Relay Failure Diagnosis Using Parallel Circuit for Constant Power

Solution Overview

Problem

Conventional methods fail to effectively diagnose relay switch failures in 12V LISB batteries, which are critical for continuous power supply in vehicles, as relays are often in a closed state and rarely switched, making it difficult to determine if they are functioning correctly.

Innovation Solution

An apparatus and method that control the relay and parallel circuits to diagnose switch failures by monitoring voltage and current states, determining if the relay switch is normal or faulty by switching operations and sensing inputs, ensuring constant power supply through a parallel circuit even when the relay is open.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If relays are maintained in closed state for long-term use, then power supply reliability is improved, but relay switch failure detection capability deteriorates

Engineering Contradiction:

Improvepower supply reliabilityVSAvoidrelay switch failure detection

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The system performs preliminary diagnostic actions by periodically switching the relay to open state and using the parallel circuit to detect potential failures before they occur during critical operation. The control unit actively tests relay functionality by controlling it to open state and monitoring through the parallel circuit, enabling preventive detection rather than waiting for failure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A parallel circuit is introduced as an intermediary diagnostic path that allows failure detection without compromising the main power supply function. The parallel circuit includes sensing units that monitor voltage and current to determine relay switch status, acting as a mediator between the relay and the control unit for non-intrusive testing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Difficulty of detecting and measuring

If relay is switched to open state for diagnosis, then relay switch failure detection is improved, but power supply continuity deteriorates

Engineering Contradiction:

Improverelay switch failure detectionVSAvoidpower supply continuity

Core Design Contradiction:

Difficulty of detecting and measuringVSReliability

Solution Approach 1:

The system performs preliminary diagnostic actions by periodically switching the relay to open state and using the parallel circuit to detect potential failures before they occur during critical operation. The control unit actively tests relay functionality by controlling it to open state and monitoring through the parallel circuit, enabling preventive detection rather than waiting for failure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A parallel circuit is introduced as an intermediary diagnostic path that allows failure detection without compromising the main power supply function. The parallel circuit includes sensing units that monitor voltage and current to determine relay switch status, acting as a mediator between the relay and the control unit for non-intrusive testing.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Difficulty of detecting and measuring

If parallel circuit is added for diagnosis, then relay switch failure detection is improved, but device complexity increases

Engineering Contradiction:

Improverelay switch failure detectionVSAvoidcircuit complexity

Core Design Contradiction:

Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The parallel circuit is designed with multi-functionality to reduce overall system complexity. It serves both as a diagnostic path for relay failure detection and as a backup power supply path, eliminating the need for separate diagnostic and backup systems. The same parallel circuit structure performs multiple functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system changes operational parameters by switching between different circuit configurations (relay closed/parallel open, relay open/parallel closed) to achieve different functions. By changing the state parameters of existing components rather than adding permanent complex structures, the system maintains simplicity while achieving diagnostic capability.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3444624B1Apparatus for diagnosing relay failure of battery using parallel circuit for constant power supply and method thereof

Publication Date: 2022.09.21 LG ENERGY SOLUTION LTD

Figure 1
Figure 2
Figure 3

AI summary

Disclosed is an apparatus and method for diagnosing a failure of a relay for a battery required to constantly supply the power to a vehicle with guaranteeing the constant power supply using a parallel circuit. The apparatus of the present disclosure includes a control unit which when voltage and current of a parallel unit is 0 in first state in which a relay unit is in closed state and the parallel unit is in open state, controls into second state in which the relay unit is in closed state and the parallel unit is in closed state, and when the voltage of the parallel unit is equal to voltage of the battery and the current of the parallel unit is 0 in the second state, controls into third state in which the relay unit is in open state and the parallel unit is in closed state, and when the current of the parallel unit is equal to current of the relay unit in the third state, determines a switch of the relay unit to be normal, and when the current of the parallel unit is 0, determines the switch of the relay unit to be faulty, a relay unit through which the current of the battery flows in closed state of the switch to supply the power, and a parallel unit which applies the current of the battery in closed state instead of the relay unit in open state in which the power supply is stopped.