Condition Monitoring of DC-Link Capacitors by Estimating Capacitance and Real-time Core Temperature

Capacitor is the basic core component of power electronic converter, and it is also one of the components that are easy to be worn out. Monitoring the health state of the capacitor is helpful to improve the reliability of the converter. Capacitance is one of the commonly used degradation indicators for condition monitoring. Many methods for condition monitoring have been proposed by scholars, but some methods are too complicated and costly to be applied in reality. In this paper, a simple and non-invasive method is proposed. After estimating the capacitance value and measuring the case temperature, the core temperature can be estimated by using the proposed online estimation algorithm. No need to measure the inner temperature. Real-time estimation of the core temperature can provide important information for condition monitoring. Simulation results verify the feasibility of capacitance estimation, and the experimental results show that the proposed method has good accuracy.