Temperature measurement device, temperature measurement method and program

Abstract

To improve measurement accuracy when measuring the temperature of a component by a temperature sensor accommodated in a housing together with a circuit.SOLUTION: A temperature measurement device 10 includes: a terminal temperature sensor 18 which outputs a sensor output value corresponding to the temperature of a terminal 17A which is a component of a control device 1 provided in a housing 11; a terminal temperature deriving unit 15BA which derives the temperature of the terminal 17A based on the sensor output value; and a terminal temperature correcting unit 15BB which estimates the true value of the temperature of the terminal 17A excluding the influence of heat generation of the circuit of the control device 1 provided in the housing 11 from the temperature derived by the terminal temperature deriving unit 15BA according to a mathematical expression corresponding to the installation and operation conditions of the control device 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a temperature measuring device, a temperature measuring method, and a program. [Background technology]

[0002] As a temperature measuring device that measures the temperature of a component included in itself, for example, a thermometer or a temperature regulator using a thermocouple (Patent Document 1) is known. In such a temperature measuring device, a temperature sensor housed in a housing measures the temperature of a terminal of the component to which the thermocouple is connected as a reference junction temperature.

[0003] In order to measure temperature using a thermocouple in this way, it is necessary to measure the reference junction temperature. However, when measuring the temperature of a component such as a terminal using a temperature sensor installed inside a housing, the reference junction temperature may not be measured accurately due to the influence of heat generated by a circuit inside the same housing. Such influence of heat is not taken into consideration in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-107089 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above-mentioned problems, and has an object to improve the measurement accuracy when measuring the temperature of a component by a temperature sensor housed together with a circuit in a housing. [Means for solving the problem]

[0006] The temperature measuring device of the present invention is characterized in that it comprises a temperature sensor configured to output a sensor output value corresponding to the temperature of a component of an equipment provided in a housing, a first temperature derivation unit configured to derive the temperature of the component based on the sensor output value, and a temperature correction unit configured to estimate the true value of the temperature of the component, excluding the influence of heat generation by a circuit of the equipment provided inside the housing, from the temperature derived by the first temperature derivation unit or the change over time in the sensor output value, using a mathematical formula corresponding to the installation status and operating status of the equipment. In addition, in one configuration example of the temperature measuring device of the present invention, the temperature correction unit estimates a first temperature difference between the temperature derived by the first temperature derivation unit and the ambient temperature outside the housing using a first formula that estimates the increase in temperature of the component due to heat generation by the circuit, estimates the second temperature difference using a second formula that uses the first temperature difference as input to estimate a second temperature difference between the true value of the temperature of the component and the ambient temperature, and estimates the true value of the temperature of the component based on the temperature derived by the first temperature derivation unit and the first and second temperature differences.

[0007] In addition, in one configuration example of the temperature measuring device of the present invention, the temperature correction unit is characterized in that it sets the constants and variables of the first and second formulas according to the installation status and operating status of the equipment. In addition, in one configuration example of the temperature measuring device of the present invention, the first and second formulas are formulas that approximate the thermal conduction characteristics in a thermal resistance circuit consisting of the environment outside the housing and the inside of the housing using a first-order lag and dead time. In addition, in one configuration example of the temperature measuring device of the present invention, the component is a terminal installed so as to be exposed inside and outside the housing, a temperature measuring junction is provided so as to contact a measurement object outside the housing, and a reference junction is further characterized in that it includes a second temperature derivation unit configured to measure the electromotive force of a thermocouple connected to the terminal exposed outside the housing, set the temperature corrected by the temperature correction unit as the temperature of the reference junction, calculate the electromotive force of the thermocouple corresponding to the temperature of this reference junction, and derive the temperature of the measurement object based on the sum of the calculated electromotive force and the measured electromotive force.

[0008] In one configuration example of the temperature measuring device of the present invention, the device is a control device configured to control the temperature of the object to be measured, the part is a terminal installed so as to be exposed inside and outside the housing, a temperature measuring junction is provided so as to contact the object to be measured outside the housing, a reference junction measures the electromotive force of a thermocouple connected to the terminal exposed outside the housing, the temperature corrected by the temperature correction unit is set as the temperature of the reference junction, the electromotive force of the thermocouple corresponding to the temperature of the reference junction is calculated, and the temperature of the object to be measured is calculated based on the sum of the calculated electromotive force and the measured electromotive force. The control device further includes a second temperature derivation unit configured to derive a temperature, and the temperature correction unit estimates the first temperature difference using the first formula for estimating the increase in temperature of the terminal due to heat generation of the power supply circuit of the control device and the first formula for estimating the increase in temperature of the terminal due to heat generation of the operation end drive circuit of the control device, estimates the second temperature difference using the second formula using the first temperature difference as an input, and estimates a true value of the temperature of the terminal based on the temperature derived by the first temperature derivation unit and the first and second temperature differences.

[0009] In addition, the temperature measurement method of the present invention is characterized by including a first step of acquiring a sensor output value corresponding to the temperature of a component of an equipment installed in a housing from a temperature sensor and deriving the temperature of the component based on the sensor output value, and a second step of estimating a true value of the temperature of the component, excluding the influence of heat generation of a circuit of the equipment installed inside the housing, from the temperature derived in the first step or the change over time in the sensor output value, using a formula corresponding to the installation status and operating status of the equipment. Furthermore, in one configuration example of the temperature measurement method of the present invention, the second step includes the steps of estimating a first temperature difference between the temperature derived in the first step and the ambient temperature outside the housing using a first equation that estimates the increase in temperature of the component due to heat generation by the circuit, estimating the second temperature difference using a second equation that estimates a second temperature difference between the true value of the temperature of the component and the ambient temperature using the first temperature difference as input, and estimating the true value of the temperature of the component based on the temperature derived in the first step and the first and second temperature differences.

[0010] In addition, in one configuration example of the temperature measurement method of the present invention, the component is a terminal installed so as to be exposed inside and outside the housing, a temperature measuring junction is provided so as to contact an object to be measured outside the housing, and a reference junction is further characterized by including a third step of measuring the electromotive force of a thermocouple connected to the terminal exposed outside the housing, setting the temperature corrected in the second step as the temperature of the reference junction, determining the electromotive force of the thermocouple corresponding to the temperature of the reference junction, and deriving the temperature of the object to be measured based on the sum of the determined electromotive force and the measured electromotive force. A temperature measurement program according to the present invention is characterized in that it causes a computer to execute each of the above steps. Effect of the Invention

[0011] According to the present invention, by providing a temperature correction unit, the influence on the temperature of the components caused by heat generated according to the operating state of the circuit inside the housing can be corrected, so that the temperature of the components can be measured with high accuracy. In the present invention, by using a formula for temperature correction, fine temperature correction can be realized without being limited by memory capacity.

[0012] In addition, in the present invention, the temperature correction unit sets the constants and variables of the formula according to the installation and operating conditions of the device, so that changes in the installation and operating conditions of the device can be reflected in the temperature correction. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram showing a configuration of a control device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a thermal resistance circuit relating to the sensor temperature and the terminal temperature in the embodiment of the present invention. [Diagram 3] FIG. 3 is a diagram showing a model of a heat conduction system relating to the sensor temperature and the terminal temperature in the embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart illustrating the operations of the terminal temperature derivation unit, the terminal temperature correction unit, and the controlled object temperature derivation unit according to the embodiment of the present invention. [Diagram 5] FIG. 5 is a block diagram showing an example of the configuration of a computer that realizes a control device and a temperature measuring device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a control device according to an embodiment of the present invention. A control device 1 such as a temperature regulator or a PLC (Programmable Logic Controller) includes a temperature measurement device 10 as described below. The control device 1 measures the temperature of a control target (measurement target) (not shown) using a thermocouple 91, and performs feedback control of the temperature of the control target by controlling on / off of an operation terminal 92 consisting of a heater according to the deviation between the measured temperature and a target temperature.

[0015] The temperature measuring device 10 constituting a part of the control device 1 measures the terminal temperature, which is the temperature of the terminal 17A to which the thermocouple 91 is connected, as the temperature of the reference junction by the terminal temperature sensor 18 housed in the housing 11. The temperature of the reference junction is a premise for the temperature measurement by the thermocouple 91.

[0016] The control device 1 includes a housing 11, a power supply circuit 12, a thermocouple input circuit 13, a terminal temperature sensor input circuit 14, a control circuit 15, an operation end drive circuit 16, terminals 17A, 17B, a terminal temperature sensor 18, a communication unit 21, and a display unit 22. The control circuit 15 includes a voltage derivation unit 15A, a terminal temperature derivation unit 15BA (first temperature derivation unit), a terminal temperature correction unit 15BB, a controlled object temperature derivation unit 15C (second temperature derivation unit), a feedback calculation unit 15D, and a memory unit 15M.

[0017] Of the above configuration, the thermocouple 91, the thermocouple input circuit 13, the terminal temperature sensor input circuit 14, the voltage derivation unit 15A, the terminal temperature derivation unit 15BA, the terminal temperature correction unit 15BB, the controlled object temperature derivation unit 15C, and the terminal temperature sensor 18 constitute the temperature measuring device 10.

[0018] Box-shaped housing 11 houses circuits 12-16 and terminal temperature sensor 18. Terminals 17A and 17B, communication unit 21, and display unit 22 are each arranged with a portion exposed from housing 11. Terminal 17A is arranged with a portion to which thermocouple 91 is connected exposed from housing 11 toward the outside of housing 11, and a portion whose temperature is measured by terminal temperature sensor 18 exposed to the internal space of housing 11.

[0019] Power supply circuit 12 converts AC power from an external power supply into DC power. Power supply circuit 12 supplies the converted DC power to circuits 12 to 16, communication unit 21, and display unit 22 to operate them.

[0020] Thermocouple input circuit 13 is connected to thermocouple 91 via terminal 17A. An electrical signal corresponding to the temperature of the controlled object is input from thermocouple 91 to thermocouple input circuit 13. This electrical signal is an electromotive force generated by the temperature difference between the temperature of the temperature measurement junction and the temperature of the reference junction of thermocouple 91. The temperature measurement junction of thermocouple 91 is in contact with the controlled object. As described above, the temperature of the reference junction is the terminal temperature (the temperature of terminal 17A). Thermocouple input circuit 13 converts the electrical signal from thermocouple 91 from analog to digital and outputs it to control circuit 15.

[0021] The terminal temperature sensor input circuit 14 is connected to the terminal temperature sensor 18. The terminal temperature sensor 18 is disposed so as to be in direct contact with the terminal 17A or in contact with a predetermined location on a circuit board connected to the terminal 17A. The terminal temperature sensor 18 is made of a resistance temperature detector whose own resistance value, that is, the sensor resistance value, changes in response to its own temperature, that is, the sensor temperature.

[0022] Since the sensor temperature increases or decreases depending on the terminal temperature of terminal 17A, the resistance value of terminal temperature sensor 18 changes according to the terminal temperature. An electrical signal (voltage signal) indicating the resistance value is output from terminal temperature sensor 18. Terminal temperature sensor input circuit 14 analog-to-digital converts the electrical signal from terminal temperature sensor 18 and outputs it to control circuit 15.

[0023] The control circuit 15 performs a process of feedback control of the temperature of the controlled object. The voltage derivation unit 15A of the control circuit 15 derives a voltage value of an electromotive force generated by a temperature difference between the temperature of the temperature measuring junction and the temperature of the reference junction, based on an electric signal from the thermocouple input circuit 13.

[0024] The terminal temperature derivation unit 15BA derives the terminal temperature of the terminal 17A based on the electrical signal from the terminal temperature sensor input circuit . The terminal temperature correction unit 15BB appropriately corrects the terminal temperature derived by the terminal temperature derivation unit 15BA. The details of the correction will be described later.

[0025] The controlled object temperature derivation unit 15C measures the electromotive force of the thermocouple 91 via the voltage derivation unit 15A, sets the temperature corrected by the terminal temperature correction unit 15BB as the temperature of the reference junction of the thermocouple 91, calculates the electromotive force of the thermocouple 91 corresponding to the temperature of this reference junction, and derives the temperature of the controlled object based on the sum of the calculated electromotive force and the measured electromotive force. The display unit 22 displays the temperature of the controlled object derived by the controlled object temperature derivation unit 15C.

[0026] The feedback calculation unit 15D generates a command to turn on or off the manipulated variable 92 based on the deviation between the temperature of the controlled object and the target temperature, and outputs the command to the manipulated variable drive circuit 16. The value of the target temperature is transmitted, for example, from a higher-level device via the communication unit 21 and stored in the memory unit 15M.

[0027] The controlled element drive circuit 16 is connected to the controlled element 92 via a terminal 17B, and controls the controlled element 92 to be turned on and off according to commands from a feedback calculation unit 15D. With the above-described configuration, feedback control of the temperature of the controlled object is realized.

[0028] Next, the derivation and correction of the terminal temperature of terminal 17A by terminal temperature derivation unit 15BA and terminal temperature correction unit 15BB will be described in detail.

[0029] In the control device 1, the power supply circuit 12 and the operation end drive circuit 16 housed in the housing 11 may generate heat depending on their own operating conditions. This heat generation affects the sensor temperature of the terminal temperature sensor 18 and the terminal temperature of the terminal 17A. In particular, a discrepancy may occur between the terminal temperature derived by the terminal temperature derivation unit 15BA and the actual terminal temperature.

[0030] The terminal temperature derivation unit 15B derives the sensor temperature corresponding to the sensor output value (resistance value) indicated by the electrical signal from the terminal temperature sensor input circuit 14, using a table or formula indicating the relationship between the sensor output value of the terminal temperature sensor 18 and the sensor temperature. The table or formula is stored in advance in the memory unit 15M. The derived sensor temperature is highly accurate and can be considered to be the same as the actual sensor temperature. The sensor temperature increases or decreases depending on the actual terminal temperature of the terminal 17A, but also increases or decreases due to heat generated by the operation of at least one of the power supply circuit 12 and the drive circuit 16 in the housing 11. For this reason, the sensor temperature may differ from the actual terminal temperature.

[0031] For example, if the terminal temperature sensor 18 is positioned closer to the heat source circuits 12, 16 than the terminal 17A and is more susceptible to thermal effects from the circuits 12, 16 than the terminal 17A, the sensor temperature derived by the terminal temperature derivation unit 15B will be higher than the actual terminal temperature.

[0032] Therefore, the terminal temperature correction unit 15BB of this embodiment corrects the sensor temperature derived by the terminal temperature derivation unit 15BA. Fig. 2 is a diagram showing a thermal resistance circuit relating to the sensor temperature and terminal temperature in this embodiment. In Fig. 2, the sensor temperature is Tsns, the actual temperature of terminal 17A is Ttml, the temperature difference between the temperature Ttml of terminal 17A and the ambient temperature Ta is ΔTtml, and the temperature difference between the sensor temperature Tsns and the ambient temperature Ta is ΔTsns.

[0033] 2, reference numeral 23 denotes a circuit board connected to terminals 17A and 17B and carrying power supply circuit 12, thermocouple input circuit 13, terminal temperature sensor input circuit 14, control circuit 15, operation end drive circuit 16, terminal temperature sensor 18, communication unit 21, etc., and reference numeral 24 denotes a control panel for fixing control device 1. Display unit 22 of control device 1 is fixed to control panel 24 in a form visible from the outside.

[0034] In addition, Z1 is the thermal impedance between the terminal 17A and the environment outside the control device, via the circuit board 23 and the housing 11, Z2 is the thermal impedance between the terminal 17A and the terminal temperature sensor 18, Z3 is the thermal impedance between the terminal temperature sensor 18 and the environment outside the control device, via the circuit board 23 and the housing 11, Z4 is the thermal impedance between the terminal temperature sensor 18 and the operation end drive circuit 16, Z5 is the thermal impedance between the terminal temperature sensor 18 and the power supply circuit 12, and Z6 is the thermal impedance between the power supply circuit 12 and the environment outside the control device. , the thermal impedance through the circuit board 23 and the housing 11, Z7 is the thermal impedance between the control end drive circuit 16 and the environment outside the control device, via the circuit board 23 and the housing 11, Z8 is the thermal impedance of the power supply circuit 12, Z9 is the thermal impedance of the control end drive circuit 16, Z10 is the thermal impedance between the power supply circuit 12 and the environment outside the control device, via the control panel 24 and the display unit 22, and Z11 is the thermal impedance between the control end drive circuit 16 and the environment outside the control device, via the control panel 24 and the display unit 22.

[0035] Fig. 3 is a diagram showing a model of a heat conduction system relating to the sensor temperature Tsns and the terminal temperature Ttml in this embodiment. The thermal resistance circuit 30 in Fig. 3 is a block diagram showing the heat conduction characteristics of the circuit in Fig. 2. In Fig. 3, ΔTsns' is an estimate of the temperature difference between the sensor temperature Tsns and the ambient temperature Ta, ΔTtml' is an estimate of the temperature difference between the temperature Ttml of the terminal 17A and the ambient temperature Ta, and Ttml' is an estimate of the temperature Ttml of the terminal 17A.

[0036] The sum of the increase in sensor temperature due to heat generation from the power supply circuit 12 in response to the on / off of the power supplies to the circuits 12-16 and the increase in sensor temperature due to heat generation from the control element drive circuit 16 that turns the control element 92 on / off is the temperature difference ΔTsns between the sensor temperature Tsns and the ambient temperature Ta. In Fig. 3, the transfer function from the power supply circuit 12 to the terminal temperature sensor 18 is F(s), and the transfer function from the control element drive circuit 16 to the terminal temperature sensor 18 is G(s).

[0037] Furthermore, the rise in the terminal temperature due to the heat generated by the power supply circuit 12 and the operation element drive circuit 16 is the temperature difference ΔTtml between the temperature Ttml of the terminal 17A and the ambient temperature Ta. In Fig. 3, the transfer function when the temperature rise that has spread to the terminal temperature sensor 18 is transmitted to the terminal 17A is H(s). In Figure 3, F1(s) is the transfer function that approximates F(s), G1(s) is the transfer function that approximates G(s), and H1(s) is the transfer function that approximates H(s).

[0038] The sensor temperature Tsns can be expressed as in equation (1) using the ambient temperature Ta and the temperature difference ΔTsns. Tsns = Ta + ΔTsns (1)

[0039] The temperature Ttml of the terminal 17A can be expressed by the ambient temperature Ta and the temperature difference ΔTtml as shown in equation (2). Ttml = Ta + ΔTtml (2)

[0040] The relationship between the temperature differences ΔTsns and ΔTtml can be expressed as formula (3) by considering thermal impedance. ΔTtml = Z × ΔTsns (3)

[0041] Since Z in equation (3) is the impedance ratio between the temperature differences ΔTsns and ΔTtml in the thermal circuit network shown in Figure 2, it can be expressed as equation (4). Z = Z1 / (Z1 + Z2) (4)

[0042] In this embodiment, since it is desired to estimate the true value of the temperature Ttml of the terminal 17A, the temperature Ttml is estimated by the formula (5) obtained from the formulas (1) to (3). Ttml=Tsns+(Z-1)×ΔTsns ···(5)

[0043] The sensor temperature Tsns can be derived by the terminal temperature derivation unit 15BA. The impedance ratio Z of the temperature differences ΔTsns and ΔTtml is experimentally obtained and approximated by a first-order lag transfer function or a first-order lag and dead time transfer function.

[0044] The temperature difference ΔTsns between the sensor temperature Tsns and the ambient temperature Ta is estimated from the operating state of the control device 1. The temperature difference ΔTsns is affected by the installation and operating conditions of the device. Installation conditions include the material of the control panel 24, the space above, below, left, and right of the control device 1, the distance to adjacent devices, and wiring. Operating conditions include the hardware configuration of the control device 1, the power supply voltage, relay ON / OFF, output signal, input signal, standby mode, and so on. The terminal temperature correction unit 15BB can know the state of the control device 1, and estimates the temperature difference ΔTsns using the recognized operating conditions.

[0045] The impedance ratio Z between the temperature differences ΔTsns and ΔTtml is the transfer function H(s) in FIG. H(s)=Z1 / (Z1+Z2) (6)

[0046] As described above, the temperature difference ΔTsns is the sum of the output of the transfer function F(s) (the increase in the sensor temperature due to the heat generated by the power supply circuit 12) and the output of the transfer function G(s) (the increase in the sensor temperature due to the heat generated by the control element drive circuit 16). H(s), F(s), and G(s) are high-order lag transfer functions, and the amount of calculation increases if they are calculated as they are. Therefore, the terminal temperature correction unit 15BB uses transfer functions H1(s), F1(s), and G1(s) that approximate H(s), F(s), and G(s) with a first-order lag and dead time. H1(s)=K H exp(-L H s) / (1+TH s) (7) F1(s)=K F exp(-L F s) / (1+T F s) (8) G1(s)=K G exp(-L G s) / (1+T G s) ···(9)

[0047] In formulas (7) to (9), K H ,K F ,K G is the gain, T H ,T F ,T G is the time constant, L H ,L F ,L G It's a waste of time.

[0048] FIG. 4 is a flowchart for explaining the operations of terminal temperature derivation unit 15BA, terminal temperature correction unit 15BB, and controlled object temperature derivation unit 15C in this embodiment. When the temperature measuring device 10 (control device 1) is powered on, the terminal temperature correction unit 15BB reads out the formula, constants, and variables for correcting the sensor temperature Tsns from the storage unit 15M (Step S100 in FIG. 4).

[0049] The constant here is the gain K in equations (7) to (9). H ,K F ,K G and the time constant T H ,T F ,T G and the dead time L H ,L F ,L G The variables are the temperature rise ΔT of the power supply circuit 12 relative to the ambient temperature Ta. 12 and the temperature rise ΔT of the operation terminal drive circuit 16 relative to the ambient temperature Ta. 16 Temperature rise ΔT 12 ,ΔT 16 is set for each operating condition of the control device 1. Gain K H ,K F ,K Gand time constant T H ,T F ,T G and dead time L H ,L F ,L G These are determined by the installation conditions of control device 1 and the hardware configuration of control device 1. The above constants and variables are obtained by prior experiments and registered in storage unit 15M. In addition, the temperature rise ΔT 12 ,ΔT 16 is set based on a standard ambient temperature Ta (e.g., 25°C).

[0050] When the control operation of the control device 1 is started (step S101 in FIG. 4), the terminal temperature derivation unit 15BA derives the terminal temperature (sensor temperature) Tsns of the terminal 17A (step S102 in FIG. 4).

[0051] Terminal temperature correction unit 15BB collects information on the operating status to check the operating status of control device 1 (step S103 in FIG. 4). The information on the operating status of control device 1 in this embodiment includes power on / off information of circuits 12-16 and on / off information of operated end 92 by operated end drive circuit 16.

[0052] The terminal temperature correction unit 15BB selects a variable corresponding to the operating status of the control device 1 from the variables read in step S100 (step S104 in FIG. 4). Specifically, the terminal temperature correction unit 15BB selects the temperature rise ΔT 12 Among them, the temperature rise ΔT corresponding to the power on / off information of the circuits 12 to 16 12 In addition, the terminal temperature correction unit 15BB selects the temperature rise ΔT 16 Among these, the temperature rise ΔT corresponding to the on / off information of the operation element 92 by the operation element drive circuit 16 16 Select .

[0053] Next, the terminal temperature correction unit 15BB calculates the constant K F ,K G ,TF ,T G ,L F ,L G and the variable ΔT selected in step S104 12 ,ΔT 16 Based on and the formula read out in step S100, the temperature difference ΔTsns between the sensor temperature Tsns and the ambient temperature Ta is estimated (step S105 in FIG. 4). The estimated value ΔTsns' of the temperature difference ΔTsns is given by formula (10). ΔTsns'=ΔT 12 ×F1(s)+ΔT 16 ×G1(s) =ΔT 12 ×K F exp(-L F s) / (1+T F s) +ΔT 16 ×K G exp(-L G s) / (1+T G s) ···(10)

[0054] Next, the terminal temperature correction unit 15BB reads out the constant K H ,T H ,L H Based on the formula read out in step S100 and the temperature difference ΔTsns' calculated in step S105, the temperature difference ΔTtml between the temperature Ttml of the terminal 17A and the ambient temperature Ta is estimated (step S106 in FIG. 4). The estimated value ΔTtml' of the temperature difference ΔTtml is given by equation (11). ΔTtml' = ΔTsns' × H1(s) = ΔTsns' × K H exp(-L H s) / (1+T H s) (11)

[0055] Finally, the terminal temperature correction unit 15BB estimates the temperature Ttml of the terminal 17A by adding the sensor temperature Tsns derived by the terminal temperature derivation unit 15BA and the estimated value ΔTtml′ of the temperature difference ΔTtml calculated in step S106 (step S107 in FIG. 4). The estimated value Ttml′ of the temperature Ttml is given by equation (12). Ttml'=Ta+ΔTtml'=Tsns-ΔTsns'+ΔTtml' (12)

[0056] In this way, the terminal temperature correction unit 15BB can correct the sensor temperature Tsns derived by the terminal temperature derivation unit 15BA and estimate the true value of the temperature Ttml of the terminal 17A. Note that the temperature Ttml of the terminal 17A may be estimated using the change over time (differentiation, integration, etc.) of the output value of the terminal temperature sensor 18 instead of the sensor temperature Tsns derived by the terminal temperature derivation unit 15BA. The controlled object temperature derivation unit 15C measures the electromotive force of the thermocouple 91 via the voltage derivation unit 15A, defines the terminal temperature Ttml' corrected by the terminal temperature correction unit 15BB as the temperature of the reference junction of the thermocouple 91, obtains the electromotive force of the thermocouple 91 corresponding to this temperature of the reference junction from a pre-prepared standard thermoelectromotive force table, and derives the temperature T of the controlled object based on the sum of the obtained electromotive force and the measured electromotive force (step S108 in FIG. 4).

[0057] Terminal temperature derivation section 15BA, terminal temperature correction section 15BB, and controlled object temperature derivation section 15C repeatedly execute the processes of steps S102 to S108 until the control operation of control device 1 is completed (YES in step S109 in FIG. 4).

[0058] As described above, in this embodiment, the influence on the temperature of terminal 17A caused by heat generated according to the operating state of circuits 12 to 16 in housing 11 can be corrected, so that the temperature of terminal 17A can be measured with high accuracy. As a result, in this embodiment, the measurement accuracy of the temperature of the controlled object can also be improved.

[0059] The inventors proposed a method of correcting the temperature of the reference junction using a table (Patent Application No. 2022-123885). However, for example, in a control device, the appropriate correction value is likely to change depending on the installation and operating conditions of the device. This results in a large number of types of correction value tables, which requires a large memory capacity. If an attempt is made to increase the number of types of correction value tables with limited memory capacity, the time resolution must be increased, which makes it impossible to perform fine correction.

[0060] On the other hand, in this embodiment, a table is not used, but rather a calculation formula is used for the correction, so that the installation status of the equipment can be reflected in the temperature correction, and also the heat-up after power-on and changes in the operating status of the equipment can be reflected in the temperature correction.

[0061] In this embodiment, the higher-order lag of the heat conduction system is approximated by the first-order lag and dead time, but this is not limiting and other approximation methods may be used. For example, the prediction calculation formula disclosed in Japanese Patent Publication No. 7-111383 is one of the other approximation methods.

[0062] The control circuit 15 described in this embodiment can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in FIG.

[0063] The computer includes a CPU 200, a storage device 201, and an interface device (I / F) 202. The I / F 202 is connected to a thermocouple input circuit 13, a terminal temperature sensor input circuit 14, an operation end drive circuit 16, a communication unit 21, a display unit 22, etc. In such a computer, a program for realizing the control method and the temperature measurement method of the present invention is stored in the storage device 201. The CPU 200 executes the processing described in this embodiment in accordance with the program stored in the storage device 201. [Industrial Applicability]

[0064] The present invention can be applied to a technique for estimating temperature. [Explanation of symbols]

[0065] 1...control device, 10...temperature measuring device, 11...housing, 12...power supply circuit, 13...thermocouple input circuit, 14...terminal temperature sensor input circuit, 15...control circuit, 15A...voltage derivation section, 15BA...terminal temperature derivation section, 15BB...terminal temperature correction section, 15C...controlled object temperature derivation section, 15D...feedback calculation section, 15M...memory section, 16...operation end drive circuit, 17A, 17B...terminal, 18...terminal temperature sensor, 21...communication section, 22...display section.

Claims

1. a temperature sensor configured to output a sensor output value corresponding to a temperature of a component of an apparatus provided in a housing; a first temperature derivation unit configured to derive a temperature of the component based on the sensor output value; and a temperature correction unit configured to estimate a true value of the temperature of the component, excluding the influence of heat generation by a circuit of the equipment provided inside the housing, from the temperature derived by the first temperature derivation unit or the change over time of the sensor output value, using a formula corresponding to the installation status and operating status of the equipment.

2. 2. The temperature measuring device according to claim 1, The temperature correction unit estimates a first temperature difference between the temperature derived by the first temperature derivation unit and the ambient temperature outside the housing using a first equation that estimates an increase in temperature of the component due to heat generation of the circuit, estimates the second temperature difference using a second equation that uses the first temperature difference as input to estimate a second temperature difference between the true value of the temperature of the component and the ambient temperature, and estimates the true value of the temperature of the component based on the temperature derived by the first temperature derivation unit and the first and second temperature differences.

3. 3. The temperature measuring device according to claim 2, A temperature measuring device characterized in that the temperature correction unit sets constants and variables of the first and second equations depending on the installation status and operating status of the device.

4. 3. The temperature measuring device according to claim 2, A temperature measuring device characterized in that the first and second formulas are formulas that approximate the thermal conduction characteristics in a thermal resistance circuit consisting of the environment outside the housing and the inside of the housing using a first-order lag and dead time.

5. The temperature measuring device according to any one of claims 1 to 4, the component is a terminal that is exposed to the inside and outside of the housing, a temperature measuring junction provided so as to contact an object to be measured outside the housing, a reference junction measuring the electromotive force of a thermocouple connected to the terminal exposed outside the housing, setting the temperature corrected by the temperature correction unit as the temperature of the reference junction, determining the electromotive force of the thermocouple corresponding to the temperature of the reference junction, and deriving the temperature of the object to be measured based on the sum of the determined electromotive force and the measured electromotive force.

6. 3. The temperature measuring device according to claim 2, the device is a control device configured to control a temperature of an object to be measured; the component is a terminal that is exposed to the inside and outside of the housing, a temperature measuring junction is provided so as to contact an object to be measured outside the housing, a reference junction measures an electromotive force of a thermocouple connected to the terminal exposed outside the housing, a temperature corrected by the temperature correction unit is set as a temperature of the reference junction, an electromotive force of the thermocouple corresponding to the temperature of the reference junction is obtained, and a second temperature derivation unit is configured to derive a temperature of the object to be measured based on a sum of the obtained electromotive force and the measured electromotive force; The temperature correction unit estimates the first temperature difference using the first formula for estimating the increase in temperature of the terminal due to heat generation of the power supply circuit of the control device and the second formula for estimating the increase in temperature of the terminal due to heat generation of the control end drive circuit of the control device, estimates the second temperature difference using the second formula which takes the first temperature difference as input, and estimates a true value of the temperature of the terminal based on the temperature derived by the first temperature derivation unit and the first and second temperature differences.

7. A first step of acquiring a sensor output value corresponding to a temperature of a component of a device provided in a housing from a temperature sensor and deriving a temperature of the component based on the sensor output value; and a second step of estimating a true value of the temperature of the component, excluding the influence of heat generation by a circuit of the equipment installed inside the housing, from the temperature derived in the first step or the change over time of the sensor output value, using a formula corresponding to the installation status and operating status of the equipment.

8. 8. The temperature measuring method according to claim 7, the second step includes the steps of estimating a first temperature difference between the temperature derived in the first step and an ambient temperature outside the housing using a first equation that estimates an increase in temperature of the component due to heat generation by the circuit, estimating the second temperature difference using a second equation that estimates a second temperature difference between the true value of the temperature of the component and the ambient temperature using the first temperature difference as an input, and estimating the true value of the temperature of the component based on the temperature derived in the first step and the first and second temperature differences.

9. The temperature measuring method according to claim 7 or 8, the component is a terminal that is exposed to the inside and outside of the housing, a temperature measuring method further comprising a third step of measuring an electromotive force of a thermocouple having a temperature measuring junction connected to the terminal exposed on the outside of the casing, setting the temperature corrected in the second step as the temperature of the reference junction, determining an electromotive force of the thermocouple corresponding to the temperature of the reference junction, and deriving a temperature of the object to be measured based on the sum of the determined electromotive force and the measured electromotive force.

10. A temperature measuring program that causes a computer to execute each step according to any one of claims 7 to 9.

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