Modified one-cycle-controlled three-phase pulsewidth modulation rectifiers with a reduced switching frequency to power line frequency ratio

In the aircraft power systems with 360-800 Hz line frequency or medium- and high-power three-phase pulse-width modulation (PWM) rectifier applications operating at the utility line frequency (50/60 Hz), the ratio of switching frequency to power line frequency will be reduced because of the increased line frequency or low switching frequency. Therefore the assumptions that the average voltage drop across the input inductor of the PWM rectifiers can be neglected if the conventional one-cycle controlled (OCC) method had been adopted can no longer be true anymore, which will deteriorate the system power factor (PF) dramatically. To solve this issue, a modified OCC scheme is proposed in this study. The proposed control method can improve the input PF of three-phase PWM rectifier without sacrificing the advantages of the conventional OCC scheme, such as no phase-locked loop and constant switching frequency. The control equation of the modified OCC method, which considered the voltage drop across the input inductor, is first derived. The theoretic analysis is supported by the experimental verification performed by a 2.5 kW modified OCC-based three-phase three-switch Vienna rectifier.