Unity power factor three-phase dither rectifier using a single switching device

Electronic equipment is now widely spread in all industrial, commercial and domestic fields, which has resulted in an increasing presence of rectifier loads in the power system. The usually used capacitor input rectifiers, however, inject a large amount of low-order harmonic currents to the power system, which causes the distortion of the system´s voltage waveform The authors have proposed a family of converters with over 99% power factor using a unique switching device and simple control schemes, named a dither converter. However, previously presented circuits are effective only for small single-phase power sources, which limit their application to home electronics and office use equipment. In this paper, a new three-phase rectifier circuit with sinusoidal input current is proposed. This circuit is composed of three fly-back transformers, a diode bridge and a single switching device, which results in a very simple circuitry and control method. Computer simulation confirmed the validity of the circuit, showing sinusoidal and balanced input currents and a ripple-less output voltage. A 3 kW experimental circuit was also made to confirm the numerical results. The circuit obtained 99.0% power factor, 85% efficiency and small output ripple voltage