Offset Correction Circuit with Switched Parallel Wiring
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Solution Overview
Problem
Conventional offset correction methods are unable to perform offset correction when current flows through a sensor unit, leading to an increase in offset drift and reduced measurement accuracy.
Innovation Solution
An offset correction device and circuit that includes a first wiring portion connected to input and output lines, a second wiring portion connected in parallel, and a switch portion that controls the conductive state of the second wiring portion, allowing for offset correction even when current flows through the sensor unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offset correction is performed only when no current flows through the sensor unit, then the measurement accuracy is maintained under static conditions, but offset drift increases when current continuously flows through the sensor unit during load operation
Solution Approach 1:
The current path is segmented into two portions: a first wiring portion that carries the load current continuously, and a second wiring portion that can be switched to carry current in the opposite direction. This segmentation allows the sensor unit to measure offset drift by comparing currents in opposite directions while the load continues to operate, resolving the contradiction between maintaining measurement accuracy and preventing offset drift during continuous current flow.
Solution Approach 2:
The switch portion periodically switches the second wiring portion to conductive state to perform offset correction measurements. This periodic action allows offset drift to be corrected at regular intervals during load operation, maintaining measurement accuracy without requiring the load to be stopped, thus resolving the contradiction between continuous operation and offset drift prevention.
2Device complexity
If a single wiring portion is used for current measurement, then the device complexity is minimized, but offset correction cannot be performed when current flows through the sensor unit
Solution Approach 1:
The offset correction function is merged with the existing current measurement function by adding a second wiring portion that shares the same sensor unit. The switch portion controls the configuration to enable both normal current measurement and offset correction measurement through the same sensor unit, thus achieving offset correction capability during current flow without significantly increasing device complexity.
Solution Approach 2:
The sensor unit is designed to serve multiple functions: it measures both the load current during normal operation and the offset current during offset correction. The switch portion and second wiring portion enable the sensor unit to perform offset correction measurements while the load continues to operate, providing multi-functionality without requiring separate measurement systems, thus resolving the contradiction between device complexity and offset correction capability.
Data Source
AI summary
An offset correction device includes: a first wiring portion; a second wiring portion; a switch portion that switches at least the second wiring portion to either a conductive state or a non-conductive state; and a control unit that controls the switch portion to perform offset correction of the sensor unit, in which the second wiring portion is disposed such that a current in a direction opposite to a current in the first wiring portion is measured by the sensor unit.