Distortion-free constant-voltage constant-current AC power supply having the unity input power factor by the use of variable capacitance devices

A new constant-voltage constant-current AC power regulator is proposed. Our original variable capacitance device of linear reactance device is utilized in the power stage. This circuit theoretically makes no distortion of output voltage waveform and a high efficiency can be obtained. For output voltage/current control and input power-factor correction, two variable capacitance devices were employed as linear capacitor. Two DC-DC converters were used for high-speed driver of these devices. The unity input power factor can be obtained all over the constant-voltage region and the constant-current region. Input current of the proposed power supply becomes almost zero at no load and at short-circuit load.