Research On Performance Control Strategy Of Phase Shifted Full Bridge Digital Power Supply

With the development of the times and the progress of science and technology,the demand for power supply in the field of high-power power consumption is also higher and higher.Higher power density,higher intelligent realization and higher reliability have become the new development direction of power supply.The phase shifting digital power supply,which combines phase shifting control technology with digital control technology,is used to shift the conduction sequence of the full bridge power regulator and digital control to replace the traditional analog control on the basis of resonance circuit.It has the advantages of high power density and high intelligence.The phase-shifting full bridge digital power supply has the advantages of high power density and intelligent realization.At the same time,due to its nonlinear time-varying,discrete sampling delay and high frequency voltage spike system characteristics,it is difficult to realize the fast and stable adjustment of output current under the change of power load when the power supply is used in high power current output application,and the dynamic performance problems of long adjustment time and large overshoot are also encountered.Dynamic performance is an important evaluation index of power supply reliability,so it is important to optimize the dynamic performance of phase shifted full bridge digital power supply.This paper takes the phase-shifting full bridge digital power supply with high power current output as the research object.After extensive reference to the relevant domestic and foreign literature,the system characteristics which affect the dynamic performance of the phase-shifting full bridge digital power supply are analyzed based on the working principle;The dynamic model of small signal from duty cycle to output current of phase shifted full bridge digital power supply is deduced;A control strategy combining the improved adaptive fuzzy PID control algorithm with the self-adaptive optimization algorithm of social spider intelligence is proposed to optimize the dynamic performance of the phase-shifting digital power supply.Through the simulation test,the design indexes of the over-regulation of the phase-shifting full bridge digital power supply are 14.79%(≤ 15%),and the adjustment time is 10ms(< 10ms).Finally,a phase-shifting full bridge digital power supply test prototype is built,and the effectiveness of the research on dynamic performance control strategy of the phase-shifting full bridge digital power supply is verified.The results show that the load ±The dynamic performance optimization of the phase-shifting full bridge digital power supply with 20% change rate has certain effectiveness.The specific research mainly includes the following four aspects:1.study on Fuzzy Adaptive PID control algorithm.The phase-shifting full bridge digital power supply belongs to the nonlinear time-varying system.It is difficult to adjust the output fluctuation of the nonlinear time-varying system quickly and smoothly by adopting the traditional linear control strategy.The adaptive fuzzy PID control algorithm can take the output error and error rate as the controller input,and get the adjustment of PID control parameters by the way of nonlinear control decision-making,and realize the nonlinear control of the system.The phase-shifting full bridge digital power supply researched in this paper has the characteristics of high output current.It is difficult to realize the full mapping from fuzzy theory domain to system output by using the traditional fuzzy adaptive PID control algorithm.The problem of missing control quantity affects the optimization of its dynamic performance.An adaptive fuzzy PID control algorithm with improved quantization factor is proposed,which is to introduce the online adjustment function of the quantization factor in the fuzzy quantization process,and realize the full mapping from the fuzzy theory domain to the system output by the way of domain expansion,and then restrain the overshoot of the system output fluctuation.2.the research of social spider intelligent optimization algorithm(SSA).SSA has the characteristics of fast convergence rate and high precision of optimization.In order to improve the convergence speed and precision of the algorithm in solving low-dimensional problems,an adaptive optimization algorithm for social spiders is proposed.The adaptive function with weight factor and the most domain disturbance strategy are introduced to reduce the vibration perception of spiders with the increase of iteration.In addition,the greedy mechanism can eliminate the second optimization target in every iteration,Choose the best target for the walk.Compared with traditional SSA,artificial fish and bat swarm intelligent optimization algorithm,the improved SSA algorithm has higher precision and convergence speed.3.the research of the improved adaptive fuzzy PID control algorithm based on the improved SSA.The time delay of discrete sampling and the initial PID control parameters of adaptive fuzzy PID control algorithm are affected by the phase shifting full bridge digital power supply.The adjustment amount based on initial PID control parameters calculated in current period can only be used for the next cycle control.The current control quantity can not meet the control standard of theoretical calculation control quantity,and reciprocating adjustment occurs,which results in the increase of output fluctuation adjustment time,which is difficult to meet the design index of overshoot ≤ 15% and adjustment time ≤ 10 ms.A new adaptive fuzzy PID control algorithm based on improved SSA is proposed.By increasing the global optimization ability of the algorithm,the accuracy of the initial control parameters of the adaptive fuzzy PID is improved,and the time of the current output fluctuation of the phase shifting full bridge digital power supply is shortened.4.the validation research of algorithm effectiveness.The phase shifting full bridge digital power supply with the improved adaptive fuzzy PID with quantitative factor can realize the overshoot of 0 and the adjustment time of 100 ms under the unit step signal response.The phase shifting full bridge digital power supply with improved social spider intelligent optimization algorithm and quantitative factor modified adaptive fuzzy PID algorithm can realize the overshoot of 14.79% and the adjustment time of 10 ms under the unit step signal response.In conclusion,the improved control strategy proposed in this paper can meet the requirements of over adjustment of design index ≤ 15%,adjustment time ≤10ms.A 1.2k W experimental prototype is built to verify the availability of the proposed improved control strategy in the real platform.The results show that the phase shifting full bridge digital power supply prototype with improved control strategy can achieve PWM control signal output,power conversion function and dynamic performance optimization to a certain extent(adjustment time ≤ 10ms).