Specific harmonic power suppression of direct-power-controlled current-source PWM rectifier

This paper focuses on specific harmonic active power suppression of a direct-power-controlled (DPC) PWM current-source rectifier (CSR) in order to achieve low distortion of the input fine currents. Total input power factor of the DPC-based PWMCSR becomes worse as the load gets lower due to the low-order harmonics in the line currents, especially the fifth and the seventh. Since the dominant low-order harmonic currents cause an oscillation in the active power at frequency of sixth, suppression of the sixth-order harmonic active power is essential to improve the total power factor particularly in the low-load range. The paper describes a theoretical aspect and a suppression technique of the harmonic active power, followed by basic configuration and operation of the DPC-based PWMCSR. Effectiveness of the proposed technique is confirmed through computer simulations and experimental tests, using a 2-kW prototype. As a result, the total harmonic distortion of the line currents is effectively reduced by 10 %, which results in approximately 20-% improvement of the total input power factor at a 350-W load condition.