Control Strategies of a Hybrid Multilevel Converter for Expanding Adjustable Output Voltage Range

This paper proposes a new arrangement and new control strategies for a hybrid multilevel converter aiming at a high power high efficiency converter system with being free from harmonic distortion of the output. The strategies enable one to expand the adjustable output voltage range up to 100% with keeping very low harmonic distortion of the output voltages. The triangular-carrier based PWM and space-vector based PWM strategies are applied to the voltage control. Effectiveness is verified by simulation and experimental results. The proposed hybrid multilevel converter is applicable to medium voltage networks as a high power grid-interface converter.