This paper presents an open-circuit (OC) fault diagnosis method of three-phase voltage-source inverters (VSIs) for permanent magnet synchronous motor (PMSM) drive systems based on the hybrid system model (HSM). On the basis of phase voltage analysis, the HSM of the PMSM-inverter system was established, which can describe the system more accurately. To quickly diagnose whether the fault occurs, a current estimator was constructed based on the healthy HSM. Different fault types of the VSI can be simulated synchronously by the HSM, and the similarity between each simulated fault type and the actual one is evaluated based on the Euclidean distance method. Therefore, the fault isolation can be carried out according to the characteristics of Euclidean distances. The proposed method has the advantages of fast diagnosis speed and strong robustness, and it does not require additional sensors. By the presented diagnosis algorithm, the fault can be detected and isolated within a time interval about 5% and 10% of the current fundamental wave period, respectively. The simulation and experimental results verify the effectiveness of the proposed method.

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The fault estimation of robot joint is of great significance to improve the reliability and stability of robot joint. Based on the design of fault diagnosis observer and the finite frequency theory, a method of H infinite fault estimation with frequency domain is proposed. The design method combines H infinite filter wave with finite frequency technology effectively, and has strong anti-interference performance, Compared with other design methods, the method proposed in this paper can improve the accuracy of fault estimation