Permanent Magnet Motor with Temperature Gradient Cooling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Permanent magnet motors using rare earth magnets, such as R-T-B based magnets, face performance deterioration due to eddy currents and high temperature demagnetization, leading to increased costs from high coercive force requirements.

Innovation Solution

A motor design with a temperature gradient across permanent magnets, utilizing high coercive force magnets at high temperatures and lower coercive force magnets at lower temperatures, combined with an efficient cooling mechanism, where the coolant is in close proximity to the magnets to minimize eddy currents and Joule heat generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high coercive force permanent magnets are used to prevent demagnetization at high temperatures, then motor reliability is improved, but manufacturing cost increases

Engineering Contradiction:

Improveresistance to thermal demagnetizationVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies local quality by creating a temperature gradient across the permanent magnet thickness, where the center region experiences higher temperatures and requires higher coercive force, while the surface regions experience lower temperatures and can use lower coercive force materials. This is achieved through the cooling mechanism that cools the magnet from the surfaces, creating distinct thermal zones within the magnet structure.

Inventive Principle:

Principle #3Local quality

2Power

If rare earth permanent magnets are used to achieve high magnetic properties, then motor power is improved, but susceptibility to thermal demagnetization increases

Engineering Contradiction:

Improvemotor outputVSAvoidresistance to thermal demagnetization

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent segments the permanent magnet into different thermal zones based on temperature distribution. The magnet is divided into a center region (experiencing high temperature) and surface regions (experiencing lower temperature due to cooling). Each region can be optimized with appropriate magnetic material properties, allowing the use of high-performance rare earth magnets only where necessary while reducing overall susceptibility to thermal demagnetization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the temperature parameter distribution within the permanent magnet by introducing a cooling mechanism. By actively cooling the magnet surfaces and creating a temperature gradient, the operating temperature of the magnet material is reduced, thereby improving its resistance to thermal demagnetization while maintaining high magnetic properties.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If cooling mechanism with close coolant proximity is implemented, then temperature control is improved, but device complexity increases

Engineering Contradiction:

Improvepermanent magnet temperature controlVSAvoidcooling system structure

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent applies the nesting principle by integrating the cooling channels directly within or adjacent to the permanent magnet structure itself. The coolant flow path is nested close to the magnet, allowing efficient heat removal without requiring a separate, complex external cooling system. This nested arrangement achieves effective temperature control while minimizing additional structural complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 design achieves high motor performance while reducing costs by optimizing coercive force distribution and utilizing efficient cooling, maintaining motor output and reducing thermal demagnetization.

Implementation Method 1

a cooling mechanism that cools inside of the motor, the cooling mechanism includes a coolant having a distance to the permanent magnet of 10 mm or less

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

when the motor using the permanent magnets is driven, eddy currents are generated in the permanent magnets, and the temperature of the permanent magnets rises by Joule heat generated by the eddy currents

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

the temperature of the permanent magnets rises by Joule heat generated by the eddy currents

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10848023B2Motor containing a permanent magnet having high and low temperature side permanent magnet parts

Publication Date: 2020.11.24 TDK CORP

AI summary

Provided is a motor including a permanent magnet, in which the permanent magnet includes a high temperature side permanent magnet part exposed to a high temperature inside the motor, and a low temperature side permanent magnet part exposed to a temperature lower than the high temperature inside the motor, and a coercive force of the high temperature side permanent magnet part is higher than the coercive force of the low temperature side permanent magnet part.