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

A pulse width rectifier referred to as a half-bridge single-phase buck-boost 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 between the new converter and a converter with four switching devices is carried out. The control strategies for the output DC voltage and input AC current 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 inductor. Given the comparatively slow dynamics of the DC output voltage, a proportional integral (PI) controller is adopted to regulate the converter output voltage. Simulation and experimental results show the improved efficiency, high power factor and low harmonic distortion characteristics of the circuit.