Novel DC–AC inverter based on phase-shift shoot-through controlled dual-active-bridge and high-frequency pulse DC link

Abstract

Bidirectional isolated DC–AC inverters are widely used in industrial applications, such as grid-connected uninterruptible power supply, renewable power energy system, electric vehicles and so on. In order to improve the conversion efficiency, realising soft switching will become the essential technology in the research of DC–AC inverters. Based on the commonly used two-stage isolated inverter, this study proposed a novel DC–AC inverter that combines dual-active-bridge (DAB) converter, switched capacitor and full-bridge inverter. Utilising the strategy of phase-shift shoot-through control, DAB will generate a high-frequency pulse DC link cooperated with switched capacitor. As a result, during the shoot-through period, when the DC link is in zero-voltage-stage, the full-bridge inverter could realise zero-voltage switching (ZVS) through discrete pulse modulation. Principles, characteristics and implementations of the proposed inverter and its control strategy are analysed in detail. A further analysis on the operation modes and ZVS constraint of DAB's secondary bridge and switched capacitor is completed. A 250 VDC to 150 VAC (peak value) 1.13 kW simulation and experimental prototype is presented to validate the ZVS of full-bridge inverter and the analysis of DAB converter and switched capacitor.