Return to S. A. Bortoff's publication list.
Abstract: This paper considers nonlinear adaptive control of variable reluctance motors (VRMs) in a low-velocity, high-torque mode of operation. A simple dynamic model for the relationship between electric torque, rotor angular position, and phase currents is proposed. The model incorporates spline functions and a set of ``Fourier'' sinusoids, and captures several experimentally-verified VRM characteristics, including flux saturation effects. Based on this model, an adaptive controller is derived using the certainty equivalence principle. The controller provides asymptotic tracking of a desired rotor position trajectory. So-called ``torque sharing functions'' are employed to smooth the commutation among phases, and to increase the peak torque available from the motor, when compared to ``hard'' commutation that energizes only one phase at a time. Experimental results from a laboratory VRM provide motivation for the model, and illustrate the controller's design and trajectory tracking performance.