Heater temperature estimation device

Abstract

To allow temperature of an electric heater to be estimated without having to examine temperature characteristics data of the electric heater in advance.SOLUTION: A heater temperature estimation device 5 is provided, comprising a detection unit 500 for detecting noise components generated in an electric heater 1, and a temperature estimation unit 56 for estimating temperature of the electric heater 1 based on the noise component. The detection unit 500 detects noise current and noise voltage as the noise components generated in the electric heater 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heater temperature estimation device that estimates the temperature of an electric heater without providing a temperature sensor. [Background technology]

[0002] Conventionally, there has been known a temperature control system that controls the current flowing through an electric heater so that the temperature of the object to be heated reaches a target temperature (Patent Document 1). The heating wire that constitutes the heater deteriorates due to high temperatures. Therefore, it is desirable to be able to detect the temperature of the heater. In the technology disclosed in Patent Document 1, a temperature sensor for control is mounted on the object to be heated, but an additional temperature sensor is required to detect the temperature of the heater. However, since it may not be possible to provide an additional temperature sensor, it is desirable to accurately estimate the temperature of the heater.

[0003] Therefore, in the technology disclosed in Patent Document 1, temperature characteristic data of the resistance ratio between the resistance value of the heater at a reference temperature and the resistance value of the heater at a temperature higher than the reference temperature is stored in advance, the resistance value when the heater is at the reference temperature is measured as the reference temperature resistance value, and resistance value-temperature characteristic data is obtained by multiplying the resistance ratio-temperature characteristic data by the reference temperature resistance value, and the temperature of the heater is estimated based on the resistance value of the heater measured during temperature control of the heated object and the resistance value-temperature characteristic data. However, the technique disclosed in Patent Document 1 has a problem in that it is necessary to check and store in advance the resistance ratio temperature characteristic data of the heater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-34293 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 provide a heater temperature estimation device that can estimate the temperature of an electric heater without checking the temperature characteristic data of the electric heater in advance. [Means for solving the problem]

[0006] The heater temperature estimation device of the present invention is characterized by comprising a detection unit configured to detect noise components generated in an electric heater, and a temperature estimation unit configured to estimate the temperature of the electric heater based on the noise components. In one configuration example of the heater temperature estimation device of the present invention, the detection section detects a noise current and a noise voltage as noise components generated within the electric heater. Furthermore, in one configuration example of the heater temperature estimation device of the present invention, the temperature estimation unit is characterized in that it estimates the temperature T of the electric heater by T = Vn × In / (4 × kB × Δf), where In is the effective value of the noise current detected by the detection unit, Vn is the effective value of the noise voltage detected by the detection unit, kB is the Boltzmann constant, and Δf is the bandwidth for measuring the noise.

[0007] Moreover, the heater temperature estimation device of the present invention is characterized in comprising a first detection unit configured to detect a current value of a current flowing through an electric heater, a second detection unit configured to detect a voltage value of a voltage applied to the electric heater, a third detection unit configured to detect noise components generated in the electric heater, a resistance calculation unit configured to calculate a resistance value of the electric heater based on the current value detected by the first detection unit and the voltage value detected by the second detection unit, and a temperature estimation unit configured to estimate a temperature of the electric heater based on the resistance value and the noise components. In addition, in one configuration example of the heater temperature estimation device of the present invention, the third detection section detects a noise voltage as a noise component generated within the electric heater. Furthermore, in one configuration example of the heater temperature estimation device of the present invention, the temperature estimation unit estimates the temperature T of the electric heater by T = Vn × Vn / (4 × kB × R × Δf), where Vn is the effective value of the noise voltage detected by the third detection unit, R is the resistance value calculated by the resistance calculation unit, kB is the Boltzmann constant, and Δf is the bandwidth for measuring noise. Effect of the Invention

[0008] According to the present invention, by providing the detection section and the temperature estimation section, it is possible to estimate the temperature of the electric heater without checking the temperature characteristic data of the electric heater in advance.

[0009] In addition, in the present invention, by providing a first detection unit, a second detection unit, a third detection unit, a resistance calculation unit, and a temperature estimation unit, it is possible to estimate the temperature of the electric heater without checking the temperature characteristic data of the electric heater in advance. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the configuration of a temperature control system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart illustrating the operation of the heater temperature estimation device according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a block diagram showing the configuration of a temperature control system according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart illustrating the operation of the heater temperature estimation device according to the second embodiment of the present invention. [Diagram 5] FIG. 5 is a block diagram showing an example of the configuration of a computer that realizes the heater temperature estimation device according to the first and second embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [First Example] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a temperature control system according to a first embodiment of the present invention. The temperature control system includes an electric heater 1, a temperature sensor 2, a control unit 3, a power regulator 4, and a heater temperature estimation device 5.

[0012] The heater 1 is provided in a heat treatment furnace 100 and heats a heating target (not shown). The temperature sensor 2 measures the temperature of the heat treatment furnace 100 or the temperature of the heating target. The control unit 3 calculates a manipulated variable so that the temperature measured by the temperature sensor 2 becomes equal to a preset target temperature. An example of a control algorithm for calculating the manipulated variable is PID.

[0013] The power regulator 4 supplies power to the heater 1 according to the operation amount output from the control unit 3. Specifically, the power regulator 4 adjusts the power supplied to the heater 1 by adjusting the timing (phase) of the on / off time for each half cycle of the AC voltage supplied from a commercial power source, for example. The above temperature control operation is similar to the technology disclosed in Patent Document 1.

[0014] Next, a heater temperature estimation device 5, which is a characteristic configuration of the present invention, will be described. The heater temperature estimation device 5 is composed of an ammeter 50, a voltmeter 51, band pass filters (BPFs) 52 and 53, effective value calculation units 54 and 55, and a temperature estimation unit 56. The ammeter 50, the voltmeter 51, the BPFs 52 and 53, and the effective value calculation units 54 and 55 constitute a detection unit 500 that detects noise components generated in the heater 1.

[0015] Fig. 2 is a flowchart explaining the operation of the heater temperature estimation device 5. The ammeter 50 measures an instantaneous value CT of the current flowing from the power regulator 4 to the heater 1 (Fig. 2, step S100). The voltmeter 51 measures an instantaneous value VT of the voltage applied from the power regulator 4 to the heater 1 (Fig. 2, step S101).

[0016] The BPF 52 extracts a noise current component by passing only components in a frequency band higher than the heater power supply frequency (e.g., 50 Hz) from the output of the ammeter 50 (step S102 in FIG. 2). The BPF 53 extracts a noise voltage component by passing only components in a frequency band higher than the heater power supply frequency from the output of the voltmeter 51 (step S103 in FIG. 2).

[0017] The effective value calculation unit 54 calculates the effective value In of the noise current based on the instantaneous value of the noise current extracted by the BPF 52 (FIG. 2, step S104). The effective value calculation unit 55 calculates the effective value Vn of the noise voltage based on the instantaneous value of the noise voltage extracted by the BPF 53 (FIG. 2, step S105).

[0018] The temperature estimation unit 56 estimates the temperature T [K] of the heater 1 using the formula (1) based on the effective value In of the noise current and the effective value Vn of the noise voltage (Step S106 in FIG. 2). T=Vn×In / (4×kB×Δf) ···(1)

[0019] In equation (1), kB [J / K] is the Boltzmann constant, and Δf [Hz] is the known bandwidth for measuring noise. The passband width of BPFs 52 and 53 is set to be equal to this bandwidth Δf. The Boltzmann constant kB is 1.38×10 -23 [J / K], so for example, if the bandwidth Δf is 5000000 [Hz] and the effective value In of the noise current is 1.8942 × 10 -7 [Arms], the effective value of the noise voltage Vn is 1.8942×10 -6 [Vrms], the heater temperature T is 1300 [K].

[0020] Thus, in this embodiment, the temperature T of the heater 1 can be estimated by calculation using the components of the thermal noise generated within the heater 1, without examining the temperature characteristic data of the heater 1 in advance.

[0021] [Second Example] Next, a second embodiment of the present invention will be described. Fig. 3 is a block diagram showing the configuration of a temperature control system according to the second embodiment of the present invention. The temperature control system of this embodiment includes an electric heater 1, a temperature sensor 2, a control unit 3, a power regulator 4, and a heater temperature estimation device 5a. The temperature control operation is the same as in the first embodiment.

[0022] Heater temperature estimation device 5a includes ammeter 50, voltmeter 51, BPF 53, effective value calculation unit 55, temperature estimation unit 56a, low pass filters (LPF) 57, 58, effective value calculation units 59, 60, and resistance calculation unit 61. Ammeter 50, LPF 57, and effective value calculation unit 59 form a first detection unit 501 that detects the current value of the current flowing to heater 1, voltmeter 51, LPF 58, and effective value calculation unit 60 form a second detection unit 502 that detects the voltage value of the voltage applied to heater 1, and voltmeter 51, BPF 53, and effective value calculation unit 55 form a third detection unit 503 that detects noise components generated in heater 1.

[0023] 4 is a flow chart for explaining the operation of the heater temperature estimation device 5a. The operations of the ammeter 50 and the voltmeter 51 (steps S200 and S201 in FIG. 4) are the same as those in the first embodiment.

[0024] The LPF 57 passes only components in the frequency band of the heater power supply frequency (e.g., 50 Hz) from the output of the ammeter 50, thereby removing noise current components and extracting the heater current component (FIG. 4, step S202). The LPF 58 passes only components in the frequency band of the heater power supply frequency from the output of the voltmeter 51, thereby removing noise voltage components and extracting the heater voltage component (FIG. 4, step S203).

[0025] The effective value calculation unit 59 calculates the effective value Irms of the heater current based on the instantaneous value of the heater current extracted by the LPF 57 (step S204 in FIG. 4). The effective value calculation unit 60 calculates the effective value Vrms of the heater voltage based on the instantaneous value of the heater voltage extracted by the LPF 58 (step S205 in FIG. 4).

[0026] The operations of the BPF 53 and the effective value calculation unit 55 (steps S206 and S07 in FIG. 4) are the same as those in the first embodiment. Next, the resistance calculation unit 61 calculates the resistance value R of the heater 1 based on the effective value Vrms of the heater voltage and the effective value Irms of the heater current using equation (2) (step S208 in FIG. 4). R = Vrms / Irms (2)

[0027] Finally, the temperature estimation unit 56a estimates the temperature T [K] of the heater 1 using the equation (3) based on the effective value Vn of the noise voltage and the resistance value R of the heater 1 (Step S209 in FIG. 4). T=Vn×Vn / (4×kB×R×Δf) ···(3)

[0028] In this way, in this embodiment, the same effect as in the first embodiment can be obtained. Note that, although the first and second embodiments do not explicitly show an example of utilizing the estimated heater temperature T, the heater temperature T may be displayed as disclosed in Patent Document 1, or the heater temperature T may be utilized for deterioration diagnosis of the heater 1. A configuration utilizing the heater temperature T is not an essential component of the present invention.

[0029] The control unit 3, BPFs 52 and 53, LPFs 57 and 58, effective value calculation units 54, 55, 59 and 60, temperature estimation units 56 and 56a and resistance calculation unit 61 described in the first and second embodiments 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.

[0030] The computer includes a CPU 200, a storage device 201, and an interface device (I / F) 202. A temperature sensor 3, a power regulator 4, an ammeter 50, a voltmeter 51, etc. are connected to the I / F 202. In such a computer, a program for implementing the heater temperature estimation method of the present invention is stored in the storage device 201. The CPU 200 executes the processes described in the first and second embodiments in accordance with the program stored in the storage device 201. [Industrial Applicability]

[0031] The present invention can be applied to a technique for estimating the temperature of an electric heater without providing a temperature sensor. [Explanation of symbols]

[0032] 1...electric heater, 2...temperature sensor, 3...control unit, 4...power regulator, 5, 5a...heater temperature estimation device, 50...ammeter, 51...voltmeter, 52, 53...bandpass filter, 54, 55, 59, 60...effective value calculation unit, 56, 56a...temperature estimation unit, 57, 58...lowpass filter, 61...resistance calculation unit, 500 to 503...detection unit

Claims

1. A detection unit configured to detect a noise component generated in the electric heater; and a temperature estimation unit configured to estimate a temperature of the electric heater based on the noise component.

2. 2. The heater temperature estimation device according to claim 1, The heater temperature estimation device according to claim 1, wherein the detection unit detects a noise current and a noise voltage as noise components generated within the electric heater.

3. 3. The heater temperature estimation device according to claim 2, The heater temperature estimation device is characterized in that the temperature estimation unit estimates the temperature T of the electric heater by T = Vn x In / (4 x kB x Δf), where In is the effective value of the noise current detected by the detection unit, Vn is the effective value of the noise voltage detected by the detection unit, kB is the Boltzmann constant, and Δf is the bandwidth for measuring noise.

4. A first detection unit configured to detect a current value of a current supplied to the electric heater; A second detection unit configured to detect a voltage value of a voltage applied to the electric heater; A third detection unit configured to detect a noise component generated in the electric heater; a resistance calculation unit configured to calculate a resistance value of the electric heater based on a current value detected by the first detection unit and a voltage value detected by the second detection unit; a temperature estimation unit configured to estimate a temperature of the electric heater based on the resistance value and the noise component.

5. 5. The heater temperature estimation device according to claim 4, The heater temperature estimation device according to claim 1, wherein the third detection unit detects a noise voltage as a noise component generated within the electric heater.

6. 6. The heater temperature estimation device according to claim 5, the temperature estimation unit estimates a temperature T of the electric heater by T = Vn x Vn / (4 x kB x R x Δf), where Vn is the effective value of the noise voltage detected by the third detection unit, R is the resistance value calculated by the resistance calculation unit, kB is the Boltzmann constant, and Δf is a bandwidth for measuring noise.

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