Design Of Bidirectional On-board Charging System With Intelligent Power Distribution

A bi-directional On-Board Charging System(OBS)is designed,and it mainly studies optimization of resonance parameter,modele of lithium battery and intelligent power equalization in the OBS,as follows:This paper introduces a variety of commonly bi-directional AC-DC converters and bi-directional DC converters,and finally selects H-bridge bidirectional AC-DC converter and CLLC Bi-DC converter with working principles.Because the resonant parameters of CLLC converter determine the efficiency of OBS,the Quantum Particle Swarm Optimization(QPSO)algorithm is introduced to optimize the parameters.In order to obtain constraints of optimization,the parameters of the converter are modeled by the method of resonant point partition,and the relationship between the parameters and DC gain,input impedance angle and relative loss rate is studied.On this basis,QPSO algorithm is used to obtain the resonance network parameters with the minimum relative loss of the circuit.Battery power balance is an important part of charge balance.For the lithium battery,the 3rd-Hermite interpolation is used to approximate the voltageelectricity curve,and the difference between 3rd-Hermite interpolation and other fitting algorithms in the approximation effect and monotonicity is compared.The s-domain model of lithium battery charge equalization is established.The bilinear transformation method is used to discretize the model,and the discrete model is further simplified.Finally,the accuracy of the model is proved by Simulink simulation experiment.The depth reinforcement learning algorithm is used to optimize the equalization strategy.The basic concept of reinforcement learning algorithm is introduced,and priority double depth Q network algorithm is introduced.In order to enhance the noise sensitivity of the learning algorithm,the hysteresis quantization is used to filter the noise and improve the stability of the algorithm.In the design of neural network,the residual layer is introduced to enhance the network expression ability,and the algorithm training process is designed.Through pre-training and simulation,the advantages of the algorithm in power balance strategy are verified.Finally,a prototype of bi-directional OBS with intelligent power distribution is designed.In order to ensure the bi-directional work of the OBS,the control algorithm is studied,and the high-precision pulse generation strategy and synchronous rectification strategy under the digital control are designed and debugged.The experiments of rectifying,bi-directional ACDC switching,resonance point zone verification,constant voltage output,synchronous rectification,power verification and other performance verification are carried out.Sufficient experiments show that the OBS meets the design requirements.The battery equalization experiment and charging module equalization experiment are carried out.Through the experimental verification,the feasibility of power allocation based on priority double depth Q network algorithm is verified.