A temperature measurement method of an electromagnetic induction temperature measurement device

Abstract

The present invention relates to a temperature measurement method of an electromagnetic induction temperature measurement device, comprising the following steps: a microprocessor outputs pulses of different frequencies to a driving module at intervals of △t, and the driving module drives the resonant circuit to oscillate; a detection and analysis module connects the output signal to the microprocessor after voltage division, rectification and filtering, and records the signal values ​​of different sizes measured by pulses of different frequencies; in the t1 period, the microprocessor compares the signal values ​​of different sizes, selects the maximum signal value therein and records it as ADm, and the pulse frequency corresponding to the ADm is f+m△f; and the real-time temperature value Tm is calculated according to ADm. This control method adjusts the driving frequency in real time, accurately grasps the resonance point of the resonant circuit in the temperature measurement device, reduces the error between components, solves the change of the resonant frequency after heating, the resonant frequency offset of the resonant circuit, and generates errors, so as to achieve the purpose of accurate temperature measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature measurement, and more specifically, to an electromagnetic induction temperature measurement device, and also to an electromagnetic induction temperature measurement method. Background Art

[0002] The existing electromagnetic heating device is equipped with a temperature sensor. The most common method is to install a temperature probe directly near the panel. The panel temperature can be detected by the temperature probe, and then the panel temperature can be controlled within a certain range through circuit control. Although this method can detect the temperature, it still has many shortcomings. For example, the temperature sensor has a certain lag in detecting the temperature. This temperature measurement method has a slow response time. At the same time, electronic components that are directly in contact with high temperatures will greatly shorten their lifespan. Contact temperature measurement is prone to delay.

[0003] In the existing temperature measurement method, the resonant frequency changes after heating, causing the resonant frequency of the resonant circuit to shift. If a fixed frequency method is used to drive the oscillation, the oscillation circuit cannot achieve standard resonance, and the test data is prone to errors. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a temperature measuring circuit capable of accurately controlling temperature, and to provide a temperature control method capable of accurately controlling temperature.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An electromagnetic induction temperature measuring device, comprising a microprocessor, a driving module, a resonant circuit and a detection and analysis module connected in sequence, and the electromagnetic induction temperature measuring device also comprises a temperature sensing layer;

[0007] The microprocessor is used to output a pulse drive signal and analyze and process the signal of the detection and analysis module;

[0008] The driving module is used to amplify the pulse signal output by the microprocessor to drive the pulse signal;

[0009] The resonant circuit is used to convert the electrical signal into a magnetic field, and includes an inductor and a capacitor, each of which is at least one, and the resonant circuit generates a coupling impedance with the temperature-sensitive layer;

[0010] The detection and analysis module is used to detect the electrical signal in the resonant circuit and calculate the temperature of the cookware.

[0011] Preferably, the temperature-sensitive layer can sense electromagnetic signals, the temperature-sensitive layer and the resonant circuit form a coupling impedance, the temperature-sensitive layer has an initial critical value of temperature change and an end critical value of temperature change, and the temperature-sensitive layer is within a temperature range defined by the initial critical value of temperature change and the end critical value of temperature change; further, under the action of the electromagnetic signal, the temperature-sensitive layer has the following relationship with the coupling impedance: K=|(R2-R1) / [R1×(T2-T1)]|

[0012] Wherein, R1 represents the coupling impedance value generated by the temperature-sensing layer and the resonant circuit when the temperature of the temperature-sensing layer is T1;

[0013] R2 represents the coupling impedance value generated by the temperature-sensing layer and the resonant circuit when the temperature of the temperature-sensing layer is T2;

[0014] T2-T1=1;

[0015] K is the absolute value of (R2-R1) / [R1×(T2-T1)] and is not less than 0.05;

[0016] The R1 and R2 are the coupling impedance values ​​at both ends of the resonant circuit measured by a bridge under specific conditions. The specific conditions defined in this patent refer to that the inductance in the resonant circuit is made of a TDKPC40 magnetic bar with a diameter of 10mm and a length of 10mm, wound 300 times with a copper wire with a diameter of 0.2mm, and the distance between the resonant circuit and the temperature-sensitive layer is set to 5mm, and the power is 25kHz.

[0017] Preferably, the temperature sensing layer is made of a thermistor material among precision alloy materials. Furthermore, the precision alloy material is precision alloy 4J36, precision alloy 4J32, iron-manganese alloy 4J59, constant elastic alloy 3J53, constant elastic alloy 3J53Y, constant elastic alloy 3J58, elastic alloy 3J54, elastic alloy 3J58, elastic alloy 3J59, elastic alloy 3J53, elastic alloy 3J61, elastic alloy 3J62, elastic alloy Ni44MoTiAl, precision alloy 4J36, precision alloy 4J32 or amorphous soft magnetic alloy (FeNiCo)78(SiB)22.

[0018] Preferably, the electromagnetic induction temperature measuring device is applied to a heating device, which is a gas stove, an induction cooker, an electric ceramic stove, an infrared stove or a kettle.

[0019] A temperature measurement method of an electromagnetic induction temperature measurement device comprises the following steps:

[0020] Step 1: The microprocessor outputs pulses of different frequencies to the driving module at intervals of △t. The minimum frequency of the pulses is f, the duty cycle is a fixed value, and the maximum frequency is f+n△f. The driving module drives the resonant circuit to oscillate;

[0021] Step 2: The detection and analysis module divides the signal of the resonant circuit, rectifies and filters it, and connects the output signal to the AD port of the microprocessor. The AD port of the microprocessor detects the signal and records the signal values ​​of different magnitudes measured by pulses of different frequencies;

[0022] Step 3: During the time period t1, the microprocessor compares the signal values ​​of different magnitudes, selects the maximum signal value and records it as ADm. The pulse frequency corresponding to ADm is f+m△f;

[0023] Step 4 calculates the real-time temperature value Tm according to ADm. In step 4, the real-time temperature Tm is calculated by table lookup. The present invention can effectively monitor the characteristics of the coupling resistance between the temperature-sensitive layer and the resonant circuit on the object to be measured changing with temperature in real time through AD detection. By adjusting the driving frequency in real time, the resonance point of the resonant circuit in the temperature measuring device can be accurately grasped, the error between devices can be reduced, and the problem of the change of the resonant frequency after heating, which causes the resonant frequency of the resonant circuit to shift and generate errors, is solved to achieve the purpose of accurate temperature measurement. By comparison, the maximum signal value within the constantly changing frequency range is found, and the maximum signal value is converted into the real-time temperature, which is the temperature of the temperature-sensitive layer. The temperature-sensitive layer is arranged on the object to be measured, so the temperature of the temperature-sensitive layer is the temperature of the object to be measured.

[0024] Preferably, 0.001 second ≤ Δt ≤ 1 second.

[0025] Preferably, the pulse frequency output by the microprocessor for the first time is the initial frequency, and when the ADm value is obtained, the microprocessor adjusts the output pulse frequency to the initial frequency.

[0026] Preferably, the pulse frequency is less than or equal to 100 kHz. Furthermore, 7.5≤pulse frequency≤100 kHz.

[0027] Preferably, the signal value is an impedance value.

[0028] Preferably, the temperature measurement method is applied to a heating device, which is a gas stove, an induction cooker, an electric ceramic stove, an infrared stove or a kettle.

[0029] Preferably, the initial frequency of the pulse is f, the signal value is AD0, the frequency of the pulse output by the microprocessor increases gradually, each time gradually increasing by △f, and when the pulse frequency is f+n△f, the signal value is ADn.

[0030] Preferably, the initial frequency of the pulse is f+nΔf, the signal value is ADn, the frequency of the pulse output by the microprocessor is gradually reduced, and Δf is gradually reduced each time. When the frequency of the pulse is f, the signal value is AD0.

[0031] Preferably, the initial frequency of the pulse is f+1 / 2Δf, and the pulse frequency is continuously increased or decreased.

[0032] Preferably, the 0.01KHz≤Δf≤0.5kHz.

[0033] Preferably, steps 1 to 4 are repeated at intervals of S seconds, where 0.01 seconds ≤ S ≤ 3000 seconds.

[0034] Within a limited frequency range, a fixed frequency is increased at a fixed interval, AD is measured, the detected AD values ​​are compared, and the maximum value or specific value of AD is found. The maximum value or specific value of AD corresponds to the temperature of the temperature-sensitive layer and can be converted into temperature by looking up a table.

[0035] Compared with the prior art, the present invention has the following beneficial effects: (1) It can effectively monitor the characteristics of the coupling resistance between the temperature-sensitive layer and the resonant circuit on the object being measured in real time through impedance detection. (2) By changing the contact temperature measurement method and adopting a variable frequency drive method to achieve standard resonant drive, this control method can accurately grasp the resonance point of the resonant circuit in the electromagnetic temperature measurement device by adjusting the drive frequency in real time, thereby reducing the error between devices. This temperature test method has the characteristics of short delay lag time, accurate temperature measurement, and little influence of external temperature on the signal, and small error. It can solve the problem of the change of resonant frequency after heating, which causes the resonant frequency of the resonant circuit to shift.

[0036] To achieve the purpose of accurate temperature measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic diagram of an electromagnetic induction temperature measuring device in Example 1 of the present invention.

[0038] FIG2 is a flow chart of a temperature measurement method according to Embodiment 2 of the present invention.

[0039] FIG. 3 is a schematic diagram showing a relationship between pulse frequency and signal value in the present invention.

[0040] Description of Reference Numerals

[0041] Cookware 1; temperature sensing layer 12; microprocessor 2; drive module 3; resonant circuit 4; detection and analysis module 5. Specific embodiments

[0043] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0044] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0045] Example 1

[0046] As shown in FIG. 1 , an electromagnetic induction temperature measuring device provides a cookware 1, wherein the cookware 1 is provided with a temperature sensing layer 12, and the electromagnetic induction temperature measuring device comprises a microprocessor 2, a driving module 3, a resonant circuit 4 and a detection and analysis module 5 which are connected in sequence;

[0047] Microprocessor 2, used for outputting pulse driving signals and analyzing and processing signals of detection and analysis module 5, microprocessor 2 has an AD port;

[0048] The driving module 3 is used to amplify the pulse signal output by the microprocessor 2 and drive the pulse signal;

[0049] The resonant circuit 4 is used to convert the electrical signal into a magnetic field, and includes an inductor and a capacitor, and the inductor and the capacitor are at least one, and the resonant circuit 4 generates a coupling impedance with the temperature sensing layer 12;

[0050] The detection and analysis module 5 is used to detect the electrical signal in the resonant circuit 4 and calculate the temperature of the cookware 1 .

[0051] The temperature sensing layer 12 forms a coupling impedance with the resonant circuit 4. The temperature sensing layer 12 has an initial critical value of temperature change and an end critical value of temperature change. In the temperature range defined by the initial critical value of temperature change and the end critical value of temperature change, the temperature sensing layer 12 has the following relationship with the coupling impedance under the action of the electromagnetic signal:

[0052] K=|(R2-R1) / [ R1×(T2-T1)]|

[0053] Wherein, R1 represents the coupling impedance value generated by the temperature-sensitive layer 12 and the resonant circuit 4 when the temperature of the temperature-sensitive layer 12 is T1;

[0054] R2 represents the coupling impedance value generated by the temperature-sensitive layer 12 and the resonant circuit 4 when the temperature of the temperature-sensitive layer 12 is T2; T2-T1=1;

[0055] K is the absolute value of (R2-R1) / [R1×(T2-T1)] and is not less than 0.05;

[0056] R1 and R2 are the coupling impedance values ​​at both ends of the resonant circuit 4 measured by a bridge under specific conditions. The specific conditions defined in this patent refer to that the inductance in the resonant circuit 4 is made of a TDK PC40 magnetic rod with a diameter of 10mm and a length of 10mm, and is wound 300 times with a copper wire with a diameter of 0.2mm, and the distance between the resonant circuit 4 and the temperature-sensitive layer 12 is set to 5mm, and the power is 25kHz.

[0057] As shown in FIG. 2 , a temperature measurement method using an electromagnetic induction temperature measurement device comprises the following steps:

[0058] Step 1: The microprocessor 2 outputs pulses of different frequencies to the driving module 3 at intervals of △t. The lowest frequency of the pulse is f. When the frequency is f, the corresponding signal value is AD0. The duty cycle is a fixed value of 50%. The highest frequency is f+n△f. When the frequency is f+n△f, the signal value is ADn. The driving module 3 drives the resonant circuit 4 to oscillate.

[0059] Step 2: The detection and analysis module 5 divides the signal of the resonant circuit, rectifies and filters it, and connects the output signal to the AD port of the microprocessor 2. The AD port of the microprocessor 2 detects the signal and records the signal values ​​of different magnitudes measured by pulses of different frequencies;

[0060] Step 3: During the time period t1, the microprocessor 2 compares the signal values ​​of different magnitudes, selects the maximum signal value and records it as ADm. The pulse frequency corresponding to ADm is f+m△f;

[0061] Step 4 calculates the real-time temperature value Tm according to ADm. In step 4, the real-time temperature Tm is calculated by looking up a table. The present invention can effectively monitor the characteristics of the coupling resistance between the temperature-sensitive layer 12 and the resonant circuit 4 on the object to be measured changing with temperature in real time through AD detection. By adjusting the driving frequency in real time, the resonant circuit 4 in the temperature measuring device can be accurately grasped to reach the resonance point, the error between devices can be reduced, and the problem of the change of the resonant frequency after heating can be solved, which causes the resonant frequency of the resonant circuit 4 to shift and generate errors, thereby achieving the purpose of accurate temperature measurement. By comparison, the maximum signal value ADm in the constantly changing frequency range is found, and the maximum signal value ADm is converted into the real-time temperature, which is the temperature of the temperature-sensitive layer 12. The temperature-sensitive layer 12 is arranged on the object to be measured, so the temperature of the temperature-sensitive layer 12 is the temperature of the object to be measured.

[0062] 0.001 seconds ≤ △t ≤ 1 second, △t can be one or more of 0.3 seconds, 0.5 seconds, and 0.7 seconds.

[0063] The pulse frequency output by microprocessor 2 for the first time is the initial frequency. When the ADm value is obtained, microprocessor 2 adjusts the output pulse frequency to the initial frequency. The initial frequency of the pulse is f. The frequency of the pulse output by microprocessor 2 increases gradually, and each time △f is gradually increased. When the pulse frequency is f+n△f, the signal value is ADn. The pulse frequency is less than or equal to 100 kHz. 7.5≤pulse frequency≤100 kHz. The signal value is the impedance value.

[0064] The temperature measurement method is applied to a heating device, which is a gas stove, an induction cooker, an electric ceramic stove, an infrared stove or a kettle.

[0065] Example 2

[0066] The difference from Example 1 is that the initial frequency of the pulse is f+n△f, the signal value is ADn, and the frequency of the pulse output by the microprocessor 2 is gradually reduced, and △f is gradually reduced each time. When the pulse frequency is f, the signal value is AD0. Figure 3 is a linear relationship diagram between the pulse frequency and the signal value, and the pulse frequency and the signal value can also be a curve relationship.

[0067] Example 3

[0068] The difference from the embodiment 1 is that 0.01 kHz ≤ Δf ≤ 0.5 kHz.

[0069] Example 4

[0070] The difference from Example 1 is that steps 1 to 4 in Example 1 are repeated every S seconds, where 0.01 seconds ≤ S ≤ 3000 seconds. The time S can be set according to different characteristics of the heating device or user needs, such as repeating steps 1 to 4 at intervals of 5 seconds, 8 seconds, 10 seconds, 15 seconds, 30 seconds, 1 minute, 3 minutes, 5 minutes, or 10 minutes.

[0071] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A temperature measurement method of an electromagnetic induction temperature measurement device, providing an electromagnetic induction temperature measurement device, comprising a microprocessor, a driving module, a resonant circuit and a detection and analysis module connected in sequence, the electromagnetic induction temperature measurement device also comprising a temperature sensing layer, the temperature sensing layer and the resonant circuit forming a coupling impedance, characterized in that: The following steps are involved: Step 1: The microprocessor outputs pulses of different frequencies to the driving module at intervals of △t, the lowest frequency of the pulses is f, and the highest frequency is f+n△f, and the driving module drives the resonant circuit to oscillate; Step 2: The detection and analysis module divides the signal of the resonant circuit, rectifies and filters it, and connects the output signal to the AD port of the microprocessor. The AD port of the microprocessor detects the signal and records the signal values ​​of different magnitudes measured by pulses of different frequencies; Step 3: During the time period t1, the microprocessor compares the signal values ​​of different magnitudes, selects the maximum signal value and records it as ADm. The pulse frequency corresponding to ADm is f+m△f; Step 4: Calculate the real-time temperature value Tm according to ADm; The temperature-sensitive layer has an initial critical value of temperature change and an end critical value of temperature change, and the temperature-sensitive layer is within the temperature range defined by the initial critical value of temperature change and the end critical value of temperature change; under the action of electromagnetic signals, the temperature-sensitive layer has the following relationship with the coupling impedance: K=|(R2-R1) / [R1×(T2-T1)]|, Wherein, R1 represents the coupling impedance value generated by the temperature-sensing layer and the resonant circuit when the temperature of the temperature-sensing layer is T1; R2 represents the coupling impedance value generated by the temperature-sensing layer and the resonant circuit when the temperature of the temperature-sensing layer is T2; T2-T1=1; K is the absolute value of (R2-R1) / [R1×(T2-T1)] and is not less than 0.05; R1 and R2 are the coupling impedance values ​​at both ends of the resonant circuit measured by a bridge under specific conditions. The specific conditions are that the inductance in the resonant circuit is made of a TDK PC40 magnetic bar with a diameter of 10 mm and a length of 10 mm, and is wound 300 times with a copper wire with a diameter of 0.2 mm, and the distance between the resonant circuit and the temperature-sensitive layer is set to 5 mm, and the power is 25 kHz.

2. The temperature measurement method of the electromagnetic induction temperature measurement device according to claim 1, characterized in that: The pulse frequency output by the microprocessor for the first time is the initial frequency. When the ADm value is obtained, the microprocessor adjusts the output pulse frequency to the initial frequency.

3. The temperature measurement method of the electromagnetic induction temperature measurement device according to claim 1, characterized in that: The pulse frequency is less than or equal to 100 kHz.

4. The temperature measurement method of the electromagnetic induction temperature measurement device according to claim 1, characterized in that: The signal value is an impedance value.

5. The temperature measurement method of the electromagnetic induction temperature measurement device according to claim 1, characterized in that: The temperature measurement method is applied to a heating device.

6. The temperature measurement method of the electromagnetic induction temperature measurement device according to claim 2, characterized in that: The method comprises the following steps: the initial frequency of the pulse is f, the frequency of the pulse output by the microprocessor increases gradually, and each time the frequency increases gradually by △f, and when the frequency of the pulse is f+n△f, the signal value is ADn.

7. The temperature measurement method of the electromagnetic induction temperature measurement device according to claim 2, characterized in that: The method comprises the following steps: the initial frequency of the pulse is f+n△f, the frequency of the pulse output by the microprocessor is gradually reduced, and △f is gradually reduced each time. When the frequency of the pulse is f, the signal value is AD0.

8. The temperature measurement method of the electromagnetic induction temperature measurement device according to claim 2, characterized in that: The method comprises the following steps: the initial frequency of the pulse is f+1 / 2△f, and the pulse frequency is continuously increased or decreased.

9. The temperature measurement method of the electromagnetic induction temperature measurement device according to claim 2, characterized in that: 0.01KHz≤△f≤0.5kHz.

10. The temperature measurement method of the electromagnetic induction temperature measurement device according to any one of claims 1 to 9, characterized in that: Repeat steps 1 to 4 in claim 1 at intervals of S seconds, where 0.01 seconds ≤ S ≤ 3000 seconds.

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