Design of circular current in the green voltage regulator based on transformer coupling

Concerning high harmonic content and low power factor of general AC voltage regulation, a high power factor AC voltage regulation is proposed under great voltage. Green voltage regulator which adopts two single phase voltage regulations to work together can minimize harmonic content and improve power factor. Based on transformer coupling, green voltage regulator has the advantages of high commonality and low voltage of thyristor. But owing to leakage reactance in circuit, current lags voltage. When the load voltage passes zero, both of thyristor groups of regulators have possibly conducted, the circuit causes circular current. There is a large loop current that destroys the thyristors. The application of detecting zero current can avoid circular current in the production of polysilicon. In order to ensure the stability and precision of detection, there is a safe delay angle, the green voltage regulator can still satisfy the high harmonic content and low power factor.