Nested Winding for Slotless Motor Eddy Current Reduction
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Solution Overview
Problem
Traditional slotless motor windings experience significant eddy-current losses and phase differences due to direct exposure in the air-gap magnetic field, leading to inefficiencies and difficulties in manufacturing, particularly for lap and slanting windings, which existing solutions fail to adequately address at high power and speed.
Innovation Solution
A nested winding configuration with inner and outer windings of different diameters, where same-phase coils are connected in parallel or series, ensuring identical or close resistances, inductances, and back-electromotive force (bemf) values, allowing for efficient phase alignment and reduced losses, and enabling various coil shapes and configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional lap winding is used, then the manufacturing process is simple, but the phase difference causes internal loop currents and losses
Solution Approach 1:
The patent extends the nested winding structure to lap windings and slanting windings by nesting inner and outer windings with different diameters. This maintains the simplicity of traditional lap winding manufacturing while eliminating phase differences through the nested configuration, where same-phase coils are connected in parallel between inner and outer windings.
Solution Approach 2:
The patent introduces a radial dimension by creating inner and outer windings at different radii (different inner and outer diameters). This dimensional change allows the same-phase coils to be positioned at different radial locations while maintaining electrical phase alignment, eliminating internal loop currents while preserving manufacturing simplicity.
2Loss of energy
If concentric windings are used, then eddy currents are reduced, but the solution is not suitable for lap windings or slanting windings
Solution Approach 1:
The patent creates a universal nested winding structure that can be applied to multiple winding types including lap windings, slanting windings, and concentric windings. The nested configuration with inner and outer windings of different diameters provides a multi-functional solution that reduces eddy currents while being adaptable to various winding configurations and motor designs.
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 nested winding design effectively reduces potential differences and losses, improves high-speed performance, enhances motor efficiency, and allows for more efficient use of motor space, supporting higher voltage levels and diverse applications.
Implementation Method 1
due to the fact that the winding of traditional coreless motors (such as U.S. Pat. No. 4,543,507) is directly exposed in an air-gap magnetic field, a very large eddy-current loss will be generated in a high-speed rotating magnetic field
Implementation Method 2
bemf is generated by the coil 1-1 and results in a phase difference between the coil 1-1 and the coil 1-2 when a magnetic field is applied to the coils
Data Source
AI summary
The invention relates to a nested winding for a slotless motor. The nested winding is formed by inner and outer windings which are nested together and have different inner and outer diameters, wherein the number of the inner and outer windings is n, same-phase coils are connected in parallel or in series, and the number n of the nested inner and outer windings is equal to or greater than two. Compared with the prior art, the nested winding has the following advantages: a potential difference between the coils connected in parallel can be effectively reduced, and accordingly, the loss of the winding is reduced, and the high-speed operating performance of the motor is improved.