Reliable Open-switch Fault Localization Scheme in Multiple Switches for Inverter-fed Permanent Magnet Synchronous Machine Drives

To improve the reliability of a pulse width modulation inverter-fed permanent magnet synchronous machine drive under open faults in multiple switches, this paper proposes an on-line open-switch fault localization scheme. An open-switch fault which often leads to secondary damage in the entire system arises due to accidental overcurrent as well as electrical and thermal stresses. Especially, the open fault in multiple switches occurs in various types of combination, which prevents a fault localization algorithm from operating reliably. To alleviate the complexity in diagnosis algorithm, this paper classifies the open faults into different categories, which enables the diagnosis algorithm to handle and identify multiple failures in switching devices in more straightforward and systematic way. The decision-making process is simple and easy due to unique fault characteristic in each group. In the proposed scheme, the fault group is simply identified from only non-zero phase current information by using the moving window-based signals instead of the entire electrical periodic data. The proposed scheme detects a fault as well as faulty switches by on-line basis without additional hardware. It is not only immune to false alarms due to inexact detection, but also independent of operating conditions. The practical usefulness of the proposed scheme is verified through the simulations and experiments.