Eccentric Annular Cover for Uniform Stator End-Winding Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Stator windings in high power motors are a primary heat source, posing challenges in cooling system design, leading to temperature control issues that affect motor efficiency and safety.
Innovation Solution
An eccentric annular cover system is used to cool stator end windings, featuring a variable radial width cavity with an inlet and outlet, and adjustable eccentricity to maintain constant tangential velocity and heat transfer coefficient, reducing temperature spread and pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional cooling system is used for stator windings, then the structure is simple, but the temperature control is insufficient leading to reduced motor efficiency
Solution Approach 1:
The cooling system applies different gap widths at different angular positions around the stator winding. The gap between the annular cover and stator yoke varies circumferentially, creating localized variations in cooling fluid flow and heat transfer coefficients. This local quality variation optimizes cooling effectiveness at different locations, thereby improving overall winding temperature control and motor efficiency.
2Temperature
If the radial width of the cavity is made variable, then the heat transfer coefficient is improved, but the device complexity increases
Solution Approach 1:
The annular cover is designed with an asymmetric cross-sectional shape where the radial width of the cooling cavity varies continuously around the circumference. This asymmetric geometry creates different gap widths at different angular positions, optimizing the heat transfer coefficient without requiring complex active control mechanisms. The asymmetry is achieved through the eccentric positioning of the annular cover relative to the stator yoke.
Solution Approach 2:
The variable radial width cavity creates dynamic flow conditions for the cooling fluid as it passes through different gap regions. The changing gap width along the circumferential direction causes variations in fluid velocity and pressure, enhancing convective heat transfer. This dynamic flow pattern improves heat transfer efficiency compared to a static, uniform gap design.
3Temperature
If the eccentricity is increased to reduce temperature spread, then the cooling performance is improved, but the pressure drop increases
Solution Approach 1:
The system optimizes the eccentricity parameter of the annular cover to achieve a balance between temperature spread reduction and pressure drop management. By carefully selecting the eccentricity value, the design creates sufficient gap variation to reduce temperature spread while avoiding excessive pressure drops that would reduce cooling fluid flow rate. This parameter optimization resolves the contradiction between thermal performance and hydraulic performance.
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 system effectively reduces winding temperature variation, allowing higher current drive and increased continuous power and torque delivery, while maintaining efficient cooling performance.
Implementation Method 1
a cover for the one or more end windings and disposed around the rotor, wherein the cover is configured to transfer a cooling fluid to cool the one or more end windings
Implementation Method 2
a first radial width of the cavity at the inlet is greater than a second radial width of the cavity at the outlet
Data Source
AI summary
A system may include a rotor, a stator disposed around the rotor, the stator includes a stator core and windings, the windings include end windings extending from a longitudinal end of the stator core. A system may include a cover for the end windings and disposed around the rotor, the cover is configured to transfer a cooling fluid to cool the end windings, and the cover includes: a body to cover the end windings, the body including a cavity for the cooling fluid, an inlet disposed in the body for the cooling fluid to enter the cavity; and an outlet disposed in the body for the cooling fluid to exit the cavity, the outlet is disposed at a portion of the body opposite to the inlet, a first radial width of the cavity at the inlet is greater than a second radial width of the cavity at the outlet.