Speed and current control of a permanent-magnet DC servo motor using a real-time microcontroller

This paper presents the digital implementation of a double-loop feedback controller for speed and current regulation on a permanent-magnet direct current servo motor based on the real-time microcontroller TMS320F28335. The topology of the controller is based on a cascade control scheme; the speed controller (external loop) sets the reference of the current controller (internal loop). In this way, a high performance on the servo drive can be obtained. A online tuned Proportional-Integral controller regulates the speed reference, the armature current is regulated using a hysteresis controller. In order to make comparisons a single topology speed controller (one control loop) and cascade topology speed and current controllers (double control loop) are digitally implemented. Simulation results are validated by practical experimentation. Electrical drive and sensor platform were developed for the tests. Additionally a data acquisition system is proposed.