A new approach to feedback-linearizing control of variable reluctance motors for direct-drive applications

Abstract

Considers feedback-linearizing control of VR (variable reluctance) motors which have been increasingly used in high performance direct-drive applications. The authors characterize all torque controllers that can make the total torque of a VR motor linear to torque command but without torque ripple. The torque controllers maximize the range of torque commands which are admissible under the physical limitation in stator currents. The whole class of all such torque controllers is parameterized in the explicit form which contains a function to be chosen freely. This free function can be used to achieve other control objectives as well as linear dynamic characteristics. As the examples for optimal choices of the free function, are actually determine two optimal free functions, one for minimal rate of change in current commands and the other for minimal power loss due to stator resistance. To illuminate further the practical use of their torque controllers, the authors present some experimental results for the case of a commercially available VR motor.