Asymmetric Redundant Resolver Layout for Accurate Angle Detection

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Solution Overview

Problem

Redundant resolvers face accuracy deterioration in angle detection and increased axial dimension when attempting to achieve redundancy, with existing solutions either compromising accuracy or significantly increasing size.

Innovation Solution

A redundant resolver design with a rotor having Nx salient poles and a stator with Ns teeth, where excitation and output windings are wound on Nsm main-system teeth and Ns-Nsm sub-system teeth, utilizing separate computation units for each system to enhance angle detection accuracy without increasing size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the stator is divided into two equal systems with equal number of teeth, then redundancy is achieved, but the accuracy of angle detection deteriorates

Engineering Contradiction:

ImproveredundancyVSAvoidaccuracy of angle detection

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The stator is segmented into two distinct systems (main system and sub-system) with different numbers of teeth. The main system uses Nsm teeth while the sub-system uses Ns-Nsm teeth, where Nsm > Ns-Nsm. This asymmetric segmentation allows the main system to maintain higher angle detection accuracy while the sub-system provides redundancy capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies asymmetry by intentionally making the number of teeth in the main system (Nsm) greater than the number of teeth in the sub-system (Ns-Nsm). This asymmetric distribution optimizes the main system's angle detection accuracy while still providing functional redundancy through the sub-system, resolving the contradiction between equal division for redundancy and unequal division for accuracy.

Inventive Principle:

Principle #4Asymmetry

2Reliability

If two resolvers are stacked in two layers, then redundancy is achieved, but the dimension in axial-line direction doubles

Engineering Contradiction:

ImproveredundancyVSAvoiddimension in axial-line direction

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent merges two resolver systems (main system and sub-system) into a single shared physical structure. Both systems utilize the same rotor and stator assembly, with windings wound on the same teeth or adjacent teeth. This merging approach achieves redundancy while maintaining a compact axial dimension equivalent to a single-system resolver.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single resolver structure serves multiple functions by implementing both main system and sub-system within the same physical components. The stator teeth and rotor structure are universally utilized by both systems, allowing one physical resolver to provide dual-system redundancy without doubling the axial dimension.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The solution improves angle detection accuracy by setting the number of main-system teeth to be larger than half the total teeth, maintaining a compact size equivalent to single-system resolvers while ensuring redundancy and accuracy.

Implementation Method 1

a rotor having Nx (Nx is a natural number) salient poles, a stator facing the rotor and having Ns (Ns is an integer equal to or larger than 3) teeth arranged in a circumferential direction, and an excitation winding and two phases of output windings wound on each tooth

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

among resolvers that make use of change in permeance at a gap between a rotor and a stator

Methodology Applied

Scientific EffectMagnetic permeance variation: Magnetic Field

Data Source

PatentUS12163809B2Redundant resolver and electric power steering device equipped with redundant resolver

Publication Date: 2024.12.10 MITSUBISHI ELECTRIC CORP

AI summary

A resolver body including a rotor having Nx (Nx is a natural number) salient poles, a stator facing the rotor and having Ns (Ns is an integer equal to or larger than 3) teeth arranged in a circumferential direction, and an excitation winding and two phases of output windings wound on each tooth; and an excitation circuit configured to apply voltage to the excitation winding. The excitation winding and the two phases of output windings wound on each of Nsm (Nsm is an integer equal to or larger than 2) teeth among the Ns teeth are set to be of a main system. The excitation winding and the two phases of output windings wound on each of Ns-Nsm teeth are set to be of a sub-system. The number Nsm of the teeth corresponding to the main system is larger than the number Ns-Nsm of the teeth corresponding to the sub-system.