Position Fault Detection for UAM Motor with Seamless Transition

Abstract

A strict fault tolerance is required in urban air mobility (UAM). The motor position sensor is one of the monitoring targets in UAMs, because it is in a harsh environment such as rain, ice, dust, vibration, etc. In this work, a resolver-based sensor method and a sensorless algorithm are fused in cooperative mode. Under normal conditions, the sensored angle and the sensorless angle are weighted equally. However, in case of sensor failure, only the sensorless method is selected. In other cases, only the sensored angle is fully respected. It is assumed here that the sensored method as well as the sensorless method may fail. To determine which of the two methods is faulty, the measured current is used as a reference. The virtual current is obtained by numerically solving the permanent magnet synchronous motor (PMSM) model in the stationary frame using the rotor angles. The position fault is then detected by comparing the virtual current to the measured current. Sigmoid functions with a step at zero are used for fault detection and fusion method robust against sudden error fluctuations or noise. Convincing performance and robustness are demonstrated by simulation and experimental results.