Research On Current Control Strategy Of APF Based On Improved SVPWM

With the rapid development of power electronic technology,more and more power electronic devices are used in industrial production and life.As the nonlinearity of power electronic devices,power quality problems become more and more serious.Active power filter can compensate for harmonics and reactive power dynamically,which is the main devices to control power quality problems.In this paper,the current control technology of shunt active power filter(APF)is studied.The main contents are as follows.Firstly,the theory of active power filter is introduced and the research status of space vector control technology is discussed specially.The basic working principle and the mathematical model of the three-phase three-wire shunt APF are introduced.Also the basic principle of SVPWM control is introduced,the implement method of the traditional SVPWM is given,and the repetitive+PI controller is designed.Secondly,for the traditional SVPWM control must use the reference voltage vector as input,which involves the design of current-voltage(I-V)conversion controller and coordinate transformation.A current control strategy combining the improved SVPWM based on division-summation and repetitive prediction is proposed.In the three-phase static coordinate system,sector judging based on the grid voltage,one switching period is divided into three time periods according to the difference of the action voltage vectors.Analyzing the variation of the filter inductor current in each period,and then sum the variation of filter inductor current in one switching period,the voltage vector action time is calculated.Thus,the design of control system is simplified.At the same time,in order to eliminate the system error of sampling delay,the deadbeat current prediction technology is introduced.The basic principle of deadbeat control and several common current prediction methods are introduced.The repeated prediction algorithm based on extrapolation is used to realize the accurate prediction of output current.Finally,the simulation model is built based on the platform of Matlab/Simulink,the relevant hardware and software is designed.The test platform is built and a series of experiments are performed.Simulation and test results demonstrate the effectiveness and feasibility of the proposed control strategy.