SYMMETRICAL UPS POWER SYSTEM BASED ON NINE-PHASE SELF-COUPLING PHASE-SHIFTING TRANSFORMER

The invention belongs to the technical field of a power supply, and particularly relates to the technical field of a high-power power-frequency uninterruptible power supply (UPS), in particular to a symmetric-type UPS power system based on a nine-phase phase-shifting autotransformer (1); the symmetric-type UPS power system includes a three-phase AC power input terminal, a three-phase AC power output terminal (18), a nine-phase phase-shift autotransformer (1), a synchronized control device for controlling output of a three-phase inverter, a power-frequency isolation transformer and three circuits of output devices; wherein a three-phase AC input terminal of the nine-phase phase-shifting autotransformer (1) is connected to the three-phase AC power input terminal, each circuit of the output devices includes a zero-sequence suppression commutating inductor, a three-phase six-pulse rectifier, a three-phase inverter and a filter inductor which are connected with each other in sequence, each circuit of the zero-sequence suppression commutating inductor (2) is connected to the three-phase AC output terminal of the phase-shifting autotransformer (1), each circuit of the filter inductor is connected to the input terminal of the power-frequency isolation transformer (15); the symmetric-type UPS power system is small in structure size and low in cost and has a good application effect.