Research On Wide Range Adjustable Pulse Current Source Based On Model Predictive Control

Due to the high cost,pulse power supply is mainly used in national defense and cutting-edge scientific research fields in the early.Thanks to the rapid development of semiconductor devices,new pulse power sources have been continuously produced in the past decade.These power supplies overcome the shortcoming of poor maintainability and low life of traditional pulse power supplies.With its high repeatability,high reliability and high efficiency,it is gradually applied to various fields of industry and civil use.A wide-range output pulse current source is proposed in practical applications,which has high requirements on the rise and fall times of the output current pulse edge,and requires the output pulse amplitude,frequency,and pulse width to be adjusted.This paper adopts a three-stage pulse generation scheme of APFCphase-shifted full-bridge-chopper circuit to complete the design of this pulse power supply,and the full-bridge converter control method with impulsive load is studied.In order to realize the soft switching characteristic of the phase-shifted full-bridge circuit as much as possible,the working mode of the phase-shifted full-bridge circuit used as the current source is expounded in detail,and the soft-switching conditions are deduced in detail.The theoretical analysis of the pulse load characteristics is carried out,and the PI control effect of the fixed parameters under the pulse load condition is simulated and analyzed.From the perspective of improving the dynamic response speed of the system,the model predictive control strategy is adopted.What's more,the v-resolution discrete method is used to establish a more accurate discrete system prediction model.The constrained model predictive controller is designed,and its explicit feedback control rate is derived offline.The dynamic performance of model predictive control and traditional digital PI control at start-up,load step change and input voltage step change are analyzed by simulation.The advantages and disadvantages and the accuracy of the output current after steady-state output are analyzed.The waveform rise and fall time,overshoot and drop are analyzed.The effects of R,L mismatch,sampling deviation,and inaccurate calculation of duty cycle loss on model predictive control output error are analyzed separately,that is,the output error of model mismatch.In order to reduce the influence of model mismatch,the Kalman filter method is used to reconstruct the system state vector,and the reconstructed vector is used to correct the current reference value.The correction effect of Kalman filter on model predictive control is analyzed.Finally,a 400 V input,rated 20A/25 V output,output current 1~20A adjustable pulse power supply experimental prototype was made.Experiments on basic function verification(wide range output),soft switch implementation,compared of model predictive control and PI control were performed.The correctness of the theoretical analysis and design of this paper.