Research Of On-line UPS Based On Converter Charging Control Strategy

Uninterrupted Power Supply (UPS) is an electronic device which is widely used in the field of industry. The capability of the on-line UPS is the best among different kinds of UPS. The traditional diode rectifier has the disadvantages of low voltage capacity factor and low power factor. To solve this problem, this dissertation focuses on the study of designing method of PWM rectifier applied in the on-line UPS. On the basis of introducing the works, we establish the mathematical model of three-phase PWM rectifier in the ABC three-phase and the αβ two-phase stationary coordinate system, as well as the mathematical model in dq two-phase synchronous rotating coordinate system which is based on switching function. After analyzing the applications and problems of the sliding-mode control for PWM rectifier, the three-phase PWM rectifier will be seen as a whole system, and establish the sliding surface computing unit based on the voltage and sliding-mode control law which is based current.This article present a innovative equalization solutionsbased on bidirectional flyback DC-DC converter topology equalizationsystem.This article can easily address this part of prone to overcharge and over discharge phenomenon of individual aging cells with the purpose of a alanced management, rather than simply blindly overall equalization. So at the beginning of the cell into a pack, we have focused on the energy balance of individual prone to aging cells, which can greatly reduce these overcharge and over discharge occurs. It can help protect these cells and maintain equalization of the battery pack. Compared to the overall balance, the efficiency of this program will greatly improve.Finally, we build a model of nonlinear control system in MATLAB, give the achievement method of space voltage vector control method and build the model to generate SVPWM wave. We through the voltage and current waveforms of line-side, as well as the DC voltage waveform to verify the characteristics of PWM rectifier that can make the input current sinusoidal, power factor and so on, and completed energy equalization simulation of the lithium battery module in the discharge process, the standing process and the charging process. Results verified that energy equalization management for a typical imbalance lithium battery pack is feasible, while achieving the effective energy equalization of the design requirements in the discharge process, the standing process and the charging process.