Design And Analysis Of On-board Charger Control System

Digital control technique is one of the most important factors of modern electronic technology.With the wide application of power electronics technology in automotive electronics,the trend toward higher efficiency and higher power density in automotive electronics is becoming increasingly significant.At present,analog control is still commonly used on on-board chargers.This paper describes a designing and optimizing method of a digital controller for on-board chargers based on power factor correction converter and LLC resonant converter.This paper first introduces the research background,direction and main content of this topic,and analyzes the current research and development status of on-board chargers in the industry.The meaning of the on-board charger as a power device for power factor correction and its important role as a charging device for an electric vehicle are both introduced.Based on the hardware architecture of the power factor correction part of the on-board charger this paper uses the small signal model analysis method to model it and obtain its mathematical model,simulates and analyzes the mathematical model by MATLAB.The voltage outer loop and current inner loop control method is used for this model.The current and voltage loop controllers are designed.The controller is analyzed according to the experiment results.Choke inductance compensator and feed forward correction compensator are added to optimize the controller.Due to the effect of the phase-locked loop on the power factor correction part and the DCDC conversion part,this paper describes the method of software phase lock in detail.Various filters are used to filter the input noise or harmonics on AC mains.And the corresponding delay compensations are performed to finally obtain the phase difference.And then PI controller is used to compensate this difference.Finally phase lock is achieved.The verification is carried out and the experimental results are given.This paper makes a detailed analysis of the operation mode of the LLC resonant conversion part,uses the fundamental wave analysis method to get the equivalent transformation of circuitry,calculates the input and output transfer function,draws the system gain curve and analyzes it.The impact of the PID controller debugging process on the system is detailed described,and the method of using loop analysis to design the controller is shared.Software loop analysis is used to identify the system.The mathematical model of the plant is obtained according to software loop analysis results.And the controller is designed and optimized based on the model of plant.The problemsencountered in the designing process are analyzed and summarized.Finally,according to the previous design and analysis results,the experimental prototype is designed.The overall verification is performed and good experimental results are obtained.