High Voltage Power Sensing Measurement System Of Electric Vehicle

The power measurement is a technical bottleneck in the development of electric vehicles,it requires accurate measurement of the voltage,current and temperature,which is used for battery management system(BMS)to estimate parameters such as the state of charge(SOC)of the battery and the state of health(SOH)of the battery.The estimations of the SOC and the SOH are important for the optimization of battery performance.As the voltage of the power battery in electric vehicles become higher and higher,the requirements of isolation withstand voltage,measurement accuracy,temperature adaptation range for power measurement become getting stricter.Usually,the power measurement module is designed integrated with the BMS,but the power measurement involves high voltage and high current signals,which may cause interference and damage to the low voltage system.Therefore,separating the high-voltage power measurement module from BMS has become a trend.Physically,high-voltage power measurement module is installed in Battery Distribution Unit connected to battery packs.Among them,the measurement signal path is minimized.In this paper,a high-voltage power sensing measurement system independent of BMS is designed for application in electric vehicle.The system collects the battery power data through a high-precision digital-to-analog converter(ADC),a current sensor,and a digital temperature sensor.Then the data signal acquisition is processed by digital filtering before transmitted to the main control unit of BMS via CAN bus.The system can not only improve the measurement accuracy of the power data,but also provide reliable power data for the BMS,so as to accurately estimate the parameters such as the SOC and SOH of the battery.Meanwhile,the reliability of the BMS can be enhanced.Specifically,the main research contents of this paper contain three aspects.Firstly,the background and significance of the research are introduced,and the domestic and foreign research present situation and development trends.On this basis,the content of this paper is clarified,the specific functions and design schemes of the system are put forward,and the measurement principles of current,voltage and temperature are studied and analyzed.Secondly,the hardware and software of the system are designed.In the aspect of hardware,the circuits of voltage measurement,current measurement,temperature measurement and system communication are designed,mainly including the selection of components involved in the circuit,circuit schematic design,printed circuit board(PCB)and welding debugging.In terms of software,it mainly includes design software of the sensor for voltage,current,temperature and the CAN bus communication module.The power data can be displayed on the LCD screen of the data receiving board and the upper computer in real time.Finally,the system is tested and the tested data are analyzed.The results show that the function and performance of the system meet the requirements of the design,and can meet the requirements of electric vehicle for high voltage power measurement.