Quote:
Originally Posted by MazdaMatt
NiHaoMike, I was not implying that a flyback transformer should be used to power the vehicle. I asked the electrical engineer about replacing the diodes with mosfets and she told me to look up how that is done in a flyback transformer circuit for an example of how it should be done with a motor.
Paul, there may be mosfet drivers that have built-in flyback control. I will research further. This would be sweet.
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A DC motor controller is actually much more like a buck converter than a flyback converter. The commutation diodes provide a path for the induced current to flow. The controller will work as a boost converter during regen, however, so it would be necessary to also use commutation diodes on the high side.
The circuits used to provide a path for leakage inductance in flyback converters are not practical for use in motor controllers. A PC power supply I have that is based on a flyback topology has a capacitor from the drain of the power MOSFET going to a pair of fast recovery rectifiers, with an inductor in the low side to limit peak current when the MOSFET turns on. To use the same design in a motor controller would require a large, expensive capacitor with a high peak current rating.
Synchronous rectification actually is generally not worth it at high voltages. But since a DC motor controller already has the correct topology for it, it wouldn't cost much to include it.