Coordinated Control of DC Output Voltage and AC Input Current for SWISS Rectifier Under Unbalanced Grid

Abstract

The SWISS rectifier is widely adopted in charging stations and distributed dc power supplies owing to its superior performance. The core control objectives are maintaining a stable output voltage on the dc side and achieving a sinusoidal and symmetrical three-phase current with a unit power factor on the ac side. However, the existing traditional dual-loop control (TDLC) method suitable for SWISS rectifiers faces challenges in achieving these objectives concurrently under unbalanced grid conditions. To address this issue, this article introduces the constant output voltage control (COVC) method and the sinusoidal and symmetrical current control (SSCC) method. Contrary to the former method, the latter method achieves sinusoidal and symmetrical current on the ac side but fails to ensure a constant and nonfluctuating output voltage on the dc side. Building upon this foundation, an improved coordination and optimization control (ICOC) method combining the advantages of these two control methods is further proposed. The ICOC method coordinates these objectives on output voltage and input current. The experimental results demonstrate that the ICOC method has significant advantages over TDLC, COVC, and SSCC, which is consistent with the theoretical analysis in this article.