CN113660746A

CN113660746A - Heating circuit and cooking device

Info

Publication number: CN113660746A
Application number: CN202010398995.7A
Authority: CN
Inventors: 马志海; 王云峰; 雷俊; 江德勇; 卞在银; 周云
Original assignee: Foshan Shunde Midea Electrical Heating Appliances Manufacturing Co Ltd
Current assignee: Foshan Shunde Midea Electrical Heating Appliances Manufacturing Co Ltd
Priority date: 2020-05-12
Filing date: 2020-05-12
Publication date: 2021-11-16
Anticipated expiration: 2040-05-12
Also published as: CN113660746B

Abstract

The application discloses heating circuit and culinary art device, heating circuit includes: a heating unit including a heating coil to perform resonance heating of an object to be heated; and the measuring coil has one part mutually inducting with the heating coil and the other part mutually inducting with the heating coil and the object to be heated respectively, and outputs corresponding measuring signals, wherein the measuring signals are used for matching with the resonance electric parameters of the heating coil collected by measurement to determine the temperature of the object to be heated. By the mode, the temperature of the object to be heated can be determined according to the measuring signal, accurate temperature control is achieved, and the real-time temperature of the object to be heated is accurately measured.

Description

Heating circuit and cooking device

Technical Field

The application relates to the technical field of heating, in particular to a heating circuit and a cooking device.

Background

Electromagnetic heating cookers such as induction cookers, electric rice cookers, electric pressure cookers and the like are novel cookers which utilize the electromagnetic induction heating principle to carry out eddy current heating on cookers, have the advantages of high thermal efficiency, convenient use, no gas combustion pollution, safety, sanitation and the like, and are very suitable for modern families.

The temperature measuring device of the existing electromagnetic heating cooker utilizes NTC (negative temperature Coefficient, thermistor) on a coil panel to indirectly measure the temperature of a cooker, but the temperature measuring device has the problems of inaccurate temperature measurement, lagging temperature measurement and the like, and the error of temperature measurement can also cause intelligent cooking control such as accurate temperature control cooking, low-temperature cooking and water boiling sensing.

Disclosure of Invention

The main technical problem who solves of this application provides a heating circuit and cooking device, can solve among the prior art electromagnetic heating cooking ware temperature measurement inaccurate, temperature measurement lag scheduling problem.

In order to solve the technical problem, the application adopts a technical scheme that: there is provided a heating circuit comprising: a heating unit including a heating coil to perform resonance heating of an object to be heated; and the measuring coil has one part mutually inducting with the heating coil and the other part mutually inducting with the heating coil and the object to be heated respectively, and outputs corresponding measuring signals, wherein the measuring signals are used for matching with the resonance electric parameters of the heating coil collected by measurement to determine the temperature of the object to be heated. In order to solve the above technical problem, another technical solution adopted by the present application is: a cooking device is provided, which comprises the heating circuit.

The beneficial effect of this application is: the heating circuit comprises a heating unit and a measuring coil, wherein the heating unit comprises a heating coil for carrying out resonance heating on an object to be heated; and one part of the measuring coil is mutually inducted with the heating coil, the other part of the measuring coil is mutually inducted with the heating coil and the object to be heated respectively, and corresponding measuring signals are output, wherein the measuring signals are used for matching with the resonance electric parameters of the heating coil collected by measurement to determine the temperature of the object to be heated. The temperature of the object to be heated is obtained through the method, and the temperature of the object to be heated can be accurately detected in real time, so that accurate temperature control is realized.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. Wherein:

FIG. 1 is a schematic diagram of an embodiment of a heating circuit of the present application;

FIG. 2 is a schematic diagram of an equivalent circuit model of the heating circuit and the object to be heated in FIG. 1;

FIG. 3 is a waveform diagram of the present application measured voltage and resonance acquisition voltage;

FIG. 4 is an equivalent circuit diagram of an embodiment of the heating circuit of the present application;

FIG. 5 is an equivalent model circuit diagram of another embodiment of the heating circuit of the present application;

FIG. 6 is a schematic diagram of sampling the voltage of the DC power stored by the energy storage capacitor C1 of FIG. 4 or FIG. 5;

FIG. 7 is a schematic diagram of the application of a resonant voltage to the resonant tank of the heating unit of FIG. 4 or FIG. 5;

FIG. 8 is a schematic structural diagram of another embodiment of a heating circuit of the present application;

fig. 9 is a schematic structural diagram of an embodiment of a cooking device according to the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

First, the heating circuit in the present application can be used in any kind of heating device, and for convenience of explanation, the heating circuit is used in a cooking apparatus as described below.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a heating circuit according to an embodiment of the present application. The heating circuit 100 in the present embodiment may include a heating unit 110 and a measuring coil 120.

The heating unit 110 may include a heating coil L1 for resonance heating of the object to be heated 200. Among them, the object to be heated 200 may be various pots, which may be placed on the heating unit 110 to be resonance-heated using the heating coil L1.

One portion of the measurement coils 120 may be mutually induced with the heating coil L1, and the other portion may be mutually induced with the heating coil L1 and the object to be heated 200, respectively, and output corresponding measurement signals for cooperating with measurement of the acquired resonant electrical parameters of the heating coil L1 to determine the temperature of the object to be heated 200.

Alternatively, the measurement signal may be correlated with the resonance electric parameter of the heating coil L1 and the thermal resistance parameter of the object to be heated 200 to determine the thermal resistance parameter of the object to be heated 200 by measuring the measurement signal and measuring the acquired resonance electric parameter of the heating coil L1, thereby determining the temperature of the object to be heated 200 according to the thermal resistance parameter.

In this embodiment, the temperature measurement of the object to be heated 200 can be realized by measuring the thermal resistance change of the object to be heated 200 at different temperatures, specifically, the thermal resistance change of the object to be heated 200 can be detected by sampling the measurement signal of the measurement coil 120, and the temperature of the object to be heated 200 is indirectly derived by the functional relationship between the thermal resistance change and the temperature of the object to be heated 200, so as to realize the non-contact coupling temperature measurement.

In the prior art, a thermistor on a heating unit is used for detecting temperature change in a heating environment, but the connection between the property of an object to be heated and the heating temperature is not considered; compared with the prior art, the present embodiment accurately obtains the thermal resistance parameter of the object to be heated 200 by detecting the mutual inductance among the measuring coil 120, the object to be heated 200, and the heating coil L1, so that the heating circuit 100 of the present embodiment can accurately measure the real-time temperature of the object to be heated 200 while heating. When the heating circuit 100 of the present embodiment is applied to a cooking device, it can implement intelligent cooking operations such as precise temperature control cooking, low-temperature cooking, accurate sensing of water boiling in the cooking device, and the like.

Specifically, the measuring coil 120 may include a first measuring sub-coil L2 and a second measuring sub-coil L3. Wherein the first measurer coil L2 may be disposed adjacent to the heating coil L1 to be mutually inductive with the heating coil L1 and the object to be heated 200, respectively; while the second measuring sub-coil L3 is in mutual inductance with the heating coil L1, in some embodiments the second measuring sub-coil L3 is wound on a magnetizer and the resonant circuit in which the heating coil L1 is located passes through the magnetizer, thereby causing the second measuring sub-coil L3 to be in mutual inductance with the heating coil L1.

One pair of homonymous terminals of the first and second measuring sub-coils L2 and L3 are connected, and the other pair of homonymous terminals of the first and second measuring sub-coils L2 and L3 serve as output terminals of the measuring coil 120 to output a measuring signal.

The first measuring sub-coil L2 and the second measuring sub-coil L3 form a differential coil, a pair of the same-name ends (marked by x in fig. 1) of the first measuring sub-coil L2 and the second measuring sub-coil L3 are connected, the induced voltages of the heating coil L1 on the first measuring sub-coil L2 and the second measuring sub-coil L3 are mutually offset, that is, the second measuring sub-coil L3 can be used for offsetting the interference of the heating coil L1 on the first measuring sub-coil L2, and meanwhile, the second measuring sub-coil L3 is required not to be influenced by the object 200 to be heated, that is, not to be interfered by the magnetic field far away from the object 200 to be heated.

The first measuring sub-coil L2 can be regarded as a thermal resistance sampling coil of the object 200 to be heated. The heating coil L1 converts the object to be heated 200 into electric energy in the form of a magnetic field and further into heat energy for resonance heating. In the case of performing the resonance heating, the object 200 to be heated, such as various kinds of cookware, may be equivalent to a circuit composed of an induction inductance and a thermal resistance.

Alternatively, the first measuring sub-coil L2 may be placed at a preset angle on the disk surface of the heating coil L1, wherein the preset angle may be in the range of 0-45 degrees. Preferably, the preset angle is 0 degree, the first measuring sub-coil L2 may be placed in parallel on the disc surface of the heating coil L1, and the first measuring sub-coil L2 may also be placed at a central position where the magnetic field on the disc surface of the heating coil L1 is weaker, so that the measurement result is more accurate.

The heating circuit 100 may further include an acquisition unit 130, in this embodiment, the acquisition unit 130 may be an acquisition coil L4, and in some embodiments, the acquisition coil L4 is wound on a magnetizer, and a resonant loop of the heating coil L1 passes through the magnetizer, so that the acquisition coil L4 and the heating coil L1 mutually induce a resonance electrical parameter of the heating coil L1. The resonant electrical parameter may be a resonant current flowing through the heating unit 110.

The sampling coil L4 may be a high frequency signal transformer of the heating coil L1, which induces a resonant current flowing across the heating coil L1 in the form of high frequency mutual inductance and generates a corresponding resonant pickup voltage for feedback to the processing circuit 140.

With continued reference to fig. 1, processing circuitry 140 may also be included in the heating circuit 100. The processing circuit 140 may connect the output terminal of the measuring coil 120 and the output terminal of the acquisition unit 130 to acquire the measurement signal and the resonance electrical parameter, determine a thermal resistance parameter of the object to be heated 200 according to the measurement signal and the resonance electrical parameter, and determine the temperature of the object to be heated 200 according to the thermal resistance parameter.

The measurement signal output by the measurement coil 120 may include a measurement voltage, and the resonant electrical parameter output by the acquisition unit 130 may include a resonant acquisition voltage corresponding to a resonant current flowing through the heating coil L1; the processing circuit 140 may determine the thermal resistance parameter of the object to be heated 200 by comparing the measured voltage and the resonance acquisition voltage, for example by comparing a phase difference between the two.

Specifically, the processing circuit 140 may include a main control chip and a processing module, when the processing circuit 140 obtains information of the measurement coil 120 and the acquisition unit 130, such as measurement voltage and resonance acquisition voltage, the information may be processed by the processing module, and then an analog signal in the circuit is converted into a digital signal and sent to the main control chip, and the main control chip analyzes the digital signal to obtain the temperature of the object to be heated 200.

The processing module at least comprises a following circuit, an amplifying circuit, a following circuit and the like; the main control chip can also simultaneously realize other functions, such as the control of a power tube in the control circuit and the like.

Further, referring to fig. 1 and fig. 2 together, fig. 2 is a schematic diagram of an equivalent circuit of the heating circuit and the object to be heated in fig. 1. In the present embodiment, the object to be heated 200 includes an induction inductance Lr and an equivalent thermal resistance Rz.

As shown in fig. 2, when the heating coil L1 in the heating unit 110 performs resonance heating, the resonance current I₁Flowing through the resonant circuit in which the heating coil L1 is located, the sampling coil L4 induces the resonant circuit I flowing through the heating coil L1₁And generates a corresponding resonant acquisition voltage U1. The measurement voltage output by the measurement coil 120 (including the measurement voltages of the first and second measurement sub-coils L2 and L3) is designated U2.

When the object to be heated 200 is placed on the heating coil L1 in the heating unit 110, the heating coil L1 mutually induces the induction inductance Lr in the object to be heated 200, thereby generating a corresponding induction current Ir, wherein the induction current Ir flows through the induction inductance Lr and the equivalent thermal resistance Rz in the object to be heated 200.

The heating coil L1 generates mutual inductance M with the induction inductance Lr in the object 200 to be heated_1rThen it satisfies the following formula:

in the present application, the second measuring sub-coil L3 of the measuring coils 120 is mutually induced with the heating coil L1, and the first measuring sub-coil L2 is mutually induced with the heating coil L1 and the object to be heated 200, respectively. Therefore, as shown in fig. 2, the inductive inductance Lr of the object to be heated 200 and the first measuring sub-coil L2 generate the mutual inductance M_r2Without mutual inductance with the second measuring sub-coil L3; the heating coil L1 and the second measuring sub-coil L3 generate mutual inductance M₁₃And a mutual inductance M12 is generated with the first measuring sub-coil L2.

For the convenience of subsequent calculations, the measurement coil 120 may be corrected in advance: the measuring coil 120 makes a voltage difference between two output terminals a preset value when the object to be heated 200 is not placed on the heating unit 110, thereby completing the correction. Alternatively, the preset value may be 0, thereby completing the return-to-zero correction such that the measurement voltage U2 output by the measurement coil 120 is caused only by the mutual inductance Mr2 between the first gauge sub-coil L2 and the induction inductance Lr of the object to be heated 200. The corrected voltage difference between the two output terminals is 0 for the following example.

Specifically, since the inductive inductance Lr generates the mutual inductance M to the first measuring sub-coil L2 when the object to be heated 200 is placed_r2(ii) a When the object 200 is not placed, the inductive inductor Lr does not generate the mutual inductance M with respect to the first measuring sub-coil L2_r2And thus when the object to be heated 200 is not placed on the heating unit 110, the voltage difference between the two output terminals of the measuring coil 120 is made 0, thereby zeroing the correcting measuring coil 120. At this time, the voltage difference between the synonym terminals of the first and second measuring sub-coils L2 and L3 is close to 0, i.e., j ω M₁₃＝jωM₁₂To zero-correct the first and second measuring sub-coils L2 and L3, that is, to make the initial U2 equal to 0.

And when the object to be heated 200 is placed on the heating unit 110, the inductive inductance Lr of the object to be heated 200 generates the mutual inductance Mr2 with respect to the first measuring sub-coil L2, and does not generate the mutual inductance with respect to the second measuring sub-coil L3; and the heating coil L1 is full after the mutual inductance M12 for the first measuring sub-coil L2 and the mutual inductance M13 for the second measuring sub-coil L3 are zero-return correctedFoot j omega M₁₃＝jωM₁₂(ii) a Therefore, the measurement voltage U2 output by the measurement coil 120 is generated only due to the mutual inductance Mr2 generated by the induced inductance Lr of the object to be heated 200 to the first measurement sub-coil L2, that is:

U2＝(jωM_r2)Ir (2)

in other words, after the return-to-zero correction of the measuring coil 120, the mutual inductance M generated between the second measuring sub-coil L3 and the heating coil L1₁₃The mutual inductance M of the heating coil L1 to the first measuring sub-coil L2 is cancelled₁₂Therefore, the measurement voltage outputted by the subsequent measurement coil 120 is generated only due to the mutual inductance Mr2 generated by the induced inductance Lr of the object to be heated 200 to the first measurement sub-coil L2.

Therefore, by substituting the above formula (1) into the formula (2), it can be seen that

In the formula (3), the resonance current I₁Can be measured by a sampling coil L4, specifically, U1 is I₁Therefore, the resonant current I1 can be obtained by sampling the resonant acquisition voltage U1 output by the coil L4; u2 is the measurement voltage output by the measurement coil 120. After the inductance values of the heating coil L1, the first measuring sub-coil L2, the second measuring sub-coil L3, the sampling coil L4 and the inductance Lr are determined and their mutual positions are determined, then M_1r，M_r2May also be determined. Therefore, the magnitude of the thermal resistance Rz of the object to be heated 200 can be calculated by the above equation (3).

Since Lr is an induction inductance of the object to be heated 200, the object to be heated 200 is generally a cookware for cooking, and the temperature coefficient of the induction inductance Lr is small; the equivalent thermal resistance Rz has a larger temperature coefficient, and most stainless steel or iron materials have the temperature coefficient of 0.001-0.007 (20 ℃), so that U2 and I are measured₁The thermal resistance Rz of the object 200 to be heated can be derived, and then the temperature of the object 200 to be heated can be obtained according to the preset thermal resistance-temperature function T ═ f (Rz).

Therefore, the present embodiment accurately obtains the thermal resistance parameter of the object to be heated 200 by detecting the mutual inductance among the measuring coil 120, the object to be heated 200, and the heating coil L1, so that the heating circuit 100 of the present embodiment can accurately measure the real-time temperature of the object to be heated 200 while heating. When the heating circuit 100 of the present embodiment is applied to a cooking device, it can implement intelligent cooking operations such as precise temperature control cooking, low-temperature cooking, accurate sensing of water boiling in the cooking device, and the like.

Further, the processing circuit 140 may perform data processing in the heating circuit 100, and as can be seen from the equation (3), the processing circuit 140 may determine the equivalent thermal resistance Rz of the object to be heated 200 from the measurement voltage U2 and the resonance acquisition voltage U1, and determine the temperature of the object to be heated 200 from the equivalent thermal resistance Rz.

The processing circuit 140 may collect waveforms of the voltage U1 and the measurement voltage U2 through high-speed AD sampling resonance, store the waveforms in a memory, and perform data processing. Since the resonant collection voltage U1 and the measurement voltage U2 are alternating currents and it can be seen from formula (3) that the measurement voltage U2 is a non-standard function, the values of the resonant collection voltage U1 and the measurement voltage U2 cannot be directly obtained. The processing circuit 140 also needs to perform digital signal processing on its waveform, such as DFT (Discrete fourier transform) processing, including:

selecting a finite discrete frequency sequence with the length of M (1-10) and analyzing the Nth trigonometric function U_2N＝C_V2N*cos(ω_Nt+Φ_V2N) (ii) a Similarly, M-length finite discrete frequency sequences are selected from U1, and the Nth trigonometric function U is analyzed_1N＝C_V1N*sin(ω_Nt+Φ_V1N)。

Due to U_2NAnd U_1NThe excitation sources are the same, the discrete frequency points are selected to be the same, so the frequencies of the two are the same, namely, the frequency is omega_Nt；C_V2NAnd C_V1NIs U_2NAnd U_1NThe amplitude value. Thus, calculate U_1NAnd U_2NThe phase difference Δ Φ of (a) can be indirectly related to Rz without comparing the specific values of the measurement voltage U2 and the resonance acquisition voltage U1. Further, to reduce the interference factor, it is preferableThe fundamental waves of U1 and U2 are selected as comparison objects.

Specifically, processing circuit 140 may obtain phase difference Δ Φ according to the following:

1) the ratio of the measurement voltage U2 to the resonance acquisition voltage U1 is obtained, and the ratio is processed, for example, an inverse tangent function operation is performed, to obtain the phase difference between the measurement voltage U2 and the resonance acquisition voltage U1. Such as the formula: tan (phi)_V2N-Φ_V1N)＝C_V2N*cos(ω_Nt+Φ_V2N)/C_V1N*sin(ω_Nt+Φ_V1N) I.e. to obtain tan (phi)_V1N-Φ_V2N) Obtaining delta phi as phi by inverse tangent function arctan_V1N-Φ_V2N。

2) The waveforms of the measurement voltage U2 and the resonance acquisition voltage U1 are compared to obtain a phase difference between the measurement voltage U2 and the resonance acquisition voltage U1. Fig. 3 is a waveform diagram of the measurement voltage and the resonance acquisition voltage according to the present application, as shown in fig. 3. By U_1NStarting from the voltage waveform a, recording U_2NThe time delta phi required by the voltage to arrive at point b is the phase difference, wherein points a and b are at the same voltage value.

3) The measured voltage U2 and the resonance collection voltage U1 are compared by a comparator to obtain a phase difference between the measured voltage U2 and the resonance collection voltage U1. For example, will U_1NAnd U_2NOutput through I/O interface of U1 in U_1NAnd U_2NAnd the positive and negative input ends of the comparator are connected into the comparator, so that the phase difference delta phi is obtained.

In addition, those skilled in the art may also obtain the phase difference Δ Φ by using other methods, which are not described in detail herein. After the phase difference delta phi is obtained, measuring delta phi corresponding to the thermal resistance Rz at the temperature of (-50-400 ℃), and establishing a relation of the two, namely T-f (delta phi). In actual use, the temperature of the object 200 to be heated can be obtained by looking up a table or a relational expression between the two.

Further, referring to fig. 4 and fig. 5, fig. 4 is an equivalent model circuit diagram of an embodiment of the heating circuit of the present application, and fig. 5 is an equivalent model circuit diagram of another embodiment of the heating circuit of the present application. The heating circuit 100 further includes a rectifying unit 150, an energy storage capacitor C1, a resonant capacitor C2, a dc power supplementing unit 160, and an inverting unit 170. The heating unit 110 in fig. 4 includes a heating coil L1 and a resonant capacitor C2 connected in series, that is, the heating coil L1 and the resonant capacitor C2 form an LC series resonant circuit; the heating circuit 110 in fig. 5 includes a heating coil L1 and a resonant capacitor C2, which are juxtaposed together, i.e., the heating coil L1 and the resonant capacitor C2 form an LC parallel resonant tank.

The rectifying unit 150 may be a rectifying bridge D1, which can rectify ac power into dc power, the commonly used commercial power is ac power, the range of the commercial power is 100-280V, and the rectifying bridge D1 can rectify the commercial power to provide dc bus voltage.

The energy storage capacitor C1 may be used to connect the rectifying unit 150 to store dc power. The resonant capacitor C2 may constitute the heating unit 110 in series or parallel with the heating coil L1, thereby forming an LC series resonant heating circuit (shown in fig. 4) or an LC parallel resonant heating circuit (shown in fig. 5). The heating coil L1 and the resonant capacitor C2 may be inverted to generate high frequency oscillation of 15KHz to 60KHz, radiate a magnetic field, and form eddy current at the bottom of the object to be heated 200 to perform electromagnetic induction heating.

And the direct current supplement unit 160 is connected with the energy storage capacitor C1 to introduce direct current supplement electric energy. The DC power supplementing unit 160 may be a diode D2, one end of which is connected to a DC power source to introduce DC power, wherein the voltage range of the introduced DC power may be 10-400V, preferably 10-50V, 140-160V and 282-367V.

The inverter unit 170 may be connected to the resonant tank of the heating unit 100 and receive the oscillation frequency signal, so that the heating unit 110 performs resonant heating in the resonant unit under the driving of the stored dc power and the introduced dc supplementary power. Specifically, the inverter unit may include a half-bridge resonance module 171 or a single-tube resonance module 172.

The inverter unit 170 in fig. 4 adopts a half-bridge resonant module, which may include two switching power transistors Q2 and Q3, and the two switching power transistors Q2 and Q3 may be connected in a totem pole manner and connected to two ends of the energy storage capacitor C1, and connected to the resonant tank of the heating unit 110 with a middle point as an output. The control ends of the switching power tubes Q2 and Q3 respectively receive oscillation frequency signals.

The inverter unit 170 in fig. 5 adopts a single-tube resonant module, which may include a power tube Q4, a power tube Q4 connected to two ends of the energy storage capacitor C1 and connected to the resonant tank of the heating unit 110, and a control end of the power tube Q4 receiving the oscillation frequency signal.

The power tubes Q2, Q3, and Q4 may receive an oscillation excitation source corresponding to the resonant circuit of the heating unit 110, and may also receive a driving signal of the processing circuit 140 to be turned on or off according to the driving signal.

It should be noted that "LC series resonance + half-bridge resonance module" in the heating circuit of fig. 4 or "LC parallel resonance + single-tube resonance module" in the heating circuit of fig. 5 is only an embodiment of the present application, and does not mean that the LC series resonance circuit can only be collocated with the half-bridge resonance module or the LC parallel resonance circuit can only be collocated with the single-tube resonance module. In other heating circuits, those skilled in the art may also match a "LC series resonance + single-tube resonance module" heating circuit or a "LC parallel resonance + half-bridge resonance module" according to actual situations, which is not described herein again.

As can be seen from the above, the dc power supplementing unit 160 can introduce dc power. Specifically, referring to fig. 6 and 7, fig. 6 is a schematic diagram of sampling the voltage of the dc power stored in the energy storage capacitor C1 in fig. 4 or 5, and fig. 7 is a schematic diagram of sampling the resonant voltage applied to the resonant tank of the heating unit 110 in fig. 4 or 5.

As shown in fig. 6, Z1 is the peak window of the voltage of the energy storage capacitor C1, and Z2 is the valley window of the voltage of the energy storage capacitor C1. As shown in fig. 7, Z11 is a peak window of the resonance voltage applied to the resonant tank of the heating unit 110, and Z22 is a valley window of the resonance voltage applied to the resonant tank of the heating unit 110.

Wherein the durations of Z1 and Z2 may be 10 microseconds to 3 milliseconds, and the durations of Z11 and Z22 may be 10 microseconds to 3 milliseconds, wherein the durations of Z1 and Z2 and Z11 and Z22 may be controlled by adjusting the amount of dc-charging energy introduced by the dc-charging unit 160.

In addition, the modules/units in the above embodiments may be self-collocated without conflict, and are not limited in the case that the present application is not particularly described.

Furthermore, in some embodiments, the acquisition unit 130 may also be a resistance sampling circuit 131. Specifically, as shown in fig. 8, fig. 8 is a schematic structural diagram of another embodiment of the heating circuit of the present application. In the present embodiment, instead of using the sampling coil L4 as the acquisition unit 130 as in the above-described embodiment, the resistance sampling circuit 131 is used as the acquisition unit 130. For example, one end of the resistance sampling circuit 131 may be coupled to the resonant tank of the heating unit 110, and the other end may be grounded, so that the resonant electrical parameter of the heating coil L1 is acquired using the resistance sampling circuit 131.

Specifically, the resistance sampling circuit 131 may include a sampling resistor R1 and a power transistor Q1, a control terminal of the power transistor Q1 may accept a resonant frequency, one path terminal of the power transistor Q1 may be connected to the resonant tank as an input terminal of the resistance sampling circuit 131, and another path terminal may be connected to the sampling resistor R1, and the connection node is used as an output terminal of the resistance sampling circuit 131 to output the collected electrical signal.

Referring to fig. 9, fig. 9 is a schematic structural diagram of an embodiment of a cooking device according to the present application. The cooking apparatus 300 includes a heating circuit 100, wherein the heating circuit 100 has the same structure as that of any one of the above embodiments, and the specific structure can be referred to the above embodiments, which are not described herein again.

The cooking device 300 may be an induction cooker, an electric cooker, or an electric pressure cooker, and will not be described herein.

The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims

1. A heating circuit, comprising:

a heating unit including a heating coil to perform resonance heating of an object to be heated;

and the measuring coil has one part mutually inducting with the heating coil and the other part mutually inducting with the heating coil and the object to be heated respectively and outputting corresponding measuring signals, wherein the measuring signals are used for matching with the resonance electric parameters of the heating coil collected by measurement to determine the temperature of the object to be heated.

2. The heating circuit of claim 1, wherein the measurement coil comprises:

a first measuring sub-coil disposed adjacent to the heating coil to be mutually inducted with the heating coil and the object to be heated, respectively;

a second measuring sub-coil which is mutually inductive with the heating coil;

and the other pair of homonymous ends of the first measuring sub-coil and the second measuring sub-coil are used as output ends of the measuring coils to output the measuring signals.

3. The heating circuit according to claim 2, wherein the measuring coil makes a voltage difference between both the output terminals thereof a predetermined value when the object to be heated is not placed on the heating unit, thereby completing the correction.

4. The heating circuit of claim 3, wherein the first measuring sub-coil is placed on the disc surface of the heating coil at a predetermined angle, the predetermined angle being in a range of 0 to 45 degrees.

5. The heating circuit of claim 4, wherein the predetermined angle is 0 degrees, and the first measuring sub-coil is placed in parallel above a disk surface of the heating coil.

6. The heating circuit of claim 3, further comprising:

the acquisition unit is used for acquiring the resonance electric parameters of the heating coil;

wherein, the collection unit includes:

a collection coil collecting the resonance electrical parameters of the heating coil; alternatively, the first and second electrodes may be,

and one end of the resistance sampling circuit is coupled on the resonance loop of the heating unit, and the other end of the resistance sampling circuit is grounded so as to acquire the resonance electric parameters of the heating coil.

7. The heating circuit of claim 6, further comprising:

the processing circuit is connected with the output end of the measuring coil and the output end of the acquisition unit so as to acquire the measuring signal and the resonance electrical parameter, determine the thermal resistance parameter of the object to be heated according to the measuring signal and the resonance parameter, and determine the temperature of the object to be heated according to the thermal resistance parameter.

8. The heating circuit of claim 7, wherein the measurement signal output by the measurement coil comprises a measurement voltage; the resonance electrical parameters collected and output by the collecting unit comprise resonance collecting voltage which corresponds to the resonance current flowing through the heating coil;

the processing circuit obtains a phase difference between the measurement voltage and the resonance acquisition voltage by comparing the measurement voltage and the resonance acquisition voltage to determine the thermal resistance parameter of the object to be heated.

9. The heating circuit of claim 8, wherein the means for the processing circuit to obtain the phase difference between the measurement voltage and the resonant pickup voltage comprises:

acquiring the ratio of the measurement voltage to the resonance acquisition voltage, and processing the ratio to acquire the phase difference between the measurement voltage and the resonance acquisition voltage; or

Comparing the waveforms of the measurement voltage and the resonant acquisition voltage to obtain a phase difference between the measurement voltage and the resonant acquisition voltage; or

Comparing, by a comparator, the measurement voltage and the resonant acquisition voltage to obtain a phase difference between the measurement voltage and the resonant acquisition voltage.

10. The heating circuit of claim 1, wherein the heating unit further comprises: a resonance capacitor that constitutes a resonance circuit of the heating unit in series or parallel with the heating coil;

the heating circuit further comprises:

the rectifying unit is used for rectifying alternating current into direct current;

the energy storage capacitor is connected with the rectifying unit to store direct current electric energy;

the direct current supplement unit is connected with the energy storage capacitor to introduce direct current supplement electric energy;

the inverter unit is connected with the resonant loop of the heating unit and receives an oscillation frequency signal, so that the heating unit performs resonant heating at a resonant frequency under the driving of the stored direct-current electric energy and the direct-current supplementary electric energy;

the inverter unit comprises a half-bridge resonance module or a single-tube resonance module.

11. A cooking device comprising a heating circuit according to any one of claims 1 to 10.