Switching Power Supply with 200V or 400V Input Voltage using a 3-Level Circuit

Abstract

This paper describes a 680W output switching power supply using a flying capacitor type 3-level PFC for single-phase 200V or 400V input. With this input specification, because the voltage and current range of the PFC converter is wider than that of a conventional power supply, the PFC inductor has a large inductance and current capacity, which leads to an increase in size. The adoption of a 3-level circuit can suppress the inductor size increase. The circuit is configured by connecting a flying capacitor type three-level chopper to the diode bridge. Like the conventional PFC, this circuit can make the reference potential of the control circuit the same as that of the DC output negative terminal. This configuration simplifies the gate drive and current detection circuits compared to other three-level circuits. In the DC/DC converter, a neutral point clamp type three-level circuit is used as a means to apply power devices whose rated voltage is lower than the circuit voltage in series. The control method, prototype, and evaluation results are demonstrated. At the rated load, efficiency exceeding 87% was obtained at both 200V and 400V inputs.