Position Sensorless Control of a Dual Three-Phase PMLSM for Electromagnetic Launch Based on the Linear Quadratic Regulator and Kalman Filter

Electromagnetic launch system has characteristics of high acceleration, intense vibration shock, and strong electromagnetic interference, which may damage the position sensor and interfere with signal processing, thus affecting both safety and stability of the system. To solve the aforementioned problems and reduce the system cost, one position sensorless control method via a reduced-order observer based on the linear quadratic regulator and Kalman filter (LQR-KF) is proposed for the dual three-phase permanent-magnet linear synchronous motor (DTP-PMLSM) adapted to electromagnetic launch in this article. The fast solution of Kalman gain in the LQR-KF observer is completed by the LQR, which can eliminate the higher order matrix operations in sensorless control based on the traditional extended Kalman filter, and greatly simplifies the computational effort. Compared to the traditional method, the observer order in the new algorithm can be obviously reduced by variable substitution of the nonlinear system, and the observed accuracy can be greatly improved by eliminating the need for Taylor series approximation of the nonlinear system. Comprehensive field-circuit coupling simulation and experiments based on a 480-kW DTP-PMLSM have fully demonstrated the simplicity and accuracy of the proposed method in this article.