Design strategies for speed control of an inverter fed permanent magnet synchronous motor drive

Permanent magnet synchronous motor (PMSM) drives are becoming more popular and replaces DC and Induction motor drives in industrial applications like rolling mills, home appliances, transport systems, robotics and factory automation, hybrid eclectic vehicles etc. Various control schemes are suggested in the literature 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 PMSM drives is that the motor always operates at a lagging power factor. In this paper, a generalised design strategy for speed control loop of an inverter fed PMSM drive is suggested. In this design for different combinations of currents, same torque can be generated, which leads to more general control scheme. The closed loop control system for PMSM drive is simulated using MATLAB. The performance figures of various cases such as internal p.f angle control, torque angle control and field oriented control can be obtained and verified through simulation for different power factors of the motor ranging from lagging to leading through unity.