Lithium-ion (Li-ion) batteries endure substantial energy loss and power recession under cold environments, requiring to be heated before starting normal operations in electric vehicles (EVs). Currently, many internal ac heating approaches powered by batteries have been proposed to achieve a fast heating speed, high efficiency, and good uniformity. However, due to the bulky size, high cost, and low ac heating frequency, the existing ac heating devices are generally improper for EV applications. In the light of this, a compact high-frequency heater is proposed in this article to achieve effective self-heating for Li-ion batteries. Specifically, based upon the resonant switched capacitors (RSCs), this heater is only powered by the on-board battery pack, leading to an easy implementation. Detailed analytical expressions of the heating current and efficiency are deduced and validated through various experiments. Illustrative results demonstrate that the proposed RSC heater is capable of effectively realizing battery self-heating without using external devices. Particularly, a reliable tradeoff between the fast heating speed (2.67 °C/min) and high efficiency (96.4%) is obtained by using two or more parallel-connected heaters. Due to the compact size, low price, high efficiency, and good reliability, the proposed heater can be also extended to preheat batteries of unmanned aerial vehicles, robots, phones, etc.

中文翻译：

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一种用于锂离子电池低温自热的紧凑型谐振开关电容器加热器

锂离子 (Li-ion) 电池在寒冷环境下承受大量能量损失和功率衰退，需要在电动汽车 (EV) 开始正常运行之前进行加热。目前，已经提出了许多由电池供电的内部交流加热方法，以实现加热速度快、效率高和均匀性好。然而，由于体积庞大、成本高、交流加热频率低，现有的交流加热装置普遍不适用于电动汽车应用。鉴于此，本文提出了一种紧凑型高频加热器，以实现锂离子电池的有效自加热。具体而言，基于谐振开关电容器 (RSC)，该加热器仅由车载电池组供电，因此易于实施。通过各种实验推导出并验证了加热电流和效率的详细分析表达式。说明性结果表明，所提出的 RSC 加热器能够在不使用外部设备的情况下有效地实现电池自加热。特别是，通过使用两个或多个并联的加热器，在快速加热速度 (2.67 °C/min) 和高效率 (96.4%) 之间实现了可靠的折衷。由于体积小、价格低、效率高、可靠性好，所提出的加热器还可以扩展到无人机、机器人、手机等的电池预热。通过使用两个或多个并联的加热器，在快速加热速度 (2.67 °C/min) 和高效率 (96.4%) 之间取得了可靠的平衡。由于体积小、价格低、效率高、可靠性好，所提出的加热器还可以扩展到无人机、机器人、手机等的电池预热。通过使用两个或多个并联的加热器，在快速加热速度 (2.67 °C/min) 和高效率 (96.4%) 之间取得了可靠的平衡。由于体积小、价格低、效率高、可靠性好，所提出的加热器还可以扩展到无人机、机器人、手机等的电池预热。