This article presents a frequency-variable resonant self-heating technique for improving the heating speed of lithium-ion batteries at very low temperatures. In contrast to the conventional heating method with a fixed current and frequency, the proposed technique can increase the battery heating current by determining the minimum impedance of the lithium-ion batteries. Then, through a variable charging/discharging frequency operation, this technique can increase the heating speed without inducing a temperature plateau because of impedance reduction. A lithium-ion battery with improved self-heating performance at low temperatures was developed and used to verify the proposed self-heating technique. A simulation model and self-heating device (dc/dc converters) were also designed and tested at –30-°C ambient temperature. The proposed frequency-variable resonant self-heating technique achieved a heating speed four times faster (from 2784 s to 717 s) than the conventional self-heating technique. Thus, lithium-ion batteries can be used at cryogenic temperatures (–30 °C) by quickly raising the battery temperature with this technique.

中文翻译：

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低温下锂离子电池变频谐振自热技术

本文提出了一种变频谐振自加热技术，用于提高锂离子电池在极低温度下的加热速度。与具有固定电流和频率的传统加热方法相比，所提出的技术可以通过确定锂离子电池的最小阻抗来增加电池加热电流。然后，通过可变充电/放电频率操作，该技术可以提高加热速度，而不会因为阻抗降低而导致温度平台。开发了一种在低温下具有改进的自热性能的锂离子电池，并用于验证所提出的自热技术。还设计了一个仿真模型和自热设备（dc/dc 转换器），并在 –30°C 环境温度下进行了测试。所提出的变频谐振自加热技术的加热速度比传统的自加热技术快四倍（从 2784 秒到 717 秒）。因此，通过使用这种技术快速提高电池温度，锂离子电池可以在低温（–30°C）下使用。