Load disturbance suppression for voltage-controlled three-phase voltage source inverter with transformer

This study concentrates on the load disturbance in voltage-controlled three-phase voltage source inverter (VSI) with transformer. High power density could be obtained when the transformer placed behind the inductor-capacitor (LC) filter, but the voltage drop on transformer leakage impedance may reduce output voltage quality in high power application. Load current feedforward control is applied to reduce output impedance and suppress load disturbance. To avoid the non-ideal high-frequency noise introduced by full feedforward strategy, simplified feedforward strategy is proposed to improve dynamic performance. The feedforward strategies implemented in both stationary frame and synchronous frame are derived, and the reduction of output impedance is analysed in detail. The distinct features of the proposed feedforward strategies are error-free steady-state fundamental output, fast dynamic response and convenient implementation. Finally, simulation and experimental results are provided to verify feasibility and validity of the proposed control strategy.