Low Harmonic 24-Pulse Rectifier Based on Square-Wave Voltage Injection

To further mitigate the input current harmonics of the 12-pulse rectifier pollution to the public power grid, a square-wave voltage injection method is proposed. The proposed 24-pulse rectifier uses a dual auxiliary transformer in cross series (CS-DAT) and an auxiliary single-phase rectifier (ASR) to suppress harmonics. The square wave voltage generated by the auxiliary diode modulation principle is added into the two three-phase bridge rectifiers (TBRs) point P and the pulse number of the input voltage in one cycle is doubled to 24 and its THD value decreases from 12.2% to 5.1%. Then the THD of the input current reduces to 1.8%, so the harmonic suppression performance of the rectifier is significantly improved. Build a test prototype with a 1.5kW output power to verify the realness of the proposed scheme.