFETs.  Example devices
are HIP8041, FAN7388 (although that is a 3-phase chip).  Many others are available.


[edit: from that thread you quote only post #3 has a good circuit - and its missing decoupling on the driver chip - that's
the origin of the erroneous caps on the bad circuit you've copied here - read the rest of the thread carefully ]
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