Optimized control scheme of hybrid inverters in high power drives

A optimized control method is developed for a AC drive system, built of a parallel interconnection of a high-power low-frequency primary inverter and a low-power high-frequency slave inverter, feeding a large induction motor where torque ripple attenuation is a primary concern. The primary inverter is the main power supply and the slave inverter is used as an active filter to attenuate the current ripple due to the primary inverter low switching frequency. Compared to the dual current hysteresis control scheme, the proposed control scheme in the paper combines elements of both voltage and current control, and it guarantees stability of the integrated system. Meanwhile, the control system combines the best features in comparison of the equivalent voltage-source inverter such as low switching losses and fast current-control dynamics. In the paper the performances of the proposed control scheme are illustrated by using simulations.