Research And Design Of BOOST Circuit Control Algorithm Based On Predictive PI Control

At present switching power technology is commonly used in power electronic technology,the DC-DC converter is the core of switching power technology.In view of the wide usage of the power source in electronics,Boost converter as a DC-DC converter could meet the requirements of the input voltage of the electronics.Boost converter has the characteristics of non-linearity,discrete and time-varying under the small-signal model.Based on the Boost converter under the conventional PID control strategy,simulation and practical application of the results show that: the system output voltage is unstable,the output accuracy is low and so on when the system is in the state of model mismatch or voltage disturbance.Based on the traditional PID control algorithm,this paper proposes a design scheme based on predictive PI control according to the process-response feature of boosted circuit.So it has a certain practical significance.Based on this research background,the research contents are as follows:(1)The working principle of Boost converter is analyzed,and then the mathematical model of Boost converter is established by using small signal modeling method.(2)By using the first-order PADE approximation,the desired closed-loop transfer function is obtained according to the function fitting method.By simulation on MATLAB software platform,the step response curve shows that Boost converter not only overshoot during boosting process,but also add the settings will appear negative-regulator phenomenon in the beginning of the response or at the static operating point.The occurrence of the negative transfer phenomenon leads to the deterioration of the dynamic quality of the control system,thus Inhibition of negative-regulator of Boost converter is critical.(3)Based on the traditional control Boost converter,a new control strategy about predictive PI algorithm is proposed.According to the controlled object model,the second-order predictive PI controller and the first-order predictive PI controller are built in SIMULINK.This predictive controller model consists of two parts,some have the form of the traditional PI controller,the other part have the prediction function.Compared with the traditional PID control scheme,the simulation results show that the control strategy based on predictive PI has good stability and fastness,high robustness and strong anti-interference ability,and has certain practical significance(4)The new predictive control algorithm is discretized and the algorithm is written in the C language and embedded in the OPTO22 PAC Control program flow.At the same time,OPTO Server and OPTO Browser of OPTO22 are used to communicate with MATLAB SIMULINK to exchange data.The user can change the various parameters of the controller on the man-machine interface,changes in parameters will make data interaction with MATLAB to observe the response curve transformation of process in real-time.(5)Based on the hardware and software environment of STM32 microcontroller,the new control algorithm is designed and tested on the hardware platform.The designed predictive PI controller and the traditional PID controller are in real-time inspection.The simulation results are verified by the results of the actual development of the hardware products.The stability,feasibility and fastness of the predictive PI control algorithm are proved.The main innovations of this paper are as follows:(1)Boost simulation mathematical is successfully applied in the industrial control software which named OPTO22.The man-machine interface of OPTO22 can realize real-time online detection,adjust parameter and observe the waveform.(2)Taking the Boost circuit as the hardware background,the predictive PI control algorithm is substituted for the traditional PID control algorithm to control the boosting circuit.Compared with the traditional PID control algorithm,the experimental results show that the PI control algorithm has the advantages of fastness,stability,strong anti-disturbance ability and high robustness in the simulation test.At the same time,through the constant debugging and correcting parameters,the actual waveforms are obtained on the hardware platform,which proves that the control quality based on predictive PI control algorithm is the best and has certain practical application value.