Redundant Resolver Tooth-Block Layout for Accurate Angle Detection
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Solution Overview
Problem
Existing redundant resolvers suffer from magnetic interference between excitation windings, leading to reduced accuracy of angle detection, and stacking resolvers in the axial direction increases the device size.
Innovation Solution
A redundant resolver design with independent excitation circuits and output windings for each system, where the stator is divided into tooth blocks, and the gap magnetic flux densities at tooth block ends are set to change mildly, reducing electrical angle second-order components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If teeth on which excitation windings of different systems are wound are adjacent to each other, then the device size is reduced, but magnetic interference occurs between different systems causing deterioration of angle detection accuracy
Solution Approach 1:
The stator is divided into M pieces (tooth blocks) in the circumferential direction, creating spatial separation between different systems. This segmentation prevents magnetic interference while maintaining a compact structure, as each system's excitation windings are located in distinct tooth blocks rather than adjacent positions.
2Reliability
If two resolvers are stacked on each other in the axial direction, then redundancy is achieved, but the dimension in the axial direction becomes twice as large
Solution Approach 1:
Instead of stacking resolvers in the axial direction (one dimension), the patent distributes multiple systems across different tooth blocks in the circumferential direction (another dimension). This dimensional transformation maintains redundancy while avoiding axial dimension increase.
3Ease of manufacture
If gap magnetic flux densities at end portions of tooth blocks change sharply, then the structure is simple, but electrical angle second-order components increase reducing angle detection accuracy
Solution Approach 1:
The patent applies different magnetic flux density characteristics to different locations: end portions of tooth blocks are designed to have mildly changing gap magnetic flux densities, while central portions can have different characteristics. This local differentiation reduces electrical angle second-order components without requiring complete structural redesign.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves the accuracy of angle detection by minimizing electrical angle second-order components, maintaining a compact size without increasing the axial dimension.
Implementation Method 1
among resolvers that make use of change in permeance at a gap between a rotor and a stator
Implementation Method 2
an excitation winding and two phases of output windings, the excitation winding and the output windings being wound on each tooth
Data Source
AI summary
The redundant resolver includes: a resolver body having a rotor, a stator opposed to the rotor and having Ns teeth arranged in a circumferential direction, and an excitation winding and two phases of output windings wound on the stator; an excitation circuit configured to supply power to the excitation winding; and an angle calculation unit configured to calculate a rotation angle on the basis of signals from the two phases of output windings. The stator is divided in the circumferential direction into M pieces which serve as M tooth blocks, N (M≥N) redundancy systems are formed on the basis of the M tooth blocks. The excitation circuit and the angle calculation unit are provided to each system so as be independent among the systems. Gap magnetic flux densities at both end portions of each tooth block are set to change mildly.