External Power Supply Early AC Failure Detection

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Solution Overview

Problem

Existing power failure detection systems are ineffective for devices receiving regulated DC power from external supplies, as they lack early detection capabilities due to the absence of access to unregulated AC or DC power, leading to delayed detection and potential device malfunctions during mains power outages.

Innovation Solution

Implementing a method within the external power supply to detect the absence of mains power and transmit this information to the electronic device via the DC power conducting leads, either through modulation of a carrier signal or DC output voltage level, allowing for early detection and estimation of the duration of DC power availability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If an external DC power supply is used instead of an internal power supply, then cost and space are reduced and maintenance is easier, but early power failure detection becomes impossible because the device lacks access to unregulated AC or DC power

Engineering Contradiction:
Improvepower supply structureVSAvoidpower failure detection capability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent introduces an intermediary communication channel between the external power supply and the device. The power supply detects AC power absence and transmits this information to the device through modulation on the DC output voltage or a carrier signal, enabling early detection without requiring the device to access unregulated power directly.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The power supply performs preliminary detection of AC power absence before the DC capacitors are fully depleted. By detecting the absence of rectified DC voltage at the power supply output and transmitting this information early, the system enables the device to prepare for shutdown before actual DC power failure occurs.

Inventive Principle:
Principle #10Preliminary action

2Difficulty of detecting and measuring

If the device monitors DC power voltage directly, then detection is simple, but detection occurs too late after capacitors deplete during AC power outage

Engineering Contradiction:
Improvepower failure detectionVSAvoiddetection delay
Core Design Contradiction:
Difficulty of detecting and measuringVSLoss of time

Solution Approach 1:

The power supply continuously monitors its own output conditions and provides feedback about AC power status to the device. When the power supply detects absence of rectified DC voltage (indicating AC power failure), it immediately transmits this information to the device, eliminating the detection delay that would occur if the device monitored DC voltage directly after capacitor depletion.

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

Enables early power failure detection and notification to the device, allowing for timely actions such as data saving and orderly shutdown, even when the device relies solely on an external DC power supply, thereby reducing downtime and ensuring system integrity during power outages.

Implementation Method 1

transmitting information representative of the absence of supply of mains power on the Alternating Current input when the absence of supply of mains power on the Alternating Current input of the external power supply is detected

Methodology Applied
Scientific EffectModulation: Phase Modulation

Data Source

PatentEP2915018B1Device and method for early detection of power failure in an external power supply
Publication Date: 2021.06.02 INTERDIGITAL MADISON PATENT HLDG
  • EP2915018B1 patent drawingFigure 1
  • EP2915018B1 patent drawingFigure 2
  • EP2915018B1 patent drawingFigure 3

AI summary

An external power supply converts AC power to DC power for a device. The external power supply and the device comprise circuits that provide early AC input failure detection so that the device can take measures such as to safe keep data as long as the external power supply continues to provide DC power to the device.