Power Switch Protection Device with Disconnection Flag Delay

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Solution Overview

Problem

Conventional protection circuits for electricity supply systems do not provide a method to safely re-enable the power switch after disconnection, leading to potential abnormal temperature rises when the semiconductor switch is reactivated.

Innovation Solution

A protection device that employs a disconnection flag, which remains on for a predetermined time after the power switch is turned off, preventing immediate reactivation and thus preventing damage to the power switch.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the power switch is immediately reactivated after disconnection, then the circuit can resume operation quickly, but the temperature may rise abnormally causing damage to the power switch

Engineering Contradiction:

Improvecircuit resumption speedVSAvoidpower switch safety

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The protection device performs preliminary cooling action by maintaining the power switch in the OFF state for a predetermined time period after overcurrent detection. This preliminary action allows the power switch to cool down before reactivation, preventing abnormal temperature rise and damage while enabling safe circuit resumption.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a disconnection flag with predetermined time delay is implemented, then the power switch is protected from immediate reactivation, but the circuit resumption is delayed

Engineering Contradiction:

Improvepower switch protectionVSAvoidcircuit interruption duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The protection device changes the temporal parameter of the disconnection flag automatically. The flag is set to ON immediately upon overcurrent detection, preventing reactivation. After a predetermined time period elapses, the flag automatically transitions to OFF, allowing circuit resumption. This parameter change approach protects the power switch during critical cooling time while minimizing unnecessary interruption duration.

Inventive Principle:

Principle #35Parameter changes

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

Prevents the power switch from being turned on immediately after disconnection, thereby avoiding damage and ensuring safe operation by allowing the temperature to stabilize before reactivation.

Implementation Method 1

the quantities of heat generation and heat radiation of an electricity supply circuit (including a power line connecting a load with a power supply, and a power switch) are calculated on the basis of a current value flowing to the load

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2843783B1Protection device for electricity supply circuit

Publication Date: 2023.01.18 YAZAKI CORP

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AI summary

When a power switch (11) is turned off, a protection device for an electricity supply circuit starts keeping time using a timer (22) and turns on a disconnection flag. Then the protection device turns off the disconnection flag when the timer (22) has counted a predetermined time. When the power switch (11) is turned off, the disconnection flag does not subsequently turn off until the predetermined time (Q1) has passed. Therefore, it is possible to prevent an excessive temperature increase in the power switch (11) and prevent damage to the power switch (11).