Conversion circuit for modulating PT100 temperature signal and outputting voltage signal

Abstract

The utility model discloses a conversion circuit for modulating a PT100 temperature signal and outputting a voltage signal. The conversion circuit comprises a PT100; a power conversion module; a main control module; rTD to a digital output converter; a precision resistor; a DAC module; the main control module is electrically connected with the power supply conversion module, the peripheral circuit, the RTD-to-digital output converter and the DAC module, the PT100 and the precision resistor are electrically connected with the RTD-to-digital output converter, and the peripheral circuit and the DAC module are electrically connected with the power supply conversion module. According to the conversion circuit for modulating the PT100 temperature signal to output the voltage signal, through the cooperative arrangement of the power supply conversion module, the main control module, the RTD-to-digital output converter, the precision resistor and the DAC module, conversion of PT100 / PT1000 temperature sensors is realized, and the temperature signal can be converted into two output modes of 0-5V or 0-10V. The application scene of the conversion scheme is effectively expanded, and the competitiveness of the product is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of conversion circuits, in particular to a conversion circuit for modulating a PT100 temperature signal to output a voltage signal. Background Art

[0002] A circuit that modulates the output voltage signal of a PT100 temperature signal. The object to be converted is a thermal resistor, namely PT100, whose resistance value changes almost linearly with the rise or fall of temperature. The working principle of PT100 is to achieve thermal equilibrium through conduction or convection, so that the indication of the thermometer can directly represent the temperature of the object being measured. When the signal of PT100 cannot be recognized by the instrument, it is necessary to design a circuit to convert its signal into 0-5V or other standard analog signals, and then input it into the instrument or automatic control system.

[0003] Convert the resistance change of PT100 into a voltage signal. Common circuits include bridge circuit, constant current source circuit or voltage divider circuit.

[0004] By measuring the voltage associated with PT100, the corresponding temperature value can be indirectly obtained. For example, when using a bridge circuit, connect PT100 to the bridge arm. When the temperature changes, the resistance value of PT100 changes, causing the bridge circuit to be unbalanced, thereby generating a voltage difference. By measuring this voltage difference, the corresponding temperature can be determined. In addition, a constant current source can be used to pass through PT100, and then the voltage at both ends can be measured. The corresponding resistance value can be calculated according to Ohm's law, and then converted to temperature by looking up a table or calculating. However, in actual applications, traditional circuits have factors such as filtering and calibration, which affect the accuracy and stability of the measurement.

[0005] At present, PT100 is widely used in engineering control, industrial manufacturing, health care and other fields, so it has a good market prospect. In the future, with the continuous advancement of technology and the continuous expansion of applications, the market demand for PT100 will continue to grow. With the continuous advancement of industrial manufacturing and scientific research, the requirements for the accuracy and reliability of PT100 will become higher and higher, so it is necessary to increase the added value of the product by increasing the accuracy and stability of the conversion.

[0006] Based on the above situation, the utility model proposes a conversion circuit for modulating the output voltage signal of a PT100 temperature signal, which can effectively solve the above problems. Utility Model Content

[0007] The purpose of the utility model is to provide a conversion circuit for modulating the output voltage signal of a PT100 temperature signal. The conversion circuit for modulating the output voltage signal of the PT100 temperature signal of the utility model has a simple structure and is easy to use. Through the coordinated setting of the power conversion module, the main control module, the RTD to digital output converter, the precision resistor and the DAC module, the conversion of multiple PT100 / PT1000 temperature sensors is realized, and the temperature signal can be converted into two output modes of 0-5V or 0-10V, which effectively expands the application scenarios of the conversion scheme and improves the competitiveness of the product.

[0008] The utility model is realized by the following technical solutions:

[0009] A conversion circuit for modulating a PT100 temperature signal to output a voltage signal, comprising:

[0010] PT100;

[0011] A power conversion module, used to convert high voltage into low voltage;

[0012] The main control module is used to receive, process and send control signals;

[0013] RTD to digital output converter for measuring the resistance value of PT100;

[0014] Precision resistors are used to provide reference parameters during PT100 temperature conversion;

[0015] DAC module, used to convert digital signals into analog signals;

[0016] Among them, the main control module is electrically connected to the power conversion module, the RTD to digital output converter, and the DAC module respectively, the PT100 and the precision resistor are electrically connected to the RTD to digital output converter, and the DAC module is electrically connected to the power conversion module.

[0017] The purpose of the utility model is to provide a conversion circuit for modulating the output voltage signal of a PT100 temperature signal. The conversion circuit for modulating the output voltage signal of the PT100 temperature signal of the utility model has a simple structure and is easy to use. Through the coordinated setting of the power conversion module, the main control module, the RTD to digital output converter, the precision resistor and the DAC module, the conversion of multiple PT100 / PT1000 temperature sensors is realized, and the temperature signal can be converted into two output modes of 0-5V or 0-10V, which effectively expands the application scenarios of the conversion scheme and improves the competitiveness of the product.

[0018] Preferably, the main control module includes a main control chip U1 and a first resistor R1, and a BOOT0 pin of the main control chip U1 is electrically connected to the first resistor R1.

[0019] Preferably, it comprises a peripheral circuit, the peripheral circuit is electrically connected to the main control module and the power conversion module respectively, and the peripheral circuit comprises a reset circuit and a download circuit;

[0020] The reset circuit comprises a second resistor R2 and a first capacitor C1, wherein one end of the second resistor R2 is electrically connected to the first capacitor C1;

[0021] The download circuit includes a connector J1, a third resistor R3, and a fourth resistor R4. The JTMS pin of the connector J1 is electrically connected to the third resistor R3, and the JTCK pin of the connector J1 is electrically connected to the fourth resistor R4.

[0022] Preferably, the power conversion module includes a power isolation module and an LDO.

[0023] Preferably, the RTD to digital output converter includes a measuring chip U2, a first external terminal P1, a second external terminal P2, a precision resistor 6, a second capacitor C2, and a third capacitor C3. The AVDD pin of the measuring chip U2 is electrically connected to the second capacitor C2, the BIAS pin and the REFIN(+) pin of the measuring chip U2 are both electrically connected to one end of the precision resistor 6, and the other end of the precision resistor 6 is respectively electrically connected to the REFIN(-) pin of the measuring chip U2 and the ISENSOR pin of the measuring chip U2, one end of the FORCE+ pin of the measuring chip U2 is respectively electrically connected to pin 3 of the first external terminal P1, pin 2 of the first external terminal P1, and FORCE2 pin of the measuring chip U2, the RTDIN+ of the measuring chip U2 is electrically connected to one end of the third capacitor C3, and the other end of the third capacitor C3 is respectively electrically connected to the RTDIN- pin of the measuring chip U2, pin 2 of the second external terminal P2, pin 1 of the second external terminal P2, and FORCE- pin of the measuring chip U2.

[0024] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0025] The utility model has a simple structure and is easy to use in the conversion circuit of the PT100 temperature signal modulated output voltage signal. Through the coordinated setting of the power conversion module, the main control module, the RTD to digital output converter, the precision resistor and the DAC module, the conversion of multiple PT100 / PT1000 temperature sensors is realized, and the temperature signal can be converted into two output modes of 0-5V or 0-10V, which effectively expands the application scenarios of the conversion solution and enhances the competitiveness of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic block diagram of the circuit of the utility model;

[0027] Figure 2This is a circuit schematic diagram of the main control module of the utility model;

[0028] Figure 3 This is a circuit schematic diagram of the reset circuit of the utility model;

[0029] Figure 4 It is a circuit principle diagram of the download circuit described in the utility model;

[0030] Figure 5 The schematic diagram of the circuit of the RTD to digital output converter of the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solution of the utility model, the preferred implementation scheme of the utility model is described below in conjunction with specific embodiments. However, it should be understood that the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationship described in the drawings is only used for illustrative purposes and cannot be understood as a limitation on this patent.

[0032] Embodiment 1:

[0033] like Figures 1 to 5 As shown, the utility model provides a conversion circuit for modulating a PT100 temperature signal to output a voltage signal, comprising:

[0034] PT1005;

[0035] A power conversion module 1, used for converting a high voltage into a low voltage;

[0036] Main control module 2, used for receiving, processing and sending control signals;

[0037] RTD to digital output converter 4, used to measure the resistance value of PT1005;

[0038] Precision resistor 6, used to provide reference parameters in the PT1005 temperature conversion process;

[0039] DAC module 7, used for converting digital signals into analog signals;

[0040] Among them, the main control module 2 is electrically connected to the power conversion module 1, the RTD to digital output converter 4, and the DAC module 7 respectively, the PT1005 and the precision resistor 6 are both electrically connected to the RTD to digital output converter 4, and the DAC module 7 is electrically connected to the power conversion module 1.

[0041] Embodiment 2:

[0042] like Figures 1 to 5 As shown, the utility model provides a conversion circuit for modulating a PT100 temperature signal to output a voltage signal, comprising:

[0043] PT1005: PT1005 is a widely used temperature sensor. Its resistance value increases with the increase of temperature. When using PT1005, it is necessary to use a corresponding measurement circuit to convert the resistance change into an easy-to-process electrical signal.

[0044] A power conversion module 1, used for converting a high voltage into a low voltage;

[0045] Main control module 2, used for receiving, processing and sending control signals;

[0046] RTD to digital output converter 4, used to measure the resistance value of PT1005;

[0047] Precision resistor 6, used to provide reference parameters in the PT1005 temperature conversion process;

[0048] DAC module 7 is used to convert digital signals into analog signals; DAC module 7 uses I 2 C communication, this chip can convert 15Bit digital quantity linearly into 0-5V or 0-10V analog voltage, and the output current linearity is 0.01%. Its main function is to convert digital signals into analog signals.

[0049] Among them, the main control module 2 is electrically connected to the power conversion module 1, the RTD to digital output converter 4, and the DAC module 7 respectively, the PT1005 and the precision resistor 6 are both electrically connected to the RTD to digital output converter 4, and the DAC module 7 is electrically connected to the power conversion module 1.

[0050] The main control module 2 includes a main control chip U1 and a first resistor R1 , and a BOOT0 pin of the main control chip U1 is electrically connected to the first resistor R1 .

[0051] The main control module 2 is mainly composed of the main control chip U1, which realizes the processing and operation of the input signal.

[0052] Further, in another embodiment, a peripheral circuit 3 is included, the peripheral circuit is electrically connected to the main control module and the power conversion module respectively, and the peripheral circuit 3 includes a reset circuit and a download circuit;

[0053] The reset circuit comprises a second resistor R2 and a first capacitor C1, wherein one end of the second resistor R2 is electrically connected to the first capacitor C1;

[0054] The reset circuit adopts power-on reset, and is composed of a second resistor R2 and a first capacitor C1. When powered on, the first capacitor C1 is equivalent to a short circuit, so that the reset pin maintains a high level for 2 machine cycles when the crystal oscillator is valid.

[0055] The download circuit includes a connector J1, a third resistor R3, and a fourth resistor R4. The JTMS pin of the connector J1 is electrically connected to the third resistor R3, and the JTCK pin of the connector J1 is electrically connected to the fourth resistor R4.

[0056] The download circuit adopts SWD burning method. When designing the download circuit, the four pins SWDIO, SWCLK, VCC and GND are brought out, and the BOOT0 pin of the main control chip U1 should be grounded.

[0057] Furthermore, in another embodiment, the power conversion module 1 includes a power isolation module and an LDO.

[0058] The power conversion module 1 is mainly composed of a power isolation module and an LDO to achieve the need to convert high voltage levels into low voltage levels. Taking the 24V to 3.3V power supply of the utility model as an example, the power isolation module is first used to convert 24V into 15V and then LDO is used to convert it into 3.3V. This method can not only ensure the reliability of power supply conversion, but also meet the power supply needs of multiple voltage levels of the entire system.

[0059] Further, in another embodiment, the RTD to digital output converter 4 includes a measuring chip U2, a first external terminal P1, a second external terminal P2, a precision resistor 6, a second capacitor C2, and a third capacitor C3. The AVDD pin of the measuring chip U2 is electrically connected to the second capacitor C2, the BIAS pin and the REFIN (+) pin of the measuring chip U2 are both electrically connected to one end of the precision resistor 6, and the other end of the precision resistor 6 is respectively electrically connected to the REFIN (-) pin of the measuring chip U2 and the ISENSOR pin of the measuring chip U2, one end of the FORCE + pin of the measuring chip U2 is respectively electrically connected to pin 3 of the first external terminal P1, pin 2 of the first external terminal P1, and FORCE2 pin of the measuring chip U2, the RTDIN + of the measuring chip U2 is electrically connected to one end of the third capacitor C3, and the other end of the third capacitor C3 is respectively electrically connected to the RTDIN - pin of the measuring chip U2, pin 2 of the second external terminal P2, pin 1 of the second external terminal P2, and FORCE - pin of the measuring chip U2.

[0060] The measurement chip U2 is an integrated chip that can reduce the system cost by 50%, and can measure the resistance values ​​of multiple models of PT100 / PT1000. The integrated chip reads the ADC code of the temperature through SPI, and the main control module 2 obtains the thermal resistance value through the formula and converts it into a temperature value. The advantage of this chip is that it has a built-in 15-bit ADC with an accuracy of 0.5°C at full scale, which can meet most needs. In practical applications, in order to ensure the measurement accuracy of the RTD to digital output converter 4, it is necessary to add the second power supply capacitor C2 and the third capacitor C3, and pay attention to the signal routing layout, which can reduce the impact of noise and interference on the measurement. In combination with the data processing and filtering performed by the main control module 2 in the software, noise and interference can be further removed to improve the stability and accuracy of the measurement.

[0061] The precision resistor 6 provides a reference parameter in the PT1005 temperature conversion process, so higher requirements are placed on the resistor accuracy to ensure the accuracy of the temperature conversion value.

[0062] The working principle of one embodiment of the utility model is as follows:

[0063] A conversion circuit for modulating the output voltage signal of a PT100 temperature signal. The RTD to digital output converter 4 converts the PT1005 resistance temperature value into a digital signal and transmits it to the main control module 2. The main control module 2 sends the digital quantity to the DAC module 7 in the corresponding data format after digital filtering, thereby completing the entire measurement process and obtaining the PT1005 resistance temperature value.

[0064] According to the description and drawings of the present invention, those skilled in the art can easily manufacture or use the conversion circuit of the present invention for modulating the output voltage signal of the PT100 temperature signal, and can produce the positive effects recorded in the present invention.

[0065] Unless otherwise specified, in the present invention, the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicating orientation or positional relationships are based on the orientation or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the orientation or positional relationship in the present invention are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood in conjunction with the drawings and according to specific circumstances.

[0066] Unless otherwise specified and limited, in the present invention, the terms "disposed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A conversion circuit for modulating a PT100 temperature signal to output a voltage signal, characterized in that: include: PT100; A power conversion module, used to convert high voltage into low voltage; The main control module is used to receive, process and send control signals; RTD to digital output converter for measuring the resistance value of PT100; Precision resistors are used to provide reference parameters during PT100 temperature conversion; DAC module, used to convert digital signals into analog signals; Among them, the main control module is electrically connected to the power conversion module, the RTD to digital output converter, and the DAC module respectively, the PT100 and the precision resistor are electrically connected to the RTD to digital output converter, and the DAC module is electrically connected to the power conversion module.

2. The conversion circuit for modulating the output voltage signal of the PT100 temperature signal according to claim 1 is characterized in that: The main control module includes a main control chip U1 and a first resistor R1 , and a BOOT0 pin of the main control chip U1 is electrically connected to the first resistor R1 .

3. The conversion circuit for modulating the output voltage signal of the PT100 temperature signal according to claim 1 is characterized in that: It includes a peripheral circuit, which is electrically connected to the main control module and the power conversion module respectively, and the peripheral circuit includes a reset circuit and a download circuit; The reset circuit comprises a second resistor R2 and a first capacitor C1, wherein one end of the second resistor R2 is electrically connected to the first capacitor C1; The download circuit includes a connector J1, a third resistor R3, and a fourth resistor R4. The JTMS pin of the connector J1 is electrically connected to the third resistor R3, and the JTCK pin of the connector J1 is electrically connected to the fourth resistor R4.

4. The conversion circuit for modulating the output voltage signal of the PT100 temperature signal according to claim 1 is characterized in that: The power conversion module includes a power isolation module and an LDO.

5. The conversion circuit for modulating the output voltage signal of the PT100 temperature signal according to claim 1 is characterized in that: The RTD to digital output converter includes a measuring chip U2, a first external terminal P1, a second external terminal P2, a precision resistor, a second capacitor C2, and a third capacitor C3. The AVDD pin of the measuring chip U2 is electrically connected to the second capacitor C2, the BIAS pin and the REFIN (+) pin of the measuring chip U2 are both electrically connected to one end of the precision resistor, and the other end of the precision resistor is respectively electrically connected to the REFIN (-) pin of the measuring chip U2 and the ISENSOR pin of the measuring chip U2, one end of the FORCE + pin of the measuring chip U2 is respectively electrically connected to pin 3 of the first external terminal P1, pin 2 of the first external terminal P1, and the FORCE2 pin of the measuring chip U2, the RTDIN + of the measuring chip U2 is electrically connected to one end of the third capacitor C3, and the other end of the third capacitor C3 is respectively electrically connected to the RTDIN - pin of the measuring chip U2, pin 2 of the second external terminal P2, pin 1 of the second external terminal P2, and the FORCE - pin of the measuring chip U2.

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