Abstract：This paper presents power flow of the double conversion transformerless UPS. The inverter has to supplying average power and oscillating power if the load is unbalanced according to instantaneous power theory. In this paper, the rectifier provides the average power and the DC-bus capacitor provides the oscillating power for the aim of power balance. However, the oscillating DC-bus voltage will lead to input currents coupling with low order harmonic. Therefore, a moving average algorithm is adopted to attenuating the oscillating component, which has a considerable impact on rectifier. This paper presents a dual-loop control scheme for three-phase four-leg PWM rectifier in UPS based on abccoordinate. This control method could effectively attenuate the impact on rectifier which is caused by the current in common leg. Thus, if one of inputs is failed, the others can be operating properly. The simulation and experimental results are in close agreement with the theoretical predictions.
雷何, 肖恩, 林新春, 康勇. UPS前置四桥臂PWM整流器控制策略[J]. 电工技术学报, 2013, 28(1): 203-208.
Lei He, Xiao En, Lin Xinchun, Kang Yong. Control Scheme for Front-End Four-Leg PMW Rectifier in UPS. Transactions of China Electrotechnical Society, 2013, 28(1): 203-208.
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2013, Vol. 28 
