Control Method for Distortionless Zero-Cross in Active Unity Power Factor Rectifiers

Accurate synchronization and harmonics control are keys to achieve a distortionless zero-cross of currents in active unity power factor rectifiers. This article proposes a method to achieve optimal operation: 1) by settling a synchronization path that feeds the phase-locked loop with the output voltage reference that sets the theoretical unity power factor operation, and 2) low-order harmonics control with zero-cross driven antiwindup to reduce distortion further. Controller design is detailed and supported by theoretical analysis; the key performances are proved by experimental verification.