Active Monostable Transient Protection Circuit for Capacitive Loads

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Solution Overview

Problem

Automotive electrical systems experience high-frequency, high-amplitude voltage transients that can damage semiconductors and other electrical devices due to their inability to effectively filter out these transients, particularly in capacitive loads.

Innovation Solution

An active monostable positive transient protection circuit with a controlled slew rate switchable voltage source and a transient voltage-triggered monostable multivibrator that disconnects the capacitive load from the power source during high-frequency transients, using a high pass filter to determine when to isolate the load and prevent excessive current flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a low pass filter is used to suppress high frequency transients, then transient suppression is improved, but the filter requires bulky capacitors and inductors

Engineering Contradiction:

Improvetransient suppressionVSAvoidfilter component size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The patent replaces the traditional passive mechanical filter (using inductors and capacitors) with an active electronic protection circuit that uses transistors, diodes, and operational amplifiers to detect and suppress transients through electronic switching and signal processing, eliminating the need for bulky passive components

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the approach from passive frequency-based filtering to active transient detection and switching, where the protection circuit monitors voltage parameters and actively switches to bypass or clamp transient voltages, achieving suppression without requiring large filter components

Inventive Principle:

Principle #35Parameter changes

2Speed

If high slew rate voltage transients are applied to capacitive load, then power delivery is improved, but excessive current flows that can damage the capacitance, source, and connected devices

Engineering Contradiction:

Improvevoltage slew rateVSAvoidexcessive current

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary protection circuit positioned between the voltage source and capacitive load that includes current-limiting elements, slew rate control circuits, and transient voltage suppressors to mediate the voltage transmission and prevent excessive current from reaching the load

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protection circuit performs preliminary action by detecting voltage transients before they can cause damage, and preemptively activates protective mechanisms such as switching elements or clamping circuits to prevent excessive current flow before it occurs

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS8310798B2Active monostable positive transient protection circuit for a capacitive load

Publication Date: 2012.11.13 AUMOVIO SYSTEMS INC

AI summary

An electrically noisy D.C. power source having high slew rate A.C. transient voltage, is cut off from a capacitive load by a switchable, constant slew rate voltage source, upon the detection of an A.C. transient voltage having a slew rate that would otherwise cause a current overload through the capacitive load or the voltage source, or the D.C. power source.