At present, the PID control based on classical control theory is widely used in the control strategy of AC servo system. PID controller has low order, and designs simply, but it has its own limitations. In recent years, many scholars have researched state feedback control based on modern control theory, this method considers performance optimum ,energy optimum and other factors, which can meet design requirements of servo system.This paper takes the classic second-order model of the servo system as the controlled object, and designs an LQR optimal output feedback controller based on internal model and state observation for the system, and compares the effectiveness with traditional PI controllers. Finally, this article discretizes the controller and verifies the results in a real servo system.

LRQ,State observation,Internal model principle,Electric machine control