A Low Output‐Ripple AC/DC Converter Under Wide Input Range and Three‐Phase Input Imbalance for Renewable Electrolysis Applications

Chopper rectifiers (uncontrolled rectifier+ DC/DC) are well‐suited for renewable‐energy–driven electrolysis due to their simple structure and easy control, avoiding the high harmonics of thyristor rectifiers and the cost of PWM rectifiers. However, their large output ripple can impact system stability. This paper proposes a new AC/DC converter to suppress six‐times line‐frequency (6 f line ) ripple, which consists of a three‐phase uncontrolled rectifier cascaded with DC/DC converter. By connecting an auxiliary circuit in series with the main circuit, the ripple is effectively compensated, significantly reducing 6 f line ripple and minimizing capacitor requirements. Additionally, considering the volatility of renewable energy and the potential unbalance in three‐phase input voltages, the proposed converter demonstrates excellent ripple suppression and a wide input voltage range, ensuring stable low‐ripple output under complex input conditions. Experimental results show that at an input phase voltage of 90 V, the output ripple is reduced by over three times. The converter can maintain a low‐ripple output voltage when the input phase voltage varies from 50 to 120 V, even when there is a 10 V amplitude deviation or a 10° phase deviation in the three‐phase input voltage.