A high-performance digital controller for high-power three-phase UPS by using one DSP

This paper focuses on the key technologies and its industrialization of high-power three-phase uninterruptible power supply(UPS) system. Firstly, the mathematical model of three-phase three-level VIENNA rectifier and three-phase two-level inverter were established respectively. The multiloop control method was realized based on the DQ coordinates, and a simplified three-level space vector pulse width modulation method which could simplify the calculation was proposed for the VIENNA rectifier. A composite control method of PI control and synchronous-frame repetitive control strategy was proposed to improve the quality of output inverter waveform. In order to improve the dynamic response of DC-bus, a power forward control strategy was proposed for the whole system. The whole system keeps unit power factor in the input side and pure sine voltage in the output side. The modulation and control method of three-phase three-level UPS was implemented in one DSP(digital signal processor). Experimental results of the 200kVA UPS system show that the proposed modulation and control method was correct and effective.