基于电驱系统高频注入的电动汽车电池包快速加热控制算法

Motor Drive System Based Battery Self-Heating for Electric Vehicles Using High Frequency Injection Frame

对锂离子电池进行低温加热是缓解其低温环境性能衰减的有效措施。该文从电动汽车整体架构出发,提出一种多周期偏置方波注入法,向电机d轴混叠注入直流电流与高频电压,使得电池母线端激励正负交变电流,该电流流过电池内阻产生焦耳热,实现电池自发热。所提控制方法,仅采用原有电驱系统硬件结构,在矢量控制基础上增加注入信号,实现方式简单,适配所有包含电驱系统的电动汽车。该文详细分析注入高频可在母线产生交变激励电流的原理,针对电池自发热目标,通过调节注入信号的频率与幅值,实现激励电流灵活可调。实验结果表明,所提控制策略能在电池侧有效激励交变电流,且幅值、频率可调。与理论分析一致。最后,搭建整车环境仓电池自发热平台,进一步验证所提方法在实际场景应用中的可行性。

The development of electric vehicles is significantly hindered by the substantial attenuation of available capacity and power in lithium-ion batteries at low temperatures,primarily due to the issue of lithium precipitation.Applying low-temperature heating to lithium-ion batteries represents an effective strategy for mitigating performance degradation under these circumstances.This paper considers the overall architecture of electric vehicles,wherein a multi-period offset-square-wave injection method is proposed.By injecting direct current and high-frequency voltage into the d-axis of the motor,a bipolar alternating current is induced in the battery bus,resulting in Joule heating through the battery’s internal resistance to achieve self-heating.The proposed method utilizes the existing hardware structure of the original electric drive system.It incorporates an injection signal into the basic vector control,offering a straightforward implementation approach suitable for all electric vehicles equipped with electric drive systems.The generation principle of alternating current in the DC bus from injected high frequency is analyzed.The relationship between the injected signal and the excitation current of the DC bus is analyzed.Finally,an experimental platform of a vehicle temperature chamber is introduced,and detailed parameters of the experimental motor and battery are listed The results show that the bus excitation current positively correlates with the injected direct current and high-frequency voltage amplitudes.Under the same injected direct current,a larger voltage injected amplitude results in a greater excitation bus current.Conversely,under the same voltage injection amplitude,increasing the injected direct current leads to an amplified excitation bus current.It is observed that an optimal point exists for the injection frequency.In this system,considering the maximum permissible root mean square(RMS)value of the high-voltage cable and the temperature rise in the electric motor,the injected direct current amplitude is set at−350 A,and the amplitude of the high-frequency square wave voltage is restricted to 25%of the maximum linear modulation voltage.The optimal frequency of 1.66 kHz has been determined.Consequently,the DC bus can generate an alternating current of 300 A RMS.The battery pack can be heated from−20°to−10°in 442 s with a temperature rise of 1.36°/min,significantly higher than traditional heating-film type external heating methods.In addition,the paper also examines the impact of temperature-induced changes in battery internal resistance on excitation current variations.The optimal operating point remains unaffected by changes in battery internal resistance,and an increase in temperature leads to a reduction in battery resistance and an increase in excitation current.Such an effect can partially mitigate the decreased battery self-heating capacity caused by reduced internal resistance.To sum up,the proposed battery self-heating method can seamlessly integrate into the field-oriented control(FOC)algorithm of electric drives in software implementation without changes to the system structure.Current close-loop control throughout the entire operational process ensures that the electric machinere mains torque-free during idle conditions and effectively maintains a vehicle standstill.