Research And Development Of Distributed Battery Management System

With the development of new energy vehicles, hybrid vehicles, pure electric vehicles need to have appropriate power battery and battery management system. Battery management system manage single cells and battery pack, namely, Condition monitoring and operation management of the battery pack, including the battery voltage, temperature, current, SOC, cell balancing, battery fault diagnosis, healthy state of single cell analysis and high-voltage protection.This paper studies the Lithium Iron Phosphate battery management system based on the JMC Transit type electric car, make theoretical analysis and experimental studies on the charge and discharge characteristics of lithium iron phosphate battery, then combined with power battery applications working conditions, design and develop a distributed battery management system The main contents and results are as follows:1. Design and develops a distributed battery management system which use Freescale MCU as the control center based on theoretical analysis of single battery charge and discharge performance and battery of group technology. The System uses high and low speed CAN bus structure, to achieve the system architecture of the distributed network. The system consists of data acquisition module, high-voltage protection module, balanced module, the main control module.2. Design the hardware circuit of the acquisition module. The module can detect a variety of operating parameters and status of the power battery, Including single voltage, single temperature, single-channel current, according to the commands of the master module to achieve the control of active equalization module front-end equalizer switch array. And send critical data to the main control module via the CAN bus in real time.3. Research and develop the high-voltage protection module. The module can detect the total current and voltage of the battery pack, the total voltage of the motor terminals, and vehicle insulation resistance in real time. And achieve real-time power calculation of the battery pack. And then complete the life-cycle management of key vulnerable devices in the high-voltage protection module.4. Analysis and research various battery equalization scheme, improve The Design of lossless equalizer circuit, Developed fast high-current balancing module,, it can perform the balance control commands from the master control module, It can make a charge and discharge balanced on any one single battery, be able to achieve higher efficiency of the battery balancing.5. Install the battery management system developed in this paper in the Transit electric car. To fully test the voltage and current acquisition accuracy, insulation resistance measurement accuracy, the SOC estimate accuracy, the efficiency of the balanced module, dual CAN bus communication reliability of the system. The results show that:The data error of the battery management system within the scope of design requirements. Its various functional modules are stable and reliable, meet the design requirements.