A Single-Phase Soft-Switching AC Voltage Regulator With Fictitious DC-Link

A single-phase soft-switching AC voltage regulator (AVR) with fictitious dc-link using a simple auxiliary resonant unit is proposed. The proposed scheme can maintain output voltage stable no matter input voltage under any variations including under-voltage, over-voltage, voltage sag and voltage swell. All main switching devices operate at zero-voltage-switching (ZVS) turn-on, while the auxiliary switches operate at zero-current-switching (ZCS) turn-off. The advantages of this topology are found in reducing the switching loss, reduced the voltage stress, and greatly reduced EMI. By using a small ac capacitor, instead of a large electrolytic capacitor on dc-link, increases the lifetime of the converter and reduces its size. Finally, some simulation results are presented for demonstration.