Research And Design On Direct Power Control Of VIENNA Rectifier

With the continuous development of power electronic technology.Many kinds of power electronic devices are widely used in the industrial field, which has brought great convenience to human life and production.However, due to its nonlinear characteristics,a large number of harmonic and reactive power are injected to the power grid, which lead to the grid "pollution",And the rectifier accounts for the largest percentage of them. Therefore, the study of high power factor, low current harmonic PWM rectifier device has become an important topic of power electronic technology research today. Three-level PWM rectifier has the characteristics of lower input current harmonic and smaller voltage change rate(dv/dt) in AC side of rectifier,. therefore it is suitable in areas of medium and large capacity of rectification. VIENNA rectifier is an excellent three-level PFC topology,it require fewer switching devices than traditional three level topology,the maximum voltage of each power device borne is half of output voltage, and without the direct connection of output voltage, so do not need to set up drive dead zone. Based on the above advantages, VIENNA rectifier received extensive attention of the researchers at home and abroad.This paper firstly analyzes the working principle of the VIENNA rectifier.By utilizing the state space average method, the mathematical model of VIENNA rectifier are deduced in three kinds of coordinate system.Then according to the characteristics of sliding mode variable structure direct power control method,by combined with the theory of instantaneous power, mathematical model of the VIENNA rectifier based on direct power control is infered; The space voltage vector model of VIENNA rectifier was analyzed, and based on this research,the effects of all kinds of basic voltage vectors on neutral-point potential are studied;Then the hysteresis direct power control scheme based on looking-up-table(LUT-DPC) is studied,according to the principle of minimum switch changes,the switching table is designed by selecting adjacent voltage vector.This method without rotating coordinate transformation, structure and design are very Simple,and with fast system dynamic response, good robustness,but also has the problem of frequency is not fixed, which brought the difficulty for filter design;According to deficiencies of LUT-DPC, the Hysteresis power control in the inner loop is replaced by direct power control based on sliding mode control(SMC-Based DPC),and the space vector pulse width modulation(SVPWM) technology is combined. This menthod not only have the advantages of LUT-DPC but also realizes the fixed switching frequency, and the input current harmonic content is lower, and it is verified by simulation.Finally,according to the project requirements, the elements parameters of hardware system are calculated, design control circuit, analysis the flow chart of the software system, and set up the experimental apparatus. The experimental results show the correctness and effectiveness of SMC-Based DPC.