Robust optimal control of Externally Excited Synchronous Machine based on passivity theory

Efficient utilization of the power supply in Electrical Drive Systems (EDS) is a subject of interest and vast research. Nonetheless, the design of EDS aims to be robust to rough operating conditions and provide high performance. The Externally Excited Synchronous Machine (EESM) has become a cheaper alternative solution over the permanent magnet synchronous machine especially in Hybrid and Electric Vehicles (HEV). This is partially due to higher material availability and partially due to comparable performance. EESM are highly coupled and non-linear processes which require complex control structures. To this end the paper proposes a robust optimal control strategy of EESM based on the principles of passivity theory. The design of the currents controllers starts from the Euler-Lagrange mathematical model of the EESM which is the basis of the Passivity Based Control (PBC) strategy. In the speed control loop a Linear Quadratic Regulator (LQR) is employed. We prove through simulation results that the proposed algorithm has better performances in contrast with the strategy based on PI algorithm. Moreover, the proposed method shows a better robustness to variations of parameters.