Electric Motor Insulation Recovery via Fan Drying

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Solution Overview

Problem

The insulation resistance between the drive battery and the chassis of electric vehicles drops rapidly due to moisture, leading to frequent restrictions on vehicle usage and recharging, as existing safety mechanisms fail to differentiate between moisture-related issues and other insulation faults.

Innovation Solution

A method and system that activate a cooling fan and promote Joule heating in the electric motor when insulation resistance falls below a threshold, aiming to dry the motor and restore insulation resistance, while also applying a degraded mode to prevent recharging if the fault is not moisture-related.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If insulation resistance monitoring is continuously performed to ensure safety, then personnel protection from electrocution is improved, but vehicle availability deteriorates due to frequent restrictions on usage and recharging

Engineering Contradiction:

Improvepersonnel protectionVSAvoidvehicle availability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system performs preliminary drying action by activating the cooling fan when insulation resistance drops below the threshold, attempting to restore insulation before restricting vehicle usage. This preliminary intervention can recover from moisture-related issues before they trigger availability restrictions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system converts the harmful effect of moisture (which causes insulation resistance drop) into a beneficial drying process by activating the cooling fan. The same moisture detection that triggers safety restrictions now initiates a recovery process that can restore insulation and maintain vehicle availability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If the cooling fan is activated to dry the electric motor when insulation resistance is low, then insulation resistance restoration is improved, but energy consumption increases

Engineering Contradiction:

Improveinsulation resistanceVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system applies partial drying action by activating the cooling fan for a limited duration or at reduced speed when insulation resistance drops, rather than continuous full-power operation. This partial action is sufficient to address moisture issues while minimizing energy consumption.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system continuously monitors insulation resistance during the drying process and provides feedback to control the cooling fan operation. When insulation resistance恢复到正常水平, the fan is deactivated, optimizing energy usage by running only as long as needed to restore insulation.

Inventive Principle:

Principle #23Feedback

3Reliability

If the vehicle is restricted to degraded mode when insulation resistance is low, then safety is improved, but loss of time occurs due to prolonged unavailability

Engineering Contradiction:

ImprovesafetyVSAvoidvehicle unavailability

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary drying action before restricting vehicle usage to degraded mode. By attempting to restore insulation resistance through fan activation first, the system can avoid or shorten the duration of availability restrictions, reducing time loss while maintaining safety.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system converts the insulation resistance drop that would normally trigger immediate availability restrictions into an opportunity for recovery. The moisture-related insulation drop initiates a drying process that can restore insulation and prevent or reduce degraded mode restrictions, turning a harmful condition into a beneficial recovery opportunity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 prolongs the use of the electric drive system by quickly restoring insulation resistance due to moisture, preventing unnecessary degradation and maintaining vehicle functionality, while accurately identifying non-moisture related faults to prevent recharging and signal maintenance needs.

Implementation Method 1

activation of a cooling fan of said electric drive motor, until a step of detection that a measurement of said insulation resistance is above said preset threshold

Methodology Applied

Scientific EffectForced Convection: Forced Convection

Implementation Method 2

a step of applying a degraded control mode to said electric motor, promoting Joule heating

Methodology Applied

Scientific EffectJoule Heating: Joule Heating

Data Source

PatentUS10059206B2Method for controlling an electric traction system and corresponding electric traction system

Publication Date: 2018.08.28 AMPERE SAS

AI summary

A method controls an electric drive system of a vehicle including an electric drive motor, a drive battery, and a drive inverter. The method includes detecting that a measurement of an insulation resistance between the battery and a chassis of the vehicle is below a preset threshold, detecting a closed state of relays connecting the battery to the inverter, and following the detecting the measurement and the detecting the closed state, activating a cooling fan of the electric drive motor until detecting that a measurement of the insulation resistance is above the preset threshold, within a limit of a first preset duration.