Hybrid Power Supply Relay Welding Detection

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Solution Overview

Problem

Existing power supply circuits for hybrid vehicles lack an effective method to detect abnormalities in relays, such as welding or immobility, which can lead to excessive current flow or failure in power storage mechanisms, particularly when multiple relays are used.

Innovation Solution

A control device that includes a voltage detection unit, a processing unit for precharge processes, and a detection unit to identify abnormal relays by analyzing voltage values across the load and power storage mechanisms, allowing for simultaneous detection across multiple power supply circuits during startup or shutdown.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple relays are used in power supply circuits to control power storage mechanisms, then the system can achieve better control flexibility and power management capability, but the risk of relay abnormalities (welding, immobility) increases and becomes harder to detect

Engineering Contradiction:

Improvecontrol flexibilityVSAvoidrelay abnormality detection

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by performing relay abnormality detection during the precharge process before the relay is fully activated. The control device detects voltage values during the precharge phase (before main relay closure) to identify potential welding or immobility issues in advance, preventing damage to power storage mechanisms and enabling early intervention before full power connection occurs.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If relay abnormality detection is performed after power supply startup, then the system can operate normally first, but abnormal relays may have already caused damage or excessive current flow

Engineering Contradiction:

Improvesystem operation continuityVSAvoidexcessive current flow damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent performs relay detection during the precharge process, which occurs before the main relay closes and full power is supplied to the system. This preliminary detection prevents excessive current flow and damage to power storage mechanisms by identifying abnormal relays in advance, while still maintaining system operation continuity by allowing normal startup once abnormalities are detected and handled.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies preliminary anti-action by preventing the harmful effect of excessive current flow before it can occur. By detecting relay abnormalities during precharge and preventing closure of relays with welding or immobility issues, the system counteracts potential damage before it happens to the power storage mechanisms.

Inventive Principle:

Principle #9Preliminary anti-action

3Device complexity

If traditional relay detection methods are used, then the detection process is simple, but the detection accuracy is insufficient to reliably identify welded or immobile relays

Engineering Contradiction:

Improvedetection method simplicityVSAvoidrelay abnormality detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent uses feedback by continuously monitoring voltage values during the precharge process and comparing them against expected ranges. The control device receives voltage feedback from the power supply circuit during precharge, analyzes this feedback to determine relay status, and adjusts control signals accordingly to prevent abnormal relay closure, achieving reliable detection without overly complex additional hardware.

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

Accurately detects abnormal relays, preventing damage and ensuring reliable operation by identifying welded or immobile relays, thereby reducing system startup and shutdown times and preventing power supply issues.

Implementation Method 1

a voltage detection unit detecting a voltage value of the load; a voltage detection unit detecting a voltage value of each of the power storage mechanisms

Methodology Applied

Scientific EffectVoltage detection: Ohm's Law

Implementation Method 2

the precharge SMR is closed and the capacitor is precharged until a certain time has elapsed while a current is limited by a limiting resistor or the like

Methodology Applied

Scientific EffectElectrical resistance: Electrical Resistance

Data Source

PatentUS8581448B2Control device of power supply circuit

Publication Date: 2013.11.12 TOYOTA JIDOSHA KK

AI summary

An ECU executes a program including a step of turning on an SMRP and an A-SMRP if an ignition switch is turned on; a step of detecting voltage values VB(1) and VB(2) of running batteries when VH is detected and if VH is higher than 180 V; a step of detecting that SMRP connected to the running battery is welded, if VB(1) is higher than 150 V; and a step of detecting that A-SMRB connected to the running battery is welded, if VB(2) is higher than 150 V.