Current Detection Circuit Offset Adjustment to Eliminate Dead Zones

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Solution Overview

Problem

Conventional current detection circuits with operational amplifiers face challenges in accurately detecting load currents due to input offset voltage variations, which result in a dead zone and limited improvement in detection current variation for constant load currents.

Innovation Solution

A current detection circuit with an operational amplifier and an offset adjustment part that adjusts the input offset voltage to zero, using a microcomputer-controlled system to monitor and adjust the offset voltage, ensuring accurate detection of load currents by generating a reference voltage and using negative feedback to eliminate the dead zone.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a voltage is added to shift the detection current to eliminate the dead zone, then the dead zone is eliminated, but the variation of the detection current due to input offset voltage is not improved

Engineering Contradiction:

Improvedetection current variationVSAvoiddetection accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent adjusts the input offset voltage parameter of the operational amplifier to optimize detection accuracy. By dynamically changing the offset voltage parameter, the system eliminates the dead zone while compensating for variations in detection current, thereby resolving the contradiction between measurement precision and reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs feedback mechanisms to monitor and adjust the input offset voltage based on detection results. This feedback loop enables real-time compensation for offset voltage variations, improving both the elimination of dead zones and the stability of detection current variation

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

The solution enables precise detection of load currents without a dead zone, even when the input offset voltage changes over time, allowing for accurate detection of load current variations and preventing over-current conditions, such as when a user's finger is caught during power window operation.

Implementation Method 1

a current detection part including an operational amplifier configured to compare a first voltage proportional to a load current supplied to a load through a drive element with a second voltage proportional to a detection current

Methodology Applied

Scientific EffectOperational amplifier voltage comparison and amplification:

Implementation Method 2

using negative feedback to eliminate the dead zone

Methodology Applied

Scientific EffectNegative feedback: Feedback

Data Source

PatentUS11448668B2Current detection circuit, current detection system, and method of adjusting current detection circuit

Publication Date: 2022.09.20 KK TOSHIBA

AI summary

According to one embodiment, a current detection circuit includes a current detection part including an operational amplifier configured to compare a first voltage proportional to a load current with a second voltage proportional to a detection current. The current detection part is configured to output the detection current. The current detection circuit includes an adjustment part configured to generate data in accordance with a result of comparing a monitor voltage proportional to the detection current with a reference voltage, and to adjust an input offset of the operational amplifier.