Porous Insulated Wire Structure for Partial Discharge Suppression
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Solution Overview
Problem
Insulated electrical wires used in motor coils face issues with partial discharge and insulation failure due to high voltage applications, leading to reduced dielectric breakdown voltage and compromised adhesion between the conductor and insulating film, especially in applications like electric vehicle motors.
Innovation Solution
The insulated electrical wire features a unique insulating film structure with a first inner side region without pores, a center region with pores, and a second outer side region without pores, enhancing adhesion and reducing the likelihood of pore communication, thereby maintaining high dielectric breakdown voltage and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pores are dispersed inside the insulating film to reduce relative permittivity, then partial discharge suppression is improved, but adhesion between conductor and insulating film deteriorates
Solution Approach 1:
The insulating film is designed with non-uniform pore distribution: the first region (adjacent to conductor) has low pore density to ensure adhesion, while the second region (away from conductor) has high pore density to reduce relative permittivity and suppress partial discharge. This local differentiation resolves the contradiction between adhesion and partial discharge suppression.
2Reliability
If pores are dispersed inside the insulating film to reduce relative permittivity, then dielectric breakdown voltage is improved, but manufacturing complexity increases
Solution Approach 1:
The insulating film is segmented into multiple regions with different pore densities. The first region has low pore density while the second region has high pore density, allowing control of dielectric breakdown voltage through strategic pore placement without requiring complex manufacturing processes throughout the entire film.
3Reliability
If porous PI enameled wire is used for electric vehicle motor winding, then insulation properties are improved, but processability deteriorates due to insulating film cracking
Solution Approach 1:
The insulating film has low pore density in the first region adjacent to the conductor, providing structural integrity and preventing cracking during bending and twisting operations. The second region has high pore density for excellent insulation properties, thus resolving the contradiction between processability and insulation 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
This configuration effectively suppresses partial discharge, maintains high adhesion, and prevents cracking during bending or twisting, ensuring reliable performance in high-voltage applications such as electric vehicle motor windings.
Implementation Method 1
When a relatively high voltage is applied to the insulated electrical wire as described above, partial discharge may occur in an insulating film of the insulated electrical wire used for a coil of a motor.
Implementation Method 2
An example of a solution to this problem includes a method of using, for the insulated electrical wire, an insulating film with a relatively low relative permittivity (hereinafter, also referred to as εr). The use of the insulating film with a relatively low relative permittivity results in a high partial discharge start voltage, whereby the occurrence of the partial discharge can be suppressed.
Data Source
AI summary
An insulated electrical wire is provided. The insulated electrical wire includes a conductor and an insulating film including pores. The insulating film at least includes a first insulating layer. The first insulating layer includes a first center region, a first inner side region, and a first outer side region. The first center region is a center region in the first insulating layer in a thickness direction and is formed of an insulating material and first pores that are the pores. The first pores are derived from a liquid thermally decomposable polymer. The first inner side region and the first outer side region are formed not to include the first pores.