High power battery characterization for parameterization of battery management systems

锂离子电池必须通过电池管理系统（BMS）进行仔细测量和管理，以实现高性能、安全运行以及准确报告荷电状态（SOC）和健康状态（SOH）。每种锂离子电池的化学性质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，以便为电池组的高性能但安全操作对BMS进行编程。历史上，这是通过在仔细控制的实验室空气热室环境中测试锂离子电池来实现的，这在电池温度几乎均匀的低速率下产生合理的结果。然而，由于两个原因，新的电池应用和系统设计使得该方法不太准确：（1）在超快充电速率下，电池温度可基本上偏离热室并且也在整个电池中变得不均匀，和（2）先进的热调节系统（例如，将电池浸入电介质冷却油中）具有比基于空气的热室大得多的热对流和传导能力。该项目将开发新的测试协议和设备，以比较和对比电池测试的保真度和准确性，在等温单元，空气热室测试，并将这些结果转化为实际的液体和浸入式热管理系统。这项技术研究将导致更快的电动汽车充电，在加拿大等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.