TWI414922B - - Google Patents

Abstract

The present invention relates to a phase-controlled alternative current voltage regulator circuit, which provides a buffer device connected to a power input terminal of a transformer and an excitation terminal of the transformer. The buffer device includes two unidirectional conductive paths having the conductive directions opposite to each other which are respectively in a connected state and in a shut-off state for providing the input power voltage of the transformer on a flywheel path with the excited electric current at the positive half cycle and the negative half cycle. A pulse width modulation control device is connected between the buffer device at the excitation terminal of the transformer and the neutral point of the power supply system to provide the input power with the function for switching between connection and shut-off several times within each half cycle and adjust the voltage at the excitation terminal of the transformer into several segments of variable voltages, such that the variable voltage may have smoother waveform by the excited electric current from the smooth induction regulating transformer. The voltage at the output terminal may be regulated by the transformer and passed through the low-pass filter to achieve fast response time for voltage regulation and small waveform distortion for output voltage, and thus improve the conventional phase-controlled voltage regulator which can only adjust the voltage once within each half cycle, so that the conventional voltage regulator cannot achieve fast voltage regulation and low harmonic current pollution, and requires a design for the filtering equipment with large volume and heavy weight.