I am currently designing a motor controller for a SUMO robotics challenge.

Each of a two motor setup exhibits a (0.15-0.40) N.m torque resulting them pulling (35-70) Amps nominally and a peak of 120 Amps when stalled (this happens frequently).

The driver needs to be compact and relevantly small. (12x9) cm is kind of the maximum.

I am having trouble finding a good technical guide to designing a proper power mosfet H-bridge controller for the motors. I know all the theory needed but I need a guide that deals with all high current related issues.

Here is the motor curve with working area highlighted in blue. RS-550 Motor curve with working area highlighted in blue.

  • \$\begingroup\$ Welcome to EE.SE. This Q&A-site is not a good place to ask for tutorials or suggestions for a complete design. If you "know all the theory" why don't you just draw a schematic, try and simulate it? When something burns ask here again! \$\endgroup\$
    – Ariser
    Feb 17, 2020 at 13:20
  • \$\begingroup\$ (Who picked that motor/working area? (Watts/litre issue?) In the right half of diagram, Ohmic losses alone are greater than power output - may become a thermal issue, if not a battery energy content one.) \$\endgroup\$
    – greybeard
    Dec 17, 2022 at 10:16

1 Answer 1


How soon is this robotics challenge? Unless it's sometime in 2025 I can tell you from experience that you probably aren't going to be able to build one in time. People that understand how to drive high power MOSFETS at high frequencies don't seem to want to share their knowledge. Go buy a Sabertooth 2x50 from Dimension Engineering and be done with it.

  • \$\begingroup\$ Thank you for your answer. It is something of a hassle but I don't think it would take to 2025! When I finish designing I will share the answer here so everybody can do it. Because frankly, a 2x50 Amps driver at 200$ is definitely overpriced and the large actively cooled radiator is a bit of an overkill. The large radiator indicates that the ON resistance of the transistors is somehow high. \$\endgroup\$
    – adnan
    Feb 6, 2020 at 12:35
  • 2
    \$\begingroup\$ Well, here we are three years later; two to go? I'd suggest closing this question, but I'm honestly a little bit curious... \$\endgroup\$ Aug 22 at 23:03

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