Inverter Cooling Fan Control to Limit Dust Ingress

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Solution Overview

Problem

Conventional power conversion devices face limitations in reducing dust entry into the casing, as existing ventilation filters are insufficient for effective dust reduction.

Innovation Solution

A power conversion device that dynamically controls the cooling fan's operation based on sensed temperature, adjusting airflow speed to minimize dust entry when cooling needs are low and maximize cooling when necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the cooling fan operates continuously to maintain cooling performance, then the cooling effect is improved, but dust and moisture entry into the casing increases

Engineering Contradiction:
Improvecooling performanceVSAvoiddust and moisture entry
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The cooling fan operates dynamically rather than continuously. The control unit adjusts the fan operation based on real-time temperature detection, switching between on and off states or adjusting rotation speed to match actual cooling needs, thereby reducing unnecessary air intake that carries dust and moisture

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters of the cooling fan based on temperature conditions. When the detected temperature exceeds a predetermined threshold, the fan operates at full speed; when temperature is within acceptable range, the fan operates at reduced speed or stops, thus balancing cooling performance with dust prevention

Inventive Principle:
Principle #35Parameter changes

2Temperature

If the ventilation fan runs at high speed to improve cooling, then heat dissipation is enhanced, but the lifespan of the cooling fan decreases due to increased wear

Engineering Contradiction:
Improveheat dissipationVSAvoidcooling fan lifespan
Core Design Contradiction:
TemperatureVSDuration of action of moving object

Solution Approach 1:

The cooling fan operates periodically based on temperature thresholds rather than continuously. The control unit monitors temperature and activates the fan only when necessary, creating periodic operation cycles that reduce cumulative runtime and mechanical wear while still achieving effective heat dissipation when needed

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system applies partial action by operating the cooling fan at reduced speed or for shorter durations when full cooling capacity is not required. This approach provides sufficient cooling for most operating conditions while significantly extending fan lifespan by avoiding continuous high-speed operation

Inventive Principle:
Principle #16Partial or excessive action

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 approach effectively reduces dust and moisture entry into the casing, extending the lifespan of the cooling fan and maintaining optimal cooling performance.

Implementation Method 1

a cooling fan that cools the heat dissipation member

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 2

a heat dissipation member that receives heat from the circuit board

Methodology Applied
Scientific EffectThermal Conduction: Conduction (thermal)

Data Source

PatentEP3748825B1Power conversion device
Publication Date: 2023.11.22 TOSHIBA MITSUBISHI ELECTRIC IND SYST CORP
  • EP3748825B1 patent drawingFigure 1
  • EP3748825B1 patent drawingFigure 2
  • EP3748825B1 patent drawingFigure 3

AI summary

A power conversion device includes: a casing including a housing portion; a circuit board housed in the housing portion, the circuit board including an inverter circuit or an inverter control circuit configured to control the inverter circuit; a cooling fan configured to generate flowing air flowing through the housing portion so as to cool the circuit board; a temperature sensor configured to sense a temperature inside the casing or outside the casing; and a cooling fan control circuit configured to drive the cooling fan. The cooling fan control circuit is configured to, if the temperature sensed by the temperature sensor is higher than a predetermined temperature set in advance, turn on the cooling fan. The cooling fan control circuit is configured to, if the sensed temperature is equal to or below the predetermined temperature, control the cooling fan so as to turn off the cooling fan or make a speed of the flowing air lower than a speed when the cooling fan is in the on state.