MCT Based, Soft Switched, Four-Quadrant AC Induction Motor Controller

Insulated gate bipolar transistors (IGBT) represent the standard component in converters for electric vehicles and motor control. However, they are a mature technology where only marginal performance improvements can be expected, and improvements in IGBT based converter efficiency can only reflect these incremental improvements. MOSFET controlled thyristors (MCTs) represent a new class of power semiconducotrs that combine thyristor current and voltage capabilities with MOS gated turn-on and turn-off. Like IGBTs, the MCT is an insulated gate, field controlled switching device, but they provide a lower conduction drop (one third to one half that of the IGBTs), superior surge current, and higher di/dt capability. For electric vehicle applications, where energy storage is at a premimum, a vector controlled, soft switched, MCT based inverter has several advantages over IGBT based systems. While the MCT is able to switch under full power, the resonant, soft switching circuit avoids turn off losses, providing the highest overall system efficiency. This proposal presents a research plan for the development, laboratory testing, and preliminary Phase II plans for in-vehicle testing of a soft switching, MCT based inverter for electric vehicle applications. ANTICIPATED BENEFITS: The core technology can be scaled to larger or smaller vehicles (both commercial and military applications), is well suited to hybrid vehicles, and industrial motor control. It offers efficiency improvements in any DC to AC converters, including those for the conversion of alternate energy sources (such as fuel cells, solar cells, etc.), space power, remote sensing, uninterruptable power supplies (UPS), etc.