Research And Design Of Bi-directional Half-bridge Converter Based On Fuzzy PID

Due to the gradual exhaustion of traditional fossil fuels,serious environmental pollution and the formation of the greenhouse effect,new energy power generation and other power electronics-related technologies have been vigorously developed.As the energy transmission part of the power generation and energy storage system,the bidirectional DC/DC converter realizes the coordination and cooperation between the new energy power generation and the energy storage system,and solves the problem of unbalanced power supply and demand.Therefore,exploring the design method of the bidirectional DC/DC converter,researching and designing the control strategy to improve the steady-state accuracy and transient response speed of the converter will further improve the coordination and stability of the system.Taking the bidirectional half-bridge converter as the research object,it deeply analyzes its working process under the independent and complementary PWM control modes,deduces the expressions of the inductor current and output ripple voltage,and obtains the operating state and the inductance and capacitance of the circuit under different control modes.Selection criteria.Based on the state space averaging method,the small-signal models under different operating modes are established,and the independent PWM mode of the bidirectional halfbridge converter is found to be a special case of the complementary PWM mode.Based on the model analysis under the complementary PWM control mode,the duty cycle and The relationship between the voltage and the power flow is derived,and the judgment condition of the power flow of the converter is deduced.According to the working process of the converter and the judgment conditions of the power flow,a bidirectional switching control strategy based on the inductor current is proposed,and a unified control model is established.Compared with the traditional control strategy,the converter can switch the working mode according to the set threshold,which simplifies the controller design.Process.In-depth analysis of the open-loop stability of the converter in two modes,analysis of the performance indicators of the converter according to the stability standard,and design of the voltage control compensation link under the two modes;with the flow direction of the average inductor current as the judgment standard,the current loop and the current loop are designed according to the bidirectional switching control strategy.Bidirectional switching current controller.On the basis of PID controller,combining the advantages of high flexibility of fuzzy control with the advantages of high precision and strong anti-interference ability of conventional PID compensation network,a fuzzy PID control strategy is proposed,PID parameters are optimized by fuzzy rules,and a fuzzy PID controller is obtained.According to the technical indicators,a test prototype of the bidirectional half-bridge converter based on fuzzy adaptive PID was made,and the test platform was built and the test verification was completed.The results show that the efficiency of the converter in buck mode reaches 95%in steady state,and the efficiency in boost mode reaches 91%;under the condition of sudden change of input voltage and load,the output can be maintained quickly and stabilized;When the switching conditions are reached,the mode switching can be performed stably.The experiment verifies the correctness of the theoretical analysis and the rationality of the control method.