Non-magnetic Resolver Shielding Ring for Electric Machine Rotor Hub
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Solution Overview
Problem
Conventional rotor hub assemblies with resolvers experience unacceptable noise levels in resolver signals due to direct electromagnetic field coupling, necessitating additional signal processing steps.
Innovation Solution
An annular electromagnetic field barrier ring, constructed from non-magnetic materials like austenitic stainless steel, is positioned between the resolver rotor and the rotor hub to reduce electromagnetic field coupling, allowing direct mounting of the resolver rotor and minimizing signal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the resolver rotor is directly mounted to the rotor hub without electromagnetic field shielding, then the device complexity is reduced and manufacturing is simplified, but the resolver signals contain unacceptable noise levels due to direct electromagnetic field coupling
Solution Approach 1:
An annular electromagnetic field barrier ring is positioned between the rotor hub and the resolver rotor to shield the resolver from direct electromagnetic field coupling. This intermediary component blocks harmful electromagnetic interference while allowing the resolver rotor to remain directly mounted to the rotor hub, thus reducing device complexity while eliminating signal noise.
Solution Approach 2:
The electromagnetic field barrier is implemented as a thin annular ring structure that provides effective electromagnetic shielding. This thin-film approach achieves the required noise reduction without adding significant structural complexity or volume to the assembly.
2Measurement precision
If additional signal processing and filtering steps are added to conventional resolver systems to reduce noise, then the signal quality is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The electromagnetic field barrier ring converts the harmful electromagnetic interference into a beneficial shielding effect. By physically blocking the direct coupling between the rotor hub and resolver rotor, the system achieves high signal quality without requiring complex software-based signal processing or filtering algorithms.
Solution Approach 2:
The electromagnetic field barrier ring serves as a physical intermediary that eliminates the need for complex control steps and signal processing. The shielding ring handles the noise reduction function at the physical level, allowing the control system to process clean signals directly without additional filtering operations.
3Measurement precision
If the resolver rotor is positioned within the electromagnetic field of the machine rotor for direct measurement, then the measurement capability is improved, but electromagnetic interference increases signal noise
Solution Approach 1:
The electromagnetic field barrier ring provides localized electromagnetic shielding specifically at the region between the rotor hub and the resolver rotor. This local shielding approach maintains the resolver's ability to measure angular position within the electromagnetic field while selectively blocking harmful interference in the critical coupling region.
Solution Approach 2:
The annular barrier ring acts as an intermediary structure that allows the resolver rotor to remain positioned within the machine rotor's electromagnetic field for measurement purposes, while simultaneously blocking direct electromagnetic coupling with the rotor hub that causes interference.
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 EM field barrier ring effectively reduces signal noise in resolver signals, enabling more accurate motor control without the need for additional signal processing, by fully circumscribing the resolver rotor and providing magnetic isolation.
Implementation Method 1
The EM field barrier ring is configured to reduce the direct coupling of the electromagnetic field of the machine rotor from the resolver rotor to thereby reduce noise in the set of resolver signals
Data Source
AI summary
A hub assembly for an electric machine includes a rotor hub and a machine rotor. Rotation of the machine rotor generates an electromagnetic (EM) field. The hub assembly includes a resolver rotor that encodes an angular position of the machine rotor as a set of resolver signals. An EM field barrier ring between the resolver rotor and the rotor hub adds a magnetic barrier between the machine rotor and the resolver rotor to reduce noise in the resolver signals. The resolver rotor may be bonded to the EM field barrier ring. The EM field barrier ring may have an L-shaped cross section, and may be press-fitted into a pocket of the rotor hub. A vehicle includes a transmission having an input member and an electric machine having a rotor shaft connected to the input member of the transmission. The electric machine includes the hub assembly noted above.