Studies on a performance enhanced dc-hfac-ac converter system for ac motor drive

This work describes a high-frequency non-resonant link power conversion system where the input dc is converted to high frequency single-phase ac (20-50 kHz) through a high frequency inverter. Then, this is converted to variable frequency three-phase ac voltage by a hfac-ac matrix converter for driving an induction motor load. The scheme is particularly attractive for Electric Vehicle type applications.

A high-frequency low-weight coaxial transformer in the ac link provides isolation, voltage boost from the battery side and auxiliary power supplies. All the switches are soft-switched to eliminate switching loss, and there is no voltage or current penalty of the devices. Although the number of self controlled switches is somewhat larger, the projected efficiency, power density and reliability will be higher than the conventional soft-switched converters using the future MCT-PEBB (Mos Controlled Thyristor-Power Electronics Building Block) based modules. The system has been analyzed thoroughly, MATLAB®-SIMULINK® simulation model has been formulated, control strategy has been developed, and the system simulation study with a three-phase ac current source has been completed. The performance of the converter system appears to be excellent. An experimental drive system will be built and tested in the future.