Universal Temperature Measuring Circuit for Two-Wire and Three-Wire PT100 Sensors
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Solution Overview
Problem
Temperature measuring circuits for PT100 sensors face compatibility issues due to different wiring methods, such as two-wire and three-wire connections, which require distinct hardware configurations, limiting their versatility and reliability.
Innovation Solution
A temperature measuring circuit with a control unit that detects differential signal levels to determine the connection type, using a combination of current output interfaces, filter circuits, and reference interfaces to provide compatible excitation currents for both two-wire and three-wire connections, allowing for software-compatible temperature measurement across different sensor configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different hardware configurations are used for two-wire and three-wire connections, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal temperature measuring circuit that can handle both two-wire and three-wire PT100 sensor connections through a single hardware configuration. The control unit automatically detects the connection type and adapts its operation accordingly, eliminating the need for separate hardware circuits for different wiring methods. This multi-functional approach maintains measurement reliability while significantly reducing device complexity.
Solution Approach 2:
The patent employs dynamic adaptation where the control unit detects the connection type (two-wire or three-wire) in real-time and dynamically adjusts its measurement protocol. The system transitions from static hardware configurations to dynamic software-based adaptation, allowing the same hardware to optimize its operation based on the actual sensor connection type without requiring physical reconfiguration.
2Measurement precision
If separate temperature measuring circuits are used for different wiring methods, then measurement precision is maintained, but adaptability decreases
Solution Approach 1:
The control unit is designed with universal compatibility to support both two-wire and three-wire PT100 sensor connections through a single circuit configuration. It maintains high measurement precision by implementing connection-type-specific measurement protocols software-based, while providing broad adaptability to different sensor wiring methods without requiring separate hardware circuits for each configuration.
Solution Approach 2:
The patent changes the measurement parameters (such as excitation current application and voltage measurement points) based on the detected connection type. For two-wire connections, it uses one set of measurement parameters, while for three-wire connections, it switches to another set of parameters. This dynamic parameter adjustment maintains measurement precision across different wiring configurations while enhancing adaptability.
3Reliability
If hardware switches are added to determine connection types, then reliability is improved, but ease of operation worsens
Solution Approach 1:
The patent replaces the mechanical switch-based connection detection system with an electronic/software-based detection mechanism. Instead of using physical switches (SW1, SW2) to determine connection types, the control unit automatically detects the sensor connection type through electrical measurements and software logic. This substitution maintains the reliability of continuous measurement operation while significantly improving ease of operation by eliminating manual switch configuration.
Solution Approach 2:
The control unit performs self-detection of the sensor connection type without requiring external intervention or manual switch configuration. The system automatically identifies whether a two-wire or three-wire connection is present and self-adjusts its measurement protocol accordingly. This self-service capability enhances ease of operation while maintaining measurement reliability through automatic adaptation.
Data Source
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AI summary
A temperature measuring circuit and a measuring method thereof relating to the field of electronic circuits. The temperature measuring circuit comprises a control unit(U1), wherein the control unit(U1) comprises a first current output interface(IEXC1), a second current output interface(IEXC2), a first input/output interface(AIN3), a second input/output interface(AIN2), and a third input/output interface(AIN7). Further, the first current output interface(IEXC1) and the first input/output interface(AIN3) of the control unit(U1) are respectively electrically connected to a first interface (CN1-1) of a temperature sensor(CN1); the second current output interface(IEXC2) and the second input/output interface(AIN2) of the control unit(U1) are respectively electrically connected to a second interface(CN1-2) of the temperature sensor(CN1); and the third input/output interface(AIN7) of the control unit(U1) is electrically connected to a third interface(CN1-2) of the temperature sensor(CN1). Thus, a temperature measuring circuit compatible with a temperature sensor(CN1) having a two-wire or three-wire system is implemented.