Rotary Electric Machine Stator Slot Insulation
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Solution Overview
Problem
Existing automotive rotary electric machines face inefficiencies in power conversion and specific performance due to limitations in stator winding design and insulation, leading to suboptimal power and torque output.
Innovation Solution
The design incorporates 'U'-shaped copper bars with a rectangular transverse section and a specific ratio of longer to shorter sides, bent to form electrical paths within stator slots, and an insulating coating with multiple layers to reduce skin effect losses and increase filling coefficient, along with a Halbach array of permanent magnets for enhanced magnetic field management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stator winding with insulation elements is used, then insulation reliability is improved, but power losses increase due to skin effect
Solution Approach 1:
The patent applies composite materials by using a double-layer insulation system combining resin layers and varnish layers. The resin layers provide primary insulation with high dielectric strength, while the varnish layers provide secondary insulation and impregnation. This composite approach maintains reliable insulation while allowing closer bar spacing and reduced skin effect, thereby reducing power losses.
Solution Approach 2:
The patent changes the insulation parameters by eliminating traditional insulation elements (paper, fabric) and using only coating-type insulation (resin and varnish layers). This parameter change reduces the overall insulation thickness and improves the filling coefficient of the stator slots, which reduces the skin effect and power losses while maintaining adequate insulation reliability through the multi-layer coating system.
2Reliability
If insulation elements are added in stator slots, then insulation reliability is improved, but filling coefficient decreases
Solution Approach 1:
The patent extracts and eliminates traditional insulation elements (insulation paper, fabric, and other bulk insulation materials) from the stator slots. By removing these elements and relying solely on coating-type insulation (resin and varnish layers applied directly to the conductor bars), the patent achieves high filling coefficient while maintaining insulation reliability through the multi-layer coating system.
Solution Approach 2:
The patent uses thin film-type insulation in the form of resin layers and varnish layers that are applied as coatings on the conductor bars. These flexible thin films provide the necessary insulation without the bulk and rigidity of traditional insulation elements, allowing maximum space utilization in the stator slots and thus achieving high filling coefficient.
3Loss of energy
If bar dimensions are optimized for reduced skin effect, then power losses decrease, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the bar dimensions by carefully selecting the ratio between the longer side and shorter side of the rectangular cross-section. This parameter optimization reduces the skin effect and power losses while keeping the manufacturing process simple. The standardized rectangular cross-section with optimized dimensions can be easily manufactured using conventional extrusion or drawing processes, thus avoiding increased manufacturing complexity.
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 significantly reduces power losses, enhances power efficiency, and increases specific performance by improving the power-to-torque ratio while maintaining cost-effectiveness.
Implementation Method 1
reduce skin effect losses
Implementation Method 2
Halbach array of permanent magnets for enhanced magnetic field management
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Electric machine (1) having: a shaft (2); a rotor (4) with permanent magnets (23) that is fitted to the shaft (2); a stator (5) having a magnetic core (6) which consists of a series of laminations made of ferromagnetic material and longitudinally crossed by a plurality of stator slots (7); and a stator winding (8) having a plurality of rigid bars (9) that are inserted in corresponding stator slots (7) and that are covered, on the outside, with an insulating coating (14). Each stator slot (7) is completely free from an insulating element interposed between the ferromagnetic material making up the laminations of the magnetic core (6) and the corresponding bars (9), so that an outer surface (18) of the corresponding bars (9) is in direct contact with an inner surface (19) of the stator slot (7) made of the ferromagnetic material.