Electric Machine Rotor Notches for NVH Reduction
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Solution Overview
Problem
Rotary electric machines in electrified powertrains generate significant noise, vibration, and harshness (NVH) effects, particularly at harmonic orders, which are difficult to mitigate without compromising performance and efficiency using existing skewing techniques or electromagnetic design constraints.
Innovation Solution
The implementation of arcuate notches on the rotor's outer diameter surface, aligned with the quadrature-axis and symmetrically flanked by additional notches, reduces NVH effects without impacting motor torque and efficiency, with the size, shape, and position of the notches optimized for specific applications to maximize noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If skewing techniques are applied to reduce NVH effects, then noise and vibration are reduced, but machine performance and operating efficiency are reduced
Solution Approach 1:
The rotor is segmented by introducing notches that divide the rotor body into distinct sections. These notches create localized modifications to the rotor structure without affecting the overall integrity, allowing vibration reduction while maintaining performance
Solution Approach 2:
Instead of applying global skewing that affects the entire rotor-stator assembly, the invention applies local modifications through notches at specific positions on the rotor. This localized approach targets NVH reduction at problem areas while preserving overall machine performance
2Object-affected harmful factors
If more stringent NVH constraints are imposed on the electromagnetic design, then noise and vibration are reduced, but machine performance and operating efficiency are reduced
Solution Approach 1:
The rotor is segmented by introducing notches that divide the rotor body into distinct sections. These notches create localized modifications to the rotor structure without affecting the overall integrity, allowing vibration reduction while maintaining performance
Solution Approach 2:
Instead of applying global skewing that affects the entire rotor-stator assembly, the invention applies local modifications through notches at specific positions on the rotor. This localized approach targets NVH reduction at problem areas while preserving overall machine performance
3Object-affected harmful factors
If rotor skewing is applied to minimize NVH effects, then noise and vibration are reduced, but torque and efficiency are reduced
Solution Approach 1:
The rotor is segmented by introducing notches that divide the rotor body into distinct sections. These notches create localized modifications to the rotor structure without affecting the overall integrity, allowing vibration reduction while maintaining performance
Solution Approach 2:
Instead of applying global skewing that affects the entire rotor-stator assembly, the invention applies local modifications through notches at specific positions on the rotor. This localized approach targets NVH reduction at problem areas while preserving overall machine performance
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 rotor notches significantly reduce machine noise and vibration while maintaining motor torque and efficiency, effectively addressing the NVH challenges in rotary electric machines by distributing vibration energy evenly and minimizing stress concentration.
Implementation Method 1
effectively addressing the NVH challenges in rotary electric machines by distributing vibration energy evenly and minimizing stress concentration
Data Source
AI summary
A rotor assembly for an electric machine, e.g., of an electrified powertrain, includes a rotor having inner and outer diameter surfaces, and a rotor shaft connected to and surrounded by the rotor. The rotor has equally-spaced rotor magnetic poles each having a quadrature-axis (“q-axis”) and a pair of direct-axes (“d-axes”). At each of magnetic pole of the rotor, the rotor defines at least three arcuate notches, including a center notch bisected by the q-axis and a pair of additional arcuate notches symmetrically flanking the center notch. The rotor may include embedded permanent magnets, which may be arranged in a dual V-shaped configuration. Each additional notch may be positioned within a sweep of a top-layer opening angle of the magnets. The center notch and/or the pair of additional notches may define tangentially-continuous fillets which smoothly transition the notch into the outer diameter surface.