Research And Implementation Of Intelligent Charger With Wide Voltage Output

Since 2020,the development of new energy vehicles has become more and more rapid.The charging quality and efficiency of traditional battery chargers are increasingly difficult to meet the requirements of today’s high standard chargers.At the same time,for different levels of load batteries,the general chargers cannot achieve a wide voltage range output,nor can they adjust the charging curve,which is not intelligent and convenient.Therefore,in order to save resources and protect the environment,it is of great practical significance to study an intelligent charger with high efficiency,safety,high adaptability and high power density.Based on the traditional two-stage converter charger circuit,this paper studies an intelligent charger with wide voltage output and adaptive recognition function.Three-stage power electronic converter is used.The former AC/DC uses staggered parallel Boost PFC(Power Factor Correction)circuit to achieve power factor correction.The DC/DC isolation circuit uses three-phase half-bridge LLC resonant circuit in parallel to achieve electrical isolation and provide high-quality DC power for the latter stage.The latter stage voltage regulating circuit uses staggered parallel Buck converter to achieve wide voltage output,which can adapt to battery packs of various voltage levels.At the same time,intelligent multi-stage constant current and constant voltage charging methods are adopted in the program architecture,and the charging control technology is more scientific and efficient.It is characterized by high charging efficiency,simple operation,wide voltage output range,safety and reliability.In this paper,the working mode and circuit characteristics of the former stagger parallel boost PFC circuit and the latter stagger parallel Buck converter are analyzed,the principle of reducing current ripple is expounded,and the two circuit subsystems are modeled,and the average current method is selected for control;The principle of three-phase half-bridge LLC resonant circuit is introduced,and the steady state of the circuit is modeled by fundamental wave analysis method.The influence of quality factor Q value and inductance ratio k value on DC gain is analyzed,and the small signal model of the system is established based on the equivalent circuit method,and the cascade double closed-loop control is adopted,and the control parameters of the circuit are designed in detail.On the basis of principle analysis,the hardware parameters and related hardware circuits of the circuit are designed,and a new high frequency pulse control signal isolation drive circuit is used.At the same time,the intelligent charging software architecture with multiple protection functions is studied,including four charging modes and five charging stages,which can realize adaptive recognition of intelligent charging of the charger.Finally,the feasibility of the control strategy is verified by simulation experiments based on theoretical analysis,and a 7kW test prototype is built based on hardware design to test the function of the whole machine and the actual waveform,to verify the correctness and effectiveness of this topic.