Zero sequence voltage suppression control with capacitor voltage balancing for a modular multilevel matrix converter

Zero sequence voltage suppression control for a modular multilevel matrix converter is investigated, which is required for applications to power systems and high power motor drives. The schemes of power flow control and capacitor voltage balancing control with voltage space vector modulation have been proposed. However, these control schemes have the problem they cause zero sequence current that affects protection for power systems and motors. To reduce the zero sequence current, the control scheme that suppresses zero sequence voltage by compensating voltage difference between input and output systems is proposed in this paper. Numerical simulation of a 9-level modular matrix converter and experiments using a 2-kW 5-level modular matrix converter are conducted to verify the control scheme.