A novel hysteresis current control for three-phase three-level PWM rectifiers

A novel hysteresis current control concept for three-phase three-level PWM rectifiers is presented. The proposed control is based on a virtual connection of the output center point and the mains star point and achieves a decoupling of the three phases. This control technique, besides having the advantages of a classical hysteresis control, provides a more regular switching of the power transistors and an intrinsic stability of the output center point voltage, and allows a full utilization of the modulation range. The novel control concept is discussed and compared to conventional current control techniques. Furthermore, the current control is digitally implemented and experimental results for controlling a Vienna rectifier are presented.