Design and experimental investigation of a three-phase high power density high efficiency unity power factor PWM (VIENNA) rectifier employing a novel integrated power semiconductor module

The development of guidelines for the practical application of a new power module (IXYS VUM25-E) realizing a bridge leg of a three-phase/switch/level PWM (VIENNA) rectifier system with low effects on the mains is discussed. The inner circuit structure of the power module is formed by a bidirectional bipolar switch and of two free-wheeling diodes. In a first step the switching losses of the power MOSFET and of the free-wheeling diodes are determined by measurement in dependency on the switched current for characteristic values of the junction temperature. The isolated driving stage of the MOSFET is designed for minimum switching losses considering the occurring switching overvoltages and the ringing between the parasitic circuit elements. The conduction losses of the semiconductor elements are calculated directly via simple analytical approximations of the mean and rms values of the device currents. Based on the knowledge of the dependency of the main loss contributions of the semiconductors of the power module on the operating parameters (mains voltage, output voltage, heat sink temperature and switching frequency) the thermally maximum allowable mains current amplitude is calculated. Furthermore, for different switching frequencies an overview over the power loss contributions of the semiconductor elements is given. Also, the reduction of the efficiency caused by the total semiconductor losses is determined. Finally, the overall efficiency of a PWM (VIENNA) rectifier system realised by using the IXYS VUM25-E module is estimated and further possible developments of this module are discussed.