Static Position Sensor Bias Fault Diagnosis in Permanent Magnet Synchronous Machines via Current Estimation

Rotor position sensor signal is a critical signal in a permanent magnet synchronous machine drive system. The alignment between the position sensor zero and the rotor quadrature axis must be accurately quantified for optimal torque generation under field-oriented control. However, the mechanical interfaces used for mounting the sensors are susceptible to failure due to environmental, manufacturing, and operational conditions resulting the position alignment to change from the previously calibrated value. In this article, a theoretical framework is presented that demonstrates the influence of the faulty static offset error in a position sensor of a permanent magnet synchronous machine and accordingly a diagnostic strategy is proposed to detect such failure mode. Both simulation and experimental results are provided to validate the theory and the diagnostic strategy. Theoretical analysis and simulations closely correlate with the experimental results. Furthermore, false positive prevention strategies for the fault diagnostic strategy are also discussed.