Modelling and experimental studies of an instantaneous torque and field weakening control scheme for an interior permanent magnet synchronous motor drive

For interior or buried permanent magnet motors, the back emf and inductances are usually non-sinusoidal functions of time which causes torque pulsations in operation at low speed. This paper presents an instantaneous torque control scheme of interior PM motor drive for both constant torque and field weakening operations, considering the limits of the available dc link voltage and current ratings of a given inverter. A scheme for the compensation of the cogging and ripple torques of this type of motors is also proposed and tested.