AN IMPROVED HYSTERESIS CURRENT CONTROLLER FOR REDUCING SWITCHING FREQUENCY

In this paper, an improved hysteresis current controller is proposed. It coordinates the switching of the three-phase switches in the d-q phase plane. In addition to the current error, information of the current error derivative is further employed so that one can take more advantage of adding the zero voltage vector for reducing the switching frequency. A simple hardware implementation of the improved hysteresis current controller is also proposed such that merits of the conventional hysteresis current controller can still be kept. Theoretical basis and some simulation and experimental results are presented to demonstrate the validity of the improved hysteresis current controller.