Crossed-feedback control of dual-redundancy permanent magnetic brushless dc servo system used in electro-hydrostatic actuator

Integrated electro-hydrostatic actuation system has the advantages of both small size and high power density. Dual-redundancy permanent magnet brushless DC motor (BLDCM) as the actuation component in electro-hydrostatic actuator (EHA) improves system reliability. But unequal electromagnetic torque in different redundant motor is a severe problem. It may impact the performance of the motor, even damage it. In this paper the cause and consequence of the unequal torque are deeply analyzed. A method of crossed-feedback control for realizing equal torque in dual-redundancy permanent magnetic brushless DC servo system is proposed. After analyzing different kind of redundancy running modes and structures of dual-redundancy motor, the system scheme is carried out. The hardware structure and control strategy of three closed loop of dual-redundancy EHA servo system for aircraft rudder are introduced. The implementation of the basic control circuits and devices are introduced too. Experiments show that the crossed-feedback control method can effectively eliminate torque unequal. The system frequency response can achieve 5 Hz, which can meets modern aircraftpsilas requirements to the actuation system, and it can be widely used in the future power-by-wire flight control system.