Open-Phase Fault Detection Method for Sensorless Five-Phase Induction Motor Drives with an Inverter Output Filter

The paper presents the sensorless five-phase induction motor drive implementation with an inverter output filter with third harmonic injection. For the sensorless operation, the required observers are presented for the first and third harmonics with consideration of the inverter output filter. Moreover, the interaction of the observers and the control system is capable to handle a deactivation of one or two phases, which improves the reliability of the complete drive system. A new idea of online open-phase fault detection is presented based on the frequency analysis of the estimated observer variables. The test setup, fault operation capabilities and an experimental verification of the proposed fault detection method are presented in the paper.