Research On On-line Uninterruptible Power Supply System

Rapid development of science and technology promotes constant renewal ofproducts in the market. There are plenty of high-end electronic products beingapplied by more and more people. At the same time, customers pay more and moreattentions to problems of power protection of electronic products, and UPS isgenerated in this big background. On-line UPS possesses the highest usage in market,it has the broadest application as a power protection device. Its protection ofelectrical equipment determines its specificity. The more precise instrument orspecial electrical equipment it is, the more importance UPS can highlight. Therefore,in order to improve the performance of UPS and meet the requirements ofapplication, an on-line UPS system is researched and designed in the paper.After consulting a large number of domestic and foreign literatures, on-line UPSsystem is studied in the paper. The two important parts in UPS: rectifier and inverterare research in detail. In rectifier section, single-phase voltage PWM rectifier circuitis mainly studied, including its working principle, selection and analysis of itscontrol strategy, and design of voltage and current double closed loop controller, etc.In inverter circuit, which is the core part of UPS system, repetitive control is adoptedas its control method in order to realize the constant frequency and constant voltageoutput of UPS, keeping a good dynamic response, high steady accuracy and lowerharmonic. With Saber simulation software platform, main circuits of each part in thesystem and control circuits are simulated and analyzed. At the same time，hardwarecircuit of the system and each control circuit are built. The software programming iscompleted by digital signal processor.The simulation results verify the correctness of each circuit design parameters，obtain the ideal simulation waveform, and provide a good basis for subsequenthardware circuit structures. PWM rectifier circuit makes the input voltage andcurrent in phase and improves the power factor of system. The repetitive control makes the UPS inverter circuit fast dynamic response in the face of disturbanceoccurs. The output voltage tracks the given voltage excellently and a steady-statesystem without static error is achieved.