Research On Direct Power Control Of PWM Rectifier

PWM rectifier can provide constant do bus voltage and get low harmonic distortion of input current. It also has line power feedback capability, PWM rectifiers is to solve electric network pollution and achieve "geen transition", improving the effectiveness of utilization and transmissioon it can adapts to apply in high-power wind power generation system..This dissertation analyze the developing status and the technological development trend of PWM rectifier, it introduce new control stratagem of PWM rectifier, PWM rectifier play a important role in wind power generation system.. The dissertation is mainly about the control system in principle analyzing, simulation and experiment validating.This dissertation mianly research on the two control stratagem of based on voltage oriented direct power control( c) and based on virtual flux-linkage oriented direct power control without line voltage sensors( VFO -DPC) , The topology, operation principle and mathematical modeling of PWM rectifiers are discussed, introduced the control structure of VO -DPC, then based on tradition switch table, improved on switch table, this paper presents the three switch state control stratagem to achieve better control performance, analyze and compare the new switch table with tradition switch table by simulation and experiment validating, verify its feasibility.This dissertation imports the virtual flux-linkage conception, through voltage, electric cuttent and estimate flux-linkage, VFO -DPC control strategy is given, grid voltage sensorless control of PWM rectifier is realized. Carried on the simulation and the experience, VFO -DPC can achieve the same control performance as VFO -DPC.VO -DPC and VFO -DPC PWM rectifiers system simulation module is built by MATLAB/SIMULINK, before and afer improved switch table, three switch state, sensorless control strage are researched by simulation model based on MATLAB/SIMULINK and get the results.Finally the dissertation builds experiment roof. The DPC system experiment accomplished in low-power PWM rectifier system and adjusted the control parameter during the experimentation. The experimrntal result based on VO -DPC control strategy indicates that DPC system has the advantage of high power factor, high efficiency, simple arithmetic and system composing, better dynamic response and so on. VFO -DPC can achieve the same control performance as VFO -DPC.