Dynamic Performance Analysis of Self-Controlled Synchronous Motor Speed Control Systems

The dynamic performance of speed control systems containing a self-controlled synchronous motor is analyzed in detail considering two practical types of position sensor used in this motor. The dynamic responses of a basic speed control system with a speed feedback loop are first analyzed for the case when the speed reference signal is stepped up. It is shown that the system is apt to become unstable when an armature voltage sensing type position sensor is used. Then it is clarified that this drawback is improved greatly by introducing a current feedback loop in the system. Finally the dynamic responses of a speed control system with a margin angle control loop are analyzed, and a method of securing safe commutation of the inverter during transients is proposed.