Multi-speed induction motor nested stator windings
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Solution Overview
Problem
Existing multi-speed induction motors face inefficiencies and weight issues due to the length and resistance of their windings, particularly in designs requiring varying torque with speed, which leads to increased copper wire usage and power losses.
Innovation Solution
A two-speed induction motor design featuring a high pole count stator winding and a low pole count stator winding, where the low pole count winding is radially interior to the high pole count winding, reducing endturn length and overall wire length, thereby improving power efficiency and reducing weight, and utilizing the annular space for terminal connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the low pole count stator winding is located radially interior to the high pole count stator winding, then the endturn length and overall wire length are reduced, improving power efficiency and reducing weight, but the terminal connection space becomes limited
Solution Approach 1:
The patent utilizes the annular space created by the radial positioning of windings in the circumferential dimension to accommodate terminal connections. By making the axial length of the low pole count winding greater than the high pole count winding, an annular space is formed at the axial ends where terminal connections can be made without interfering with the radial winding arrangement.
2Quantity of substance
If the low pole count stator winding is located radially interior to the high pole count stator winding, then the outer circumference of the low pole count winding is reduced, minimizing copper wire requirements, but the axial length must be increased to provide terminal connection space
Solution Approach 1:
The patent compensates for the reduced circumferential space by extending the axial length of the low pole count winding beyond the high pole count winding. This dimensional adjustment in the axial direction creates an annular space that provides sufficient room for terminal connections while maintaining the space-saving radial arrangement.
3Adaptability or versatility
If multi-speed operation is implemented with separate stator windings for different pole counts, then speed variability is achieved, but the motor weight and complexity increase due to additional windings
Solution Approach 1:
The patent employs a nested winding arrangement where the low pole count stator winding is positioned radially interior to the high pole count stator winding. Both windings share the same stator core and slots, with the inner winding having a smaller outer circumference. This nesting approach allows multi-speed operation while minimizing the total copper wire requirements and motor weight compared to separate independent windings.
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 enhances power efficiency and reduces weight by minimizing I^2R losses and copper wire requirements, while providing space for efficient terminal connections, optimizing performance for applications like fan or pump impellers.
Implementation Method 1
The speed of an induction machine is a function of the number of stator pole pairs and frequency of the alternating current (ac) input voltage supplied to the stator. By selectively varying the number of stator poles, the speed of the induction machine can be varied.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A multi-speed induction motor (10) includes at least two stator windings (a low pole count winding (16) and a high pole count winding (14)) wound around a common stator core. A plurality of stator teeth (22) extend radially inward from a stator yoke (20), thereby defining a plurality of slots open to its inner diameter. The high pole count winding (14) is wound around the stator core first, such that the high pole count winding is located adjacent to the stator yoke. The low pole count winding is wound subsequently, such that it is radially interior to the high-pole count winding (14).