H∞ control of permanent magnet linear motor in transportation systems

A robust H
_∞
controller for permanent magnet linear motor (PMLM) in transportation systems is designed in this paper. First, the state space equations of the motor are established. Then the H
_∞
control theory is applied to design a robust controller which allows mass variation of the moving part ranging from 0 to 100 percent of nominal load. The simulation and experimental results show that the system can achieve robust performance under either no load or nominal load.