I am working on a fairly small motor controller (2kW). The power input is AC 110-220VAC, so there is a PFC stage that boosts the initial DC voltage to 390VDC. After this stage, I require a 160-165VDC stage for brushless DC motor commutation. PFC and commutation are not a problem.

I have been looking at manufacturers online and they seem to be low on high output voltage controllers (input range as well..)

What is a viable and efficient buck stage for this circuit?

My current thought process is down a path of using a lower voltage, synchronous buck, controller chip and isolating the chip from the input/output via a low power DC supply and external gate drivers. That all seems very complicated...

What ideas do you have stack??

  • 1
    \$\begingroup\$ I would think you would want some isolation in the power supply somewhere, that usually happens after the PFC. I would look at something like a phase-shifted full bridge for 2KW at 165VDC. \$\endgroup\$ – John D Sep 3 '17 at 18:47
  • \$\begingroup\$ 2 kW PWM voltage regulation is not a walk in the park no matter what topology you choose. We need you to be braver and think about what MOSFETs you might use and what sort of switching frequency and efficiency you think you need. \$\endgroup\$ – Andy aka Sep 3 '17 at 18:53
  • 1
    \$\begingroup\$ Does the motor controller require such a stable voltage? If the motor insulation can handle it, 50%PWM at 300V is not different from 100%PWM at 150V. So... Do you need the buck? After all, you got MOSFETs and a big inductor that happens to be a motor, that's all you need to make a buck converter... \$\endgroup\$ – peufeu Sep 3 '17 at 18:54
  • \$\begingroup\$ I'm amused by the fact that you call a 2kW controller "fairly small". What do you consider to be a "normal size"? :-) \$\endgroup\$ – Dave Tweed Sep 3 '17 at 20:10
  • \$\begingroup\$ @JohnD - No isolation necessary on this one. I'll save the 3%. \$\endgroup\$ – Optimizer Sep 3 '17 at 21:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.