Predictive Deadbeat-repetitive Current Control Of Three-level Active Power Filter

400Hz power quality problems such as harmonic,reactive power and unbalanced power system in aviation power supply system seriously affect the normal operation of the system.Active power filter(APF)is expected to solve the above power quality problems of aviation power supply system.This thesis mainly studies the APF circuit topology and control method of T type three-level 400 Hz for high frequency,high power density and high performance requirements of airborne electrical equipment.The thesis first analyzes the switching function model of T three-level topology,deduces the mathematical model of three-phase stationary coordinate system and dq coordinate system,and analyzes its working principle.To solve the DC voltage imbalance problem of T three-level circuit topology,a space voltage vector pulse width modulation(SVPWM)method based on the midpoint capacitance voltage balance strategy is presented.On the basis of traditional predictive current control,the transfer function of predictive current control is derived.According to the predictive current control delay and converter sampling and control calculation delay,the deadbeat control method of T type three-level400 Hz APF circuit is studied.Secondly,the deadbeat control method of the predicted current under the dq axis system is discretized by the latter term difference method,and by "two-step prediction" of a given current,the delay compensation problem of deadbeat control(DBC)system is solved.Meanwhile,aiming at the periodic output current control error caused by the APF control method,this thesis inhibits this kind of periodic error by combining repeated control with the deadbeat control method to predict the current.The current tracking speed and accuracy of the APF are further improved.Moreover,the author designed a T three-level 400 Hz active power filter experimental platform using a gallium nitride(GaN)switch device,including independent isolation drive modules,LCRL filters and FPGA-based controllers.Based on the Verilog HDL hardware description language,this thesis designs a predictive deadbeat-repetitive control program.Finally,the experiment verifies that the control method combined with DBC and repetitive control has good compensation effect in 400 Hz active power filter.Total current harmonic distortion rate(THDi)decreased from 10.5% to 3.13% and the three-phase current imbalance decreased from 95.5% to 7.1% respectively.