Electric vehicles require high transient torque to start and accelerate faster. Moreover, many industrial drives like those used with weaving machines, conveyors, cargo handling, hoists, and printing presses also require high transient torque. This dissertation presents the invention of a system reconfiguration and control technique for a multiphase motor drive to obtain up to 93% higher torque for acceleration. Wide bandgap (WBG) devices enable the next-generation efficient and lightweight motor drives for use in industrial, automotive, ship propulsion, aerospace, and rail applications. This dissertation provides a comprehensive review of the different major ac motor drive applications that would benefit from WBG devices. This dissertation also discusses the technical challenges, converter design considerations and design trade-offs in realizing the full potential of WBG devices in motor drives. There is a trade-off between high switching frequency and other issues such as high dv/dt and electromagnetic interference. The problem of high common mode currents, bearing damage and insulation damage caused by high dv/dt are discussed. Silicon Carbide (SiC) and Gallium Nitride (GaN) inverters are designed, built and tested for motor drive applications and the performance is validated with experimental results. To achieve transient peak torque higher rated current needs to be forced into the motor for short duration. The duration of overload is determined by the magnitude of current during overload and the thermal characteristics of the motor. The switching devices of power electronics converter cannot be overloaded. Therefore, transient peak torque capability of an electric drive is limited by the power electronics converter. The invention presented in this dissertation makes it possible to achieve 93% higher transient torque in a multiphase motor drive. The superior acceleration capability of the invention is validated with experimental results. SiC and GaN inverters are used to drive an induction motor. Both the inverters are able to operate at switching frequency of 200 kHz.
