An Isolated Buck-Boost Converter with Hybrid Three-Level Rectifier for Wide and High Output Voltage Applications

An isolated Buck-Boost (IBB) converter with hybrid three-level rectifier, which is composed of a two-level diode rectifying-leg and a semi-active three-level rectifying-leg, is analyzed and evaluated in this paper. The diodes and active switches in the semi-active three-level rectifying-leg is only half of output voltage, which makes this converter more suitable for high output voltage applications. Both step-up and step-down voltage conversion are realized by adopting optimized phase-shift modulation strategy. In addition, soft-switching of all the active switches and diodes on both primary and secondary sides are achieved within wide operation range. All these features make the IBB converter be suitable for wide and high output voltage applications. Operational principles and characteristics of this converter are analyzed in detail. Experimental results with a 2kW prototype are provided to evaluate the effectiveness and advantages of the presented converter.