ARM-based Design And Implementation Of Battery Management System

With the shortage of petroleum and the increase of environment pressure, hybrid vehicles(HVs) and electric vehicles (EVs) are becoming the trend of the automotive industry. As anindispensable component in the battery pack battery management system (BMS) plays an importantrole in guaranteeing safety driving, prolonging life-span of battery and estimating state of charge(SOC). The charge and discharge management strategy, real-time data acquiring and energybalancing strategies are the major components of BMS and the bases of real-time monitoring andautomatic balancing.First of all, the research status of BMS is introduced; some charge and discharge strategies,date acquiring and energy balancing means are compared. Based on this, the strategy and meansused in this thesis are proposed. Then, the design of hardware is introduced, the working principleand some matters need attention are focused on. Finally, a BMS is designed and verified. The mainwork of the thesis are as follows:(1) The advantages and disadvantages of some charge and discharge strategies, data acquiringand energy balancing means are analyzed in detail. Then, the strategy and acquiring means used inthis thesis are presented.(2) The batteries operating data are acquired, the voltage of the battery is measured bydifferential circuit, the current is measured by Hall sensor and temperature is measured by digitalthermometer. A charge management circuit which can charge the battery in constant current (CC),constant power (CP) and constant voltage (CV) mode and a electronic load which can discharge inCC mode are also designed.(3) Two balancing circuits respectively based on multi-winding Flyback converter and SelectFlyback converter are realized. The working principle, realization, advantages and disadvantages ofthese two circuits are analyzed. Peak current detection method is used to short the equalization timeof Select Flyback circuit which traditionally use fixed duty cycle control mode.(4) STM32is used as the microcontroller of the BMS, which has rich peripherals and firmwarelibrary. The internal ADC is used to acquire data of the battery. PWM control signals are generatedby the internal timer. CAN bus is used to connect data acquiring board and balancing board. Thesystem can also communicate with PC with RS232interface.The BMS presented in this thesis can manage the charge and discharge of the batteryefficiently, acquire the voltage, current and temperature data and especially balance the batteries toimprove the efficiency and prolong the life-span of the battery in two different ways. The two balancing strategies have the advantages of simple circuit structure, high efficiency and speed ofenergy transfer. In general, the BMS presented can meet the design requirement perfectly.