Dual-Layer Insulated Wire for High PDIV Motor Coils

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Solution Overview

Problem

Conventional insulated electric wires fail to maintain high partial discharge inception voltage, especially in high temperature environments, due to degradation from inverter surge voltage and heat dissipation issues, which affects the reliability of motor coils in miniaturized and high-power applications.

Innovation Solution

The insulated electric wire features a dual-layer insulating coating with a first layer containing an imide structure and a second layer formed from a polyimide resin with an imide concentration of 15% to 36%, using specific aromatic tetracarboxylic dianhydrides and diamines, enhancing the partial discharge inception voltage and thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single-layer insulating coating is used to reduce device complexity, then manufacturing is simpler, but the partial discharge inception voltage is insufficient in high temperature environments

Engineering Contradiction:

Improvepartial discharge inception voltageVSAvoidinsulating coating structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The insulating coating is divided into two distinct layers: a base layer containing an imide structure that provides thermal stability, and an outer layer made of polyimide resin with controlled imide concentration (15-36%) that provides electrical insulation. This segmentation allows each layer to perform its specific function optimally, achieving high partial discharge inception voltage while maintaining manufacturing feasibility

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses a composite insulating coating structure combining two different resin systems (imide-containing resin and polyimide resin) with specific compositional ratios. This composite approach leverages the complementary properties of each material to achieve both thermal resistance and high electrical insulation performance that neither material could provide alone

Inventive Principle:

Principle #40Composite materials

2Power

If inverter surge voltage is increased to improve motor power, then motor output increases, but partial discharge occurs and degrades the insulating coating film

Engineering Contradiction:

Improvemotor powerVSAvoidpartial discharge

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent optimizes the imide concentration parameter in the outer insulating layer to a specific range (15-36%) to achieve the desired balance between electrical insulation and thermal properties. This parameter optimization allows the coating to withstand high inverter surge voltages without partial discharge while maintaining compatibility with motor power requirements

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If the proportion of insulated electric wires is increased for motor miniaturization, then motor size decreases, but heat dissipation degrades and temperature increases

Engineering Contradiction:

Improvemotor sizeVSAvoidcoil temperature

Core Design Contradiction:

Volume of moving objectVSTemperature

Solution Approach 1:

The insulating coating is designed with spatially varying properties: the base layer has high thermal stability to handle elevated temperatures, while the outer layer has optimized electrical properties for insulation. This local quality differentiation allows the coating to function effectively in the high-temperature environment created by increased wire density in miniaturized motors

Inventive Principle:

Principle #3Local quality

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 increases the partial discharge inception voltage at high temperatures, preventing insulating coating degradation and ensuring reliable operation in miniature and high-power motor applications, while maintaining good weldability and adhesion.

Implementation Method 1

the use of such polyamide-imide resin insulating varnish provides the insulating coating film with a low relative permittivity, thereby provides the insulated electric wire with a high partial discharge inception voltage (PDIV)

Methodology Applied

Scientific EffectDielectric: Dielectric

Implementation Method 2

an insulating coating provided around a perimeter of the conductor, the insulating coating including: a first insulating coating film around the perimeter of the conductor, the first insulating coating film being formed of a resin containing an imide structure in its molecule

Methodology Applied

Scientific EffectThermal stability:

Data Source

PatentUS9484124B2Insulated electric wire and coil using same

Publication Date: 2016.11.01 PROTERIAL LTD

AI summary

An insulated electric wire includes a conductor and an insulating coating provided around a perimeter of the conductor. The insulating coating includes a first insulating coating film around the perimeter of the conductor, the first insulating coating film being formed of a resin containing an imide structure in its molecule, and a second insulating coating film around a perimeter of the first insulating coating film, the second insulating coating film being formed of a polyimide resin comprising a repeat unit represented by Formula 1, and having an imide concentration of not less than 15% and not more than 36%,wherein R1 is a tetravalent group derived from decarboxylation of an aromatic tetracarboxylic acid, and R2 is a divalent group derived from deamination of an aromatic diamine.