Maximum torque control of servo motor for wide speed range

Based on the mathematical model and current control theory of surface mounted servo motor, this paper presents a novel combined current control algorithm, aiming to achieve the maximum torque output in wide speed range. Through the combination of different current control algorithms, the full utility of voltage and current limits as well as the demagnetizing limit of permanent magnet, the capability of output torque at high speed is enhanced and the scope of high-speed operation is expanded. In this paper, the rules how these performance properties such as output torque, power, power factor, demagnetizing coefficient and efficiency affected by speed under different current control algorithms were examined both in simulation and experiment, which proved that with this algorithm the maximum torque and output power can be obtained in wide speed range. It also has the advantages of simple structure, easy work-up procedure, and wide application in high speed machine tool servo system.