Self-Calibrating Current Sensor with Binary Input Circuit

Solution Overview

Problem

Current sensing devices, particularly those with adjustable thresholds, often require calibration in high-voltage or shock hazard environments, violating safety codes when traditional methods are used, and existing self-calibrating solutions are inconvenient or unsafe.

Innovation Solution

A self-calibrating current sensor that accepts a binary input and stores a command to initiate calibration in a safe, powered-down mode, allowing automatic recalibration upon power-up without exposing the operator to shock hazards, using a sensor, binary input circuit, and controller circuit configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional calibration methods are used to adjust threshold values, then the current sensor can be calibrated to specific current conditions, but the operator must open the housing and work in high-voltage environments violating safety codes

Engineering Contradiction:

Improvethreshold calibration accuracyVSAvoidshock hazard exposure

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The calibration is performed automatically during the power-up sequence before the device is operational. The microcontroller automatically initializes the threshold value from stored calibration data, eliminating the need for manual adjustment in hazardous environments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The device performs self-calibration using stored calibration data in its memory. The microcontroller automatically configures the threshold values without requiring external intervention or manual adjustment, allowing calibration to be done safely during power-up rather than in hazardous operating conditions.

Inventive Principle:

Principle #25Self-service

2Device complexity

If fixed threshold current sensors are used, then the device complexity is reduced, but users must carry large inventories of different threshold sensors for various motor applications

Engineering Contradiction:

Improvesensor configuration simplicityVSAvoidthreshold adjustment flexibility

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The threshold value is made dynamically adjustable through software configuration rather than being fixed during manufacturing. The microcontroller allows the threshold to be programmed and modified based on specific application requirements, providing versatility without requiring multiple fixed-threshold device variants.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The threshold parameter is changed from a fixed physical characteristic to a programmable software parameter. This allows the same hardware device to be adapted to different current monitoring requirements by simply changing the threshold value in the microcontroller, eliminating the need for multiple inventory items.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If manual calibration adjustment is made while the motor is running, then the threshold can be set for over/under current detection, but the cabinet door must remain open exposing the operator to high voltage

Engineering Contradiction:

Improvethreshold adjustment convenienceVSAvoidhigh voltage exposure

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The calibration is performed automatically during the power-up sequence before the device is operational. The microcontroller automatically initializes the threshold value from stored calibration data, eliminating the need for manual adjustment in hazardous environments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The device performs self-calibration using stored calibration data in its memory. The microcontroller automatically configures the threshold values without requiring external intervention or manual adjustment, allowing calibration to be done safely during power-up rather than in hazardous operating conditions.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS8125239B2Self calibrating current sensor

Publication Date: 2012.02.28 FUNCTIONAL DEVICES

AI summary

A self-calibrating current sensor for sensing the state of the current passing through a load line enclosed within a housing comprises a sensor disposed adjacent the load line for sensing a current passing through the load line, the sensor having an output at which a signal indicative of the level of current passing through the load line is present, the sensor being positioned with the housing, a binary input circuit configured to generate at least one binary signal, the binary input circuit being configured to change the level of the at least one binary signal without the need of opening the housing, and a controller circuit having a first input coupled to the output of the sensor for receiving the signal indicative of the level passing through the supply line and having a second input coupled to the binary input circuit for receiving the at least one binary signal, the controller being configured to provide a signal indicative of the status of the current in the load line on an output. A method of calibrating a current sensor is also provided.