Position control of PM linear motors for fault-tolerant actuation

This paper studies the control of two-phase permanent magnet linear motors for high performance and fault tolerant systems in steer-by-wire applications. The modelling of tubular AC motors used in the study is presented, and control development and evaluation are provided. The system consists of three main control elements - an inner current loop to control the output force, an outer loop to control the position of the motor sliders and a condition monitoring unit to detect possible fault conditions and take corrective actions. The performance and fault tolerance issues for the individual 2-phase actuators and the whole system are also discussed.