Stator Wedge Shoulder Width for Ventilation Duct Cooling
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Solution Overview
Problem
The conventional stator design of rotating electric machines experiences significant ventilation loss and increased friction resistance due to the abrupt direction change of cooling gas, leading to inefficient cooling performance and higher power requirements for fans, which can result in reduced reliability and efficiency.
Innovation Solution
The stator design is modified by ensuring the width of the shoulder portions at ventilation duct locations matches the slot width, eliminating abrupt flow path changes and incorporating chamfered portions to reduce ventilation resistance and enhance cooling gas flow efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the conventional stator design with wedges having shoulder portions wider than slot width is used, then the stator coils are securely held in slots, but the cooling gas experiences abrupt direction change leading to increased ventilation loss and friction resistance
Solution Approach 1:
The wedge shoulder portion width is made equal to the slot width specifically at the ventilation duct location, while maintaining adequate width elsewhere to secure the stator coils. This local differentiation allows the cooling gas to flow smoothly through the ventilation duct without abrupt direction changes, reducing ventilation loss while still providing sufficient holding strength for the stator coils.
2Loss of energy
If the wedge shoulder portion width is reduced to match slot width at ventilation duct, then ventilation resistance decreases, but the securing force on stator coils may be insufficient
Solution Approach 1:
The wedge is designed with differentiated shoulder portion widths: at the ventilation duct location, the width equals the slot width to minimize ventilation resistance, while at other locations the width is sufficient to provide adequate securing force on the stator coils. This spatial variation in geometric parameters resolves the contradiction between ventilation efficiency and coil securing strength.
3Temperature
If fans operate with higher power to overcome increased ventilation loss, then cooling performance is maintained, but overall machine efficiency decreases
Solution Approach 1:
The wedge shoulder portion width parameter is changed from being uniformly wider than slot width to being equal to slot width at the ventilation duct location. This parameter modification reduces ventilation resistance and friction resistance, allowing cooling gas to flow more efficiently through the ventilation duct, thereby maintaining cooling performance while reducing fan power consumption.
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 configuration reduces pressure loss in ventilation ducts, allows for efficient cooling of stator coils and core, and decreases the power required for fan operation, thereby improving the overall efficiency and reliability of the rotating electric machine.
Implementation Method 1
cooling gas 11 flows into the ventilation ducts 5 to cool the stator coils 7 and the stator core 1
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
Multiple radially extending inner spacers (4T, 4S) are provided in a stator core (1) at a distance from each other in the circumferential direction at intervals between a prescribed number of stacked magnetic steel plates, and ventilation ducts (5a, 5b) for cooling gas flow are formed in the radial direction. The perimeter of each ventilation duct (5a, 5b) is defined by the inner spacers (4T, 4S) and a magnetic steel plate (9) separated by the inner spacers. The cooling gas, which flows in the rotor direction of rotation, is split laterally to both sides of a rotor coil (7) and directed toward the outer circumference. Portions of the shoulder parts of a wedge (8) are cut off such that the width of the shoulder parts of the wedge (8) at positions corresponding to the ventilation ducts (5a, 5b) roughly matches the slot width. As a result, pressure loss in the ventilation ducts of the stator core is reduced, and the stator coil and the stator core can be cooled efficiently.