Application of two-phase VSC with integral compensation in speed control of a PM synchronous servomotor

Permanent magnet (PM) synchronous servomotors have been widely used as actuators for motion control because of their high torque-to-weight ratio, high efficiency, and because they require less maintenance but simple circuits. However, it is well known that the performance obtained by traditional controllers are sensitive to parameter variations or encounter problems associated with impact load disturbances on the plant. The object of this paper is to describe the control performance of a two-phase variable structure control (VSC) and the VSC with integral compensation (IVSC) for the speed control of the PM synchronous servomotor drive system. Moreover, a modified two-phase IVSC (MIVSC) is developed by utilizing the merits of both VSC and IVSC so that the control system has fast motion without overshoot in transient response and zero steady-state error. Simulation and experimental results show that the control characteristics of the two-phase VSC, IVSC and MIVSC are quite effective in both command tracking and load regulation.