电压型变频调速系统滤波电容介质损耗因数的监测

Monitoring of dielectric loss factor of filter capacitor in voltage-type variable-frequency speed control system

根据介质损耗因数对电容器进行故障诊断时需要准确提取同频率电压和电流信号的相位信息,而对于电压型变频调速系统而言,由于整流器及逆变电路会使直流侧滤波电容器外加电压、电流波形发生畸变,导致相位信息提取难度加大。为此,本文在同步采集滤波电容端电压和电流的基础上,使用加海明窗插值FFT算法计算电压、电流给定频率分量的相位,进而得出介质损耗因数。仿真分析及实验结果表明,所提出的监测方法具有较高的精确度以及较强的抗干扰能力。

Capacitor fault diagnosis by monitoring the dielectric loss factor needs to accurately extract the phases of voltage and current with the same frequency.For the voltage-type variable-frequency speed control system,waveforms of the applied voltage and current on the DC-side filter capacitor are distorted due to the interference of rectifier and inverter circuit,which makes it more difficult to obtain their correct phase information.On the basis of sampling the voltage and current of the capacitor synchronously,this paper uses Hamming window-interpolation FFT algorithm to calculate the phases of the components of voltage and current at the given frequency,then obtains the dielectric loss factor.Simulation and experimental results show that the proposed monitoring method has high accuracy and strong anti-jamming ability.