Half-bridge single-phase buck-boost type AC-DC converter with sliding-modecontrol of the input source current

A pulse width rectifier referred to as a half-bridge single-phase buck-boos t type AC-DC converter is proposed. The efficiency of the circuit is higher than that presented by other converters of this type, as only one reverse blocking power semiconductor conducts at any time. A comparative study betw een the new converter and a converter with four switching devices is carrie d out. The control strategies for the output DC voltage and input AC curren t are also presented and discussed. To achieve sinusoidal input current and high power factor, sliding-mode control of the input current is proposed. This nonlinear control strategy, applied to this single-phase step-up/down type AC-DC converter, also reduces the size, weight and cost of the DC indu ctor. Given the comparatively slow dynamics of the DC output voltage, a pro portional integral (PI) controller is adopted to regulate the converter out put voltage. Simulation and experimental results show the improved efficien cy, high power factor and low harmonic distortion characteristics of the ci rcuit.