Rotating Electric Machine Torque Ripple Reduction
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Solution Overview
Problem
Rotating electric machines in electric vehicles generate significant noise due to torque pulsations, which existing technologies have not adequately addressed, particularly in reducing noise under load conditions.
Innovation Solution
The design incorporates a stator core with wave winding patterns and cross conductors that connect slot conductors across specific slot pitches, along with magnetic resistance-altering portions on the rotor, to cancel out torque pulsations and reduce noise. This configuration includes a stator winding with slot conductor groups inserted in successive slots and layers, and magnetic auxiliary salient pole portions offset from the q-axis to minimize torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional winding technologies and rotor designs are used, then the rotating electric machine can generate sufficient torque, but significant noise is generated due to torque pulsations
Solution Approach 1:
The patent applies local quality by creating magnetic auxiliary salient pole portions with specific magnetic resistance characteristics at localized positions on the rotor. These portions have different magnetic resistance properties compared to the surrounding rotor structure, allowing selective modification of magnetic flux distribution in specific regions to reduce torque pulsations while maintaining overall torque generation capability
Solution Approach 2:
The patent changes magnetic resistance parameters by introducing magnetic auxiliary salient pole portions with controlled magnetic resistance values. By adjusting the magnetic resistance of these auxiliary portions relative to the main magnetic poles, the patent optimizes the magnetic circuit characteristics to minimize torque ripple and associated noise while preserving sufficient torque output
2Object-generated harmful factors
If magnetic auxiliary salient pole portions are added to reduce torque pulsations, then noise is reduced, but device complexity increases
Solution Approach 1:
The patent merges the function of torque reduction with the existing rotor structure by integrating magnetic auxiliary salient pole portions into the rotor body. These auxiliary portions are combined with the main magnetic poles and rotor core to form a unified structure that achieves noise reduction without requiring separate, independent components
Solution Approach 2:
The magnetic auxiliary salient pole portions serve multiple functions: they modify magnetic flux distribution to reduce torque pulsations, maintain rotational balance, and work cooperatively with the main magnetic poles for torque generation. This multi-functionality reduces the need for additional dedicated components
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 reduces noise in rotating electric machines by minimizing torque ripple and cogging torque, leading to quieter operation, especially under load conditions, without compromising torque output.
Implementation Method 1
a stator winding assuming a plurality of phases, which includes a plurality of coil windings wound with a wave winding pattern... a rotor rotatably disposed via an air gap so as to be allowed to rotate relative to the stator core, which includes a plurality of magnets
Implementation Method 2
the rotor includes magnetic resistance-altering portions located at positions each offset along a circumferential direction from a q-axis passing through a center of a salient pole at a corresponding magnetic auxiliary salient pole portion
Data Source
AI summary
A rotating electric machine includes a stator core, a stator winding, and a rotor rotatably disposed via an air gap so as to be allowed to rotate relative to the stator core. A magnetic resistance-altering portion is provided on every other magnetic pole of magnetically-assisted salient pole members. A magnetic pole provided with the magnetic resistance-altering portion and a magnetic pole without the magnetic resistance-altering portion are alternately arranged.