A novel soft-switching three-arm automatic voltage regulator

In this paper, a novel soft-switching three-arm series-compensation automatic voltage regulator is proposed. The proposed automatic 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. The reduction in the number of main switches not only increases the system reliability but simplify the control circuit. Moreover, a unipolar PWM scheme is used to reduce the input current and the output voltage harmonics. Some simulation results are presented to verify the feasibility of the proposed softswitching AVR.