A High-Reliability and High-Efficiency Off-Grid Inverter Suitable for Direct-Driven Wind Generator Systems

This paper presents a coupled inductor dual-buck full-bridge inverter (CI DBFBI) to solve the shoot-through problem of the conventional inverter and increase the input-voltage utilization rate of the dual-buck half-bridge inverter (DBHBI). Hysteresis current control is used in the CI DBFBI. All switches and diodes operate at each half line cycle, and the freewheeling current flows through the independent diodes instead of the body diodes of the switches, so the efficiency can be increased. The filter inductors are closely coupled to reduce the weight and volume of the proposed inverter and increase the efficiency. As shoot-through problem does not exist, dead time between the switches need not set, and then waveform quality of the output voltage can be improved. The input-voltage utilization rate of the CI DBFBI is twice that of the DBHBI under the same output-voltage condition. The operating principle is illustrated. A 1-kVA CI DBFBI has been established and tested. Experimental results verify the theoretical analysis.