H∞ speed control of an induction motor with the two-mass resonant system by LMI

In industrial motor drive systems, a shaft torsional vibration is often generated when a motor and a load are connected with a flexible shaft. This paper treats the vibration suppression control of such a system. In this paper, a control system design method using linear matrix inequality (LMI), which is a tool for control design that replaces or complements Lyapunov-Riccati equations, is provided and the H_∞ speed controller for an induction motor by LMI is proposed. In the H_∞ speed controller, weights are used to satisfy tracking and disturbance rejection. Experimental results show the validity of the proposed H_∞ speed controller by LMI, and this controller is compared with the state feedback controller