Electromagnetic induction heating circuit and control method thereof, and electromagnetic heating device

Abstract

The present application relates to an electromagnetic induction heating circuit and a control method thereof, and an electromagnetic heating device. A first-class resonant heating component and a second-class resonant heating component are provided at the same time, and more than two heating coils are provided in the second-class resonant heating component at the same time. The coupling between each heating coil and the first-class resonant heating component is not exactly the same, and the first-class switching device is used to adjust the heating power of the first-class resonant heating component. When the first-class resonant heating component is heated at a power lower than a preset power threshold, the controller controls the heating coil in the second-class resonant heating component that has a small coupling with the first-class resonant heating component to access the circuit. Due to the presence of the heating coil, the reverse voltage and current value of the first-class switching device are maintained at a relatively large value, which ultimately ensures that the first-class resonant heating component is heated at a power lower than the preset power threshold, thereby achieving low-power continuous heating.

Description

Technical Field

[0001] The present application relates to the field of magnetic induction technology, and in particular to an electromagnetic induction heating circuit and a control method thereof, and an electromagnetic heating device. Background Art

[0002] IH (Induction Heat) heating is a method of heating the object to be heated in the appliance by using electromagnetic induction. With the rapid development of science and technology, this heating method has been applied to rice cookers and other equipment. Due to its advantages of fast heating, strong firepower, more power saving and good heat convection, this type of home appliance is deeply loved by users.

[0003] In rice cookers and other devices that use IH heating, IGBT (Insulated Gate Bipolar Transistor) is generally used to control the resonance of the LC parallel circuit to generate eddy current for heating. This circuit topology and components determine that the heating power cannot be too low. Therefore, it is difficult for traditional IH heating to achieve low-power continuous heating. Summary of the invention

[0004] Based on this, it is necessary to provide an electromagnetic induction heating circuit and a control method thereof, and an electromagnetic heating device to address the problem that traditional IH heating devices are difficult to heat continuously at low power.

[0005] An electromagnetic induction heating circuit comprises: a first type of resonant heating component; a second type of resonant heating component, which is provided with more than two heating coils, and the coupling between each heating coil and the first type of resonant heating component is not completely the same; a first type of switching device, which is connected to the first type of resonant heating component and forms a heating branch with the first type of resonant heating component and is connected to a power supply; a controller, the second type of resonant heating component and the first type of switching device are respectively connected to the controller, and the controller is used to control the heating coil of the second type of resonant heating component to connect a heating coil with a smaller coupling with the first type of resonant heating component for heating when it is determined that the first type of resonant heating component is operating at a power less than a preset power threshold, so as to achieve low-power continuous heating.

[0006] In one embodiment, the electromagnetic induction heating circuit further comprises a second type of switching device, wherein the second type of switching device is connected to the second type of resonant heating component, and forms another heating branch with the second type of resonant heating component connected to a power supply, and the second type of switching device is connected to the controller.

[0007] In one embodiment, the first type of resonant heating component includes a first resonant capacitor and a first heating coil, the first type of switching device includes a first switching device, the first end of the first resonant capacitor is connected to the first end of the first heating coil and the common end is connected to the first end of the first switching device, the second end of the first switching device is connected to a power supply and the second type of switching device, the control end of the first switching device is connected to the controller, the second end of the first resonant capacitor is connected to the second end of the first heating coil and the common end is connected to the power supply and the second type of resonant heating component.

[0008] In one embodiment, the first type resonant heating component also includes a first switching device, the second end of the first heating coil is connected to the first end of the first switching device, the second end of the first switching device is connected to the second end of the first resonant capacitor, and the control end of the first switching device is connected to the controller.

[0009] In one embodiment, the second type of resonant heating component includes a second resonant capacitor, a gating device and more than two heating coils, the second type of switching device includes a second switching device, the first end of each heating coil and the first end of the second resonant capacitor are connected to each other, and the common end is connected to the first end of the second switching device, the second end of the second switching device is connected to the first type of switching device and the power supply, the control end of the second switching device is connected to the controller, the second end of each heating coil is respectively connected to the gating device, the gating device is connected to the second end of the second resonant capacitor and the first type of resonant heating component, and the gating device is connected to the controller.

[0010] In one embodiment, the second type of resonant heating component includes more than two heating coils, the same number of switching devices as the heating coils, and the same number of resonant capacitors as the heating coils. The second type of switching devices includes the same number of switching devices as the heating coils, the first end of any heating coil is correspondingly connected to the first end of a resonant capacitor, the first end of each resonant capacitor is correspondingly connected to the first end of a switching device, the second end of each switching device is respectively connected to the first type of switching device and a power supply, the control end of each switching device is respectively connected to the controller, the second end of any heating coil is respectively connected to the first end of a switching device, the second end of each switching device and the second end of each resonant capacitor are connected to each other, and the common end is connected to the first type of resonant heating component and a power supply, and the control end of each switching device is respectively connected to the controller.

[0011] In one embodiment, the number of the heating coils is two.

[0012] In one embodiment, the electromagnetic induction heating circuit also includes a rectifier device, wherein the first end of the rectifier device and the second end of the rectifier device are respectively connected to a power source, the third end of the rectifier device is connected to the first type of resonant heating component and the second type of resonant heating component, and the fourth end of the rectifier device is connected to the first type of switching device and the second type of switching device.

[0013] In one embodiment, the electromagnetic induction heating circuit also includes a first filter circuit and a second filter circuit, the first end of the rectifier device is connected to the first end of the first filter circuit, the second end of the rectifier device is connected to the second end of the first filter circuit, the third end of the first filter circuit and the fourth end of the first filter circuit are respectively connected to a power supply, the first end of the second filter circuit is connected to the third end of the rectifier device, the second end of the second filter circuit is connected to the fourth end of the rectifier device, the third end of the second filter circuit is connected to the first type of resonant heating component and the second type of resonant heating component, and the fourth end of the second filter circuit is connected to the first type of switching device and the second type of switching device.

[0014] In one embodiment, the electromagnetic induction heating circuit also includes a fuse and a varistor, the third end of the first filter circuit is connected to the first end of the fuse and the first end of the varistor, the second end of the fuse is connected to the live wire of the power supply, and the second end of the varistor is connected to the fourth end of the first filter circuit and the neutral wire of the power supply.

[0015] A control method for the electromagnetic induction heating circuit as described above comprises: obtaining the power of the first type of resonant heating component; determining whether the power is less than a preset power threshold; when the power is less than the preset power threshold, controlling the heating coil of the second type of resonant heating component to connect a heating coil with a smaller coupling with the first type of resonant heating component for heating, so as to achieve low-power continuous heating.

[0016] In one embodiment, after determining whether the power is less than a preset power threshold, it also includes: when the power is greater than or equal to the preset power threshold, controlling the heating coil of the second type of resonant heating component to connect the heating coil with a large coupling with the first type of resonant heating component for heating, so as to achieve high-power continuous heating.

[0017] In one embodiment, the controlling of the heating coil of the second type of resonant heating component to connect a heating coil with a smaller coupling to the first type of resonant heating component for heating comprises: controlling a selecting device of the second type of resonant heating component to select the heating coil of the second type of resonant heating component to connect a heating coil with a smaller coupling to the first type of resonant heating component for heating.

[0018] In one embodiment, the control of connecting a heating coil of the second type of resonant heating component that has a smaller coupling with the first type of resonant heating component for heating comprises: controlling the switching device corresponding to the heating coil of the second type of resonant heating component that has a smaller coupling with the first type of resonant heating component to be turned on.

[0019] In one embodiment, before the step of controlling the heating coil of the second type of resonant heating component, which has a smaller coupling with the first type of resonant heating component, to connect for heating to achieve low-power continuous heating when the power is less than the preset power threshold, it also includes: obtaining the coupling size between each heating coil in the second type of resonant heating component and the first type of resonant heating component.

[0020] An electromagnetic heating device comprises the electromagnetic induction heating circuit described above, wherein the controller is used to perform heating control according to the method described above.

[0021] In one embodiment, the electromagnetic heater is an electric rice cooker.

[0022] The above-mentioned electromagnetic induction heating circuit and its control method, and electromagnetic heating equipment are provided with a first-class resonant heating component and a second-class resonant heating component at the same time, and more than two heating coils are provided in the second-class resonant heating component at the same time, and the coupling of each heating coil with the first-class resonant heating component is not exactly the same, and the first-class switching device is used to adjust the heating power of the first-class resonant heating component. Through this setting method, multiple parts can be controlled to be heated at the same time, realizing multi-stage heating control; and when the first-class resonant heating component is heated at a power lower than the preset power threshold, the controller will control the heating coil in the second-class resonant heating component with a small coupling with the first-class resonant heating component to be connected to the circuit. Due to the presence of the heating coil, the reverse voltage and current value of the first-class switching device are maintained at a relatively large value, which ultimately ensures that the first-class resonant heating component is heated at a power lower than the preset power threshold, realizing low-power continuous heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a schematic diagram of the structure of an electromagnetic induction heating circuit in an embodiment;

[0025] Figure 2This is a schematic diagram of the structure of an electromagnetic induction heating circuit in another embodiment;

[0026] Figure 3 This is a schematic diagram of the structure of an electromagnetic induction heating circuit in another embodiment;

[0027] Figure 4 This is a schematic diagram of the structure of an electromagnetic induction heating circuit in yet another embodiment;

[0028] Figure 5 This is a schematic diagram of the structure of an electromagnetic induction heating circuit in another embodiment;

[0029] Figure 6 This is a schematic diagram of the structure of an electromagnetic induction heating circuit in another embodiment;

[0030] Figure 7 This is a schematic diagram of the structure of an electromagnetic induction heating circuit in yet another embodiment;

[0031] Figure 8 This is a schematic diagram of the structure of an electromagnetic induction heating circuit in another embodiment;

[0032] Fig. 9 This is a schematic diagram of the structure of an electromagnetic induction heating circuit in another embodiment;

[0033] Fig.10 This is a flow chart of a control method for an electromagnetic induction heating circuit in one embodiment;

[0034] Fig.11 FIG. 4 is a flow chart of a control method of an electromagnetic induction heating circuit in another embodiment. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0036] See also Figure 1, an electromagnetic induction heating circuit, comprising: a first-class resonant heating component 10; a second-class resonant heating component 20, provided with more than two heating coils, and the coupling between each heating coil and the first-class resonant heating component 10 is not completely the same; a first-class switching device 30, connected to the first-class resonant heating component 10, and forming a heating branch with the first-class resonant heating component 10 and connected to a power supply; a controller (not shown), the second-class resonant heating component 20 and the first-class switching device 30 are respectively connected to the controller, and the controller is used to determine when the first-class resonant heating component 10 is running at a power less than a preset power threshold, and control the heating coil of the second-class resonant heating component 20, and the heating coil with a smaller coupling with the first-class resonant heating component 10 is connected for heating, so as to achieve low-power continuous heating.

[0037] Specifically, the resonant heating component is a component that can store energy when powered on, and generates alternating current through resonance when powered off, thereby generating a changing magnetic field according to Faraday's law of electromagnetic induction. The magnetic field acts on utensils such as pots and pans that hold items to be heated, generating eddy currents to heat the items to be heated. The first type of switch device 30 is used to adjust the power of the first type of resonant heating component 10. By controlling the on time and off time of the first type of switch device 30, the first type of switch device 30 performs heating operations at different powers.

[0038] In the solution of this embodiment, when the first type resonant heating component 10 operates at a power lower than the preset power threshold, the controller controls the heating coil in the second type resonant heating component 20 that is coupled with the first type resonant heating component 10 to be connected for heating. Due to the existence of the heating coil, the reverse voltage and current value of the first type switching device 30 are kept at a relatively large value, thereby maintaining low-power heating. This solution reduces the impact on the power grid and the impact on other electrical equipment, and can be implemented by using devices with lower withstand voltage, thereby effectively reducing costs.

[0039] In one embodiment, a preset power threshold is used to distinguish whether the first type of resonant heating component 10 operates at low power or high power. When the heating power of the first type of resonant heating component 10 is greater than the preset power threshold, it is considered to be operating at high power. When the heating power of the first type of resonant heating component 10 is less than the preset power threshold, it is considered to be operating at low power.

[0040] It should be noted that the size of the preset power threshold value can be set differently in different types of devices. For example, in one embodiment, when the above-mentioned electromagnetic induction heating circuit is applied to an electric rice cooker, the preset power threshold value can be set to 800W, that is, when the operating power of the first type of resonant heating component 10 is greater than 800W, the electric rice cooker is considered to be heated at high power, and when the operating power of the first type of resonant heating component 10 is less than 800W, the electric rice cooker is considered to be heated at low power.

[0041] Correspondingly, in another embodiment, when the operating power of the first type resonant heating component 10 is greater than the preset power threshold, that is, when the first type resonant heating component 10 is operating at high power, the controller can control the second type resonant heating component 20 to connect the heating coil that is coupled with the first type resonant heating component 10 to achieve high power continuous heating. In this case, the reverse voltage and current of the first type switching device 30 can be kept at a relatively small value, the stress borne by the first type switching device 30 is small, and the loss is relatively small, so the first type resonant heating component 10 can be controlled to be in a continuous high power heating state.

[0042] Furthermore, in one embodiment, when the first type of resonant heating component 10 is operated at a power less than a preset power threshold, the heating coil with a small coupling with the first type of resonant heating component 10 in the second type of resonant heating component 20 is controlled to be connected, and the heating coil with a small coupling is relative to the coupling of each coil in the second type of resonant heating component 20 with respect to the first type of resonant heating component 10. In order to achieve low-power continuous heating, the coupling of all heating coils with the first type of resonant heating component 10 is analyzed, and the heating coil with a relatively small coupling is selected for connection. The specific heating coil can be selected according to the actual use scenario, as long as it is not the heating coil with the largest coupling.

[0043] In one embodiment, the smaller the coupling between the selected heating coil and the first type of resonant heating component 10, the better. For example, in a more detailed embodiment, the heating coil with the smallest coupling with the first type of resonant heating component 10 among all the heating coils of the second type of resonant heating component 20 can be directly selected for connection to achieve low-power continuous heating control; the heating coil with the largest coupling with the first type of resonant heating component 10 can be directly selected for connection to achieve high-power continuous heating control.

[0044] It can be understood that when the first type of switching device 30 is connected to the first type of resonant heating component 10 and forms a heating branch with the first type of resonant heating component 10 and is connected to a power supply, the first type of resonant heating component 10 can be connected to the power supply and the first type of switching device 30 can be grounded to form a closed loop; the first type of resonant heating component 10 can be grounded and the first type of switching device 30 can be connected to the power supply to form a closed loop; the first type of resonant heating component 10 can also be connected to the positive end (or negative end) of the power supply and the first type of switching device 30 can be connected to the negative end (or positive end) of the power supply to form a closed loop. The specific connection method can be selected according to the specific form of the power supply and the first type of switching device 30. Figure 1 As shown, the first type of resonant heating component 10 and the first type of switching device 30 are respectively connected to the two ends of the power supply.

[0045] See also Figure 2In one embodiment, the electromagnetic induction heating circuit further includes a second type of switching device 40, which is connected to the second type of resonant heating component 20, and forms another heating branch with the second type of resonant heating component 20 and connected to the power supply, and the second type of switching device 40 is connected to a controller (not shown).

[0046] Specifically, the second type of switch device 40 is used to adjust the power of the second type of resonant heating component 20. According to the different structures of the second type of resonant heating component 20, the specific type of the second type of switch device 40 is not unique. Since when the first type of resonant heating component 10 is operated at a power less than the preset power threshold, only one heating coil in the second type of resonant heating component 20 that is less coupled with the first type of resonant heating component 10 is connected to the circuit, in one embodiment, only one switch device may be provided to control the power of the heating coil, and in the second type of resonant heating component 20, one of the heating coils may be connected to the circuit by gating. In another embodiment, the second type of switch device 40 may include more than two switch devices, and one switch device may be provided for each heating coil in the second type of resonant heating component 20 to perform corresponding power control.

[0047] It can be understood that when the second-type switching device 40 is connected to the second-type resonant heating component 20 and forms another heating branch with the second-type resonant heating component 20 and is connected to the power supply, the second-type resonant heating component 20 can be connected to the power supply and the second-type switching device 40 can be grounded to form a closed loop; the second-type resonant heating component 20 can be grounded and the second-type switching device 40 can be connected to the power supply to form a closed loop; the second-type resonant heating component 20 can also be connected to the positive end (or negative end) of the power supply and the second-type switching device 40 can be connected to the negative end (or positive end) of the power supply to form a closed loop. The specific connection method can be selected according to the specific form of the power supply and the second-type switching device 40. Figure 2 As shown, the second type of resonant heating component 20 and the second type of switching device 40 are respectively connected to the two ends of the power supply.

[0048] See also Figure 3 In one embodiment, the first type of resonant heating component 10 includes a first resonant capacitor C1 and a first heating coil L1, the first type of switching device 30 includes a first switching device, the first end of the first resonant capacitor C1 is connected to the first end of the first heating coil L1 and the common end is connected to the first end of the first switching device, the second end of the first switching device is connected to the power supply and the second type of switching device 40, the control end of the first switching device is connected to the controller (not shown), the second end of the first resonant capacitor C1 is connected to the second end of the first heating coil L1 and the common end is connected to the power supply and the second type of resonant heating component 20.

[0049] Specifically, the specific type of the first type of resonant heating component 10 is not unique. In this embodiment, the first type of resonant heating component 10 adopts a structural form with only one first heating coil L1, and correspondingly only one first switch device is needed to realize the power regulation of the first heating coil L1. At this time, the first heating coil L1 is connected in parallel with the first resonant capacitor C1, and the two are connected in parallel to the first switch device. When the first switch device is turned on, the power flows in through the first switch device to store energy for the first heating coil L1; when the first switch device is turned off, the first heating coil L1 resonates with the first resonant capacitor C1 to generate a changing current, and based on Faraday's law of electromagnetic induction, a changing magnetic field is generated, which acts on utensils such as pots and pans for holding hot items on standby, generating eddy currents, thereby realizing the heating operation.

[0050] Further, in one embodiment, please refer to Figure 4 The first type resonant heating component 10 also includes a first switch device K1, the second end of the first heating coil L1 is connected to the first end of the first switch device K1, the second end of the first switch device K1 is connected to the second end of the first resonant capacitor C1, and the control end of the first switch device K1 is connected to a controller (not shown).

[0051] Specifically, in the solution of this embodiment, a first switch device K1 is provided at the second end of the first heating coil L1, and the first switch device K1 is used to control whether the first heating coil L1 is connected to the circuit for heating. Through this solution, when the first heating coil L1 is not needed for heating operation, the first heating coil L1 can be disconnected by the first switch device K1, which can effectively improve the working reliability of the electromagnetic induction heating circuit. At the same time, due to the existence of the first switch device K1, the safety performance of the first type of resonant heating component 10 can also be improved. After the first switch device K1 controls the first heating coil L1 to be disconnected, only the heating coil of the second type of resonant heating component 20 is connected for heating. At this time, different heating power adjustments can be achieved by controlling the number of heating coils of the second type of resonant heating component 20 connected to the electromagnetic induction heating circuit. Through this solution, only one heating coil can be connected for heating, thereby achieving lower power heating control.

[0052] It should be noted that the specific type of the first switch device K1 is not unique, and it can be a power switch tube or other types of devices with switching functions such as relays, as long as they can be turned on or off under different control signals of the controller.

[0053] Please refer to Figure 3 or Figure 4In one embodiment, the second type resonant heating component 20 includes a second resonant capacitor C2, a gating device K and more than two heating coils L, the second type switching device 40 includes a second switching device, the first end of each heating coil L and the first end of the second resonant capacitor C2 are connected to each other, and the common end is connected to the first end of the second switching device, the second end of the second switching device is connected to the first type switching device 30 and the power supply, the control end of the second switching device is connected to the controller (not shown), the second end of each heating coil L is respectively connected to the gating device K, the gating device K is connected to the second end of the second resonant capacitor C2 and the first type resonant heating component 10, and the gating device K is connected to the controller.

[0054] Specifically, the specific structure of the second type of resonant heating component 20 is not unique, as long as it can connect the corresponding heating coil L to perform multi-stage heating under the control of the controller according to the working state of the first type of resonant heating component 10. The scheme of this embodiment adopts a gating device K to select the heating coil L to connect to the circuit. At this time, different heating coils L share a resonant capacitor C, that is, the second resonant capacitor C2, and share a second type of switching device 40, that is, the second switching device. After the controller controls the corresponding heating coil to connect to the circuit through the gating device K according to the working state of the first type of resonant heating component 10, the heating coil L and the second resonant capacitor C2 are heated under the control of the second switching device. Through this scheme, the number of second switching devices and resonant capacitors C can be effectively reduced, thereby effectively reducing the circuit volume and reducing the circuit cost.

[0055] Figure 3 In the illustrated embodiment, the first type resonant heating assembly 10 is not provided with the first switch device K1, and the heating operation of the first heating coil L1 is realized only by the control of the first switch device. Figure 4 In the illustrated embodiment, the first type of resonant heating component 10 is provided with a first switching device K1, and the first heating coil L1 is controlled by the first switching device K1 and the first switching device to realize the heating operation. In both cases, the second type of resonant heating component 20 can be heated by sharing the resonant capacitor C and the second type of switching device 40.

[0056] It can be understood that in the scheme of gating the heating coils by the gating device K of the second type resonant heating component 20, the number of heating coils is not unique, as long as the coupling between each heating coil and the first type resonant heating component 10 (specifically, the first heating coil L1 in the first type resonant heating component 10) is not completely the same. For example, in a more detailed embodiment, the number of heating coils is two.

[0057] Specifically, in this embodiment, two heating coils are connected to the gating device K, and the coupling sizes of these two heating coils with the first type of resonant heating component 10 are different. The controller controls the gating device K to achieve access control of the two heating coils. When the first type of resonant heating component 10 is running at low power, the heating coil with smaller coupling is selected to be connected to achieve low-power continuous heating; and when the first type of resonant heating component 10 is running at high power, the heating coil with larger coupling is selected to be connected to achieve high-power continuous heating control. For other numbers of heating coils, the method of controlling low-power continuous heating is similar to that of high-power continuous heating, as long as the coupling between the heating coil connected during low-power heating and the first type of resonant heating component 10 is less than the coupling between the heating coil connected during high-power heating and the first type of resonant heating component 10.

[0058] See also Figure 5 In one embodiment, the second type of resonant heating component 20 includes more than two heating coils L, the same number of switch devices K2 as the heating coils L, and the same number of resonant capacitors C as the heating coils L. The second type of switch device 40 includes the same number of switch devices 41 as the heating coils L. The first end of any heating coil L is correspondingly connected to the first end of a resonant capacitor C, the first end of each resonant capacitor C is correspondingly connected to the first end of a switch device 41, the second end of each switch device 41 is respectively connected to the first type of switch device 30 and the power supply, the control end of each switch device 41 is respectively connected to the controller (not shown), the second end of any heating coil L is respectively connected to the first end of a switch device K2, the second end of each switch device K2 and the second end of each resonant capacitor C are connected to each other, and the common end is connected to the first type of resonant heating component 10 and the power supply, and the control end of each switch device K2 is respectively connected to the controller.

[0059] Specifically, the two or more heating coils L in the second type of resonant heating component 20 may also be in a form without sharing the resonant capacitor C. In this case, each heating coil L is connected in parallel with a corresponding resonant capacitor C, and each heating coil L realizes corresponding heating power control through a switching device 41. At the same time, each heating coil L is also separately provided with a switching device K2 to control whether the heating coil L is connected to the electromagnetic induction heating circuit. Figure 5 In the illustrated embodiment, the first type of resonant heating component 10 is a resonant heating component of the type in which the first heating coil L1 is accessed and controlled by a first switching device K1. It is to be understood that in other embodiments, the first type of resonant heating component 10 may also be a resonant heating component in which the first heating coil L1 is directly connected to the second end of the first resonant capacitor C1 and a power supply.

[0060] It is understandable that the specific type of the switch device K2 is not unique, as long as it can control whether the corresponding heating coil L is connected to the circuit according to the control signal of the controller. For example, in one embodiment, the switch device K2 is similar to the first switch device K1 and can be implemented by a power switch tube or a relay.

[0061] In the scheme of this embodiment, the access of each heating component needs to be achieved by turning on a corresponding switch device K2, and each heating component corresponds to a resonant capacitor C. When performing multi-stage heating, more accurate heating control can be achieved, and at least one heating component can be selected in the second resonant heating component to access the electromagnetic induction heating circuit according to actual needs, thereby effectively improving the working reliability of the electromagnetic induction heating circuit.

[0062] Similarly, in the solution where each heating coil L in the second type resonant heating component 20 corresponds to a resonant capacitor C, the number of heating coils L is not unique, as long as the coupling between each heating coil L and the first type resonant heating component 10 (specifically, the first heating coil L1 in the first type resonant heating component 10) is not completely the same. For example, in a more detailed embodiment, the number of heating coils L is two.

[0063] In this embodiment, two heating coils L are respectively connected to a switch device K2, and the coupling sizes of the two heating coils L and the first type resonant heating component 10 are different. The controller controls the on and off of the switch device K2 to achieve access control of the two heating coils L. When the first type resonant heating component 10 is running at low power, the switch device K2 corresponding to the heating coil L with smaller coupling is selected to be turned on to achieve low-power continuous heating; and when the first type resonant heating component 10 is running at high power, the switch device K2 corresponding to the heating coil L with larger coupling is selected to be turned on to achieve high-power continuous heating control.

[0064] It should be noted that the specific types of the above-mentioned switch device 41, the first switch device and the second switch device are not unique, as long as they can be controlled by on and off so that the corresponding heating coil is heated at different powers. For example, in one embodiment, the switch device 41, the first switch device and the second switch device all use power switch tubes. Further, in a more detailed embodiment, the switch device 41, the first switch device and the second switch device all use IGBT (Insulated Gate Bipolar Transistor).

[0065] See also Figure 6In one embodiment, the electromagnetic induction heating circuit further includes a rectifier device 50, a first end of the rectifier device 50 and a second end of the rectifier device 50 are respectively connected to a power source, a third end of the rectifier device 50 is connected to the first type of resonant heating component 10 and the second type of resonant heating component 20, and a fourth end of the rectifier device 50 is connected to the first type of switching device 30 and the second type of switching device 40.

[0066] Specifically, the rectifier device 50 is a device that converts the connected AC power supply into a DC power supply for power supply. Through the rectifier device 50, the AC power input at the first end of the rectifier device 50 and the second end of the rectifier device 50 can be converted into a DC power supply, so that the electromagnetic induction heating circuit is applied in AC power supply scenarios, such as various household appliances. It can be understood that the specific type of the rectifier device 50 is not unique, as long as it can convert the connected AC power supply into DC power for heating. For example, in one embodiment, the rectifier device 50 can specifically adopt a bridge rectifier device 50.

[0067] For further information, see Figure 7 In one embodiment, the electromagnetic induction heating circuit further includes a first filter circuit 60 and a second filter circuit 70, a first end of the rectifier device 50 is connected to a first end of the first filter circuit 60, a second end of the rectifier device 50 is connected to a second end of the first filter circuit 60, a third end of the first filter circuit 60 and a fourth end of the first filter circuit 60 are respectively connected to a power source, a first end of the second filter circuit 70 is connected to a third end of the rectifier device 50, a second end of the second filter circuit 70 is connected to a fourth end of the rectifier device 50, a third end of the second filter circuit 70 is connected to the first type resonant heating component 10 and the second type resonant heating component 20, and a fourth end of the second filter circuit 70 is connected to the first type switching device 30 and the second type switching device 40.

[0068] Specifically, in the scheme of this embodiment, filter circuits are provided on both sides of the rectifier device 50. Through the first filter circuit 60, the interference components in the AC power supply can be filtered out, and then the AC power supply is transmitted to the sorting device for rectification operation. At the same time, a second filter circuit 70 is also provided on the output side of the rectifier device 50 to ensure that there are no interference components in the DC power output from the rectifier device 50 to the heating coil. Through the design of the first filter circuit 60 and the second filter circuit 70, the working reliability of the electromagnetic induction heating circuit can be effectively improved. It should be pointed out that the specific forms of the first filter circuit 60 and the second filter circuit 70 are not unique. In one embodiment, the first filter circuit 60 is an EMC filter circuit, that is, an electromagnetic compatibility filter circuit, and the second filter circuit 70 can be implemented by an RC filter circuit or the like.

[0069] For further information, see Figure 8In one embodiment, the electromagnetic induction heating circuit also includes a fuse F and a varistor Z, the third end of the first filter circuit 60 is connected to the first end of the fuse F and the first end of the varistor Z, the second end of the fuse F is connected to the live wire of the power supply, and the second end of the varistor Z is connected to the fourth end of the first filter circuit 60 and the neutral wire of the power supply.

[0070] Specifically, the fuse F is a current fuse, which mainly plays an overload protection role. When the current abnormally rises to a certain height and temperature, the fuse F itself melts and cuts off the current, protecting the safe operation of the circuit. The varistor Z is a resistor device with nonlinear volt-ampere characteristics, which is mainly used to clamp the voltage when the circuit is subjected to overvoltage, absorbing excess current to protect sensitive devices. Through the design of the fuse F and the varistor Z, the safety performance of the electromagnetic induction heating circuit can be effectively improved.

[0071] The electromagnetic induction heating circuit is provided with a first-class resonant heating component 10 and a second-class resonant heating component 20 at the same time, and more than two heating coils are provided in the second-class resonant heating component 20 at the same time, and the coupling of each heating coil with the first-class resonant heating component 10 is not completely the same, and the first-class switch device 30 is used to adjust the heating power of the first-class resonant heating component 10. Through this setting mode, multiple parts can be controlled to be heated at the same time, and multi-stage heating control can be realized; and when the first-class resonant heating component 10 is heated at a power lower than the preset power threshold, the controller will control the heating coil in the second-class resonant heating component 20 that is less coupled with the first-class resonant heating component 10 to be connected to the circuit. Due to the existence of the heating coil, the reverse voltage and current value of the first-class switch device 30 are maintained at a relatively large value, and finally ensure that the first-class resonant heating component 10 is heated at a power lower than the preset power threshold, so as to realize low-power continuous heating.

[0072] See also Fig.10 , a control method of the electromagnetic induction heating circuit as above comprises step S100, step S200 and step S300.

[0073] Step S100, obtaining the power of the first type of resonant heating component. Step S200, determining whether the power is less than a preset power threshold. Step S300, when the power is less than the preset power threshold, controlling the heating coil of the second type of resonant heating component, and connecting the heating coil with a small coupling with the first type of resonant heating component to heat, so as to achieve low-power continuous heating.

[0074] The structure of the electromagnetic induction heating circuit is as shown in the above embodiments and the accompanying drawings. Specifically, the structure of the electromagnetic induction heating circuit is as shown in the above embodiments and the accompanying drawings. The resonant heating component is a component that can store energy when powered on, and generates an alternating current through resonance when powered off. According to Faraday's law of electromagnetic induction, a changing magnetic field is generated. The magnetic field acts on utensils such as pots and pans for holding items to be heated, generating eddy currents to achieve heating of the items to be heated. The first type of switch device 30 is used to adjust the power of the first type of resonant heating component 10. By controlling the on time and off time of the first type of switch device 30, the first type of switch device 30 performs heating operations at different powers.

[0075] When the first type resonant heating component 10 is running at a power lower than the preset power threshold, the controller controls the heating coil in the second type resonant heating component 20 that is coupled with the first type resonant heating component 10 to be connected for heating. Due to the existence of the heating coil, the reverse voltage and current value of the first type switching device 30 are kept at a relatively large value, thereby maintaining low-power heating. This solution reduces the impact on the power grid and the impact on other electrical equipment, and can also be implemented by using devices with lower withstand voltage, thereby effectively reducing costs.

[0076] It is understandable that the way in which the controller obtains the power of the first type of resonant heating component 10 is not unique. In one embodiment, the controller can directly obtain the corresponding power according to the control instruction issued by the user in combination with the actual use scenario of the electromagnetic induction heating circuit. For example, in one embodiment, when the electromagnetic induction heating circuit is used in an electric rice cooker, the controller can obtain the power of the current electromagnetic induction heating circuit according to the operating mode selection instruction sent by the user to the electric rice cooker. After obtaining the power of the first type of resonant heating component 10, the controller can directly compare and analyze it with the preset power threshold.

[0077] It should be noted that the size of the preset power threshold value can be set differently in different types of devices. For example, in one embodiment, when the above-mentioned electromagnetic induction heating circuit is applied to an electric rice cooker, the preset power threshold value can be set to 800W, that is, when the operating power of the first type of resonant heating component 10 is greater than 800W, the electric rice cooker is considered to be heated at high power, and when the operating power of the first type of resonant heating component 10 is less than 800W, the electric rice cooker is considered to be heated at low power.

[0078] See also Fig.11 In one embodiment, after step S200, step S400 is also included.

[0079] Step S400, when the power is greater than or equal to the preset power threshold, the heating coil of the second type resonant heating component is controlled to be connected with the heating coil with the largest coupling with the first type resonant heating component for heating, so as to achieve high power continuous heating.

[0080] Specifically, when the operating power of the first type resonant heating component 10 is greater than the preset power threshold, that is, when the first type resonant heating component 10 is operating at high power, the controller can control the second type resonant heating component 20 to connect the heating coil that is coupled with the first type resonant heating component 10 to achieve high-power continuous heating. In this case, the reverse voltage and current of the first type switching device 30 can be kept at a relatively small value, the stress borne by the first type switching device 30 is small, and the loss is relatively small, so the first type resonant heating component 10 can be controlled to be in a continuous high-power heating state.

[0081] In one embodiment, the heating coil of the second type of resonant heating component is controlled to be connected to the heating coil with a smaller coupling with the first type of resonant heating component for heating, including: controlling the selection device of the second type of resonant heating component to select the heating coil of the second type of resonant heating component, and connecting the heating coil with a smaller coupling with the first type of resonant heating component for heating.

[0082] Specifically, in the scheme of this embodiment, the second type of resonant heating component 20 includes a second resonant capacitor C2, a gating device K and more than two heating coils L, the second type of switching device 40 includes a second switching device, the first end of each heating coil L and the first end of the second resonant capacitor C2 are connected to each other, and the common end is connected to the first end of the second switching device, the second end of the second switching device is connected to the first type of switching device 30 and the power supply, the control end of the second switching device is connected to the controller (not shown), the second end of each heating coil L is respectively connected to the gating device K, the gating device K is connected to the second end of the second resonant capacitor C2 and the first type of resonant heating component 10, and the gating device K is connected to the controller.

[0083] The gating device K is used to select the heating coil L to access the circuit. At this time, different heating coils L share a resonant capacitor C, that is, the second resonant capacitor C2, and share a second type of switch device 40, that is, the second switch device. According to the working state of the first type resonant heating component 10, the controller controls the corresponding heating coil to access the circuit through the gating device K, and then the heating coil L and the second resonant capacitor C2 are heated under the control of the second switch device. Through this solution, the number of second switch devices and resonant capacitors C can be effectively reduced, thereby effectively reducing the circuit volume and reducing the circuit cost.

[0084] In one embodiment, the heating coil of the second type of resonant heating component is controlled to be connected to the heating coil with a smaller coupling with the first type of resonant heating component for heating, including: controlling the switching device corresponding to the heating coil of the second type of resonant heating component with a smaller coupling with the first type of resonant heating component to be turned on.

[0085] Specifically, in the scheme of this embodiment, the second type of resonant heating component 20 includes more than two heating coils L, the same number of switch devices K2 as the heating coils L, and the same number of resonant capacitors C as the heating coils L. The second type of switch devices 40 includes the same number of switch devices 41 as the heating coils L. The first end of any heating coil L is correspondingly connected to the first end of a resonant capacitor C, the first end of each resonant capacitor C is correspondingly connected to the first end of a switch device 41, the second end of each switch device 41 is respectively connected to the first type of switch device 30 and the power supply, the control end of each switch device 41 is respectively connected to the controller (not shown in the figure), the second end of any heating coil L is respectively connected to the first end of a switch device K2, the second end of each switch device K2 and the second end of each resonant capacitor C are connected to each other, and the common end is connected to the first type of resonant heating component 10 and the power supply, and the control end of each switch device K2 is respectively connected to the controller.

[0086] The two or more heating coils L in the second type of resonant heating component 20 may also be in a form without sharing the resonant capacitor C. In this case, each heating coil L is connected in parallel with a corresponding resonant capacitor C, and each heating coil L implements corresponding heating power control through a switching device 41. At the same time, each heating coil L is also individually provided with a switching device K2 to control whether the heating coil L is connected to the electromagnetic induction heating circuit. Figure 5 In the illustrated embodiment, the first type of resonant heating component 10 is a resonant heating component of the type in which the first heating coil L1 is accessed and controlled by a first switching device K1. It is to be understood that in other embodiments, the first type of resonant heating component 10 may also be a resonant heating component in which the first heating coil L1 is directly connected to the second end of the first resonant capacitor C1 and a power supply.

[0087] Furthermore, in one embodiment, the controller is also used to adjust the power of the first type resonant heating component 10 by controlling the duty cycle of the first type switching device 30; and / or the controller is also used to adjust the power of the second type resonant heating component 20 by controlling the duty cycle of the second type switching device 40. That is, the controller controls the on-time and off-time of the first type switching device 30 so that the first type resonant heating component 10 works at a corresponding power, and controls the on-time and off-time of the second type switching device 40 so that the second type resonant heating component 20 works at a corresponding power.

[0088] It should be noted that, in one embodiment, before step S300, the method further includes: obtaining the coupling degree between each heating coil in the second type of resonant heating component and the first type of resonant heating component.

[0089] Specifically, in the scheme of this embodiment, before analyzing the type of heating coil L that needs to be connected to the second type of resonant heating component 20 in combination with the power of the first type of resonant heating component 10, the controller will first obtain the coupling size of each heating coil L in the second type of resonant heating component 20 with the first type of resonant heating component 10, that is, the coupling of each heating coil L with the first heating coil L1, so that the controller can realize the selection operation of the heating coil L in combination with the power of the first type of resonant heating component 10.

[0090] It can be understood that in the scheme of this embodiment, the coupling size can specifically refer to the coupling value between each heating coil L and the first type of resonant heating component 10; it can also be the coupling size relationship between each heating coil L and the first type of resonant heating component 10, that is, there is no need to know the specific value of the coupling between the heating coil L and the first type of resonant heating component 10, but only need to know which heating coils L among the heating coils L are coupled with the first type of resonant heating component 10 in descending order.

[0091] The method for obtaining the coupling size between each heating coil L in the second type resonant heating component and the first type resonant heating component 10 is not unique. In one embodiment, since the relative position of each heating coil L in the second type resonant heating component 20 has been set when the electromagnetic heating device using the above-mentioned electromagnetic induction heating circuit leaves the factory, when other conditions are basically the same, the coupling size relationship between each heating coil L and the first type resonant heating component 10 is basically determined. At this time, it can be set in the controller in a preset manner, and the coupling size relationship between each heating coil L and the first type resonant heating component 10 can be directly called when performing heating control. In other embodiments, the controller obtains the relative position of each heating coil L and the first type resonant heating component 10, the magnetic medium information around each heating coil L, and other related quantities for analysis to obtain the coupling size relationship between each heating coil L and the first type resonant heating component 10, or obtains the coupling value of each heating coil L and the first type resonant heating component 10.

[0092] It should be pointed out that the relationship between the step of obtaining the coupling size between each heating coil in the second type of resonant heating component and the first type of resonant heating component and step S100 and step S200 is not unique. It can be performed before step S100, between step S100 and step S200, or after step S200, as long as it is implemented before the access selection of the heating coil L according to heating in step S300 or step S400.

[0093] The control method of the electromagnetic induction heating circuit is provided with a first-class resonant heating component 10 and a second-class resonant heating component 20 at the same time, and more than two heating coils are provided in the second-class resonant heating component 20 at the same time, and the coupling of each heating coil with the first-class resonant heating component 10 is not completely the same, and the first-class switch device 30 is used to adjust the heating power of the first-class resonant heating component 10. Through this setting method, multiple parts can be controlled to be heated at the same time to achieve multi-stage heating control; and when the first-class resonant heating component 10 is heated at a power lower than the preset power threshold, the controller will control the heating coil in the second-class resonant heating component 20 that is less coupled with the first-class resonant heating component 10 to be connected to the circuit. Due to the presence of the heating coil, the reverse voltage and current value of the first-class switch device 30 are maintained at a relatively large value, and finally ensure that the first-class resonant heating component 10 is heated at a power lower than the preset power threshold, so as to achieve low-power continuous heating.

[0094] An electromagnetic heating device comprises the electromagnetic induction heating circuit mentioned above, and a controller is used to perform heating control according to the method mentioned above.

[0095] Specifically, the resonant heating component is a component that can store energy when powered on, and generates alternating current through resonance when powered off, thereby generating a changing magnetic field according to Faraday's law of electromagnetic induction. The magnetic field acts on utensils such as pots and pans that hold items to be heated, generating eddy currents to achieve heating of the items to be heated. The first type of switch device 30 is used to adjust the power of the first type of resonant heating component 10. By controlling the on time and off time of the first type of switch device 30, the first type of switch device 30 performs heating operations at different powers; and the second type of switch device 40 is used to adjust the power of the second type of resonant heating component 20. According to the different structures of the second type of resonant heating component 20, the specific type of the second type of switch device 40 is not unique.

[0096] Since when the first type resonant heating component 10 is operated at a power lower than the preset power threshold, only one heating coil in the second type resonant heating component 20 that is smaller in coupling with the first type resonant heating component 10 is connected to the circuit, in one embodiment, only one second type switch device 40 may be provided for power control, and in the second type resonant heating component 20, one of the heating coils may be connected to the circuit in the form of gating. In another embodiment, the second type switch device 40 may include more than two switch devices, and one switch device may be provided for each heating coil in the second type resonant heating component 20 for corresponding power control.

[0097] In the solution of this embodiment, when the first type resonant heating component 10 operates at a power lower than the preset power threshold, the controller controls the second type resonant heating component 20 to connect a heating coil that is smaller and coupled to the first type resonant heating component 10. Due to the existence of the heating coil, the reverse voltage and current value of the first type switching device 30 are kept at a relatively large value, thereby maintaining low-power heating. This solution reduces the impact on the power grid and the impact on other electrical equipment, and can be implemented by using devices with lower withstand voltage, thereby effectively reducing costs.

[0098] It should be noted that the specific type of electromagnetic heating device is not unique, as long as it is a device that is heated by electromagnetic induction. For example, in one embodiment, it can be an electromagnetic heating type household appliance. Further, the electromagnetic heating type household appliance is an electric rice cooker.

[0099] Specifically, by setting the electromagnetic induction heating circuit in the electric rice cooker, the electric rice cooker can realize a multi-stage heating function, thereby ensuring that the cooked rice is more uniform and has a better taste. In addition, since low-power continuous heating can be realized, the effect of slow cooking can also be achieved, and when the user cooks porridge, it is not easy to overflow, which effectively improves the cooking reliability of the electric rice cooker.

[0100] It should be noted that the arrangement of the heating coils in each resonant heating assembly in the rice cooker is not unique. In a more detailed embodiment, please refer to Fig. 9 , the first type of resonant heating component 10 includes a first heating coil L1, the second type of resonant heating component 20 includes two heating coils, and the electromagnetic induction heating circuit also includes a rectifier device 50, a first filter circuit 60, a second filter circuit 70, a fuse F and a varistor Z for explanation.

[0101] At this time, the first heating coil L1 can be arranged at the bottom of the inner pot, one heating coil in the second type resonant heating assembly 20 can be arranged at the R corner of the inner pot, and the other heating coil in the second type resonant heating assembly 20 can be arranged at the top side of the inner pot. The coupling between the two heating coils and the first heating coil L1 is unequal, and only the one with the smaller coupling with the first heating coil L1 of the two heating coils in the second type resonant heating assembly 20 is connected at the same time, so as to realize the low-power continuous heating operation of the rice cooker according to the rectified and filtered direct current.

[0102] The electromagnetic heating device is provided with a first-class resonant heating component 10 and a second-class resonant heating component 20 at the same time, and more than two heating coils are provided in the second-class resonant heating component 20 at the same time, and the coupling of each heating coil with the first-class resonant heating component 10 is not completely the same, and the first-class switch device 30 is used to adjust the heating power of the first-class resonant heating component 10. Through this setting method, multiple parts can be controlled to be heated at the same time, and multi-stage heating control can be realized; and when the first-class resonant heating component 10 is heated at a power lower than the preset power threshold, the controller will control the heating coil in the second-class resonant heating component 20 that is less coupled with the first-class resonant heating component 10 to be connected to the circuit. Due to the existence of the heating coil, the reverse voltage and current value of the first-class switch device 30 are maintained at a relatively large value, and finally ensure that the first-class resonant heating component 10 is heated at a power lower than the preset power threshold, so as to realize low-power continuous heating.

[0103] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. An electromagnetic induction heating circuit, characterized in that: include: The first type of resonant heating assembly; The second type of resonant heating assembly is provided with more than two heating coils, and the coupling of each heating coil with the first type of resonant heating assembly is not completely the same; A first type of switch device, connected to the first type of resonant heating component, and forming a heating branch with the first type of resonant heating component and connected to a power supply; A controller, wherein the second type of resonant heating component and the first type of switching device are respectively connected to the controller, and the controller is used to control the heating coil of the second type of resonant heating component to connect the heating coil with a small coupling with the first type of resonant heating component for heating when it is determined that the first type of resonant heating component is operating at a power less than a preset power threshold, so as to achieve low-power continuous heating.

2. The electromagnetic induction heating circuit according to claim 1, characterized in that: It also includes a second type of switching device, which is connected to the second type of resonant heating component and forms another heating branch with the second type of resonant heating component and connected to a power supply. The second type of switching device is connected to the controller.

3. The electromagnetic induction heating circuit according to claim 2, characterized in that: The first type of resonant heating component includes a first resonant capacitor and a first heating coil, the first type of switching device includes a first switching device, the first end of the first resonant capacitor is connected to the first end of the first heating coil and the common end is connected to the first end of the first switching device, the second end of the first switching device is connected to a power supply and the second type of switching device, the control end of the first switching device is connected to the controller, the second end of the first resonant capacitor is connected to the second end of the first heating coil and the common end is connected to the power supply and the second type of resonant heating component.

4. The electromagnetic induction heating circuit according to claim 3, characterized in that: The first type resonant heating component also includes a first switching device, the second end of the first heating coil is connected to the first end of the first switching device, the second end of the first switching device is connected to the second end of the first resonant capacitor, and the control end of the first switching device is connected to the controller.

5. The electromagnetic induction heating circuit according to any one of claims 2 to 4, characterized in that: The second type of resonant heating component includes a second resonant capacitor, a gating device and more than two heating coils, the second type of switching device includes a second switching device, the first end of each heating coil and the first end of the second resonant capacitor are connected to each other, and the common end is connected to the first end of the second switching device, the second end of the second switching device is connected to the first type of switching device and the power supply, the control end of the second switching device is connected to the controller, the second end of each heating coil is respectively connected to the gating device, the gating device is connected to the second end of the second resonant capacitor and the first type of resonant heating component, and the gating device is connected to the controller.

6. The electromagnetic induction heating circuit according to claim 5, characterized in that: The number of the heating coils is two.

7. The electromagnetic induction heating circuit according to any one of claims 2 to 4, characterized in that: The second type of resonant heating assembly comprises more than two heating coils, the same number of switch devices as the heating coils, and the same number of resonant capacitors as the heating coils, and the second type of switch devices comprises the same number of switch devices as the heating coils; The first end of any one of the heating coils is correspondingly connected to the first end of a resonant capacitor, the first end of each of the resonant capacitors is correspondingly connected to the first end of a switching device, the second end of each of the switching devices is respectively connected to the first type of switching device and the power supply, the control end of each of the switching devices is respectively connected to the controller, the second end of any one of the heating coils is correspondingly connected to the first end of a switching device, the second end of each of the switching devices and the second end of each of the resonant capacitors are connected to each other, and the common end is connected to the first type of resonant heating component and the power supply, and the control end of each of the switching devices is respectively connected to the controller.

8. The electromagnetic induction heating circuit according to claim 7, characterized in that: The number of the heating coils is two.

9. The electromagnetic induction heating circuit according to any one of claims 2 to 4, characterized in that: It also includes a rectifier device, wherein the first end of the rectifier device and the second end of the rectifier device are respectively connected to a power source, the third end of the rectifier device is connected to the first type of resonant heating component and the second type of resonant heating component, and the fourth end of the rectifier device is connected to the first type of switching device and the second type of switching device.

10. The electromagnetic induction heating circuit according to claim 9, characterized in that: It also includes a first filter circuit and a second filter circuit, the first end of the rectifier device is connected to the first end of the first filter circuit, the second end of the rectifier device is connected to the second end of the first filter circuit, the third end of the first filter circuit and the fourth end of the first filter circuit are respectively connected to a power supply, the first end of the second filter circuit is connected to the third end of the rectifier device, the second end of the second filter circuit is connected to the fourth end of the rectifier device, the third end of the second filter circuit is connected to the first type of resonant heating component and the second type of resonant heating component, and the fourth end of the second filter circuit is connected to the first type of switching device and the second type of switching device.

11. The electromagnetic induction heating circuit according to claim 10, characterized in that: It also includes a fuse and a varistor, the third end of the first filter circuit is connected to the first end of the fuse and the first end of the varistor, the second end of the fuse is connected to the live wire of the power supply, and the second end of the varistor is connected to the fourth end of the first filter circuit and the neutral wire of the power supply.

12. A control method for an electromagnetic induction heating circuit according to any one of claims 1 to 11, characterized in that: include: Obtaining the power of the first type of resonant heating component; Determining whether the power is less than a preset power threshold; When the power is less than the preset power threshold, the heating coil of the second type of resonant heating component is controlled to connect the heating coil with a smaller coupling with the first type of resonant heating component for heating, so as to achieve low-power continuous heating.

13. The control method according to claim 12, characterized in that: After determining whether the power is less than a preset power threshold, the method further includes: When the power is greater than or equal to the preset power threshold, the heating coil of the second type of resonant heating component is controlled to connect the heating coil with the largest coupling with the first type of resonant heating component for heating, so as to achieve high-power continuous heating.

14. The control method according to claim 12, characterized in that: The controlling of the heating coil of the second type resonant heating component, wherein the heating coil with a smaller coupling with the first type resonant heating component is connected for heating, comprises: The gating device controlling the second type of resonant heating component switches on the heating coil of the second type of resonant heating component, and the heating coil with a smaller coupling with the first type of resonant heating component is connected for heating.

15. The control method according to claim 12, characterized in that: The controlling of the heating coil of the second type resonant heating component, wherein the heating coil with a smaller coupling with the first type resonant heating component is connected for heating, comprises: The switching device corresponding to the heating coil of the second-type resonant heating component that has a smaller coupling with the first-type resonant heating component is controlled to be turned on.

16. The control method according to claim 12, characterized in that: Before the step of controlling the heating coil of the second type resonant heating component to connect the heating coil with a smaller coupling with the first type resonant heating component for heating when the power is less than the preset power threshold, so as to achieve low-power continuous heating, the step further includes: The coupling degree between each heating coil in the second type of resonant heating component and the first type of resonant heating component is obtained.

17. An electromagnetic heating device, characterized in that: It comprises the electromagnetic induction heating circuit according to any one of claims 1-11, and the controller is used to perform heating control according to the method according to any one of claims 12-16.

18. The electromagnetic heating device according to claim 17, characterized in that: The electromagnetic heating device is an electric rice cooker.

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