I think I have a modest understanding of how an ESC for RC hobby crafts works, and how a BLDC motor works. I've been wondering about how to make an ESC that could run a motor with large current required like a motor for an ebike when the motor is not spinning fast like a quadcopter motor. Could a circuit like the one in https://www.instructables.com/id/Make-Your-Own-ESC/ be used in conjunction with an IGBT on each output? That way it could handle higher loads than the ESC could normally.
Edit: I've been trying to do some basic calculations on sizing a motor that would accomplish my desired acceleration, and top speed of an ebike, and I anticipate using a 72V 18S lithium battery. I think I would be looking at about 150A during peak acceleration to about 60 mph.
Best Answer
You would not use an IGBT for this. IGBTs are more suited for very high voltage setups (>600-1000V) that switch quickly (but not as quickly as a MOSFET). For your purposes, you would just use bigger MOSFETs or parallel MOSFETs.
MOSFETs have a number of things going for them:
When IGBTs start coming into play is at higher voltages. To construct MOSFETs to withstand these higher voltages, tradeoffs have to be made that start to result in higher losses than if you used a fundamentally different approach (i.e. IGBTs). A low voltage MOSFET has less losses than a low voltage IGBT. As voltage is increased, there is a point when the IGBT has less losses than the MOSFET.
So at pretty much any reasonable eBike voltage and reasonable eBike current, you are better off using bigger MOSFETs or parallel MOSFETs. You might want to parallel MOSFETs even if singular, large MOSFETs are available just to spread the heat out over a larger area which makes it easier to manage. They are probably also more available too.
At increasing power levels, there is a point when the current become unmanageable for a given voltage. It could be that the wiring itself is unmanageable, or large MOSFETs are unmanageable, or parallel MOSFETs are unmanageable, or a number of other things. At this point, you increase the voltage so the current can be reduced to achieve the same power level and start using IGBTs instead.