Integrated Power Module Composite for Electric Machine Thermal Management

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Solution Overview

Problem

Conventional electric rotating machines face challenges with increased assembly time due to multiple modules, heat sink corrosion, and temperature issues caused by direct heat transfer from the stator to the heat sink, leading to potential damage to switching devices.

Innovation Solution

The electric rotating machine incorporates a power module composite with a housing, heat sink, and molding resin to insulate and cool the switching devices, eliminating direct contact between the heat sink and rear bracket, and using an insulating material to adhere the heat sink to the power module, reducing thermal stress and corrosion concerns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple separate modules are used for upper and lower arms of the inverter, then the switching devices can be independently controlled, but the projected area and number of modules increase, leading to increased assembly time

Engineering Contradiction:
Improveindependent control capabilityVSAvoidassembly time
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent combines multiple separate power modules (upper and lower arms for each phase) into a single integrated power module. The housing contains all switching devices, lead frames, and circuit boards in one unified structure, eliminating the need to mount multiple separate modules on the bracket, thus reducing assembly time while maintaining independent control capability through separate circuit board designs

Inventive Principle:
Principle #5Merging (Combining)

2Temperature

If the heat sink is connected to the positive electrode of the battery, then it can effectively dissipate heat, but electrolytic corrosion occurs and creepage distances are restricted

Engineering Contradiction:
Improveheat dissipation efficiencyVSAvoidcorrosion resistance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent introduces an insulating material as an intermediary between the heat sink and the power module. This insulating material layer prevents direct electrical contact between the heat sink (connected to positive electrode) and the power module components, thereby eliminating electrolytic corrosion while maintaining thermal dissipation effectiveness through the insulating material's thermal conductivity

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If the heat sink directly contacts the bracket, then heat transfer from stator to heat sink is improved, but the temperature of switching devices rises adversely

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidswitching device temperature
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent segments the heat dissipation path by introducing distinct thermal zones: the heat sink is thermally coupled to the housing (which contains the power module) through insulating material, creating a controlled thermal pathway. This segmentation allows heat to be dissipated from the switching devices through the housing to the heat sink without direct bracket contact, preventing adverse temperature rise in switching devices while maintaining effective heat transfer

Inventive Principle:
Principle #1Segmentation

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 results in a high-reliability, easily assembled control apparatus with reduced temperature rise in the heat sink and switching devices, enhancing the machine's reliability and efficiency while allowing for downsizing and reduced assembly time.

Implementation Method 1

a heat sink that is fixed to the housing and refrigerates the power module

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

an insulating material to adhere the heat sink to the power module, reducing thermal stress

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP2840687B1Dynamo-electric machine
Publication Date: 2019.06.26 MITSUBISHI ELECTRIC CORP
  • EP2840687B1 patent drawingFigure 1
  • EP2840687B1 patent drawingFigure 2
  • EP2840687B1 patent drawingFigure 3

AI summary

Two or more switching devices (36) and two or more lead frames (41, 42, 43, and 44) are integrally molded by use of a molding resin (37) so that a power module (30) is formed; the power module (30) is made to adhere to a heat sink (32) via an insulating material (31); the power module (30) and the heat sink (32) are fixed to a housing (33) of the power module composite (23); the power module composite (23) is fixed to a case (6) of an electric rotating machine (1) via the housing (33).