Research On Some Key Technologies Of Electric Vehicle Charger

Energy conservation and emission reduction have become the focus of worldwide attention,and electric vehicles have become the main development direction of new energy vehicles because of their features of cleanliness and environmental protection.As an indispensable part of the current electric vehicle,the electric vehicle-mounted charger is a key component of its research.The research on the common key technologies is of great significance for the development of electric vehicles.In the two-stage cascading architecture of on-board chargers,traditional PI dual-loop controllers are limited in bandwidth and gain due to the poor dynamic performance and robustness of the controllers for the front-stage PFC AC/DC converters.Researching and designing high-performance controllers has become one of the key issues to be solved urgently.In addition,because the aluminum electrolytic capacitor is widely used in the output filter circuit of the on-board charger inverter,the failure of the electrolytic capacitor will cause the charger to malfunction and have a relatively low lifetime,which greatly affects the reliability of the system.Electrolytic capacitance of on-board chargers will become a research hotspot.For the rear-stage DC/DC converter of the vehicle-mounted charger,in order to realize the high-efficiency operation of the converter,relevant researches have been made and various improved topology structures have been proposed,and for the improved topology structure,an appropriate method is needed to make the converter small Signal modeling analysis studies,thus laying the foundation for the matching design of the controller.The dissertation adopts the solution of PFC AC/DC converter with integrated power decoupling.By establishing the super-local model of PFC AC/DC converter and matching the modelless power controller of the converter,the purpose is to improve the dynamic and static characteristics of the system.At the same time improve system robustness.Based on this,a parallel power decoupling circuit strategy is adopted at the output side of the converter,which makes it possible to replace the electrolytic capacitor with a thin film capacitor with excellent performance.The Proportional resonant(PR)controller is designed to improve the control of the decoupling circuit.The energy storage device accurately absorbs the pulsating power at the output side of the converter and realizes the power decoupling function of the converter,aiming at reducing the output voltage ripple of the converter and simultaneously improving the system reliability.The system simulation analysis was completed by Matlab/Simulink,the feasibility of the scheme was verified,the prototype was made,and the system experimental test was completed based on the dSPACE rapid control prototyping platform.The effectiveness of the system integrated solution strategy was verified.Finally,the dissertation focuses on an improved method of modeling the phase-shifted full-bridge converter in the rear stage of the on-board charger.Aiming at the technical deficiency of the traditional phase-shifted full-bridge DC/DC converter in the rear of an electric vehicle-mounted vehicle charger,an improved phase-shifted full-bridge converter topology is proposed and adopted.The process of the circuit is analyzed in detail and applied for the first time.The switching element average model method completes the small signal modeling analysis of the circuit working in DCM.The simulation model was established using Matlab/Simulink,and the effectiveness of the modeling was proved by the circuit sweep method.The purpose was to lay a foundation for the rational design of the controller.