Speed Observer and Motion Controller Design for Permanent Magnet Synchronous Motors

Permanent magnet synchronous motorâ€™s (PMSM) three phase stator currents are decomposed into flux generating current and torque generating current using mathematical Park and Clarke transformations and decoupling methods, so that PMSM is controlled like DC motor with high efficiency and with high performance. PMSM is controlled cascaded control structure consisting of three main control loops which are current, speed and position control loops and current loop consists of two loops which are d current, related with flux, and q current, related with torque. One of the most important criteria whil e designing cascaded control loops is bandwidth. Control loop with higher bandwidth means, lower settling time that defines how fast control is occur. While designing control loops with desired bandwidth, small overshoot is acceptable for current loop; However, overshoot and steady state error for position control loop and for speed control loop are undesirable. Moreover, for low speed application speed observer is necessary, since incremental encoder resolution is decreased in low speed control. According to mentioned problems and design criteria, in that paper it is described that current loop with state feedback decoupling, PID controller with pseudo feedback derivative current controller design, speed control loop with approximate first order transfer function using PI controller with no overshoot and no steady state error, proportional (P) position controller guaranteeing no overshoot in desired bandwidth and that PID liked full order speed observer with approximated first order transfer function.Controllers and observer designs are simulated in Matlab Simulink Keywords- PMSM, Motion Control, Cascaded Control, Pseudo Derivative Feedback, State Feedback Decoupling, Bandwidth, Speed observer, Speed Control with no overshoot.