Research on Phase Current Reconstruction and Fault-Tolerant Control for EMA Control Unit

During the whole-life service of the aviation electro-mechanical actuator, the current sensor may be faulty due to the manufacturing demerits or exposure to harsh operating conditions. In order to improve the fault tolerance capability of the system, a new three-phase current reconstruction method for Electro-Mechanical Actuator (EMA) control unit is proposed in this paper. Firstly, the limitations posed by the installation position of the DC-link current sensor on the traditional phase current reconstruction method are presented. In real applications, considering the DC-link current sensor is normally placed before the DC-link capacitor due to the utilization of busbar, the relationship between EMA DC-link current and phase current is analyzed in detail. Later, based on the above relationship, the phase current of EMA can be successfully reconstructed. With the reconstructed phase current, a fault-tolerant control method for EMA is also presented. Simulation and experimental results verify the effectiveness of the proposed method and the feasibility of the fault-tolerant control method. Compared to the conventional method, the proposed current reconstruction method reduces the dependency on the accuracy and rate of the DC-link current measurement. Besides, the proposed method shows a low computational burden and has practical engineering value.