Contactor Precharge Control for Arc-Cleaned Contact Surfaces

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Contactors in high-voltage applications, such as lithium-ion batteries, face issues with non-conductive particles depositing on contact surfaces, leading to insufficient electrical contact due to contamination, which existing methods fail to address effectively.

Innovation Solution

A method where the contactor is partially precharged before closure, creating an arc that cleans the contact surfaces by thermal energy and UV radiation, utilizing a precharging device with a resistor or electron pump to charge the DC link capacitance up to 60-95% of the battery voltage, only when excessive contact resistance is detected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the contactor is hermetically sealed to prevent moisture and contamination entry, then protection against external contaminants is improved, but non-conductive particles can still deposit on contact surfaces from the interior during production or operation

Engineering Contradiction:

Improveprotection against external contaminantsVSAvoidelectrical contact quality

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The contactor performs self-cleaning through arc generation during normal switching operations. The arc automatically burns off deposited particles on the contact surfaces without requiring external maintenance or additional cleaning mechanisms, allowing the system to maintain its own reliability

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The harmful arc that occurs during contact closure is converted into a beneficial cleaning tool. The arc's thermal energy and UV radiation actively remove non-conductive particles from contact surfaces, transforming a potentially damaging phenomenon into a self-maintaining mechanism

Inventive Principle:

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

2Reliability

If an arc is produced to clean contact surfaces by burning off particles, then contact surface cleanliness is improved, but component aging and damage may occur due to thermal stress and erosion

Engineering Contradiction:

Improvecontact surface cleanlinessVSAvoidcontactor lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

Instead of producing a full-strength arc that would cause significant erosion, the invention uses the partial arc that naturally occurs during contact closure. This partial arc is sufficient to clean particles but limited in duration and intensity to minimize damage to contact components

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The cleaning action occurs periodically during normal switching operations rather than through continuous arcing. Each contact closure provides a brief cleaning impulse, maintaining cleanliness over time without subjecting components to sustained thermal stress

Inventive Principle:

Principle #19Periodic action

3Reliability

If the contactor is closed with fully charged DC link capacitance to ensure proper operation, then operational reliability is improved, but excessive current flow and potential short-circuit currents occur

Engineering Contradiction:

Improveoperational reliabilityVSAvoidcurrent flow during closure

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The DC link capacitance is precharged to a controlled voltage level before contactor closure to prevent excessive inrush current. This preliminary charging action ensures the capacitance is ready for operation while limiting the voltage difference that would cause dangerous current spikes during switching

Inventive Principle:

Principle #10Preliminary 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 method effectively cleans contact surfaces, optimizing the lifetime and reliability of contactors and battery systems by minimizing component aging and preventing short-circuit currents, suitable for electric vehicles and energy storage systems.

Implementation Method 1

an arc arises when the contactor is closed... The arc that arises corrodes possible contamination particles on the contact surface in the vicinity of a contact point of the two contacts of the contactor by way of the thermal energy released or the correspondingly released UV radiation

Methodology Applied

Scientific EffectArc: Electric Arc

Implementation Method 2

The arc that arises corrodes possible contamination particles on the contact surface in the vicinity of a contact point of the two contacts of the contactor by way of the thermal energy released

Methodology Applied

Scientific EffectThermal energy: Heating

Implementation Method 3

The arc that arises corrodes possible contamination particles on the contact surface in the vicinity of a contact point of the two contacts of the contactor by way of the thermal energy released or the correspondingly released UV radiation

Methodology Applied

Scientific EffectUV radiation: Radiation

Data Source

PatentUS12255471B2Method for operating a contactor

Publication Date: 2025.03.18 ROBERT BOSCH GMBH

AI summary

A method for operating a contactor (10) is described, wherein the contactor (10) comprises at least two contacts (18, 20, 22) electrically conductively connected to one another in a closed state of the contactor (10), having the method steps of partially charging an DC link capacitance (103) in electrical contact with the contactor (10) and closing the contactor (10).