Online Monitoring of DC-Link Capacitor in Accelerator Pulsed Power Supply

Most magnet power supplies of Lanzhou heavy ion accelerators cooling storage ring are switch mode power supplies, operating in the mode of high pulsed current and high-precision. There are a large number of capacitors with various levels. The reliable operation of capacitors is very crucial for the reliability and stability of power supply. Based on the impedance frequency characteristics of capacitor and the FFT algorithm, this study extracts capacitor voltage and current at specific frequencies, enabling online monitoring of ESR and capacitance values. A 400 V, 10000 μF electrolytic capacitor is taken as an example to evaluate the ESR on different current conditions, and the ESR parameter of the capacitor is measured by an LCR meter. The error between the monitoring results and the measurement results is within 5%, which verifies the effectiveness of the method. The proposed method is also applicable to thin film capacitor, which helps to improve the reliability of capacitor operation and achieve efficient and predictable maintenance.