Electronic – Mosfet type to drive a 100A DC motor using pwm

dc motormosfet-driverpwm

I have a bunch of custom made DC motors. They are supposed to work in a range between 80Vdc and 120Vdc. Nominal power is around 800-1000W (they're custom made for a custom application, so specs are somewhat foggy…).

Now they start just by switching a clean contact, I'm requested to give them a ramp up and be able to choose the rotating speed (not the sense of rotation).

I'm planning to drive the motors using PWM and some industrial microcontroller or PLC (although I'll be prototyping using an Arduino), but I'm having the worst time finding a suitable MOSFET to drive such a bulky motor. Any recommendation on that matter is greatly appreciated.

UPDATE: So, I ended up using an IRFB4115PbF mosfet, and it works great.

Best Answer

You may want an IGBT for this; the way to use them is very similar to a MOSFET but they tend to be much more sturdy devices (for instance, all IGBTs rated at >100A seem to have voltage ratings >250V as well!). This is important because of inductive kick that is quite easy to get with motor loads. MOSFETs are in theory protected by their body diodes, but in practice need a snubber circuit as well for reliability.

An example of a suitable IGBT is AOK50B60D1, a 100A, 600V part for $2.13 @ 1k. It is rated at 300W, but would likely dissipate quite a bit less in your case.

If you do want a MOSFET, try something like IRFB4115PBF, 150V, 104A, $1.87; or IPP048N12N3.

EDIT

A bit more detail: IGBT vs MOSFET: Choose Wisely, by IRF

IGBTs have been the preferred device under these conditions:

  • Low duty cycle
  • Low frequency (<20kHz)
  • Narrow or small line or load variations
  • High-voltage applications (>1000V)
  • Operation at high junction temperature is allowed (>100 ° C)
  • >5kW output power

Typical IGBT applications include:

  • Motor control: Frequency <20kHz, short circuit/in-rush limit protection
  • Uninterruptible power supply (UPS): Constant load, typically low frequency
  • Welding: High average current, low frequency (<50kHz), ZVS circuitry
  • Low-power lighting: Low frequency (<100kHz)

MOSFETs are preferred in:

  • High frequency applications (>200kHz)
  • Wide line or load variations
  • Long duty cycles
  • Low-voltage applications (<250V)
  • < 500W output power

Typical MOSFET applications include:

  • Switch mode power supplies (SMPS): Hard switching above 200kHz
  • Switch mode power supplies (SMPS): ZVS below 1000 watts
  • Battery charging
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