Control of hybrid step motors via a simplified linearization technique

Abstract

In this paper, we propose a simplified linearization technique for control of hybrid step motors that is based on a tracking approach. Our controller consists of a current tracking controller and a torque controller. In particular, our torque controller contains a function which can be chosen freely under some constraints imposed by the physical limitation in stator currents. Any controller that can make the generated torque of a hybrid step motor linear to the torque command can always be represented by our torque controller with a specific choice of the free function. As an example for optimal choices of the free function, we present a method of determining the free function that gives minimal power loss due to stator resistance. We also present a method of obtaining the full dynamic model of a hybrid step motor. Prior works consider the special cases when the torque component due to variable reluctance is negligible or sinusoidal. Our results in this paper can be applied equally well to these special cases.