Current Sensor Resistance Correction Circuit
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Solution Overview
Problem
Existing current sensors face challenges in accurately correcting the resistance value for current detection due to shunt resistor deterioration, with previous methods either requiring indirect correction using sub-resistors or complicating the configuration with multiple shunt resistors and input terminals.
Innovation Solution
A current sensor design that includes a resistance value correction circuit with multiple correction resistors connected in series with the shunt resistor, applying alternating current signals to detect terminal voltages and calculate the shunt resistor's resistance value for direct correction, thereby improving accuracy without complicating the configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple shunt resistors are provided for correction, then the resistance value correction accuracy is improved, but the device complexity increases
Solution Approach 1:
The correction resistors are divided into multiple segments (first correction resistor, second correction resistor, third correction resistor) with different resistance values and accuracy levels. Each segment handles a specific correction task, allowing the system to achieve high correction accuracy without requiring multiple complete shunt resistor sets. This segmentation reduces device complexity while maintaining measurement precision.
Solution Approach 2:
Different correction resistors are assigned different resistance values and accuracy characteristics based on their specific functions. The first correction resistor has higher accuracy for fine corrections, while other resistors handle coarser adjustments. This local quality differentiation allows the system to achieve overall high accuracy without uniformly high complexity across all components.
2Reliability
If sub-resistors are used for indirect correction, then the correction capability is improved, but the device complexity and configuration complexity increase
Solution Approach 1:
The correction resistors are merged into the existing shunt resistor structure, sharing the same terminal nodes and integration circuitry. The first correction resistor is connected between the same terminals as the shunt resistor, and the second and third correction resistors are connected in series with each other and parallel to the shunt resistor. This merging eliminates the need for separate correction circuits and reduces configuration complexity while maintaining correction capability.
Solution Approach 2:
The correction resistors serve multiple functions: they can be used individually or in combination, provide both direct and indirect correction paths, and work with the same measurement circuitry as the shunt resistor. This multi-functionality reduces the need for dedicated correction components and simplifies the overall device configuration.
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
This design allows for high-accuracy correction of the resistance value for current detection, enhancing the accuracy of current measurement without the need for multiple shunt resistors or complex configurations, by leveraging the higher resistance accuracy of correction resistors farther from the shunt resistor.
Implementation Method 1
the terminal voltage of the shunt resistor and a part of the correction resistors in a first period, and terminal voltages of all of the correction resistors in a second period
Data Source
AI summary
A current sensor for detecting a current based on a terminal voltage and a resistance value of a shunt resistor, includes: a resistance value correction circuit having: correction resistors; a signal application unit; a voltage detection unit that detects terminal voltages of the shunt resistor and a part of the correction resistors in a first period, and terminal voltages of all of the correction resistors in a second period; and a correction unit that corrects the resistance value for current detection based on a calculated resistance value of the shunt resistor. Resistance values and resistance accuracies of the correction resistors are higher as the plurality of correction resistors are disposed farther from the shunt resistor.