An improvement technique for the efficiency of high-frequency switch-mode rectifiers

A new technique for improving the efficiency of single-phase high-frequency switch-mode boost rectifiers is proposed. This rectifier includes an additional boost converter that follows the main high-frequency switching device. The additional converter, which is controlled at lower frequencies, bypasses almost all the current in the main switch and the high frequency switching loss is greatly reduced accordingly. Both switching devices are controlled by a simple method; each controller consists of a one-shot multivibrator, a comparator and an AND gate, and the maximum switching frequency can be limited without any clock generator. The rectifier works cooperatively in high efficiency and acts as though it were a conventional high-frequency switch-mode rectifier with one switching device. The proposed method is verified by experiment. This paper describes the rectifier configuration and design, and discusses the steady-state performance concerning the switching loss reduction and efficiency improvement. Transient performance is also included.