Stator Coil Welding Structure for Insulation-Safe Segment Conductors
Solution Overview
Problem
The challenge is to balance miniaturization, high output, and cost reduction in rotary electric machines, where increasing voltage and current requirements lead to reduced flexibility and increased heat capacity of segment conductors, complicating stator manufacturing and reducing manufacturability.
Innovation Solution
The stator coil features a welding portion with exposed conductor wire portions that have a root, transition, and bonding portions, where the transition portion offsets the conductor wire's center axis radially by a predetermined amount, and the bonding portion is offset in the radial direction, with pressing marks at boundary portions, and uses an overlay welding structure with a lower-melting-point alloy, and the conductor wire is made of oxygen-free copper or aluminum alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cross-sectional area of the conductor and thickness of the insulating coating are increased to handle higher voltage and current, then the heat capacity is increased, but the flexibility of the segment conductor is decreased and manufacturability is reduced
Solution Approach 1:
The exposed conductor wire portion is divided into three functional segments: root portion (for insulating coating adhesion), transition portion (for radial offset and flexibility), and bonding portion (for welding). This segmentation allows each part to be optimized independently, with the transition portion providing the necessary flexibility for manufacturing while the root and bonding portions maintain electrical insulation and connection integrity.
Solution Approach 2:
Different portions of the conductor wire are given different local properties: the root portion maintains the insulating coating for electrical insulation, the transition portion is offset radially to provide flexibility and ease of positioning, and the bonding portion is prepared for welding. This local differentiation allows the conductor to simultaneously satisfy insulation requirements and manufacturing ease without requiring uniform increases in thickness throughout.
2Ease of manufacture
If the segment conductor is made more flexible to improve manufacturability, then the ease of manufacture is improved, but the heat capacity is reduced which affects high output performance
Solution Approach 1:
The conductor is segmented such that only the transition portion has reduced thickness for flexibility, while the root and bonding portions maintain sufficient thickness for heat capacity and electrical insulation. This localized thinning allows improved manufacturability without sacrificing overall power handling capability.
Solution Approach 2:
The thickness parameter of the conductor wire is varied along its length: thicker at the root and bonding portions for heat capacity and insulation, and thinner at the transition portion for flexibility. This parameter variation allows simultaneous satisfaction of power requirements and manufacturing ease.
3Reliability
If the insulating coating thickness is increased to prevent electrical insulation deterioration, then the electrical insulation is improved, but the flexibility of the segment conductor is decreased
Solution Approach 1:
The insulating coating is selectively removed from the transition portion to create the exposed conductor wire portion. This extraction of the insulating material where it is not needed allows the conductor to be bent and positioned during manufacturing, while the insulating coating is retained at the root and bonding portions where electrical insulation is critical.
Solution Approach 2:
The insulating coating is applied non-uniformly: present at the root portion for electrical insulation, removed at the transition portion for flexibility and positioning, and present at the bonding portion for welding protection. This local differentiation of insulating properties allows simultaneous satisfaction of insulation reliability and operational flexibility.
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 approach enhances the manufacturability of the stator, improves manufacturing yield, and reduces costs while maintaining high output and miniaturization, by minimizing heat damage to the insulating coating and preventing electrical insulation deterioration.
Implementation Method 1
a transition portion for offsetting a center axis of the conductor wire in a radial direction by a predetermined amount of displacement
Implementation Method 2
a boundary portion between the root portion and the transition portion and a boundary portion between the transition portion and the bonding portion have pressing marks
Implementation Method 3
uses an overlay welding structure with a lower-melting-point alloy
Implementation Method 4
minimizing heat damage to the insulating coating
Implementation Method 5
when a voltage is applied to the stator coil, a rotating magnetic field is generated, and a rotor is rotated by the rotating magnetic field
Data Source
AI summary
This disclosure is directed to a stator of a rotary electric machine. The stator includes a stator coil having a welding portion of segment conductors. Each of the segment conductors includes an exposed conductor wire portion. The exposed conductor includes a root portion adjacent to an insulating coating. A thickness of the insulating coating is 50 μm or more. The predetermined amount of displacement is 1±0.4 times or 2±0.4 times the thickness of the insulating coating. A length of the transition portion is 0.5 times or more and 2 times or less of a thickness of the conductor wire.