Temperature acquisition circuit, temperature acquisition module and electronic equipment

Abstract

The invention provides a temperature acquisition circuit, a temperature acquisition module and electronic equipment, which are applied to the technical field of automation control, the circuit comprises a main circuit and a reference voltage generation circuit provided with a reference resistor, the main circuit outputs a first sampling current to a first connecting line of a heat sensor and outputs a second sampling current to a second connecting line, the reference voltage generation circuit outputs reference voltage of the reference resistor in response to the first sampling current and the second sampling current, and the main circuit calculates the ratio of the resistance voltage to the reference voltage and determines the resistance value of the thermal resistor based on the obtained ratio and the resistance value of the reference resistor; when the ratio of the thermal resistor voltage to the reference voltage is calculated, the deviation between the first sampling current and the second sampling current is eliminated, so that the obtained resistance value of the thermal resistor is not influenced by the deviation of the sampling current, and the resistance value of the thermal resistor in the temperature sensor is accurately acquired.

Description

Technical Field

[0001] The present application relates to the field of automation control technology, and in particular to a temperature acquisition circuit, a temperature acquisition module and an electronic device. Background Art

[0002] In industrial control systems, temperature sensors are commonly used to collect the temperature of the work site. Among them, three-wire thermal sensors are widely used because of their large sampling range and wide application range. Combined with actual use experience, it can be seen that the temperature sampling accuracy of the temperature sensor has a direct impact on the operation of the industrial control system. Low temperature sampling accuracy will not only affect the control process and control accuracy of the industrial control system, but may even cause the control system to crash, which will seriously affect the production progress. Therefore, how to accurately collect the resistance value of the thermal resistor in the temperature sensor and provide a reliable basis for accurately converting the temperature value has become one of the technical problems that technicians in this field need to solve urgently. Summary of the invention

[0003] In view of this, the present application is committed to providing a temperature acquisition circuit, a temperature acquisition module and an electronic device, which can eliminate the deviation of the sampling current caused by leakage current, accurately acquire the resistance value of the thermistor in the temperature sensor, and provide a reliable basis for accurately converting the temperature value.

[0004] In a first aspect, the present application provides a temperature acquisition circuit, which is applied to a three-wire thermal sensor, wherein the three-wire thermal sensor includes a thermal resistor, a first connecting wire connected to one end of the thermal resistor, and a second connecting wire and a compensation wire connected to the other end of the thermal resistor. The temperature acquisition circuit includes: a main circuit and a reference voltage generating circuit, wherein:

[0005] The reference voltage generating circuit includes a reference resistor;

[0006] The main circuit is configured to: output a first sampling current to the first connecting line, output a second sampling current to the second connecting line, and collect a thermal resistor voltage output by the thermal resistor in response to the first sampling current;

[0007] The reference voltage generating circuit is configured to: output a reference voltage of the reference resistor in response to the first sampling current and the second sampling current;

[0008] The main circuit is further configured to calculate a ratio of the resistor voltage to the reference voltage, and determine a resistance value of the thermal resistor based on a product of the ratio and a resistance value of the reference resistor.

[0009] In an optional implementation, the main circuit includes: an analog-to-digital converter ADC and at least one voltage acquisition circuit, wherein:

[0010] The ADC includes a reference voltage acquisition port and a plurality of external port groups, wherein:

[0011] The external port group is connected to the voltage collection circuit in a one-to-one correspondence;

[0012] The voltage collection circuit is connected to the three-wire thermal sensor in a one-to-one correspondence;

[0013] The reference voltage acquisition port is connected to the output end of the reference voltage generation circuit, and the input end of the reference voltage generation circuit is respectively connected to the compensation line of each of the three-wire thermal sensors;

[0014] The ADC is configured to: calculate a ratio of a resistance voltage of a thermal resistor in a target thermal sensor to the reference voltage, and determine a resistance value of the thermal resistor in the target thermal sensor based on a product of the ratio and a resistance value of the reference resistor;

[0015] Wherein, the target thermal sensor is any one of the three-wire thermal sensors.

[0016] In an optional implementation, the external port group includes a first constant current source port, a second constant current source port and a resistance voltage acquisition port;

[0017] The voltage acquisition circuit includes: a first energy supply circuit, a second energy supply circuit and a sampling subcircuit, wherein:

[0018] The first energy supply circuit is connected between the first constant current source port and the first connecting line;

[0019] The second energy supply circuit is connected between the second constant current source port and the second connecting line;

[0020] The sampling subcircuit is connected to the resistance voltage acquisition port and the first connection line and the second connection line respectively.

[0021] In an optional implementation, the resistance voltage acquisition port includes a first voltage acquisition port and a second voltage acquisition port;

[0022] The sampling subcircuit includes a first subcircuit and a second subcircuit, wherein:

[0023] The first subcircuit includes a first resistor and a first mutual inductor, wherein:

[0024] One end of the first resistor is connected to the first voltage acquisition port, and the other end of the first resistor is connected to one end of the first mutual inductor;

[0025] The other end of the first mutual inductor is used to connect the first connecting line;

[0026] The second subcircuit includes a second resistor and a second mutual inductor, wherein:

[0027] One end of the second resistor is connected to the second voltage acquisition port, and the other end of the second resistor is connected to one end of the second transformer;

[0028] The other end of the second mutual inductor is used to connect the second connecting line.

[0029] In an optional implementation, the temperature acquisition circuit provided in the first aspect of the present application further includes: a first protection circuit, wherein:

[0030] An input terminal of the first protection circuit is connected to the first sub-circuit and the second sub-circuit respectively, and a ground terminal of the first protection circuit is grounded.

[0031] In an optional implementation, the reference voltage generating circuit further includes: an auxiliary resistor, wherein:

[0032] One end of the reference resistor is used to connect to the compensation line, and the other end of the reference resistor is connected to the auxiliary resistor;

[0033] The other end of the auxiliary resistor is grounded.

[0034] In an optional implementation, the temperature acquisition circuit provided in the first aspect of the present application further includes: a second protection circuit, wherein:

[0035] One end of the second protection circuit is connected to the reference resistor and a connection point of the compensation line, and the other end of the second protection circuit is grounded.

[0036] In an optional implementation, the temperature acquisition circuit provided in the first aspect of the present application further includes: a controller, wherein:

[0037] The controller is in communication connection with the main circuit;

[0038] The controller is configured to determine a current sampling temperature value based on a preset mapping relationship between a thermal resistor resistance value and a sampling temperature.

[0039] In a second aspect, the present application provides a temperature acquisition module, comprising: a three-wire thermal sensor and a temperature acquisition circuit as described in any one of the first aspects of the present application, wherein:

[0040] The temperature acquisition circuit is connected to the three-wire thermal sensor.

[0041] In a third aspect, the present application provides an electronic device, comprising: a temperature acquisition module as described in the second aspect of the present application.

[0042] Based on the above content, in the temperature acquisition circuit provided in the present application, the thermistor outputs a thermistor voltage in response to the first sampling current, and the reference resistor outputs a reference voltage in response to the first sampling current and the second sampling current. When calculating the ratio of the thermistor voltage to the reference voltage, the deviation between the first sampling current and the second sampling current can be eliminated, ensuring that the resistance value of the thermistor obtained based on the obtained ratio and the reference resistor is not affected by the sampling current deviation, thereby accurately acquiring the resistance value of the thermistor in the temperature sensor, providing a reliable basis for accurately converting the temperature value. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 It is a structural block diagram of a temperature acquisition circuit provided by an embodiment of the present invention.

[0045] Figure 2 It is a structural block diagram of another temperature acquisition circuit provided by an embodiment of the present invention.

[0046] Figure 3 The present invention provides a circuit topology block diagram of a temperature acquisition circuit. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] As mentioned above, in industrial control systems, temperature sensors are commonly used to collect the temperature of the work site. Among them, three-wire thermal sensors are widely used due to their large sampling range and wide application range. Combined with actual use experience, it can be seen that the temperature sampling accuracy of the temperature sensor has a direct impact on the operation of the industrial control system. Low temperature sampling accuracy will not only affect the control process and control accuracy of the industrial control system, but may even cause the control system to shut down, which will seriously affect the production progress.

[0049] The inventors have found that there are many factors that affect the resistance acquisition accuracy of the temperature sensor thermistor in practical applications, such as the sampling current error caused by leakage current and the sampling deviation of the analog-to-digital converter (ADC) itself, such as offset error, nonlinear error and gain error, etc. Among them, the sampling current error has the greatest impact on the sampling accuracy of the temperature sensor. Eliminating the sampling current error is of great significance to improving the sampling accuracy of the temperature sensor. Therefore, how to focus on eliminating the sampling current error and accurately acquire the resistance value of the thermistor in the temperature sensor to provide a reliable basis for accurately converting the temperature value has become one of the technical problems that technical personnel in this field need to solve urgently.

[0050] To solve the above problems, the present application provides a temperature acquisition circuit, which provides a first sampling current and a second sampling current. The thermistor outputs a thermistor voltage in response to the first sampling current, and the reference resistor outputs a reference voltage in response to the first sampling current and the second sampling current. When calculating the ratio of the thermistor voltage to the reference voltage, the deviation between the first sampling current and the second sampling current can be eliminated, ensuring that the resistance value of the thermistor obtained based on the obtained ratio and the reference resistor is not affected by the sampling current deviation, thereby accurately acquiring the resistance value of the thermistor in the temperature sensor, and providing a reliable basis for accurately converting the temperature value.

[0051] Based on the above content, the present application provides a temperature acquisition circuit, which is applied to a three-wire thermal sensor. Figure 1 As shown, the three-wire thermal sensor (Resistance Temperature Detector, RTD) includes a thermal resistor Rs, a first connecting line S1, a second connecting line S2 and a compensation line S3, wherein one end of the thermal resistor Rs is connected to one end of the first connecting line S1, and the other end of the thermal resistor Rs is connected to the second connecting line S2 and the compensation line S3 respectively. The resistance value of the thermal resistor Rs will change with the change of the ambient temperature. By collecting the resistance value of the thermal resistor Rs, the collected temperature value can be determined based on the corresponding relationship between the resistance value of the thermal resistor and the temperature. It should be noted that in this application, it is considered that the line resistances of the first connecting line S1, the second connecting line S2 and the compensation line S3 are the same.

[0052] To facilitate the description of the connection relationship between the temperature acquisition circuit and the three-wire thermal sensor provided in the present application and the resistance acquisition process, this embodiment is described by taking the acquisition of the thermal resistor resistance of a thermal sensor as an example.

[0053] Combination Figure 1 As shown, the temperature acquisition circuit provided in this embodiment includes a main circuit 10 and a reference voltage generating circuit 20 .

[0054] The main circuit 10 is connected to the first connecting line S1 and the second connecting line S2 of the three-wire thermal sensor respectively, wherein the connection point between the main circuit 10 and the first connecting line S1 is Figure 1 The connection point between the main circuit 10 and the second connecting line S2 is marked as E1. Figure 1 The reference voltage generating circuit 20 is marked as M1, and the input end is connected to the compensation line S3 of the three-wire thermal sensor. The connection point between the two is Figure 1 In the figure, it is marked as com. Further, the voltage output terminal of the reference voltage generating circuit 20 is connected to the main circuit 10, and the ground terminal of the reference voltage generating circuit 20 is grounded. It can be understood that the connection points E1, M1 and com can all be regarded as external connection terminals of the temperature acquisition circuit. In practical applications, according to Figure 1 The connection relationship shown is used to connect a three-wire thermal sensor, and the resistance value of the thermal resistor can be collected through the temperature collection circuit provided in this application.

[0055] In this embodiment, the main circuit 10 provides two sampling currents, namely, outputting the first sampling current I0 to the first connecting line S1 of the three-wire thermal sensor, and outputting the second sampling current I1 to the second connecting line S2. On this basis, the main circuit 10 can also collect the voltage across the thermal resistor Rs, namely, the thermal resistor voltage Vs. Figure 1 It can be seen from the connection relationship shown that, among the two sampling currents provided by the main circuit 10, only the first sampling current I0 flows through the thermal resistor Rs. Therefore, the thermal resistor voltage described in this embodiment is output by the thermal resistor Rs in response to the first sampling current I0.

[0056] Furthermore, the first sampling current I0 and the second sampling current I1 enter the reference voltage generating circuit 20 through the compensation line S3 of the three-wire thermal sensor. The reference voltage generating circuit 20 is provided with a reference resistor R1, and the first sampling current I0 and the second sampling current I1 both flow through the reference circuit R1. Therefore, the reference voltage generating circuit provides a reference voltage V REF It is generated by the reference circuit R1 in response to the first sampling current I0 and the second sampling current I1.

[0057] In a preferred embodiment, in order to further improve the sampling accuracy, the reference circuit R1 includes a precision resistor, which uses the extremely small resistance deviation of the precision resistor to provide a reference voltage with higher accuracy. Taking a precision resistor with a resistance of 2.2kΩ and a deviation of 5ppm / ℃ as an example, the maximum error introduced is only 100ppm (calibrable error) + 225ppm (uncalibrable error). It should be noted that the calibrable error mentioned in this application refers to the inherent error of the device itself, which will not change with temperature. In practical applications, it can be eliminated by calibration and will not be considered in subsequent calculations of sampling accuracy. Correspondingly, an uncalibrable error refers to an error that changes with temperature, cannot be eliminated by calibration, and needs to be considered in subsequent calculations of sampling accuracy. This concept is used in all embodiments of the present application, and will not be repeated in the subsequent content.

[0058] It should be noted that the resistance of the reference circuit R1 in the present application is known. Based on this, after the main circuit 10 collects the thermal resistor voltage of the thermal resistor Rs and the reference voltage at both ends of the reference resistor R1, the resistance of the thermal resistor Rs can be determined based on the thermal resistor voltage, the reference voltage and the resistance of the reference resistor R1. Specifically, the ratio of the thermal resistor voltage to the reference voltage is first calculated, and then the product of the obtained ratio and the reference resistor R1 is calculated, and the result is the resistance of the thermal resistor. As for the calculation principle of the thermal resistor resistance value that can be obtained according to this calculation process, it will be expanded in the subsequent content in combination with the specific circuit topology, and will not be described in detail here.

[0059] To sum up, through the temperature acquisition circuit provided in this embodiment, the thermistor outputs a thermistor voltage in response to the first sampling current, and the reference resistor outputs a reference voltage in response to the first sampling current and the second sampling current. When calculating the ratio of the thermistor voltage to the reference voltage, the deviation between the first sampling current and the second sampling current can be eliminated, ensuring that the resistance value of the thermistor obtained based on the obtained ratio and the reference resistor is not affected by the sampling current deviation, thereby accurately acquiring the resistance value of the thermistor in the temperature sensor, providing a reliable basis for accurately converting the temperature value.

[0060] Furthermore, since the calculation process of the thermal resistor resistance is not affected by the deviation between the first sampling current and the second sampling current, but is only related to the resistance deviation of the reference resistor, when the reference resistor uses a precision resistor, the accuracy of the thermal resistor resistance calculation result can be further improved.

[0061] It should be noted that in Figure 1 Based on the core principle of temperature acquisition provided by the illustrated embodiment, the temperature acquisition circuit provided by the present application can simultaneously acquire the resistance values ​​of multiple three-wire thermal sensors. Figure 2 As shown, in Figure 1 Based on the illustrated embodiment, the present application provides another temperature acquisition circuit.

[0062] In the temperature acquisition circuit provided in this embodiment, the main circuit 10 includes an analog-to-digital converter 110 and at least one voltage acquisition circuit 120 (in Figure 2 In the illustrated embodiment, two paths are shown).

[0063] Specifically, the analog-to-digital converter 110 includes a reference voltage acquisition port ( Figure 2 V REF+ and V REF- ) and multiple external port groups ( Figure 2 ) In combination with the external port group P0 and the external port group P1 Figure 2 As shown, the external port groups of the analog-to-digital converter 110 are connected to the voltage collection circuit 120 in a one-to-one correspondence, and the voltage collection circuits 120 connected to each external port group are different from each other. Further, the voltage collection circuit 120 is connected to the three-wire thermal sensor in a one-to-one correspondence. Specifically, Figure 2 As shown, taking one of the voltage acquisition circuits as an example, one external terminal of the voltage acquisition circuit is connected to the first connection line of the three-wire heating sensor, and the connection point between the two is marked as E1. Correspondingly, the other external terminal of the voltage acquisition circuit is connected to the second connection line of the three-wire heating sensor, and the connection point between the two is marked as M1. The connection between the remaining three-wire heating sensors and the voltage acquisition circuit adopts the same method, which will not be repeated here. The analog-to-digital converter 110 acquires the thermal resistance voltage of the three-wire heating sensor connected to it through any voltage acquisition circuit 120.

[0064] The compensation lines of each three-wire thermal sensor are connected to the input end of the reference voltage generation circuit, as mentioned above, and the corresponding connection points are marked as com in the figure. Further, the output end of the reference voltage generation circuit is connected to the reference voltage acquisition port of the analog-to-digital converter, and the ground end of the reference voltage generation circuit is grounded.

[0065] Based on the above connection relationship, the analog-to-digital converter 110 can use any one of the three-wire thermal sensors as the target thermal sensor, and use its own integrated constant current source circuit to output the first sampling current to the first connection line of the target thermal sensor, and output the second sampling current to the second connection line of the target thermal sensor, thereby collecting the thermal resistor voltage of the thermal resistor of the target thermal sensor in response to the first sampling current output. Further, the reference voltage generation circuit 20 outputs the reference voltage of the reference resistor R1 in response to the first sampling current and the second sampling current, and the analog-to-digital converter 110 finally determines the resistance value of the thermal resistor in the target thermal sensor based on the resistance voltage of the thermal resistor in the target thermal sensor, the reference voltage fed back by the reference voltage generation circuit 20, and the resistance value of the reference resistor R1, that is, calculates the ratio of the resistance voltage of the target thermal sensor to the reference voltage, and determines the resistance value of the thermal resistor of the target thermal sensor based on the product of the obtained ratio and the resistance value of the reference resistor R1.

[0066] In actual applications, each three-wire thermal sensor is set at a position where temperature collection is required. The analog-to-digital converter 110 can use each of the three-wire thermal sensors connected to it as a target thermal sensor in a preset order, and can collect the resistance value of the thermal resistor of the three-wire thermal sensor at each position in turn according to the preset order.

[0067] Taking a main circuit including a voltage acquisition circuit as an example, a circuit topology of an optional temperature acquisition circuit is provided below, and based on this circuit topology, the implementation principle of the temperature acquisition circuit provided in this application for eliminating sampling current deviation and improving sampling accuracy is introduced.

[0068] See also Figure 3 As shown, in the temperature acquisition circuit provided in this embodiment, the external port group of the analog-to-digital converter 110 includes a first constant current source port I out0 , the second constant current source port I out1 And a resistor voltage acquisition port, wherein the resistor voltage acquisition port includes a first voltage acquisition port V IN0 And the second voltage acquisition port V IN1 , the reference voltage acquisition port is still V REF+ and V REF- Shown.

[0069] The voltage collection circuit 120 includes a first energy supply circuit, a second functional circuit and a sampling sub-circuit.

[0070] Combination Figure 3 As shown, the first energy supply circuit includes a resistor R4, one end of the resistor R4 is connected to the first constant current source port I out0 The other end of the resistor R4 is connected to the first connection line of the three-wire thermal sensor, and the analog-to-digital converter 110 is connected to the first constant current source port I out0And the first energy supply circuit outputs a first sampling current to the first connecting line.

[0071] The second energy supply circuit includes a resistor R5, one end of which is connected to a second constant current source port I out1 The other end of the resistor R5 is connected to the second connection line of the three-wire thermal sensor, and the analog-to-digital converter 110 is connected to the second constant current source port I out1 And the second energy supply circuit outputs a second sampling current to the second connecting line.

[0072] It should be noted that the resistors R4 and R5 mainly limit the sampling current in practical applications to prevent excessive energy consumption of the thermal resistors during the temperature sampling process.

[0073] The sampling subcircuit is connected to the resistance voltage acquisition port of the analog-to-digital converter 110 and the first connection line and the second connection line of the three-wire thermal sensor respectively. Specifically, the sampling subcircuit includes a first subcircuit and a second subcircuit, wherein the first subcircuit includes a first resistor R2 and a first mutual inductor L1, and the second subcircuit includes a second resistor R3 and a second mutual inductor L2. Figure 3 As shown, one end of the first resistor R2 is connected to the first voltage acquisition port V IN0 The other end of the first resistor R2 is connected to one end of the first mutual inductor L1, and the other end of the first mutual inductor L1 is used to connect the first connecting line S1, that is, the first resistor R2 is connected in series with the first inductor L1, and the obtained first sub-circuit is connected to the first voltage acquisition port V IN0 Correspondingly, one end of the second resistor R3 is connected to the second voltage acquisition port V IN1 The other end of the second resistor R3 is connected to one end of the second mutual inductor L2, and the other end of the second mutual inductor L2 is used to connect the second connecting line S2, that is, the second resistor R2 is connected in series with the second mutual inductor L2, and the obtained second sub-circuit is connected to the second voltage acquisition port V IN1 Between the second connecting wire S2 of the three-wire thermal sensor.

[0074] It should be noted that the first resistor R2 and the second resistor R3 mainly play the role of limiting the current of the circuit to which they belong, and the first inductor L1 and the second inductor L2 constitute a common-mode inductor, which mainly plays a filtering role and helps to improve the acquisition accuracy of the thermal resistor voltage.

[0075] As an optional implementation, the reference voltage generating circuit 20 further includes an auxiliary resistor R6 in addition to the reference resistor R1. Figure 3As shown, one end of the reference resistor R1 is connected to the compensation line S3, and the other end of the reference resistor R1 is connected to the auxiliary resistor R6, and the other end of the auxiliary resistor R6 is grounded. The auxiliary resistor R6 can raise the common mode voltage during the process of the analog-to-digital converter 110 collecting the reference voltage, which helps to improve the sampling accuracy of the reference voltage. Further, the reference voltage generation circuit 20 also includes a current limiting resistor R7 and a current resistor R8, combined with Figure 3 As shown, the current limiting resistor R7 is connected to the first voltage acquisition port V IN0 Between one end of the reference circuit R1, the current limiting resistor R8 is connected to the second voltage acquisition port V IN1 Between the other end of the reference resistor R1. The current limiting resistors R7 and R8 can limit the current size of the circuit, which helps to improve the safety of circuit operation.

[0076] In an optional implementation, the temperature acquisition circuit provided in this embodiment further includes a first protection circuit 130 and a second protection circuit 140. Figure 3 As shown, the first protection circuit 130 includes a first transient voltage suppressor (TVS) diode U1 and a second transient voltage suppressor diode U2, wherein one end of the first transient voltage suppressor diode U1 and one end of the second transient voltage suppressor diode U2 are respectively used as input ends of the first protection circuit 130, one end of the first transient voltage suppressor diode U1 is connected to the first sub-circuit, and the other end of the first transient voltage suppressor diode U1 is grounded, and correspondingly, one end of the second transient voltage suppressor diode U2 is connected to the second sub-circuit, and the other end of the second transient voltage suppressor diode U2 is grounded. Similar to the structure of the first protection circuit 130, the second protection circuit 140 includes a third transient voltage suppressor diode U3 and a fourth transient voltage suppressor diode U4, wherein the first transient voltage suppressor diode U3 and the fourth transient voltage suppressor diode U4 are connected in parallel, and one end of the resulting parallel branch is used as one end of the second protection circuit 140, connected to the connection point of the reference resistor R1 and the compensation line S3, and the other end of the parallel branch is grounded. The first protection circuit 130 and the second protection circuit 140 can prevent electrostatic interference between the temperature acquisition circuit and the external connection (ie, the connection points E1, M1 and com) from damaging the analog-to-digital converter 110, thereby protecting the operation safety of the analog-to-digital converter 110.

[0077] Furthermore, the temperature sampling circuit provided in this embodiment is also provided with capacitors C1-C9. The connection relationship of each capacitor in the circuit can be seen in Figure 3 In practical applications, capacitors C1-C9 mainly play a filtering role, which has a positive effect on improving circuit stability and sampling accuracy.

[0078] The following is based on Figure 3The circuit topology diagram shown introduces the working principle of the temperature acquisition circuit provided in this application.

[0079] based on Figure 3 As shown, in the actual measurement process, the analog-to-digital converter 110 outputs a sampling current through its own integrated constant current source. Specifically, the first sampling current I0 is output through the first constant current source port I out0 The output is input into the first connection line S1 through the first energy supply circuit and the terminal E1 and flows through the thermal resistor Rs, and further, it also passes through the reference resistor R1 and the auxiliary resistor R6, and finally grounded to form a closed loop; accordingly, the second sampling current I1 is output through the second constant current source port I out1 The second sampling current I1 is outputted through the second energy supply circuit and the terminal M1 and inputted into the second connection line S2. The second sampling current I1 does not pass through the thermal resistor Rs, but passes through the compensation line S3, the reference resistor R1 and the auxiliary resistor R6 and then is grounded to form a loop.

[0080] Based on the flow path of the above sampling current, there is the following electrical balance relationship:

[0081] U E1 =I0×(2r+R s +R1+R6)+I1×(r+R1+R6)

[0082] U M1 =I1×(2r+R1+R6)+I0×(r+R1+R6)

[0083] Where: r is the single-wire resistance of the first connecting wire, the second connecting wire and the third connecting wire in the three-wire thermal sensor. By default, the resistance of the three wires is equal;

[0084] U E1 for Figure 3 The voltage at point E1;

[0085] U M1 for Figure 3 The voltage at point M1.

[0086] Based on the above, the voltage across Rs, that is, the thermal resistor voltage U EM Calculate according to the following formula:

[0087] U EM =U E1 ―U M1 =I0×Rs+(I0―I1)×r

[0088] Reference voltage U REF Then:

[0089] U REF =(I0+I1)×R1

[0090] In practical applications, there is a matching error of ±0.5% between the first sampling current and the second sampling current, which has a great influence on the acquisition accuracy and needs to be eliminated.

[0091] Assume that the first sampling current I0 flows through the thermal resistor Rs:

[0092] U EM =U E1 ―U M1 =I0×Rs+(I0―I1)×r

[0093] The code value corresponding to this state is recorded as Code1, then:

[0094]

[0095] Wherein, CodeFS represents the full-scale code value corresponding to the thermal sensor.

[0096] Furthermore, assuming that the second sampling current I1 flows through the thermal resistor Rs:

[0097] U EM =U E1 ―U SM1 =I1×Rs+(I1―I0)×r

[0098] The corresponding code value in this state is recorded as Code2, then:

[0099]

[0100] Since the current values ​​flowing through the reference resistor R1 are the same twice, the reference voltage values ​​are the same twice. Adding equation (1) and equation (2) together, we get:

[0101]

[0102] Based on formula (3), it can be seen that the sampling value of the thermal resistor Rs is only related to the resistance value of the reference resistor R1, and the first sampling current and the second sampling current have no effect on the calculation of the thermal resistor resistance value. Therefore, the temperature acquisition circuit provided by the present application can effectively eliminate the error caused by the sampling current deviation. Further, it can be seen that the sampling value of the thermal resistor Rs is only related to the resistance value of the reference resistor R1. In the temperature acquisition circuit provided by the present application, the reference resistor R1 adopts a precision resistor, and its resistance deviation is smaller. Therefore, the accuracy and reliability of the thermal resistor resistance acquisition result can be further improved.

[0103] As mentioned above, the accuracy of temperature acquisition will also be affected by the performance deviation of the analog-to-digital converter itself, such as the error caused by leakage current at the reference voltage acquisition port, the integral nonlinearity error, offset error and gain error of the analog-to-digital converter, and of course, the error introduced by the leakage current of the transient suppression diode in the aforementioned first protection circuit and the second protection circuit. These errors include calibrable errors and non-calibrable errors. In practical applications, they can be calibrated or offset by relevant technologies, which will not be described in detail here.

[0104] In an optional implementation, the temperature acquisition circuit provided in any of the above embodiments further includes a controller, which is connected to the main circuit in communication. Specifically, when the main circuit includes an analog-to-digital converter, the controller is connected to the analog-to-digital converter in communication. After the main circuit determines the thermal resistor resistance value of the three-wire thermal sensor according to the above content, the obtained thermal resistor resistance value is fed back to the controller, and the controller determines the current sampling temperature value based on the preset mapping relationship between the thermal resistor resistance value and the sampling temperature. The preset mapping relationship between the thermal resistor resistance value and the sampling temperature can be provided by the manufacturer of the three-wire thermal sensor or determined through experiments, and this application does not make specific limitations on this.

[0105] Furthermore, the present application provides a temperature acquisition module, comprising: a three-wire thermal sensor and a temperature acquisition circuit as provided in any of the above embodiments, wherein:

[0106] The temperature acquisition circuit is connected to the three-wire thermal sensor.

[0107] Furthermore, the present application also provides an electronic device, comprising: at least one temperature acquisition module as provided in the above embodiment.

[0108] Those skilled in the art will appreciate that the contents disclosed in this disclosure may be subject to various variations and improvements. For example, the various devices or components described above may be implemented by hardware, or by software, firmware, or a combination of some or all of the three.

[0109] In addition, although the present disclosure makes various references to certain units in the system according to embodiments of the present disclosure, any number of different units can be used and run on the client and / or server. The units are only illustrative, and different aspects of the system and method can use different units.

[0110] Flowcharts are used in this disclosure to illustrate the steps of the method according to the embodiments of the present disclosure. It should be understood that the preceding or following steps are not necessarily performed precisely in order. On the contrary, various steps may be processed in reverse order or simultaneously. At the same time, other operations may also be added to these processes.

[0111] Those skilled in the art will appreciate that all or part of the steps in the above method can be completed by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, etc. Optionally, all or part of the steps in the above embodiment can also be implemented using one or more integrated circuits. Accordingly, each module / unit in the above embodiment can be implemented in the form of hardware or in the form of a software functional module. The present disclosure is not limited to any particular form of combination of hardware and software.

[0112] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It should also be understood that terms such as those defined in common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined as such herein.

[0113] The above is an explanation of the present disclosure and should not be considered as a limitation thereof. Although several exemplary embodiments of the present disclosure are described, it will be readily understood by those skilled in the art that many modifications may be made to the exemplary embodiments without departing from the novel teachings and advantages of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure as defined in the claims. It should be understood that the above is an explanation of the present disclosure and should not be considered to be limited to the specific embodiments disclosed, and modifications to the disclosed embodiments and other embodiments are intended to be included within the scope of the appended claims. The present disclosure is defined by the claims and their equivalents.

Claims

1. A temperature acquisition circuit, characterized in that: Applied to a three-wire thermal sensor, the three-wire thermal sensor includes a thermal resistor, a first connecting wire connected to one end of the thermal resistor, and a second connecting wire and a compensation wire connected to the other end of the thermal resistor. The temperature acquisition circuit includes: a main circuit and a reference voltage generation circuit, wherein: The reference voltage generating circuit includes a reference resistor; The main circuit is configured to: output a first sampling current to the first connecting line, output a second sampling current to the second connecting line, and collect a thermal resistor voltage output by the thermal resistor in response to the first sampling current; The reference voltage generating circuit is configured to: output a reference voltage of the reference resistor in response to the first sampling current and the second sampling current; The main circuit is further configured to calculate a ratio of the resistor voltage to the reference voltage, and determine a resistance value of the thermal resistor based on a product of the ratio and a resistance value of the reference resistor.

2. The temperature acquisition circuit according to claim 1, characterized in that: The main circuit includes: an analog-to-digital converter ADC and at least one voltage acquisition circuit, wherein: The ADC includes a reference voltage acquisition port and a plurality of external port groups, wherein: The external port group is connected to the voltage collection circuit in a one-to-one correspondence; The voltage collection circuit is connected to the three-wire thermal sensor in a one-to-one correspondence; The reference voltage acquisition port is connected to the output end of the reference voltage generation circuit, and the input end of the reference voltage generation circuit is respectively connected to the compensation line of each of the three-wire thermal sensors; The ADC is configured to: calculate a ratio of a resistance voltage of a thermal resistor in a target thermal sensor to the reference voltage, and determine a resistance value of the thermal resistor in the target thermal sensor based on a product of the ratio and a resistance value of the reference resistor; Wherein, the target thermal sensor is any one of the three-wire thermal sensors.

3. The temperature acquisition circuit according to claim 2, characterized in that: The external port group includes a first constant current source port, a second constant current source port and a resistance voltage acquisition port; The voltage acquisition circuit includes: a first energy supply circuit, a second energy supply circuit and a sampling subcircuit, wherein: The first energy supply circuit is connected between the first constant current source port and the first connecting line; The second energy supply circuit is connected between the second constant current source port and the second connecting line; The sampling subcircuit is connected to the resistance voltage acquisition port and the first connection line and the second connection line respectively.

4. The temperature acquisition circuit according to claim 3, characterized in that: The resistance voltage acquisition port includes a first voltage acquisition port and a second voltage acquisition port; The sampling subcircuit includes a first subcircuit and a second subcircuit, wherein: The first subcircuit includes a first resistor and a first mutual inductor, wherein: One end of the first resistor is connected to the first voltage acquisition port, and the other end of the first resistor is connected to one end of the first mutual inductor; The other end of the first mutual inductor is used to connect the first connecting line; The second subcircuit includes a second resistor and a second mutual inductor, wherein: One end of the second resistor is connected to the second voltage acquisition port, and the other end of the second resistor is connected to one end of the second transformer; The other end of the second mutual inductor is used to connect the second connecting line.

5. The temperature acquisition circuit according to claim 4, characterized in that: Also includes: A first protection circuit, wherein An input terminal of the first protection circuit is connected to the first sub-circuit and the second sub-circuit respectively, and a ground terminal of the first protection circuit is grounded.

6. The temperature acquisition circuit according to claim 1, characterized in that: The reference voltage generating circuit further includes: an auxiliary resistor, wherein: One end of the reference resistor is used to connect to the compensation line, and the other end of the reference resistor is connected to the auxiliary resistor; The other end of the auxiliary resistor is grounded.

7. The temperature acquisition circuit according to claim 6, characterized in that: Also includes: The second protection circuit, wherein One end of the second protection circuit is connected to the reference resistor and a connection point of the compensation line, and the other end of the second protection circuit is grounded.

8. The temperature acquisition circuit according to any one of claims 1 to 7, characterized in that: Also includes: controller, where The controller is in communication connection with the main circuit; The controller is configured to determine a current sampling temperature value based on a preset mapping relationship between a thermal resistor resistance value and a sampling temperature.

9. A temperature acquisition module, characterized in that: include: A three-wire thermal sensor and a temperature acquisition circuit as claimed in any one of claims 1 to 8, wherein: The temperature acquisition circuit is connected to the three-wire thermal sensor.

10. An electronic device, characterized in that: include: At least one temperature acquisition module as claimed in claim 9.

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