Electric Motor Stator Harmonic Reduction via Localized Winding
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Solution Overview
Problem
Electrical machines with concentrated windings suffer from undesired harmonic components in the magnetomotive force, leading to losses and acoustic impairments, which are not effectively reduced by existing technologies.
Innovation Solution
The electrical machine design features a stator with a doubled number of notches and varying turns in each winding, along with differing tooth widths, to eliminate or significantly reduce harmonic components, particularly those of low order, by using a higher-order harmonic as the operating wave.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If concentrated windings are used in electrical machines, then compact design is achieved, but undesired harmonic components occur in the magnetomotive force
Solution Approach 1:
The patent applies local quality by varying the number of turns of windings in specific notches rather than using uniform windings throughout. This localized modification of winding characteristics allows selective cancellation of harmonic components while maintaining the compact concentrated winding structure, thereby resolving the contradiction between compact design and harmonic reduction.
Solution Approach 2:
The patent changes the parameter of winding turns in specific notches to eliminate harmonic components. By adjusting the number of turns in selected notches according to the Fourier decomposition analysis, the magnetomotive force waveform is modified to reduce harmonics while preserving the overall compact design of the concentrated winding system.
2Object-generated harmful factors
If the number of notches is increased beyond the minimum required, then harmonic components are reduced, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the stator into a specific number of notches (e.g., 12 notches for a 4-pole machine) and selectively modifying windings in specific notches rather than uniformly increasing the total number of notches. This segmented approach allows harmonic reduction through targeted winding variations without proportionally increasing overall device complexity.
Solution Approach 2:
The patent uses partial action by modifying windings in only certain notches rather than all notches. This selective modification achieves harmonic cancellation with minimal changes to the overall structure, avoiding the complexity increase that would result from uniformly increasing the number of notches throughout the entire stator.
3Loss of energy
If harmonic components are eliminated through winding modifications, then losses and acoustic impairments are reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by implementing winding variations only in specific notches where harmonic cancellation is needed, rather than modifying all windings uniformly. This localized approach reduces manufacturing complexity compared to complete winding reconfiguration, as only selected portions of the winding system require special attention during assembly.
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
This design effectively reduces or eliminates undesired harmonic components, minimizing losses and acoustic impairments, making it suitable for use in electric vehicle drive systems, particularly in hybrid vehicles.
Implementation Method 1
Each magnetic pole pair in the rotor comprises two magnetic poles, a north pole and a south pole... A torque is generated whenever the harmonic order of the wave of the magnetomotive force and the harmonic order of a wave of the flux density coincide
Data Source
AI summary
An electrical machine comprising a stator (1) and a rotor (2) movable relative to the stator is provided. The stator (1) comprises a doubled number of notches (3) with respect to a pole pair number p of the rotor. This is combined with differing numbers (n1, n2) of turns per phase winding or with differing tooth widths (Z1, Z2) of teeth (6, 7) of the stator which are formed between neighboring notches (3).