Using reverse-blocking IGBTs in power converters for adjustable-speed drives

A new semiconductor power device that is urgently needed particularly in power converter topologies, the reverse blocking insulated gate bipolar transistor (RB-IGBT), has been realized by adding minor changes to the structure of a standard IGBT to make it capable of withstanding reverse voltage. However, the switching behavior of the device´s intrinsic diode during reverse recovery is not as good as a discrete IGBT and series diode implementation. This paper analyzes the use of this device in three power converter topologies that may benefit from it, namely: 1) the matrix converter, 2) the two-stage direct power converter (DPC), and 3) the three-level voltage source rectifier. A commutation method to override the poor reverse-recovery characteristic of the RB-IGBT intrinsic diode in a two-stage DPC is proposed. A loss analysis shows that by using RB-IGBTs the efficiency of the two-stage DPC becomes similar to a two-level voltage source converter.