Soft-switched performance-enhanced high frequency nonresonant link phase-controlled converter for AC motor drive

High frequency link power conversion techniques are receiving a lot of attention in the literature. As the size and cost of traditional converters are shrinking, we are seeing the emergence of high frequency link power conversion with all its characteristic advantages. The paper describes a performance-enhanced high-frequency nonresonant link power conversion system where the input DC is converted to high frequency (20 to 50 kHz range) single-phase AC, and then converted to variable frequency variable voltage three-phase AC for driving an AC motor load. A lightweight ultra-low leakage inductance transformer in the high frequency link provides the advantages of isolation, voltage level boost in the secondary, and auxiliary power supplies. The scheme is particularly attractive for electric vehicle type applications. All the switches are soft-switched, and there is no voltage or current penalty of the devices. Although the number of components are somewhat higher, there are overall advantages of improved efficiency, power density and reliability in the total system, particularly when used with MCT-PEBB (power electronic building block) based modules. The system was analyzed thoroughly, designed, control strategy was developed, modelled for simulation, and then performance was evaluated. An experimental laboratory drive with 30 hp induction motor is being built and evaluated