基于PWM高频开关振荡的超级电容SOH在线监测

Online Monitoring of Supercapacitor SOH Using PWM High-frequency Switching Oscillations

超级电容的健康状态会直接影响其性能表现,因此对健康状态进行在线监测具有重要的意义。针对现有超级电容器健康状态在线监测技术存在的问题,如监测精度不高、容易过拟合及测量过程复杂等,提出一种基于PWM高频开关振荡的新方法。所提方法利用变换器在运行过程中由PWM开关电压自激产生的高频振荡电流,并采用快速傅里叶变换结合半功率带宽法来提取振荡信号中的固有频率和阻尼比特征,进而在线估计超级电容器的高频阻抗。通过预先标定高频阻抗与SOH之间的关系,可以实现对超级电容器SOH的准确量化。为了验证所提方法的可行性和有效性,构建了一个小型超级电容器储能试验系统。试验结果显示,该方法能够有效地监测到超级电容器SOH的变化情况,且具备安全性高、灵敏度好以及支持连续监测的优点。

The health status of supercapacitors is directly impacting their performance,making the online monitoring of their health status highly significant.In view of the issues existing in the current online monitoring technology for the state of health(SOH)of supercapacitors,such as low monitoring accuracy,ease of overfitting,and complex measurement process,a new method based on PWM high-frequency switching oscillation is proposed.The high-frequency oscillating current generated by the self-excitation of the PWM switching voltage during the operation of the converter is utilized.Fast Fourier transform(FFT)combined with the half-power bandwidth method is used to extract the natural frequency and damping ratio characteristics from the oscillation signal,enabling the estimation of the supercapacitor’s high-frequency impedance online.Through pre-calibration of the relationship between high-frequency impedance and SOH,the accurate quantification of the supercapacitor SOH is achieved.A small supercapacitor energy storage experimental system is constructed to verify the feasibility and effectiveness of this proposed method.The experimental results indicate that this proposed method can effectively monitor the changes in the supercapacitor SOH,and it possesses the advantages of high safety,good sensitivity,and support for continuous monitoring.