Thin resolver using the easy magnetization axis of the grain-oriented silicon steel as an angle indicator

Jisho Oshino,Ichiro Sasada

doi:10.1063/1.4977494

Abstract

A new type of thin resolver is presented, in which the easy axis of the magnetic anisotropy in the grain-oriented silicon steel is used as an angle indicator. The total thickness including a rotor, PCB coils and a back yoke can be made less than 4 mm. With a rotor of 50 mm diameter, a good linear response (non-linearity error &lt; 0.4%) between the mechanical angle input and the electrical angle output has been obtained. The influence of a weak magnetic anisotropy in the non-grain-oriented silicon steel used for the back yoke on the accuracy of the resolver can be deleted by the method proposed in this paper.

Highlights

Variable reluctance (VR) resolvers are widely used in electric vehicles (EV) and hybrid electric vehicles (HEV) to detect the rotor angle of motors for their control.[1,2]
A new type of thin resolver which is axial type and uses a circular grain-oriented silicon-steel (GO-SiFe) rotor, printed circuit board (PCB) coils and a back yoke has been proposed from our group,[4] in which an well-defined easy axis of the uniaxial anisotropy in the GO-SiFe is used as a direction indicator
It is interesting to note that the other channel of the quadrature dose not change much because of the 45 degree angle between neighboring coil sections and the easy axis giving the influence of the magnetic anisotropy to all the magnetic couplings

Summary

Introduction

Variable reluctance (VR) resolvers are widely used in electric vehicles (EV) and hybrid electric vehicles (HEV) to detect the rotor angle of motors for their control.[1,2] In the VR resolver, 2X type, and 3X or 5X type can be obtained by modifying the shape of the rotor, which is one of advantages of the resolver.[2]. A new type of thin resolver which is axial type and uses a circular grain-oriented silicon-steel (GO-SiFe) rotor, printed circuit board (PCB) coils and a back yoke has been proposed from our group,[4] in which an well-defined easy axis of the uniaxial anisotropy in the GO-SiFe is used as a direction indicator. A smaller diameter resolver, typically 50 mm, is preferable for automotive applications, for example, steering motor control In this case the back yoke should be prepared with inexpensive materials such as NGO-SiFe. there is a concern with the use of NGO-SiFe, that is, a weak magnetic anisotropy induced during rolling process of NGO-SiFe along the rolling direction may cause offsets in sinusoidal outputs and deteriorate the accuracy of the resolver. The dispersion of directions may affect the sensitivity and the accuracy, especially nonlinearity error in the input-output relationship

Methods

Results

Conclusion