High power battery characterization for parameterization of battery management systems

锂离子电池必须由电池管理系统(BMS)仔细测量和管理，以实现高性能、安全运行和准确报告荷电状态(SOC)和健康状态(SOH)。每种锂离子电池的化学成分和形式都具有独特的电压、电流和热响应特性，这些特性是SOC、温度、操作模式(充电、放电或待机)、速率(电流)和退化(容量损失和/或内阻增长)的函数。因此，必须详细测量每种锂离子电池类型以确定其特性，以便对BMS进行编程，以实现电池组的高性能和安全运行。从历史上看，这是通过在精心控制的实验室空气基热室环境中测试锂离子电池来实现的，在电池温度几乎一致的低速率下可以产生合理的结果。然而，新的电池应用和系统设计使这种方法变得不那么准确，原因有两个：(1)在超快充电速度下，电池温度可能会大幅偏离热室，并且在整个电池和整个电池中变得不均匀，(2)先进的热调节系统(例如，将电池浸入介质冷却油中)具有比空气基热室更强的热对流和传导能力。该项目将开发新的测试方案和设备，以比较和对比等温单元、空气热室测试中电池测试的保真度和准确性，并将这些结果转化为实际的液体和浸没式热管理系统。这项技术研究将导致电动汽车充电速度更快，在加拿大这样的寒冷气候下表现更好。

Lithium ion batteries must be carefully measured and managed by the battery management system (BMS) to achieve high performance, safe operations, and accurate reporting of the state of charge (SOC) and state of health (SOH). Each lithium ion cell chemistry and format have unique voltage, current, and thermal response characteristics that are a function of SOC, temperature, operating mode (charge, discharge, or standby), rate (current), and degradation (capacity loss and/or internal resistance growth). Consequently, each lithium ion cell type must be measured in detail to determine its characteristics so as to program the BMS for high performance, but safe operation, of the battery pack. Historically, this has been accomplished by testing lithium ion cells in carefully controlled laboratory air-based thermal chamber environment, which produces reasonable results at low rates where the cell temperature is nearly uniform. However, new battery applications and system designs render this method less accurate because of two reasons: (1) at ultrafast charging rate the cell temperature can deviate substantially from the thermal chamber and also become non uniform throughout and across the cell, and (2) advanced thermal conditioning systems (e.g. immersing the battery in dielectric cooling oil) have much greater thermal convection and conduction capabilities than air based thermal chambers. This project will develop new test protocols and equipment to compare and contrast the fidelity and accuracy of battery testing in isothermal units, air thermal chamber testing, and translate those results practical liquid and immersion style thermal management systems. This technology research will lead to faster charging electric vehicles that perform better in cold climates like Canada.