Segmented Stator Core Layout for Low Shaft Voltage Motors
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Solution Overview
Problem
Existing rotary electric machines using divisional cores face issues with shaft voltage and torque ripple due to gaps between cores, which increase manufacturing complexity and costs, and existing solutions do not adequately address these problems.
Innovation Solution
A rotary electric machine design with a stator core composed of divisional cores divided in the circumferential direction, where the division number N satisfies P<N<2P or 2P<N<4P, and each core has an arc-shaped back and inward teeth, with coils wound in a distributed manner, reducing shaft voltage and torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the division number of the stator core is increased to improve material cost and yield, then the material cost is reduced, but the number of components increases leading to increased manufacturing cost and assembly difficulty
Solution Approach 1:
The stator core is divided into multiple divisional cores (N divisions) that can be assembled together. This segmentation allows for improved material utilization and reduced material cost while maintaining a manageable number of components through optimized division numbers.
Solution Approach 2:
The patent specifies optimal ranges for the division number N relative to the number of pole pairs P (P<N<2P or 2P<N<4P). By changing this parameter within specific ranges, the patent achieves a balance between material cost reduction and manufacturing complexity control.
2Loss of substance
If divisional cores are combined to reduce material cost, then material cost is reduced, but gaps form between divisional cores causing permeance harmonics and shaft voltage
Solution Approach 1:
The patent specifies optimal ranges for the division number N relative to the number of pole pairs P (P<N<2P or 2P<N<4P). By changing this parameter within specific ranges, the patent achieves a balance between material cost reduction and manufacturing complexity control.
Solution Approach 2:
The patent converts the potentially harmful effect of gaps between divisional cores into a beneficial outcome by selecting specific division numbers that cause the gap-induced permeance harmonics to cancel out, thereby reducing shaft voltage rather than increasing it.
3Object-affected harmful factors
If the division number is set to an integer multiple of the number of poles to eliminate shaft voltage, then shaft voltage is reduced, but torque ripple increases
Solution Approach 1:
The patent defines specific ranges for the division number N relative to the number of pole pairs P (P<N<2P or 2P<N<4P). These ranges are carefully selected to avoid integer multiples of poles, thereby preventing both shaft voltage and torque ripple issues simultaneously.
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 design achieves reduced material and manufacturing costs while effectively suppressing shaft voltage and torque ripple, improving yield and manufacturing efficiency.
Implementation Method 1
a rotor (30) including a rotor core (31) fixed to a shaft (32) present at a center axis of the stator (10), the rotor core being provided with magnetic poles
Implementation Method 2
the rotor being rotatable relative to the stator (10)
Data Source
AI summary
A rotary electric machine includes: a stator including a stator core composed of a plurality of divisional cores divided in a circumferential direction and combined in an annular shape, and a coil wound in a distributed manner on the stator core; and a rotor including a rotor core provided with magnetic poles of which a number of pole pairs is P, the rotor being rotatable relative to the stator. Each divisional core has a core back, a plurality of teeth protruding in a radially inward direction from the core back, and winding slots, and the divisional cores have equal numbers of teeth. Where a division number of the divisional cores is N, P<N<2P is satisfied.