感应电动机电源切换的UPS逆变器控制策略

针对重要负荷无缝供电的要求,提出了一种利用UPS逆变器控制实现的切换策略,使以感应电动机为代表的重要负荷在电源故障之后能快速平稳地切换到备用电源。通过分析典型动态负荷感应电动机的运行机理,说明了在失电状态下的残压变换规律和决定冲击大小的因素。对UPS中的逆变器通过空间矢量(SVPWM)方式进行调制,并对输出电压相位提出了一种相位分割的方式进行调整,最终实现在市电与备用电源存在相位差的情况下,对感应电动机负荷进行电源切换,有效避免了传统电源切换过程中对电动机的大电流的冲击。通过理论分析和Simulink仿真,最后进行了实验室试验,证明了策略的正确性和可行性。

Control strategy of UPS for the inductor motor

This paper proposes a switching scheme by controlling the inverter in the UPS to meet the demand of uninterrupted power supply for important load. It can make the load such as inductor motors get supplied by the stand-by power after power failure quickly and smoothly. The operational mechanism of the inductor motor is analyzed and the variation of the residual voltage and the influence factors of the impact current are explained. The inverter in the UPS is in Space Vector Modulation (SVPWM), which can immediately track the residual voltage to support the motor. It controls the phase of the output voltage of the inverter toward the stand-by power and makes the switching of the power supply smooth. This phase control scheme can make the power switch for the inductor motor succeed avoiding the impact of the surge current when the phase difference exists. The validity and the feasibility are convinced by the theoretical analysis and the simulation by Simulink as well as experiments in the laboratory.