Vehicle Contactor Sequencing for Closed-Failure Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing contactor systems in vehicles fail to appropriately determine the failure of contactors when an external charger is connected to charge the battery, leading to unnecessary power exchange and potential discomfort due to simultaneous contactor closures and high in-rush currents.

Innovation Solution

A contactor failure determination apparatus that controls the sequential closure of contactors to avoid simultaneous closure, using voltage sensors to determine contactor failures based on voltage changes, preventing loud noise and high in-rush currents, and ensuring proper electrical connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If multiple contactors are closed simultaneously at vehicle startup, then electrical connection is established quickly, but loud noise is generated and passenger comfort deteriorates

Engineering Contradiction:

Improveelectrical connection establishment speedVSAvoidnoise level

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent segments the contactor closure process into distinct sequential stages: first the precharge contactor closes, then after a predetermined time interval, the main contactor closes. This temporal segmentation eliminates simultaneous closure noise while maintaining efficient electrical connection establishment.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If contactor closure sequence is delayed to reduce noise, then passenger comfort improves, but vehicle startup time increases

Engineering Contradiction:

Improvenoise levelVSAvoidvehicle startup time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The precharge contactor closes before the main contactor to perform preliminary electrical connection. This preliminary action prepares the circuit in advance, allowing the main contactor to close quickly afterward without causing excessive noise, thus balancing comfort with startup speed.

Inventive Principle:

Principle #10Preliminary action

3Speed

If external charging contactor and main contactor are closed simultaneously, then charging connection is established quickly, but high in-rush current damages electrical devices

Engineering Contradiction:

Improvecharging connection establishment speedVSAvoidin-rush current

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The external charging contactor closes in advance before the main contactor to establish preliminary charging connection. This preliminary action allows the charging circuit to prepare and limit current flow, preventing dangerous in-rush current when the main contactor subsequently closes.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The predetermined time interval between contactor closures acts as a cushioning period that allows electrical components to prepare for full power connection. This beforehand cushioning prevents sudden high in-rush current by gradually establishing the electrical path.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Device complexity

If contactor failure determination is not implemented, then system complexity is reduced, but contactor failures go undetected causing unnecessary power exchange

Engineering Contradiction:

Improvesystem complexityVSAvoidcontactor failure detection accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The control unit monitors voltage changes across contactors during switching operations to detect failures. This feedback mechanism provides real-time information about contactor status, enabling reliable failure detection while maintaining relatively simple system architecture through intelligent sensing.

Inventive Principle:

Principle #23Feedback

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

The apparatus effectively determines contactor failures, reducing discomfort and preventing electrical device damage by avoiding simultaneous contactor closures and high in-rush currents, ensuring reliable vehicle operation.

Implementation Method 1

voltage sensors to detect changes in voltage across circuits

Methodology Applied

Scientific EffectVoltage detection: Ohm's Law

Implementation Method 2

establishing electrical connections through contactors with higher resistance

Methodology Applied

Scientific EffectElectrical resistance: Electrical Resistance

Data Source

PatentUS12606004B2Contactor failure determination apparatus for vehicle

Publication Date: 2026.04.21 MAZDA MOTOR CORP

AI summary

To provide a contactor failure determination apparatus capable of appropriately determining failure of a contactor provided in a vehicle, a voltage sensor capable of detecting rising or dropping of a voltage of a second circuit including an external charger is provided. When a vehicle start request is made, a first control for closing one external charging contactor is executed, a second control for closing a pre-charge contactor is executed after execution of the first control, a third control for closing a main contactor, which is not parallel with the pre-charge contactor, is executed after execution of the second control, and in response to the voltage sensor detecting that the voltage of the second circuit has risen after execution of the third control, it is determined that the other external charging contactor has failed in a closed state.