Indirect adaptive feedforward control in compensating cogging torque and current measurement inaccuracies for Permanent Magnet motors

Theoretically, if the inverse transfer function of the plant is known, feedforward control can achieve zero error between the reference and the output. The main aim of this paper is to design a simple feedforward model and to compensate for the errors brought about by a change in the cogging torque and current measurement inaccuracies. The reference position, speed and acceleration have been designed so that they can be used as inputs to the feedforward model. The feedforward model is a stable form of the inverse transfer function of the motor dynamics of a PM motor. MRAS technique has been used to compensate for changes to the cogging torque and current measurement inaccuracies. A successful indirect adaptive feedforward control has been designed for three different shapes of the back EMF (sinusoidal, trapezoidal and a mix of the first two shape using real motor back EMF) and the control scheme is validated through hardware experimentation.