Temperature measuring circuit and cooking device

Abstract

The present application discloses a temperature measurement circuit and a cooking device. The temperature measurement circuit is used to detect the temperature of a cookware when heating the cookware. The temperature measurement circuit includes a resonant circuit that receives a DC signal. An excitation circuit, connected to the resonant circuit, controls the on / off state of the DC path of the resonant circuit to generate a resonant signal. A sampling circuit, connected to the excitation circuit, samples the resonant signal to obtain a characteristic signal. The temperature measurement circuit provided in the present application has a fast temperature measurement speed, high accuracy, and a simple measurement method.

Description

Technical Field

[0001] The present application relates to the technical field of household appliances, and in particular to a temperature measurement circuit and a cooking device. Background Art

[0002] Electromagnetic induction heating, also known as induction heating, utilizes magnetic flux lines generated by a coil to cut through the cookware, generating eddy currents within the material being heated. The Joule heating effect of these eddy currents heats the cookware, achieving the desired effect. Due to its flame-free, environmentally friendly, safe, and energy-efficient properties, electromagnetic induction heating is gaining increasing popularity among consumers and has become a frequently used cooking device.

[0003] In electromagnetic heating cooking technology, in order to pursue highly intelligent cooking, it is generally chosen to measure the temperature of the pot, so as to control and adjust the cooking mode according to the temperature changes of the pot. For example, when it is detected that the temperature of the pot has dropped, the heating power can be automatically increased to speed up cooking efficiency.

[0004] Generally speaking, most pot temperature measurement systems use a thermistor on a coil disk through a ceramic panel to measure the pot's temperature indirectly. This indirect measurement method is subject to issues such as inaccuracy and lag. If the pot's temperature suddenly cools down, the induction cooker won't be able to detect it in time and may continue to heat it at low power, resulting in low cooking efficiency. Summary of the Invention

[0005] The main technical problem solved by the present application is to provide a temperature measuring circuit and a cooking device with fast temperature measuring speed, high accuracy and simple measuring method.

[0006] A technical solution employed in this application is to provide a temperature measurement circuit for detecting the temperature of a cookware when the cookware is heated. The temperature measurement circuit comprises: a resonant circuit that receives a DC signal; an excitation circuit connected to the resonant circuit and configured to control the on / off state of the DC path of the resonant circuit to generate a resonant signal; and a sampling circuit connected to the excitation circuit and configured to sample the resonant signal to obtain a characteristic signal.

[0007] Furthermore, the characteristic signal includes at least one of a resonance voltage amplitude, a resonance frequency, and a resonance period width.

[0008] Furthermore, the sampling circuit includes: a first resistor, a first end of the first resistor is connected to the excitation circuit, and a second end of the first resistor is connected to the processing circuit, for collecting the amplitude of the resonant voltage.

[0009] Furthermore, the sampling circuit further includes: a first diode, wherein the anode of the first diode is connected to the excitation circuit, and the cathode of the first diode is connected to the first end of the first resistor; a second resistor, wherein the first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is grounded; and a first capacitor, wherein the first end of the first capacitor is connected to the first end of the second resistor, and the second end of the first capacitor is connected to the second end of the second resistor.

[0010] Furthermore, the sampling circuit includes: a sampling coil, which is arranged corresponding to the resonant circuit and is used to collect the resonant frequency or the resonant period width.

[0011] Furthermore, the resonant circuit includes a resonant coil and a resonant capacitor connected in parallel with the resonant coil, with a DC signal inputted to one end of the resonant coil. The excitation circuit includes a first power transistor, a gate of the first power transistor inputting a first pulse modulation signal, a source of the first power transistor connected to the other end of the resonant coil and the sampling circuit, and a drain of the first power transistor connected to ground. The first power transistor is configured to be turned on or off according to the first pulse modulation signal, thereby turning on or off the DC path of the resonant circuit.

[0012] Furthermore, the period of the first pulse modulation signal is fixed.

[0013] Furthermore, the resonant circuit includes a resonant coil and a resonant capacitor connected in series with the resonant coil. The excitation circuit includes: a second power tube, a gate of the second power tube inputting a second pulse modulation signal, a source of the second power tube inputting a DC signal. A third power tube, a gate of the third power tube inputting a third pulse modulation signal, a source of the third power tube connected to the drain of the second power tube and the resonant coil, respectively, and a drain of the third power tube connected to ground. The second power tube and the third power tube, under the control of the second pulse modulation signal and the third pulse modulation signal, respectively, output a DC signal to the resonant circuit, causing the resonant circuit to resonate and generate a resonant signal. The second pulse modulation signal and the third pulse modulation signal are in opposite phases.

[0014] Furthermore, the periods of the second pulse modulation signal and the third pulse modulation signal are fixed.

[0015] Furthermore, the temperature measurement circuit includes: a second diode, the positive electrode of the second diode inputs the AC signal, and the negative electrode of the second diode is connected to the resonant circuit for rectifying the AC signal to input a DC signal to the resonant circuit.

[0016] In order to solve the above technical problems, another technical solution adopted in the present application is: providing a cooking device, which includes a temperature measuring circuit, and the temperature measuring circuit is the temperature measuring circuit provided by the previous technical solution.

[0017] The beneficial effects of this application are as follows: Unlike the prior art, the temperature measurement circuit provided by this application inputs a DC signal to a resonant circuit and controls the on / off state of the resonant circuit's DC path via an excitation circuit, causing the resonant circuit to generate a resonant signal. A sampling circuit then samples the resonant signal to obtain a characteristic signal, and a processing circuit ultimately determines the temperature of the cookware based on the characteristic signal. In this manner, compared to conventional methods of measuring the temperature of cookware using a thermistor component, the temperature measurement circuit provided by this application can measure the cookware's temperature promptly and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without inventive efforts. Among them:

[0019] Figure 1 1 is a schematic structural diagram of a first embodiment of a temperature measurement circuit provided by the present application;

[0020] Figure 2 It is a schematic diagram of the resonance period, resonance frequency and resonance voltage amplitude of the resonance signal;

[0021] Figure 3 1 is a schematic structural diagram of a second embodiment of a temperature measurement circuit provided by the present application;

[0022] Figure 4 2 is a schematic diagram of the circuit structure of a third embodiment of the temperature measurement circuit provided in this embodiment;

[0023] Figure 5 2 is a schematic diagram of the circuit structure of a fourth embodiment of the temperature measurement circuit provided in this embodiment;

[0024] Figure 6 This is a structural diagram of an embodiment of the arrangement of the sampling coil and the heating coil of the present application;

[0025] Figure 7 This is a circuit diagram of an embodiment of the arrangement of the sampling coil and the heating coil of the present application;

[0026] Figure 8 This is a structural diagram of another embodiment of the arrangement of the sampling coil and the heating coil of the present application;

[0027] Figure 9 This is a circuit diagram of another embodiment of the arrangement of the sampling coil and the heating coil of the present application;

[0028] Figure 10This is a schematic structural diagram of an embodiment of a cooking device of the present application;

[0029] Figure 11 1 is a flow chart of an implementation method of a cookware temperature measurement method provided in this embodiment. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It will be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some, rather than all, structures related to the present application are shown in the drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0032] Generally speaking, during the cooking process, water or other ingredients are often added to the pot midway through cooking. For example, when stewing soup, different ingredients require different simmering times, so different ingredients are added in batches. Alternatively, additional water may be added when necessary. Adding cold water or ingredients can cause the pot's temperature to drop suddenly. If the pot's temperature change cannot be detected and the heat cannot be adjusted in time, the pot must be reheated at the current heat, which is time-consuming. This embodiment utilizes a temperature measurement circuit to resonate, and then promptly reflects the pot's temperature change trend based on the resonant signal's resonant period width, resonant frequency, or resonant voltage amplitude. This facilitates controlling the pot's heating based on the temperature change detection results, thereby saving heating time. The detection results are reliable and highly sensitive.

[0033] The temperature measurement circuit provided in the present application is used to detect the temperature of the cookware in a scenario where the cookware is heated. This embodiment does not limit the heating method of the cookware. For example, the cookware can be heated by electromagnetic heating, ceramic heating, or electric heating.

[0034] After extensive research, the inventors discovered that the resonant inductor of a resonant circuit can mutually couple with the cookware during resonance. Therefore, when the cookware temperature changes, this mutual coupling will correspondingly alter the inductance and reflected internal resistance of the resonant inductor. These inductance and reflected internal resistance can be determined by measuring the resonant frequency, resonant cycle width, or voltage amplitude of the resonant inductor or resonant signal. Therefore, the temperature measurement circuit provided in this embodiment can indirectly determine the cookware temperature based on the resonant frequency, resonant cycle width, or voltage amplitude.

[0035] See Figure 1 , Figure 1 This is a schematic diagram of the structure of the first embodiment of the temperature measurement circuit provided by this application. Figure 1 As shown, specifically, the temperature measurement circuit 100 includes a resonant circuit 101 , an excitation circuit 102 , a sampling circuit 103 and a processing circuit 104 which are connected in sequence.

[0036] A DC signal is input into resonant circuit 101 to power the entire temperature measurement circuit 100. The excitation circuit 102 controls the conduction and disconnection of the DC path in resonant circuit 101, causing resonant circuit 101 to resonate and generate a resonant signal. Specifically, resonant circuit 101 resonates with the cookware, generating a resonant signal that varies with the cookware's temperature.

[0037] The circuit for sampling the resonant signal is the sampling circuit 103, thereby obtaining a characteristic signal. Based on the characteristic signal, the processing circuit 104 can determine the temperature of the pot.

[0038] In this embodiment, the characteristic signal includes at least one of the resonance voltage amplitude, the resonance frequency and the resonance period width. Figure 2 , Figure 2 It is a schematic diagram of the resonant period, resonant frequency and resonant voltage amplitude of the resonant signal, such as Figure 2 As shown in FIG. 1 , the maximum value MAX of each resonant signal is the resonant voltage amplitude, the time difference T between two adjacent resonant signals is the resonant period, and the inverse of the resonant period f is the resonant frequency.

[0039] Resonant frequency calculation formula:

[0040]

[0041] Where f is the frequency in Hertz (Hz); L is the inductance in Henry (H); and C is the capacitance in Farad (F).

[0042] Resonant frequency refers to the phenomenon that occurs in a circuit containing capacitors and inductors in parallel, where, within a very short period of time, the capacitor's voltage gradually increases while the current gradually decreases; the inductor's current gradually increases while the inductor's voltage gradually decreases. Meanwhile, within another very short period of time, the capacitor's voltage gradually decreases while the current gradually increases; the inductor's current gradually decreases while the inductor's voltage gradually increases. The voltage increase can reach a positive maximum, while the voltage decrease can reach a negative maximum. Similarly, the direction of the current can also change between positive and negative directions during this process, a phenomenon known as electrical oscillation in the circuit. When the sinusoidal frequency of the external input voltage to a resonant circuit reaches a certain frequency (the circuit's resonant frequency), the inductive reactance and capacitive reactance of the resonant circuit become equal, Z = R, and the resonant circuit appears to be purely resistive, a phenomenon known as resonance. When resonance occurs, the resonant circuit amplifies the input by Q times, where Q is the quality factor.

[0043] The resonant period is the inverse of the resonant frequency, that is, the calculation formula of the resonant period is:

[0044]

[0045] The resonant voltage amplitude is the maximum absolute value of the resonant signal waveform within one resonant period.

[0046] In this embodiment, the process and principle of the resonant circuit 101 generating a resonant signal that changes with the temperature of the cookware are as follows:

[0047] When the excitation circuit 102 controls the DC path to be conductive, power is supplied to the resonant circuit 101, and the resonant inductor converts electric field energy into magnetic field energy. When the excitation circuit 102 controls the DC path to be disconnected, the resonant inductor (not shown) and resonant capacitor (not shown) of the resonant circuit 101 resonate, converting magnetic field energy into electric field energy. Due to the mutual coupling between the cookware and the resonant inductor, this process can output a resonant signal reflecting the temperature change of the cookware.

[0048] The temperature measurement circuit 100 provided in this embodiment provides a DC signal to power the resonant circuit 101. The excitation circuit 102 controls the conduction and disconnection of the DC path of the resonant circuit 101, causing the resonant circuit 101 to resonate and output a resonant signal. This resonant signal carries information about the temperature change of the cookware. The sampling circuit 103 then samples the resonant signal to obtain a characteristic signal, which is then used by the processing circuit 104 to determine the cookware temperature based on the characteristic signal. In this way, compared to traditional methods of measuring the temperature of cookware using thermal sensors, the temperature measurement circuit 100 provided in this embodiment can measure the cookware temperature promptly and accurately.

[0049] In one embodiment, the sampling circuit 103 includes a first resistor (not shown), the excitation circuit 102 is connected to the first end of the first resistor, and the processing circuit 104 is connected to the second end of the first resistor, for sampling the resonant voltage amplitude. In practice, the first resistor is connected in series with the resonant circuit 101, thereby acting as a voltage divider. Because the change in voltage across the first resistor is the same as the change in the resonant voltage, the resonant voltage amplitude can be sampled using the first resistor.

[0050] In another specific embodiment, the sampling circuit 103 further includes a sampling coil (not shown), and the resonant circuit 101 is configured corresponding to the sampling coil for collecting the resonant period width or the resonant frequency.

[0051] Optionally, the processing circuit 104 may be a CPU (Central Processing Unit), which may be an integrated circuit chip with signal processing capabilities. The processing circuit 104 may also be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. The general-purpose processor may be a microprocessor or any conventional processor.

[0052] In one specific embodiment, the manufacturer conducts multiple tests to develop a table of correspondences between cookware temperature and changes in resonant frequency, or between cookware temperature and changes in resonant period width, or between cookware temperature and changes in resonant voltage amplitude. During the actual heating process, the manufacturer then determines the cookware temperature based on the table and the changes in resonant period width, resonant voltage amplitude, or resonant frequency obtained by the resonance of the temperature measurement circuit.

[0053] See Figure 3 , Figure 3 This is a schematic diagram of the structure of the second embodiment of the temperature measurement circuit provided by this application. Figure 3 As shown, the temperature measurement circuit 100 provided in this embodiment includes a resonant circuit 101 , an excitation circuit 102 , a sampling circuit 103 , a processing circuit 104 and a control circuit 105 .

[0054] The excitation circuit 102 is connected to the resonant circuit 101 , the control circuit 105 and the sampling circuit 103 respectively, and the sampling circuit 103 is connected to the processing circuit 104 .

[0055] A DC signal is input to resonant circuit 101 to provide power. Excitation circuit 102 controls the on / off switching of the DC path in resonant circuit 101, causing it to output a resonant signal that varies with the cookware temperature. Specifically, resonant circuit 101 resonates with the cookware, generating a resonant signal that varies with the cookware temperature.

[0056] The sampling circuit 103 samples the output resonance signal to obtain a characteristic signal. The processing circuit 104 is used to determine the temperature change of the cookware based on the characteristic signal.

[0057] The control circuit 105 is used to output a periodic PPG (Programme Pulse Generator) control signal to control the on / off of the excitation circuit 102 .

[0058] The temperature measurement circuit 100 provided in this embodiment inputs a DC signal to the resonant circuit 101 to power it, and uses the control circuit 105 to output a periodic PPG control signal to control the on / off switching of the excitation circuit 102, thereby controlling the on / off switching of the DC path of the resonant circuit 101, so that the resonant circuit 101 generates a resonant signal. The sampling circuit 103 then samples the resonant signal to obtain a characteristic signal, and finally uses the processing circuit 104 to determine the temperature change of the cookware based on the characteristic signal. In this way, compared with the traditional method of measuring the temperature of the cookware using a thermistor component, the temperature measurement method provided by the temperature measurement circuit 100 of this solution can timely and accurately measure the temperature of the cookware.

[0059] See Figure 4 , Figure 4 FIG. 1 is a schematic diagram of the circuit structure of the third embodiment of the temperature measurement circuit provided in this embodiment. Figure 4 As shown, in the temperature measurement circuit 100 provided in this embodiment, the resonant circuit 101 includes a resonant capacitor C1 and a resonant coil L1 connected in parallel with the resonant capacitor C1. A DC signal DC is input to one end of the resonant coil L1 to provide power. A cookware pan is placed above the resonant coil L1 so that when the resonant circuit 101 resonates, it couples with the cookware pan and generates a resonant signal that changes with the temperature of the cookware pan. The cookware pan is inductively coupled to the resonant coil L1, and the resonant coil L1 and the resonant capacitor C1 resonate. When the temperature of the cookware pan changes, the coupling inductance changes, thereby affecting the resonant period width, resonant voltage amplitude, or resonant frequency of the resonant signal.

[0060] Optionally, the temperature measurement circuit 100 includes a second diode D2, wherein an AC signal AC is input to the anode of the second diode D2, and the resonant circuit 101 is connected to the cathode of the second diode D2, for rectifying the AC signal AC to provide a required DC signal DC for the resonant circuit 101. It is understood that any other feasible rectification circuit can be used to rectify the AC signal AC according to actual application scenarios, and this is not specifically limited here.

[0061] The excitation circuit 102 includes a first power transistor Q1. A first pulse modulation signal PWM1 is input to the gate G of the first power transistor Q1. The other end of the resonant coil L1 and the sampling circuit 103 are connected to the source C of the first power transistor Q1. The drain E of the first power transistor Q1 is grounded. The first power transistor Q1 is configured to be turned on or off based on the first pulse modulation signal PWM1, thereby turning on or off the DC path of the resonant circuit 101.

[0062] Optionally, the period of the first pulse modulation signal PWM1 is set to be fixed.

[0063] Optionally, the sampling circuit 103 includes a first resistor R1, a source electrode C of the first power transistor Q1 is connected to a first end of the first resistor R1, and the processing circuit 104 is connected to a second end of the first resistor R1. The first resistor R1 is used to collect the resonant voltage amplitude. Optionally, the sampling circuit 103 may further include a first diode D1, a second resistor R2, and a first capacitor C2. The first end of the first resistor R1 is connected to the source electrode C of the first power transistor Q1 via the first diode D1.

[0064] Specifically, the source electrode C of the first power transistor Q1 is connected to the anode of the first diode D1, the first end of the first resistor R1 is connected to the cathode of the first diode D1, the second end of the first resistor R1 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is grounded. The first end of the second resistor R2 is connected to the first end of the first capacitor C2, and the second end of the second resistor R2 is connected to the second end of the first capacitor C2.

[0065] The first capacitor C2 is a filter capacitor for filtering the resonant signal, and the first resistor R1 and the second resistor R2 are voltage-dividing resistors for dividing the resonant voltage signal output by the resonant circuit 101 .

[0066] Since the first resistor R1 and the second resistor R2 are connected in series to the resonant circuit 101, when the resonant circuit 101 resonates and generates a resonant voltage signal, the first resistor R1 and the second resistor R2 can act as a voltage divider, that is, the change in the voltage across the first resistor R1 and the second resistor R2 is synchronized with the voltage change of the resonant voltage signal. Therefore, the change in the voltage amplitude across the first resistor R1 or the second resistor R2 can reflect the change in the resonant voltage amplitude of the resonant voltage signal.

[0067] Optionally, the first power transistor Q1 may be an IGBT field effect transistor with a damping diode. The period of the first pulse modulation signal PWM1 is set to be fixed.

[0068] This embodiment provides a temperature measurement circuit 100 designed based on a single-tube resonant circuit. Only one power tube is needed to make the resonant circuit 101 resonate and output a resonant signal, thereby making the control circuit of the temperature measurement circuit 100 simpler, saving materials and reducing costs.

[0069] See Figure 5 , Figure 5 FIG. 1 is a circuit diagram of a fourth embodiment of the temperature measurement circuit provided in this embodiment. Figure 5 As shown, the resonant circuit 101 includes a resonant capacitor C1 and a resonant coil L1 connected in series with the resonant capacitor C1. A cookware pan is placed above the resonant coil L1, so that when the resonant circuit 101 resonates, it couples with the cookware pan and generates a resonant signal that changes with the temperature of the cookware pan.

[0070] The excitation circuit 102 includes a third power tube Q3 and a second power tube Q2.

[0071] The second pulse modulation signal PWM2 is input to the gate G of the second power tube Q2, and the direct current signal DC is input to the source C of the second power tube Q2. The third pulse modulation signal PWM3 is input to the gate G of the third power tube Q3, and the source C of the third power tube Q3 is connected to the drain E of the second power tube Q2 and one end of the resonant coil L1, respectively. The drain E of the third power tube Q3 is grounded.

[0072] Among them, the third power tube Q3 and the second power tube Q2 output the required DC signal DC to the resonant circuit 101 under the control of the third pulse modulation signal PWM3 and the second pulse modulation signal PWM2, respectively, so that the resonant circuit 101 resonates and generates a resonant signal, which carries the temperature change of the cookware Pan.

[0073] In this embodiment, the second pulse modulation signal PWM2 and the third pulse modulation signal PWM3 are in antiphase. That is, when the second pulse modulation signal PWM2 is low, the third pulse modulation signal PWM3 is high. Conversely, when the second pulse modulation signal PWM2 is high, the third pulse modulation signal PWM3 is low. This approach ensures that the third power transistor Q3 and the second power transistor Q2 cannot be turned on simultaneously, thereby preventing current feedthrough caused by simultaneous conduction.

[0074] The third power tube Q3 and the second power tube Q2 may be IGBT field effect tubes with damping diodes.

[0075] Optionally, the periods of the third pulse modulation signal PWM3 and the second pulse modulation signal PWM2 are fixed.

[0076] Optionally, the temperature measurement circuit 100 includes a second diode D2, wherein the AC signal AC is input to the anode of the second diode D2, and the excitation circuit 102 is connected to the cathode of the second diode D2 to rectify the AC signal AC to input a DC signal DC that meets the requirements to the excitation circuit 102. It is understood that any other feasible rectifier circuit can be used to rectify the AC signal AC according to actual application scenarios, and this is not specifically limited here.

[0077] Optionally, the sampling circuit 103 includes a first resistor R1, the other end of the resonant coil L1 is connected to the first end of the first resistor R1, and the processing circuit 104 is connected to the second end of the first resistor R1. The first resistor R1 is used to collect the resonant voltage amplitude. Optionally, the sampling circuit 103 may further include a first diode D1, a second resistor R2, and a first capacitor C2. The first end of the first resistor R1 is connected to the other end of the resonant coil L1 via the first diode D1.

[0078] Specifically, the other end of the resonant coil L1 is connected to the anode of the first diode D1, the first end of the first resistor R1 is connected to the cathode of the first diode D1, the second end of the first resistor R1 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is grounded. The first end of the second resistor R2 is connected to the first end of the first capacitor C2, and the second end of the second resistor R2 is connected to the second end of the first capacitor C2.

[0079] The first capacitor C2 is a filter capacitor for filtering the resonant signal, and the first resistor R1 and the second resistor R2 are voltage-dividing resistors for dividing the resonant voltage signal output by the resonant circuit 101 .

[0080] This embodiment provides a temperature measurement circuit 100 designed based on a half-bridge resonant circuit, so that the temperature measurement circuit 100 has good temperature measurement performance and high temperature measurement efficiency.

[0081] Optionally, in the temperature measurement circuit 100 provided in the above two embodiments, the sampling circuit 103 may further include a sampling coil L2, with the resonant coil L1 provided corresponding to the sampling coil L2, for collecting the resonant cycle width or resonant frequency. Specifically, the sampling coil L2 and the resonant coil L1 are mutually coupled to collect the resonant cycle width or resonant frequency.

[0082] In a specific application scenario, please refer to Figure 6 and Figure 7 , Figure 6 This is a structural diagram of an embodiment of the arrangement of the sampling coil and the resonant coil of the present application. Figure 7Schematic diagram of the circuit structure of an embodiment of the arrangement of the sampling coil and the resonant coil of the present application. In this embodiment, the sampling coil L2 is arranged at the center of the resonant coil L1 to collect the resonant signal.

[0083] Please refer to Figure 8 and Figure 9 , Figure 8 This is a structural diagram of another embodiment of the arrangement of the sampling coil and the resonant coil of the present application. Figure 9 The circuit structure diagram of another embodiment of the arrangement of the sampling coil and the resonant coil of the present application is shown in FIG. The sampling coil L2 of this embodiment is a current transformer, which is sleeved on the lead wire of the resonant coil L1 to collect the resonant signal.

[0084] In addition to the above two configurations, the sampling coil L2 may be configured relative to the resonant coil L1 in other ways, which are not limited here.

[0085] See also Figure 10 , Figure 10 This is a schematic block diagram of the structure of an embodiment of the cooking device of the present application. Figure 10 As shown, the cooking device 110 of this embodiment includes a temperature measuring circuit 100, which is the temperature measuring circuit provided by any of the above embodiments.

[0086] In some embodiments, cooking device 110 utilizes electromagnetic induction heating, such as an induction cooker or an IH rice cooker. This eliminates the need for open flames or conductive heating, generating heat directly at the bottom of the pot, significantly improving thermal efficiency. An induction cooker is an electrical cooking appliance that utilizes the principle of electromagnetic induction heating. It consists of a high-frequency induction heating coil, a high-frequency power conversion device, a controller, and a ferromagnetic pot base.

[0087] An induction cooker is mainly composed of two parts: one is the electronic circuit system that can generate a high-frequency alternating magnetic field (including the induction cooker coil disk, that is, the heating coil mentioned above); the other is the structural shell used to fix the electronic circuit system and carry the cookware (including the stove panel that can withstand high temperature and sudden changes in temperature).

[0088] See Figure 11 , Figure 11 FIG. 1 is a flow chart of an embodiment of a method for measuring the temperature of a cookware provided in this embodiment. Figure 11 As shown, the pot temperature measurement method provided in this embodiment is implemented using the temperature measurement circuit provided in any of the above embodiments, wherein a DC signal is provided to the temperature measurement circuit during temperature measurement. Specifically, the pot temperature measurement method may include the following steps:

[0089] S201: Inputting a pulse modulation signal to the temperature measuring circuit to stimulate the temperature measuring circuit to resonate and output a resonant signal that changes with the temperature of the cookware.

[0090] In this embodiment, if the temperature measurement circuit is the temperature measurement circuit provided in the third embodiment, the temperature measurement circuit utilizes single-transistor resonance to generate a resonant signal. That is, the temperature measurement circuit includes a single power transistor. Therefore, in this case, the control circuit can directly provide a pulse modulation signal to the power transistor to operate the temperature measurement circuit, thereby cooperating with the cookware to output a resonant signal.

[0091] If the temperature measurement circuit is the temperature measurement circuit provided in the fourth embodiment, it utilizes half-bridge resonance to generate a resonant signal. This means the temperature measurement circuit includes at least two power transistors. Therefore, in this case, the control circuit needs to provide at least two pulse modulation signals to the temperature measurement circuit to drive the two power transistors, respectively, thereby cooperating with the cookware to output a resonant signal. The two pulse modulation signals are in antiphase.

[0092] Optionally, the period of the pulse modulation signal provided by the temperature measurement circuit is set to be fixed.

[0093] As for the specific characteristics of the pulse modulation signal provided, such as duty cycle, period or frequency, etc., they can be set according to the specific application scenario and are not specifically limited here.

[0094] S202: Acquire a characteristic signal of the resonance signal.

[0095] In this embodiment, the characteristic signal of the resonance signal may include a change value of a resonance period, a change value of a resonance frequency, or a change value of a resonance voltage amplitude of the resonance signal.

[0096] S203: Determine the temperature of the cookware according to the characteristic signal.

[0097] In this embodiment, the manufacturer, through multiple tests, obtains a table of correspondences between the cookware temperature and changes in resonant frequency, or between the cookware temperature and changes in resonant period width, or between the cookware temperature and changes in resonant voltage amplitude. During the actual heating process, the cookware temperature is then determined based on the table and the changes in resonant period width, resonant voltage amplitude, or resonant frequency obtained by the resonance of the temperature measurement circuit.

[0098] The cookware temperature measurement method provided in this embodiment includes inputting a pulse modulated signal into a temperature measurement circuit to stimulate resonance in the temperature measurement circuit and output a resonant signal that varies with the cookware temperature. A characteristic signal of the resonant signal is obtained, and the cookware temperature is determined based on the characteristic signal. In this way, the cookware temperature can be determined quickly, accurately, and efficiently.

[0099] In summary, the temperature measurement circuit provided in this application inputs a DC signal to power a resonant circuit and, through an excitation circuit, controls the on / off switching of the resonant circuit's DC path, causing the resonant circuit to generate a resonant signal containing information about the cookware's temperature changes. A sampling circuit then samples the resonant signal to generate a characteristic signal, which is then processed by a processing circuit to determine the cookware's temperature based on the characteristic signal. This method, compared to traditional methods of measuring cookware temperature using a thermistor component, allows for timely and accurate measurement of the cookware's temperature using the temperature measurement circuit provided in this solution.

[0100] The above description is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

[0101] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules or units described above is merely a logical functional division. In actual implementation, other division methods may be used, such as combining or integrating multiple units or components into another system, or ignoring or not implementing certain features.

Claims

1. A temperature measurement circuit, characterized in that: The temperature measuring circuit is used to detect the temperature of the cookware when the cookware is heated. The temperature measuring circuit includes: a resonant circuit, the resonant circuit inputting a DC signal; an excitation circuit, connected to the resonant circuit, and configured to control the on / off of a DC path of the resonant circuit so as to cause the resonant circuit to generate a resonant signal; a sampling circuit connected to the excitation circuit, configured to sample the resonance signal to obtain a characteristic signal; wherein the characteristic signal includes at least one of a resonance voltage amplitude, a resonance frequency, and a resonance period width; a processing circuit, connected to the sampling circuit, and configured to determine the temperature of the cookware according to the characteristic signal; Wherein, the sampling circuit includes: a first resistor, wherein a second end of the first resistor is connected to the processing circuit and is used to collect the resonant voltage amplitude; a first diode, wherein an anode of the first diode is connected to the excitation circuit, and a cathode of the first diode is connected to a first end of the first resistor; a second resistor, wherein a first end of the second resistor is connected to the second end of the first resistor, and a second end of the second resistor is grounded; A first capacitor, wherein a first end of the first capacitor is connected to a first end of the second resistor, and a second end of the first capacitor is connected to a second end of the second resistor.

2. The temperature measurement circuit according to claim 1, characterized in that: The sampling circuit comprises: A sampling coil is provided corresponding to the resonant circuit and is used to collect the resonant frequency or the resonant period width.

3. The temperature measurement circuit according to claim 1, characterized in that: The resonant circuit includes a resonant coil and a resonant capacitor connected in parallel with the resonant coil, and the DC signal is input to one end of the resonant coil; The excitation circuit includes: a first power tube, wherein a gate of the first power tube inputs a first pulse modulation signal, a source of the first power tube is connected to the other end of the resonant coil and the sampling circuit, and a drain of the first power tube is grounded; The first power tube is configured to be turned on or off according to the first pulse modulation signal, thereby turning on or off the DC path of the resonant circuit.

4. The temperature measurement circuit according to claim 3, characterized in that: The period of the first pulse modulation signal is fixed.

5. The temperature measurement circuit according to claim 1, characterized in that: The resonant circuit includes a resonant coil and a resonant capacitor connected in series with the resonant coil; The excitation circuit includes: a second power tube, wherein a gate of the second power tube inputs a second pulse modulation signal, and a source of the second power tube inputs a DC signal; a third power tube, wherein a gate of the third power tube inputs a third pulse modulation signal, a source of the third power tube is respectively connected to a drain of the second power tube and the resonant coil, and a drain of the third power tube is grounded; Wherein, the second power tube and the third power tube respectively output the DC signal to the resonant circuit under the control of the second pulse modulation signal and the third pulse modulation signal, so that the resonant circuit resonates and generates the resonant signal; The second pulse modulation signal and the third pulse modulation signal are in anti-phase.

6. The temperature measurement circuit according to claim 5, characterized in that: The periods of the second pulse modulation signal and the third pulse modulation signal are fixed.

7. The temperature measurement circuit according to claim 1, characterized in that: The temperature measurement circuit comprises: A second diode, wherein the anode of the second diode inputs an AC signal, and the cathode of the second diode is connected to the resonant circuit, and is used to rectify the AC signal to input the DC signal to the resonant circuit.

8. A cooking device, characterized in that: The cooking device includes a temperature measuring circuit, and the temperature measuring circuit is the temperature measuring circuit according to any one of claims 1 to 7.

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