Evaluation of a Hybrid Module for Three-Phase Direct Matrix Converter

Abstract

As a direct AC/AC conversion concept, the direct matrix converter (DMC) outperforms its counterparts (e.g. AC-DC-AC) in terms of compactness and lifespan due to omitting the bulky and fragile dc-link capacitors. However, most of off-the-shelf DMC modules suffer from high current spikes due to their degraded reverse recovery characteristics (RRC) caused by the silicon-based diode. This paper firstly investigates the impacts of RRC of diodes on the current commutation of a DMC. Then, four kinds of bi-directional switches, which serve as building blocks for a DMC, are analyzed and compared in detail. Based on that, a three-phase hybrid DMC module, which consists of 18 IGBTs and 18 silicon carbide (SiC) junction barrier Schottky (JBS) diodes connected in a common-collector arrangement, is proposed in this paper. Thanks to the reverse-recovery-free property of the employed SiC JBS diode, the hybrid module presents mitigated current spikes. The effectiveness of this hybrid module has been verified in a 7.5 kW DMC system with current spike waveforms under different output voltages provided.