Study of PWM Rectifier/Inverter for a High Speed Generator Power System

The main advantages of the high speed machine are small size and high power density. However, the high speed machine suffers from higher loss density and cooling difficulty due to small cooling area, especially the high frequency harmonic currents produced by the power conversion system increase the loss and temperature of high speed machine. The output high frequency AC power of the high speed PM generator needs to be converted into the AC power with constant frequency and constant voltage using AC/DC/AC converter. The normal AC/DC conversion through diode rectifier will generate harmonic currents in the generator winding which will cause additional losses and increase temperature rise of the generator. How to reduce the harmonic components is an important problem to be solved for the power conversion system. In order to reduce the current harmonics produced by the AC/DC power conversion and meet the requirements on self-starting, a PWM rectifier/inverter with current harmonics repression function is investigated. The mathematical model of PWM Rectifier is established. Space voltage vector phase angle is determined by testing the zero crossing of line voltage, the no-error of current in the stable state is obtained through double closed loop. The simulation results and experimental results show the feasibility of the proposed design structure and control strategy.