Resolver Mounting Structure for EMI Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Variable reluctance resolvers in electric machines, such as those used in hybrid vehicles, are susceptible to performance degradation due to excessive electromagnetic interference (EMI), which affects the accuracy of rotational position and speed determination.
Innovation Solution
A mounting structure with a low magnetic relative permeability is used to isolate the resolver rotor from the rotating hub, preventing direct contact and thereby reducing EMI interference. This structure includes an annular mounting structure, such as an L-shaped sleeve and annular plate, made from materials like stainless steel, which circumscribes the rotating member and has a magnetic relative permeability of no greater than about 2, while the rotating member has a permeability of at least about 50, ensuring effective magnetic isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resolver rotor is directly mounted on the rotating hub, then the mounting structure is simple, but electromagnetic interference degrades resolver performance
Solution Approach 1:
A mounting structure with low magnetic relative permeability (μr ≤ 2) is introduced as an intermediary between the rotating hub and the resolver rotor. This mounting structure acts as a magnetic mediator that prevents direct magnetic flux transfer while still providing mechanical support, thereby reducing electromagnetic interference and improving resolver performance without requiring complete structural redesign
2Object-affected harmful factors
If a mounting structure with low magnetic permeability is used to isolate the resolver rotor, then electromagnetic interference is reduced, but the magnetic isolation effectiveness may be insufficient
Solution Approach 1:
The mounting structure is constructed from composite or specially selected materials with specifically controlled magnetic relative permeability (μr ≤ 2), such as non-magnetic alloys or composite materials combining non-magnetic substrates with magnetic shielding layers. This composite material approach enables simultaneous achievement of low magnetic permeability for EMI reduction and sufficient mechanical strength for reliable mounting
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 effectively limits EMI interference, enhancing the performance and accuracy of resolver operations by preventing direct magnetic flux transfer and electrical current induction, thus improving the reliability of rotational position and speed measurements.
Implementation Method 1
The mounting structure has a lesser magnetic relative permeability than the rotating member... The mounting structure has a magnetic relative permeability of no greater than about 2 and the rotating member has a magnetic relative permeability of at least about 50
Data Source
AI summary
An apparatus including a rotating member, a resolver and a mounting structure. The resolver includes a resolver stator and a resolver rotor fixedly mounted on the rotating member via a mounting structure. The mounting structure has a low magnetic relative permeability and isolates the resolver rotor from the rotating member by preventing direct contact between the rotating member and the resolver rotor. The disclosed apparatus may be an electric machine having a rotor fixed to the rotating member and be suitable for use in a hybrid vehicle. The mounting structure advantageously has a relative permeability of no greater than about 2 and may be formed out of stainless steel material. The rotating member may be a rotor hub formed out of steel material having a relative permeability of at least about 50.