Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control

MPaulHolmes · 01-09-2015, 07:26 PM

This is a very neat idea. From a field oriented control perspective, you know you are commanding too much torque for a given speed when the PI loops for Id and Iq are no longer converging. The radius of (Vd,Vq) is bigger than Vmax. So, you could boost until convergence starts to happen again. And always attempt to reduce boost as long as convergence is happening.

For what I have planned (the board is almost done), the boost stage would just be a 4th IGBT half bridge that's controlled by the same microcontroller. It would be bolted right next to the other 3 IGBTs. It would be connected to the same ring capacitor. It would look identical to a 4 phase motor controller. The only difference would be that you hook up the "4th phase leg" to the inductor rather than to the motor.

You would have to move to buck mode when in regen though.

01-09-2015, 07:26 PM	#1559 (permalink)
MPaulHolmes PaulH Join Date: Feb 2008 Location: Maricopa, AZ (sort of. Actually outside of town) Posts: 3,832 Michael's Electric Beetle - '71 Volkswagen Superbeetle 500000 Thanks: 1,362 Thanked 1,202 Times in 765 Posts	This is a very neat idea. From a field oriented control perspective, you know you are commanding too much torque for a given speed when the PI loops for Id and Iq are no longer converging. The radius of (Vd,Vq) is bigger than Vmax. So, you could boost until convergence starts to happen again. And always attempt to reduce boost as long as convergence is happening. For what I have planned (the board is almost done), the boost stage would just be a 4th IGBT half bridge that's controlled by the same microcontroller. It would be bolted right next to the other 3 IGBTs. It would be connected to the same ring capacitor. It would look identical to a 4 phase motor controller. The only difference would be that you hook up the "4th phase leg" to the inductor rather than to the motor. You would have to move to buck mode when in regen though. __________________ kits and boards Last edited by MPaulHolmes; 01-09-2015 at 07:39 PM..