Bar Stator Winding Layout to Reduce Rotary Machine Power Loss
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Solution Overview
Problem
Rotary electric machines for automotive powering face limitations in energy efficiency and specific performance (power and torque) due to traditional stator winding designs that result in significant power losses and suboptimal use of space within the stator slots.
Innovation Solution
The design incorporates 'U'-shaped copper bars with a rectangular cross section, where the ratio of long to short sides is greater than 2, and an insulating coating with multiple layers, along with a direct contact between the bars and the ferromagnetic material, to reduce skin effect losses and increase the coefficient of filling in the stator slots, enhancing energy efficiency and specific performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional stator windings are manufactured with rigid bars inserted into stator slots, then the manufacturing process is simple, but the energy efficiency and specific performance are limited due to significant power losses
Solution Approach 1:
The patent changes the geometric parameters of the copper bars by introducing a rectangular cross-section with a specific aspect ratio (long side/short side > 2) and positioning them at optimized angles (30-60 degrees) relative to the slot axis. This parameter optimization reduces skin effect losses and improves current distribution, thereby reducing power losses and enhancing energy efficiency without complicating the manufacturing process
Solution Approach 2:
The patent introduces asymmetry in the bar configuration by using rectangular cross-sections with different side lengths and orienting them at specific non-symmetric angles (30-60 degrees) relative to the slot axis. This asymmetric arrangement optimizes the current path and reduces eddy current losses, leading to improved energy efficiency while maintaining manufacturing simplicity
2Ease of manufacture
If rigid bars are inserted into stator slots with conventional arrangements, then the manufacturing process is straightforward, but the coefficient of filling in the stator slots is suboptimal
Solution Approach 1:
The patent optimizes the filling coefficient by changing the geometric parameters of the copper bars, specifically using a rectangular cross-section with aspect ratio > 2 and arranging them at optimized angles. This allows better space utilization within the stator slots, increasing the quantity of copper material that can be accommodated while maintaining the straightforward insertion manufacturing process
3Device complexity
If conventional stator windings are used, then the device complexity is low, but the specific performance (power and torque) is limited
Solution Approach 1:
The patent enhances specific performance by optimizing geometric parameters including bar aspect ratio (>2), bar orientation angles (30-60 degrees), and slot filling arrangement. These parameter optimizations improve power density and torque output without significantly increasing device complexity, as the fundamental winding structure remains similar to conventional designs
Solution Approach 2:
The patent introduces dimensional optimization by considering the three-dimensional arrangement of rectangular bars with specific aspect ratios and orientations within the slot. This spatial optimization in multiple dimensions maximizes the use of available space and improves electromagnetic performance, thereby enhancing specific power and torque without adding complex structural elements
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 and enhances energy efficiency and specific performance by optimizing the stator winding layout and insulating coating, leading to improved power and torque output per unit mass and volume.
Implementation Method 1
reduce skin effect losses
Implementation Method 2
direct contact between the bars and the ferromagnetic material
Implementation Method 3
a rotor, which generally has permanent magnets and is fitted to the shaft so as to rotate with the shaft itself
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electric machine (1) having: a shaft (2); a rotor (4) with permanent magnets (23), which is fitted to the shaft (2); a stator (5) having a magnetic core (6), which consists of a series of laminations made of a ferromagnetic material and is longitudinally crossed by a plurality of stator slots (7); and a stator winding (8) having a plurality of rigid bars (9), which are inserted in corresponding stator slots (7) and are covered, on the outside, with an insulating coating (14). Each stator slot (7) has a rectangular cross section having a long side (12) arranged radially and a short side (13) arranged circumferentially. Each stator slot (7) houses eight bars (9) lined up one behind the other. Each bar (9) has a rectangular cross section having a long side (12) parallel to the short side (13) of the corresponding stator slot (7) and a short side (13) parallel to the long side (15) of the corresponding stator slot (7). In each bar (9), the ratio between the long side (12) and the short side (13) of the rectangular cross section is greater than 2. Main figure: figure 2