Novel approach of constant switching-frequency inverter control with optimum current transient response

Abstract

Power converters with carrier based pulsewidth modulation (PWM) are currently the most widespread solution in industrial drive applications. However, the average dead time of the current controller affect the transient behavior of the whole drive. Therefore hysteresis and predictive current control can be seen as an alternative to PWM, providing enhanced transient response with the major drawback of variable inverter switching-frequency. In this paper a novel predictive current controller is proposed, using a penal weight in switching state selection for controlling the switching-frequency. Consequently inverter switching-frequency will no longer dependent on current controller sampling time facilitating sampling frequency to be increased up to some 100kHz at an inverter switching-frequency of just a few kHz. Hence - compared to classical predictive current control - a further reduction of the transient response time can be accomplished.