An infrared radiation temperature current sensor converting to voltage signal device

Abstract

The utility model relates to electrical measurement technical field discloses a kind of current sensor conversion voltage signal device of infrared radiation temperature, including shell, signal processing circuit being set in shell and output interface for output signal, further include double-path infrared temperature measurement module and built-in reference heat source module;Double-path infrared temperature measurement module is fixed in shell, including the measurement infrared sensor and reference infrared sensor of side-by-side arrangement;Built-in reference heat source module includes a reference resistance being set in the shell interior and located in the sensing direction of reference infrared sensor, and for providing constant drive current to reference resistance constant-current drive circuit, constant-current drive circuit is electrically connected with signal processing circuit.The utility model compared with prior art has the advantages that: difference inhibits common-mode interference, greatly improves signal-to-noise ratio;Proportional operation realizes self-calibration;Direct output current linear voltage greatly facilitates the access and use of rear-end system.

Description

Technical Field

[0001] This utility model relates to the field of electrical measurement technology, specifically to a device that converts an infrared radiation temperature current sensor into a voltage signal. Background Technology

[0002] Current measurement is a core component of power monitoring, equipment protection, and energy efficiency management. Traditional current sensors, such as current transformers and Hall effect sensors, require electrical connections or magnetic coupling, which presents problems such as difficulty in insulation, inconvenient installation, and susceptibility to electromagnetic interference. Furthermore, they are not suitable for special environments such as high voltage, enclosed spaces, or corrosive environments.

[0003] Non-contact infrared temperature-measuring current sensors offer an ideal solution. Their principle is based on the Joule heating effect generated when current flows through a conductor. An infrared sensor measures the conductor's surface temperature non-contactly, from which the current magnitude can be deduced. This method achieves complete electrical isolation and offers high safety.

[0004] However, existing infrared temperature-measuring current sensors have significant drawbacks:

[0005] 1. The temperature rise of a conductor is not only related to the current, but also strongly depends on the heat dissipation conditions such as ambient temperature, wind speed, installation posture and conductor surface condition. This results in different temperatures measured under different environments for the same current, leading to poor measurement accuracy and stability.

[0006] 2. Infrared sensors are susceptible to interference from ambient background radiation and are inherently subject to zero-point drift and sensitivity drift.

[0007] Existing single-point temperature measurement and software compensation schemes have complex compensation models, are difficult to adapt to dynamically changing environments, lack long-term stability, and the output signal is essentially a "temperature voltage" rather than a voltage signal that directly and linearly represents the current.

[0008] Therefore, this application proposes a novel infrared current sensing device that can fundamentally suppress environmental interference, achieve self-calibration, and directly output a high-precision voltage signal linearly related to the current. Utility Model Content

[0009] (I) Technical problems to be solved

[0010] The technical problem this invention aims to solve is that the single-point temperature measurement plus software compensation scheme has a complex compensation model, is difficult to adapt to dynamically changing environments, lacks long-term stability, and the output signal is essentially a "temperature voltage" rather than a voltage signal that directly and linearly represents the current.

[0011] II. Technical Solution

[0012] To solve the above-mentioned technical problems, the technical solution provided by this utility model is as follows: a device for converting an infrared radiation temperature current sensor into a voltage signal, including a housing, a signal processing circuit disposed inside the housing, and an output interface for outputting signals, and also including a dual-channel infrared temperature measurement module and a built-in reference heat source module;

[0013] The dual-channel infrared temperature measurement module is fixed inside the housing and includes a measuring infrared sensor and a reference infrared sensor arranged side by side. The sensing direction of the measuring infrared sensor faces the outside of the housing and is used to sense the infrared radiation of the current conductor being measured. The sensing direction of the reference infrared sensor faces the inside of the housing.

[0014] The built-in reference heat source module includes a reference resistor disposed inside the housing and located in the sensing direction of the reference infrared sensor, and a constant current driving circuit for providing a constant driving current to the reference resistor, the constant current driving circuit being electrically connected to the signal processing circuit.

[0015] The input terminal of the signal processing circuit is electrically connected to the output terminals of the measuring infrared sensor and the reference infrared sensor, respectively, for receiving the measuring voltage signal and the reference voltage signal, and processing the measuring voltage signal and the reference voltage signal to output a standard voltage signal that has a preset linear proportional relationship with the magnitude of the measured current.

[0016] As an improvement, the signal processing circuit includes a differential amplification unit, a proportional operation unit, and a linearization output unit;

[0017] The differential amplifier unit is used to differentially amplify the measured voltage signal and the reference voltage signal respectively to suppress common-mode interference signals.

[0018] The input terminal of the proportional calculation unit is connected to the output terminal of the differential amplification unit, and is used to calculate the ratio between the measured signal after differential amplification and the reference signal.

[0019] The input terminal of the linearization output unit is connected to the output terminal of the proportional calculation unit, and is used to perform mathematical operations and linear amplification on the proportional value to generate the standard voltage signal.

[0020] As an improvement, the linearization output unit includes a square root operation circuit for performing a square root operation on the proportional value related to the square value of the current, so that the standard voltage signal and the measured current are linearly related.

[0021] As an improvement, the measuring infrared sensor and the reference infrared sensor are infrared thermopile sensors or microbolometers with the same model, spectral response characteristics and sensitivity.

[0022] As an improvement, the surface of the reference resistor is coated with a coating whose emissivity is similar to that of the surface of the conductor carrying the measured current.

[0023] As an improvement, the constant current driving circuit provides a constant driving current with an adjustable set value.

[0024] As an improvement, the housing is provided with an infrared transmission window at a position corresponding to the sensing direction of the measuring infrared sensor, and the material of the infrared transmission window is silicon, germanium or zinc sulfide.

[0025] III. Beneficial Effects

[0026] The advantages of this utility model compared with the prior art are as follows:

[0027] 1. Differential common-mode interference suppression: The measuring and reference infrared sensors are in the same environment, subject to the same background radiation, ambient temperature fluctuations, and their own drift. The signal processing circuit first performs differential processing on the two signals, which can effectively suppress these common-mode interferences and significantly improve the signal-to-noise ratio.

[0028] 2. Self-calibration through proportional calculation: The built-in reference resistor generates a known and stable reference temperature rise under constant current drive. The signal processing circuit calculates the ratio of the measured target signal to the reference signal. This ratio directly reflects the ratio of the heating power of the measured conductor to the known reference heating power, thereby automatically offsetting systematic errors such as changes in infrared sensor sensitivity and circuit gain drift, achieving real-time self-calibration.

[0029] 3. Direct output current and linear voltage: Through subsequent square root and linearization circuits, the signal representing the proportion of heating power is converted into a standardized voltage signal that is directly proportional to the primary side current, which greatly facilitates the access and use of the back-end system.

[0030] 4. Simple and reliable structure: The entire device is integrated into a single housing with no moving parts. It uses mature electronic components and circuits, ensuring stability and reliability. It is easy to mass-produce and is very suitable for long-term stable operation in industrial settings. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of a device for converting an infrared radiation temperature current sensor into a voltage signal, according to this utility model.

[0032] Figure 2 This is a schematic diagram of the front structure of a device for converting an infrared radiation temperature current sensor into a voltage signal, according to this utility model.

[0033] Figure 3 This is a schematic diagram of the rear structure of a device for converting an infrared radiation temperature current sensor into a voltage signal, according to this utility model.

[0034] Figure 4 This is the left-hand view of a device for converting an infrared radiation temperature current sensor into a voltage signal according to this utility model.

[0035] Figure 5 This is a cross-sectional view (AA) of a device for converting an infrared radiation temperature current sensor into a voltage signal, according to this utility model.

[0036] Figure 6 This is a schematic diagram illustrating a specific application scenario of the device for converting an infrared radiation temperature current sensor into a voltage signal according to this utility model.

[0037] As shown in the figure: 1. Outer shell; 11. Infrared transmission window; 2. Signal processing circuit; 21. Differential amplifier unit; 22. Proportional operation unit; 23. Linearization output unit; 3. Output interface; 4. Dual-channel infrared temperature measurement module; 41. Measuring infrared sensor; 42. Reference infrared sensor; 5. Built-in reference heat source module; 51. Reference resistor; 52. Constant current drive circuit; 6. Measured current wire. Detailed Implementation

[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0039] As attached Figure 2 Appendix Figure 3 Appendix Figure 4 and attached Figure 5 As shown, this utility model provides a device for converting an infrared radiation temperature current sensor into a voltage signal. Its shape is a sealed engineering plastic housing 1. A circular infrared transmission window 11 is opened at the front end of the housing 1, and the window material is a silicon wafer with good infrared transmission performance. Cable holes are provided on the side wall of the housing 1 for leading out the cable of the output interface 3.

[0040] Inside the outer casing 1, a circuit board is horizontally fixed. Two identical infrared thermopile sensors of the same model and batch are mounted side-by-side on the circuit board near the infrared transmission window 11, forming a dual-channel infrared temperature measurement module 4. The measuring infrared sensor 41 faces the infrared transmission window 11 and is used to measure the surface temperature of the external current-carrying wire 6. The sensing surface of the reference infrared sensor 42 faces the interior space of the casing.

[0041] As attached Figure 1 and attached Figure 6As shown, a built-in reference heat source module 5 is installed approximately 2 cm in front of the reference infrared sensor 42. The built-in reference heat source module 5 includes a fixedly mounted wire-wound ceramic reference resistor 51 with a resistance of approximately 10Ω. Its surface is treated with a matte black coating to stabilize its surface emissivity at around 0.95, which is close to the surface emissivity of most oxidized metal wires. The reference resistor 51 is connected to a constant current drive circuit 52 on the circuit board. In this embodiment, the constant current drive circuit 52 is built using a REF200 dual-channel constant current source chip, providing a constant drive current I_ref, which can be set to 10mA, to the reference resistor 51, thereby generating a constant and known reference temperature rise.

[0042] The signal processing circuit 2 is integrated on the same circuit board. The weak voltage signals V_meas and V_ref output by the measuring infrared sensor 41 and the reference infrared sensor 42 are first sent to the differential amplification unit 21, which is composed of a high-precision instrumentation amplifier (such as INA333). This unit also receives the ambient temperature signal measured by the thermistor built into the sensor, which is used to initially compensate for the influence of ambient temperature on the absolute radiation value.

[0043] The two amplified signals are fed into a proportional operation unit 22 composed of an analog divider chip (such as AD734). This unit performs the core operation: V_out_pre = K*(V_meas') / (V_ref'), where V_meas' and V_ref' are the signals after differential processing, and K is the proportional coefficient. The value of V_out_pre reflects the ratio of the heating power of the current-measuring wire 6 to the heating power of the reference resistor 51.

[0044] The V_out_pre signal then enters the linearization output unit 23. This unit first uses a square root circuit composed of a logarithmic-exponential circuit or an integrated analog multiplier (such as AD538) to perform a square root operation on V_out_pre, obtaining a voltage signal proportional to the measured current I. Finally, this signal is scaled and level-shifted by a non-inverting amplifier circuit composed of an operational amplifier, outputting the final standard voltage signal V_out (in this example, it is set as follows: when I = 0A, V_out = 0.5V; when I = rated current, V_out = 4.5V). V_out is transmitted to the host computer or PLC through output interface 3.

[0045] In practical applications, the infrared transmission window 11 of the device is aligned with the conductor 6 of the current being measured, and the power supply is turned on. The device then begins continuous operation, outputting real-time linear current-voltage signals. Due to the adoption of a proportional self-calibration principle, even with drastic changes in ambient temperature or slow drift of the sensor over time, the device can maintain high-precision measurements, significantly outperforming traditional single-sensor solutions.

[0046] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0047] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

[0048] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A device for converting an infrared radiation temperature current sensor into a voltage signal, comprising a housing (1), a signal processing circuit (2) disposed within the housing (1), and an output interface (3) for outputting a signal, characterized in that: It also includes a dual-channel infrared temperature measurement module (4) and a built-in reference heat source module (5); The dual-channel infrared temperature measurement module (4) is fixed inside the housing (1) and includes a measuring infrared sensor (41) and a reference infrared sensor (42) arranged side by side. The sensing direction of the measuring infrared sensor (41) is towards the outside of the housing (1) and is used to sense the infrared radiation of the current conductor being measured. The sensing direction of the reference infrared sensor (42) is towards the inside of the housing (1). The built-in reference heat source module (5) includes a reference resistor (51) disposed inside the housing (1) and located in the sensing direction of the reference infrared sensor (42), and a constant current driving circuit (52) for providing a constant driving current to the reference resistor (51), the constant current driving circuit (52) being electrically connected to the signal processing circuit (2). The input terminal of the signal processing circuit (2) is electrically connected to the output terminals of the measuring infrared sensor (41) and the reference infrared sensor (42) respectively, for receiving the measuring voltage signal and the reference voltage signal, and processing the measuring voltage signal and the reference voltage signal to output a standard voltage signal that has a preset linear proportional relationship with the magnitude of the measured current.

2. The device for converting an infrared radiation temperature current sensor into a voltage signal according to claim 1, characterized in that: The signal processing circuit (2) includes a differential amplifier unit (21), a proportional operation unit (22), and a linearization output unit (23); The differential amplifier unit (21) is used to differentially amplify the measured voltage signal and the reference voltage signal respectively to suppress common-mode interference signals; The input terminal of the proportional calculation unit (22) is connected to the output terminal of the differential amplification unit (21) and is used to calculate the ratio between the measured signal and the reference signal after differential amplification. The input terminal of the linearization output unit (23) is connected to the output terminal of the proportional operation unit (22) for performing mathematical operations and linear amplification on the proportional value to generate the standard voltage signal.

3. The device for converting an infrared radiation temperature current sensor into a voltage signal according to claim 2, characterized in that: The linearization output unit (23) includes a square root operation circuit for performing a square root operation on the proportional value related to the square value of the current, so that the standard voltage signal and the measured current are linearly related.

4. The device for converting an infrared radiation temperature current sensor into a voltage signal according to claim 1, characterized in that: The measuring infrared sensor (41) and the reference infrared sensor (42) are infrared thermopile sensors or microbolometers with the same model, spectral response characteristics and sensitivity.

5. The device for converting an infrared radiation temperature current sensor into a voltage signal according to claim 1, characterized in that: The surface of the reference resistor (51) is coated with a coating whose emissivity is similar to that of the surface of the current-measuring conductor.

6. The device for converting an infrared radiation temperature current sensor into a voltage signal according to claim 1, characterized in that: The constant current driving circuit (52) provides a constant driving current with an adjustable set value.

7. The device for converting an infrared radiation temperature current sensor into a voltage signal according to claim 1, characterized in that: The housing (1) has an infrared transmission window (11) at a position corresponding to the sensing direction of the measuring infrared sensor (41), and the material of the infrared transmission window (11) is silicon, germanium or zinc sulfide.

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