Controlling a very high current motor


(Daniel Oakleigh) #1

I’m working on motorising a beach wheelchair for a friend who has CP. She enjoys using it but has to rely on her family to push her around. She usually gets around by herself quite well on her power chair.

I have this chunky 12vdc motor that I salvaged from a car wheelchair hoist. It may well be overkill but I would like to use it for something, if not for this project. Does anyone have experience with controlling high current dc motors, or know where I could go for info re heavy duty driver components and circuits? I’m a relative noob with electronics but I figure that this is a good way to learn.
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(Stephen Davies) #2

Hi Dan,
sounds like you want to build an H-bridge. Not terribly difficult depending on the motors current requirements.

You can get single chip H-bridges with internal switching transistors (MOSFETs) up to about 10A. Beyond that you will need to use external MOSFETs and suitable interface chips. Texas Instruments have a range of brushed DC (BDC) controllers in their DRV88xx range. These have internal MOSFETs. If you require more current look for suitable ‘half bridge driver’ chips. You’ll need a pair to make a full H-bridge plus external MOSFETs. TI part UCC27282 is a good example.

Another option would be checking Aliexpress or Banggood for high current DC motor controllers.

Suggest you drop by the space one night during electronics Wednesdays to discuss.

Regards,
Stephen


(Daniel Oakleigh) #3

Thanks Stephen. I tried to post a picture of the motor spec label but it didn’t seem to work. The motor is 700W, 12v, 100A (presumably starting current draw), so I’ll be needing some fairly special components. The power leads look to be maybe 8mm diameter (at a guess, although I haven’t measured them).

I dropped in last Wednesday but was too tired to do much. I’ll try to come in again sometime soon.
Cheers,
Dan.


(Stephen Davies) #4

FYI - https://www.infineon.com/cms/en/product/power/gate-driver-ics/tle7181em/


(Chris Jones) #5

If, in the interests of saving time, you’d be interested in buying a controller instead of building it, or perhaps just for more information about existing designs, it might be worth looking at this site:
https://www.4qd.co.uk/
I bought a motor controller from them many years ago. It worked well and it was easy to use.

These days there are probably similar products available much cheaper from China, however the documentation and support might not be as good.