Design Of The Charger Of The Electric Vehicle Based On BMS

As people pay more attention to energy saving and emission reduction, it is an inevitable trend that electric vehicles replace the traditional fuel vehicles because of the advantages of environmental protection, energy and other aspects. Power battery as a key component of their performance and service life is directly related to the performance of electric vehicles. A high-performance power battery charger is the key component to ensure battery performance, extend battery life.In this paper, connect with the characteristicof battery management system (BMS) and design thepower battery charger system. The benefits of the system:Because the BMS includes the battery group information, the battery sampling circuit is saved; according to the battery state information, the charger output voltage or current can be adjusted immediately, so better charge effects can be achieved; when any fault occurs in charging the battery and charger can be protected immediately, so the system reliability and security is improved; the charger applies to the different BMS control system and the charger commonality is improved. Take an example of the lead-acid battery, the concrete method of BMS control charger is designed:Optimize the traditional three stage charging method; determine the critical condition of every stage;get the charging method of every stage;choose CAN communication as the communication way.In this paper, the charger design is finished on the basis of the charger design specifications and BMS charge control requirements, including main circuit and control system design mainly. The main circuit design includes PFC circuit design and DC-DC main circuit design. In the PFC circuit design, choose average current control Boost converter as the PFC circuit by compared with the circuit topologies and control modes, design main circuit parameters and control circuit parameters, then optimize the control circuit parameters; the DC-DC main circuit design includes topologies selection, main circuit parameters design and control circuit parameters design. It puts great emphasis on compensation circuit design, the small signal model is built firstly, considered the actual situations of the power switch conduction loss, the magnetic components loss and etc. Based on the frequency-domain analysis results, finish the compensation circuit design including voltage loop compensation circuit design and current loop compensation circuit design. Lastly,simulation verification of PFC circuit design is finished by using SIMPLIS, and simulation verification of the DC-DC main circuit design is finished by using Saber. The control system design includes sampling circuit design, protection circuit design and MCU circuit design. The sampling circuit design includes output voltage and current sampling circuit, the input voltage sampling circuit and temperature sampling circuit mainly. The protection circuits are mainly input overvoltage protection, output overvoltage and over current protection. The control system's merits are complete functions,reliability and low cost.In this paper, based on the power battery charger principle design, the PCB design and prototype building are finished. Experimental study on the prototype performance is finished: the main modules are tested and charging experiments are done for 72V and 60V lead-acid battery group respectively. The experiment results show that the designed charger has good performances.