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）进行仔细的测量和管理，以实现高性能、安全运行，并准确报告充电状态（SOC）和健康状态（SOH）。每种锂离子电池的化学性质和格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、工作模式（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，但安全操作。从历史上看，这是通过在精心控制的实验室空气热室环境中测试锂离子电池来完成的，在电池温度几乎均匀的低速率下产生合理的结果。然而，新的电池应用和系统设计使得这种方法不太准确，因为两个原因：(1)在超快充电速率下，电池温度会大大偏离热室，并且在整个电池中变得不均匀；(2)先进的热调节系统（例如将电池浸入介电冷却油中）具有比空气热室更大的热对流和导热能力。该项目将开发新的测试方案和设备，以比较和对比在等温单元、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入式热管理系统。这项技术研究将使充电速度更快的电动汽车在加拿大这样的寒冷气候中表现更好。

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.