Motor Frequency Converter Thermal Management via Segmented Cooling

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Solution Overview

Problem

Conventional frequency converters for motors suffer from ineffective thermal insulation between heat-generating elements and other components on the circuit board, leading to poor heat dissipation, potential contamination, and reduced product lifetime due to impurities in the cooling air and misalignment issues during assembly.

Innovation Solution

The implementation of a heat insulation member between the heat sink and circuit board, along with a separating member and airflow guiding structures to isolate and efficiently cool heat-generating elements, using insulating materials and a fin-like heat sink design to enhance airflow and reduce electromagnetic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooling air is blown to all elements on the circuit board using a fan, then heat dissipation is improved, but impurities in the air contaminate internal devices and pins causing potential short-circuits or damage

Engineering Contradiction:
Improveheat dissipationVSAvoidcontamination risk
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent divides the cooling system into separate channels: a first cooling channel directs air to the heat sink for IGBT cooling, while a second cooling channel directs air to capacitors and coils. This segmentation prevents contaminated air from reaching sensitive circuit board elements while maintaining effective heat dissipation for all heat-generating components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a separating member as an intermediary structure that physically divides the cooling air flow paths. This separator acts as a barrier between the main cooling air flow and the circuit board area, allowing heat-generating elements to be cooled while protecting sensitive components from contamination by impurities in the cooling air.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If safety distance is increased between elements on the circuit board to prevent contamination, then reliability is improved, but the size of the frequency converter increases

Engineering Contradiction:
Improvecontamination protectionVSAvoiddevice size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The separating member serves as an intermediary structure that provides contamination protection without requiring increased safety distances between circuit board elements. By introducing this physical barrier, the patent maintains compact device dimensions while effectively preventing impurity contamination of sensitive components.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If heat conductive silica gel is used to adhere IGBT to the heat sink, then heat dissipation is improved, but position deflection and rotation occur during assembly affecting alignment

Engineering Contradiction:
Improveheat dissipationVSAvoidalignment precision
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The patent incorporates pre-formed positioning structures (positioning protrusions and positioning grooves) that establish precise alignment between the IGBT, heat sink, and circuit board before the adhesive bonding process. This preliminary mechanical positioning ensures accurate alignment is maintained during assembly, preventing the position deflection and rotation that would otherwise occur during silica gel adhesion.

Inventive Principle:
Principle #10Preliminary action

4Device complexity

If natural cooling is used for secondary heat-generating elements, then device complexity is reduced, but heat dissipation is insufficient reducing element lifetime

Engineering Contradiction:
Improvecooling system complexityVSAvoidheat dissipation efficiency
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The patent implements a segmented cooling approach where different cooling methods are applied to different heat-generating elements based on their thermal requirements. The IGBT receives forced cooling through the heat sink, while capacitors and coils receive cooling through the second cooling channel, optimizing heat dissipation efficiency without unnecessarily increasing overall system complexity.

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 solution effectively isolates heat-generating elements from other components, improves heat dissipation, reduces the risk of contamination, and enhances the operational quality and lifetime of the frequency converter by ensuring precise alignment and efficient cooling.

Implementation Method 1

the heat conduction of the main heat-generating element and the heat sink may still make other elements on the circuit board to operate under high temperature

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

blows the cooling air to a heat sink 202 using a fan 201

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 3

there is no effective thermal insulation measures to be taken between main heat-generating element and other elements on the circuit board, as well as between the heat sink and the circuit board

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP2090146B1Electronic device and frequency converter of motor
Publication Date: 2014.07.09 DANFOSS DRIVES AS
  • EP2090146B1 patent drawingFigure 1
  • EP2090146B1 patent drawingFigure 2
  • EP2090146B1 patent drawingFigure 3

AI summary

The present invention provides an electronic device, comprising: a circuit board having at least one first heat-generating element and at least one second heat-generating element mounted thereon; a heat sink connected to said at least one first heat-generating element; a fan facing said heat sink; and an airflow guiding member placed between said fan and said heat sink for guiding the cooling air from said fan to said heat sink and said at least one second heat-generating element respectively. Said electronic device may further comprise a separating member for separating a main body of said at least one second heat-generating element from said circuit board, so as to prevent the cooling air guided to said at least one second heat-generating element from flowing to said circuit board; a bracket for separating said at least one first heat-generating element from other elements on said circuit board, so as to thermally insulate between them; and a flow-guiding gate guiding the airflow from said fan, and dispensing more airflow flow through the region on the heat sink corresponding to at least one first heat-generating element.