Algorithms for dual-zone control of a permanent-magnet synchronous motor

The article is aimed at extending the speed range of a permanent-magnet synchronous motor in the main-motion electric drive of a machine tool (while maintaining the power characteristics). In this work, the electric drive of a permanent-magnet synchronous motor was mathematically modeled using the SimInTech software. As input data for modeling, the following DC motor parameters were used: nominal power of 2.2 kW, voltage of 315 V, speed of 1500 rpm, energy conversion efficiency of 90.5%, and nominal current of 6 A. An algorithm for controlling the electric drive was developed to include two control zones: zone of maximum power and increased speed zone. It is shown that in the maximum power zone, the nominal characteristics are maintained, while in the increased speed zone, an increase in motor speed of up to two times is achieved in the main-motion electric drive of the machine tool without a decrease in its power characteristics. Numerical experiments were conducted, as well as an analysis comparing the control algorithm and conventional control methods, which confirmed the theoretical values. The modeling results showed that with the control of permanent-magnet synchronous motors, the power consumption of a control system in the second zone does not exceed the nominal values. Thus, the developed system for controlling permanent-magnet synchronous motors provides effective control over the main-motion electric drive of a machining tool that demonstrates improved performance in machining materials made of low-hardness metals. The present study is of practical importance for industries in which increasing motor speed in machine tools constitutes an important factor in improving capacity and reducing machining time.