Dual-Electrical-Port Control of Cascaded Doubly-Fed Induction Machine for EV/HEV Applications

This paper presents a dual-electrical-port control scheme for four-quadrant operation of cascaded doubly-fed induction machine (CDFIM), which has conventionally been used as a variable-speed drive or variable-speed constant-frequency generator for limited-speed-range applications. The proposed control method enables the synchronous control of both power winding (PW) and control winding (CW) currents, and as a consequence, not only the control complexity but also the rotor slip frequency and related core losses are significantly reduced in comparison with the previously proposed single-electrical-port control scheme. It is for the first time revealed that the CDFIM drive that indirectly couples PW and CW through induction behavior can be readily controlled like a conventional induction motor to achieve the highest torque density. The torque density-speed region of the CDFIM falls within that of the power machine in singly-fed operation mode, and only a half of that of the power machine in doubly-fed operation mode, which shows the urgent need for torque density enhancement of brushless doubly-fed machines for electric vehicle/hybrid electric vehicle applications. Computer simulations and experiments are implemented to verify the dynamic performance of the proposed control method.