A novel robust harmonic injection method for single-switchthree-phase discontinuous-conduction-mode boost rectifiers

摘要

This paper describes a new robust low-cost harmonic-injectionnmethod for single-switch three-phase discontinuous-conduction-mode (DCM)nboost rectifiers. In the proposed method, a periodic voltage is injectednin the control circuit to vary the duty cycle of the rectifier switchnwithin a line cycle so that the fifth-order harmonic of the inputncurrent is reduced to meet the IEC555-2 requirement. Since the injectednvoltage signal, which is proportional to the inverted AC component ofnthe rectified three-phase line-to-line input voltages, is employed, theninjected duty-cycle variations are naturally synchronized with thenthree-phase line-to-neutral input voltages. In addition, the injectednharmonic signal naturally contains desirable higher order harmonics,nsuch as sixth, twelfth, eighteenth, etc., which are more effective innimproving total harmonic distortions (THDs) than harmonic-injectionnmethods based on the sixth-order harmonic only