MOS control device concepts for AC-AC matrix converter applications: the HCD concept for high-efficiency anode-gated devices

Reverse blocking MOS controlled devices will enable high efficiency ac-ac matrix converter systems to replace dc-linked type circuits. The trend in bidirectional switches is to replace the combination of a unidirectional blocking device and a diode with a monolithic reverse blocking device only. The diode on-state loss is eliminated, part count is reduced, and the system is less bulky. This paper discusses the various reverse blocking concepts suitable for MOS controlled devices for high voltage matrix converter applications. They include the junction isolation, the trench isolation, and the anode-gated (AG) concepts. AG is the only concept not technologically limited beyond 1200 V. However, increasing drift region thickness with voltage rating necessitates innovations to achieve fast switching and low losses without compromising V_ce(sat). Herein we propose the high channel density concept to further improve the efficiency of AG devices. Simulation results indicate the concept drastically reduces turnoff losses and improve switching speed.