Research On On-Board AC Integrated Battery Charger For Electric Vehicles

Electric vehicle(EV)has the advantages of energy saving,environmental protection,high efficiency,and intelligence,which represents the future development direction of the automotive industry.Promoting EV can alleviate environmental pollution and energy shortages.In recent years,with the EV market expanding constantly,its related charging technology has become a research hotspot in the field of EV.As a new charging scheme for EV,the on-board AC integrated charger reuses motor windings and motor driver during charging,and transforms the original drive system into a charging system directly.It has the advantages of compact structure,low cost,high power density convenient use,etc.Based on a typical on-board AC integrated charger,this paper conducts a comprehensive study on the single-phase power input AC integrated charger and the three-phase power input AC integrated charger from five respects,winding multiplexing mode,topology design,mathematical model,control strategy design and experimental-simulation research.In the on-board AC integrated charger,the charging current directly flows through the motor windings,which may generate starting torque.To ensure the safety of charging,it is necessary to control the rotor to stand still during charging.Starting from the fundamental plane component of the winding current,the winding multiplexing method that realizes the rotor static is deduced using the torque balance method.Starting from the perspective of the stator magnetic motive force,the phase relationship of the winding current of the two types of integrated charging systems is analyzed and compared.According to the winding multiplexing method,the motor windings are reconstructed,and different types of integrated charging system topologies are designed.After the motor is connected into the circuit,its equivalent impedance,magnetic circuit coupling,and electromagnetic torque have the key influence on the performance of the system.Using the phase relationship of the winding currents,the mathematical model of the motor is simplified,and the equivalent model of the motor in the singlephase and three-phase integrated chargers are obtained.In order to evaluate the pulsation torque in on-board AC integrated charger,an electromagnetic torque model was established,the influence of the initial position of the rotor on the pulsation torque was studied,and an optimization control method of the pulsation torque in the integrated charger is given.According to the motor equivalent model,the AC-DC converter of the single-phase and three-phase integrated charger is further modeled.By analyzing the characteristics of the mathematical model of the AC-DC converter and the performance requirements of the integrated charging system,a phase current direct tracking control strategy is designed.The proposed control strategy has fast current response and good system robustness,and is suitable for various types of single-phase and three-phase integrated chargers.By building an experimental platform and simulation model,the single-phase and three-phase integrated chargers were tested respectively.The experimental and simulation results verified the correctness of the research content.