Current Sensor Shunt 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, leading to decreased accuracy and increased power consumption, with complex configurations required in existing techniques.
Innovation Solution
A current sensor with a resistance value correction circuit that includes a correction resistor connected in series with the shunt resistor, applying an AC signal to calculate and correct the shunt resistor's resistance value, using a power supply circuit to generate low-voltage power for the signal application unit and high-power for voltage detection units, thereby improving accuracy without complicating the configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resistance value of the shunt resistor is corrected by passing a correction current through the shunt resistor or by providing multiple shunt resistors, then the resistance value for current detection can be corrected, but the configuration becomes complex and power consumption increases
Solution Approach 1:
The correction circuit is segmented into distinct functional blocks: a correction current generation unit that generates correction current, a correction current application unit that applies the correction current to the shunt resistor, and a resistance value calculation unit that calculates the corrected resistance value. This segmentation allows each unit to be optimized independently and simplifies the overall configuration by clearly defining the function of each component.
Solution Approach 2:
The correction current generation and application functions are extracted from the main current detection path and implemented as a separate correction circuit. This extraction allows the correction operation to be performed independently without interfering with the normal current measurement function, thereby simplifying the overall system configuration and reducing complexity.
2Measurement precision
If the resistance value of the shunt resistor is corrected by passing a correction current through the shunt resistor or by providing multiple shunt resistors, then the resistance value for current detection can be corrected, but power consumption increases and heat generation occurs
Solution Approach 1:
The correction current is applied periodically rather than continuously. The correction current application unit applies correction current to the shunt resistor only during specific correction periods, while during normal operation periods, the correction current is not applied. This periodic action significantly reduces power consumption and heat generation compared to continuous correction current application, while still maintaining the ability to correct resistance value drift over time.
3Measurement precision
If the resistance value of the shunt resistor is corrected by providing a sub-resistor and correction resistor, then the resistance value for current detection can be corrected, but the configuration becomes complex
Solution Approach 1:
The correction circuit is designed to be universal and multi-functional. The correction current generation unit can generate correction current for various correction scenarios, and the correction current application unit can apply the correction current to the shunt resistor in different operational modes. This multi-functionality allows a single correction circuit design to handle various resistance value correction needs without requiring additional components or complex configurations.
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 accurate resistance value correction for current detection with reduced power consumption and simplified configuration, enhancing detection accuracy while minimizing heat generation and power usage.
Implementation Method 1
a shunt resistor 4 provided in series in a path through which a detection target current flows
Implementation Method 2
a signal application unit 6 that applies an alternating current signal to a series circuit of the shunt resistor 4 and the correction resistor 5
Data Source
AI summary
A current sensor for a detection target current using a shunt resistor includes: a resistance value correction circuit having a correction resistor; a signal application unit that applies an alternating current signal to a series circuit of the shunt resistor and the correction resistor; a voltage detection unit that detects terminal voltages of the shunt resistor and the correction resistor; and a correction unit that calculates a resistance value of the shunt resistor and corrects the resistance value for detection; and a power supply circuit having a first power supply generation unit that generates a first power supply of the signal application unit from an input power supply of an outside; and a second power supply generation unit that generates a second power supply of the voltage detection unit.