A generalized approach to the design of the speed control system for inverter-driven permanent magnet synchronous motor

Different types of control schemes have been suggested for variable speed AC drives fed from static power sources. Among them, field oriented control employing vector control strategies has become quite popular in recent years. A disadvantage of the scheme when applied to synchronous motor drives is that the motor always operates at a lagging power factor.In this work, a generalized design strategy is suggested for the speed control loop of an inverter-fed synchronous motor drive, in which, its inherent flexibility to generate the same torque for different combinations of currents, is exploited that can achieve more general types of control. Existing control schemes such as unity power factor control, torque angle control, as well as field-oriented control etc can be obtained as special cases. The scheme has been validated through extensive simulations as well as laboratory experiments.