Application Research Of PWM Rectifier In UPS

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 single phase voltage PWM rectifier applied in the on-line UPS.The PWM rectifier can not only reduce the pollution caused by traditional diode rectifier in the UPS, making the source’green’, but also has the advantages of power flow in two directions. Nowadays, researchers are paying lots of attention on the PWM rectifier, due to its advantages. This dissertation presents the development of a PWM rectifier and its characters, achievements, applications, topologies and current control algorithms.The principle of the single-phase voltage PWM rectifier and the PWM modulation technology are analyzed firstly. The dual polarity modulation is discussed, the inductor voltage equation and the capacitor current equation comes from this control theory. Based on the analyzed above, the small-signal model of single-phase voltage PWM rectifier is introduced. Then the current control loop and the voltage control loop is compensated by the PI controller. And both controllers are discreted with the help of MATLAB.The traditional current control algorithm is limited by the DSP clock speed, and could not execute frequently enough. In order to solve this problem, this dissertation introduces the predictive current control algorithm to replace the traditional current control algorithm.The hardware and software of the single-phase voltage PWM rectifier are designed. The hardware design contains:inductor in the AC side, the capacitor in the DC side and the power IPM selection. The control system is based on the16-bit fixed point DSC dsPIC33FJ16GS504, all of the DSP program is written in C language, the software flow is given in detail. At last, Experiment is carried out, and the result shows the whole system works properly. The predictive current control algorithm can stabilize the output DC voltage and unit power factor.