A novel soft-switching single-phase three-arm AC voltage regulator

A novel soft-switching single-phase three-arm AC voltage regulator (SSTAVR) is proposed in this paper. The proposed AC voltage regulator (AVR) uses a three-arm topology that operates as a rectifier and an inverter. The rectifier arm is switched at high switching frequency, to perform power factor correction and simultaneously transfer the power demand for the load to the DC link capacitor. The inverter arm is also switched at high switching frequency, for regulation of the output voltage. In order to achieve low switching losses and high efficiency, the common arm is switched at the line frequency. Using simple resonant units, the rectifier arm and the inverter arm are operated at zero-voltage-switching (ZVS) turn-on, while the auxiliary switches are operated at zero-current-switching (ZCS) turn-off. The three-arm topology reduces the number of switching devices. As a result, the system is also more reliable and cheaper. The proposed AVR can deliver a sinusoidal input current with unity power factor and good output voltage regulation. A unipolar PWM scheme reduces the input current and the output voltage harmonics. Some simulation results for the proposed SSTAVR, rated at 500 W and operated at 40 kHz, are presented for verification.