Parametric Fault Diagnosis Of Power Electronic Circuit Based On Hybrid System Theory

With rapid development of power electronic technology, power electronic devices have been applied widely in industry area. Playing roles as controllers or power supplies, the stability of power electronic devices make the assurance of continuous production. Severe fault of power electronic devices can even paralyze the whole system. Therefore, in order to improve reliability and maintainability of power electronic system, researches on fault diagnosis of power electronic circuits is essential.This paper presents an approach to parametric fault diagnosis of power electronic circuits. Based on the structure and working method of power electronic devices, the equivalent model for actual circuit application and degradation mechanism is analyzed. Diagnosis targets include electrolytic capacitor, power MOSFET, power diode and other power electronic components. The parameters of these components can be identified by using least square algorithm via a general modeling method of power electronic circuits based on the theory of hybrid dynamical systems. A multi-channel and high speed data acquisition system is designed for the parameter identification of power electronic circuits. This approach is verified by diagnosis of aluminum electrolytic capacitor in a three-phase rectifying circuit.Besides, with the purpose of improving the reliability of the system, a method to realize the pre-diagnosis is discussed based on the analysis of the trend of ESR with time.