Active Switched-Capacitor Embedded Quasi-Z-Source Inverter and PWM Methods for High Boost Capability and Switching Loss Reduction

Abstract

This paper proposes a novel topology, named a single-phase active switched-capacitor embedded quasi-Z-source inverter (ASC-EqZSI), and two pulse-width modulation (PWM) methods, namely, PWM1 and PWM2 methods for the proposed ASC-EqZSI topology to improve the boost capability and reduce switching loss. The boost capability can be improved by using an additional non-shoot-through (NST) state, referred to as the NST2 state, besides conventional shoot-through (ST) and NST states. In the NST2 state, the switch in the impedance network is switched on to boost the dc-link voltage while generating the ac output voltage. A PWM1 method is suggested to control both the NST2 and ST time intervals with one carrier signal for improving the boost capability. A PWM2 method aims to reduce the commutation count of the switches and diodes in the proposed topology while maintaining the enhanced boost capability. The switching loss can be reduced by almost 40%. A comparative analysis between the proposed topology with the PWM2 method and five other topologies with an active switched Z-network is performed. The proposed topology with the PWM2 method has a higher ac voltage gain and efficiency with fewer components. Simulation and experimental results are carried out to validate the performances of the proposed topology and PWM methods.

Keywords

• Active switched-capacitor
• boost capability
• high voltage gain
• impedance network
• pulse-width modulation
• quasi-Z-source inverter