Vehicle Contactor Failure Detection via Charging Voltage Response

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

There is a need for a contactor failure determination apparatus that can accurately diagnose the failure of contactors in a vehicle, particularly when an external charger is connected, to prevent unnecessary power exchange and ensure reliable electrical connections.

Innovation Solution

The apparatus includes a controller that executes a series of control steps to close the external charging contactors and the main contactors in a specific order, while opening the pre-charge contactor. The failure of the external charging contactor is determined based on the change in voltage detected by a voltage sensor after these control steps are executed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the external charging contactor and the main contactor are closed at the same time, then the electrical connection is established quickly, but a relatively loud noise is generated due to the simultaneous closing of multiple contactors

Engineering Contradiction:

Improvespeed of electrical connection establishmentVSAvoidnoise

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent segments the contactor closing operation into distinct phases: first closing the external charging contactor, then closing the main contactor after a predetermined time interval. This temporal segmentation prevents simultaneous closing of multiple contactors, thereby eliminating the loud noise while still establishing electrical connection efficiently

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The external charging contactor is closed in advance before the main contactor is closed. This preliminary action allows the system to prepare the charging path beforehand, and the predetermined time interval ensures that by the time the main contactor closes, the noise from simultaneous operation is avoided while maintaining connection speed

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If the main contactor is closed before the external charging contactor, then the contactor closing sequence is simplified, but a high in-rush current is introduced into the external charger side from the battery

Engineering Contradiction:

Improvecomplexity of contactor closing sequenceVSAvoidin-rush current

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The external charging contactor is closed in advance as a preliminary action before closing the main contactor. This sequence ensures that the charging path is prepared and the external charger is ready to receive power, preventing high in-rush current while maintaining a relatively simple two-step closing procedure

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The contactor closing operation is segmented into two distinct steps with a predetermined time interval: first the external charging contactor, then the main contactor. This segmentation prevents the harmful in-rush current effect while keeping the overall control logic straightforward and manageable

Inventive Principle:

Principle #1Segmentation

3Use of energy by moving object

If the pre-charge contactor remains closed during external charging, then the battery can be charged, but unnecessary power exchange between the battery and the motor circuit occurs

Engineering Contradiction:

Improvebattery charging efficiencyVSAvoidunnecessary power exchange

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The pre-charge contactor's state is dynamically controlled based on the charging mode: it remains closed during normal battery charging to allow power flow, but is opened when external charging is active to prevent unnecessary power exchange between the battery and motor circuit. This dynamic state management ensures energy efficiency while maintaining charging functionality

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The pre-charge contactor's function is locally optimized for different operating conditions: during external charging, it is opened to isolate the battery from the motor circuit and prevent energy loss, while during other charging modes it remains closed to enable normal battery charging operations

Inventive Principle:

Principle #3Local quality

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 configuration allows for the appropriate determination of contactor failures, preventing loud noise from simultaneous contactor closures and avoiding high in-rush currents that could damage electrical devices.

Implementation Method 1

a voltage sensor configured to detect rising or dropping of a voltage of the second circuit

Methodology Applied

Scientific EffectVoltage detection: Ohm's Law

Data Source

PatentUS12240438B2Contactor failure determination apparatus for vehicle

Publication Date: 2025.03.04 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 an external charging request is made, a first control for closing each 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 second main contactor is executed after execution of the second control, and response to the voltage sensor detecting that the voltage of the second circuit has not risen after execution of the third control, it is determined that at least one of the external charging contactors has failed in an open state.