A voltage division ratio adjustment circuit, a switch control circuit and a cooking appliance

Abstract

The present invention discloses a voltage-dividing ratio adjustment circuit, a switch control circuit and a cooking appliance, wherein the voltage-dividing ratio adjustment circuit comprises: an oscillation circuit, wherein the first end of the oscillation circuit is used to connect to a power supply, and the second end of the oscillation circuit is used to connect to a resonance end of an IGBT module; a first voltage detection end, connected to the first end of the oscillation circuit through a first resistor; a second voltage detection end, connected to the second end of the oscillation circuit through a second resistor; the voltage-dividing ratio adjustment circuit also comprises: a first adjustable resistor, one end of which is connected to the first voltage detection end and the other end is grounded; and / or a second adjustable resistor, one end of which is connected to the second voltage detection end and the other end is grounded. With such a configuration, when the mains voltage is low or high, the IGBT module can be normally turned on by adjusting the resistance value of the first adjustable resistor or the resistance value of the second adjustable resistor.

Description

Technical Field

[0001] The present invention relates to the field of electronic circuits, and in particular to a voltage division ratio adjustment circuit, a switch control circuit and a cooking appliance. Background Art

[0002] Existing common electromagnetic heating cooking appliances such as induction cookers and IH rice cookers generally use single-tube parallel resonant electromagnetic induction heating technology. In the single-tube parallel resonant electromagnetic induction heating technology, a synchronization circuit is required to compare and detect the voltage at the power supply end and the resonance end. When the voltage at the resonance end is zero, the power device IGBT is turned on.

[0003] At present, in order to make the product work in a wide voltage range, such as 80V~270V, the traditional single synchronous circuit is difficult to meet the requirements. Because at high voltage, the resonant end voltage has not reached zero, but the IGBT has been controlled to turn on, which will cause hard turn-on. The hard turn-on will bring serious power device loss and EMI problems, and will cause the power device temperature to rise too high, or even damage the power device; at low voltage, the resonant end voltage is still not turned on when it reaches zero, causing the power device IGBT to reverse conduct, which will generate excessive conduction loss, causing the power device IGBT temperature to rise too high, seriously affecting the service life of the IGBT. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problem in the prior art that the traditional single synchronous circuit is difficult to meet the requirements of working within a wide voltage range, thereby providing a voltage division ratio adjustment circuit, a switch control circuit and a cooking appliance.

[0005] To achieve the above-mentioned purpose, an embodiment of the present invention provides a voltage division ratio adjustment circuit, which includes: an oscillation circuit, a first end of the oscillation circuit is used to connect to a power supply, and a second end of the oscillation circuit is used to connect to a resonance end of an IGBT module; a first voltage detection end is connected to the first end of the oscillation circuit through a first resistor; a second voltage detection end is connected to the second end of the oscillation circuit through a second resistor;

[0006] The voltage division ratio adjustment circuit also includes: a first adjustable resistor, one end of which is connected to the first voltage detection end and the other end is grounded; and / or a second adjustable resistor, one end of which is connected to the second voltage detection end and the other end is grounded.

[0007] Optionally, the first adjustable resistor and the second adjustable resistor both include multiple resistor modules connected in parallel, and the resistor module includes a voltage divider resistor and a switch module; the control end of the switch module is used to receive a control signal, the first end of the switch module is grounded, and the second end of the switch module is connected to the first voltage detection end through the voltage divider resistor, or the second end of the switch module is connected to the second voltage detection end through the voltage divider resistor.

[0008] Optionally, the oscillation circuit includes a first inductor and a first capacitor; the first end of the first inductor is used to connect to the power supply, and the second end of the first inductor is connected to the first end of the IGBT module; one end of the first capacitor is connected to the first end of the first inductor, and the other end of the first capacitor is connected to the second end of the first inductor.

[0009] An embodiment of the present invention further provides a switch control circuit, which includes: the voltage division ratio adjustment circuit described in any one of the above embodiments.

[0010] Optionally, the switch control circuit also includes: a control module, a first input terminal of the control module is connected to the first voltage detection terminal, and a second input terminal of the control module is connected to the second voltage detection terminal; a first output terminal of the control module is connected to the control terminal of the IGBT module; the control module is also provided with multiple second output terminals, and the control module sends a control signal to the control terminal of the switch module in the multiple resistance modules through the second output terminal; the IGBT module, the other end of the IGBT module is grounded.

[0011] Optionally, the control module includes: a synchronization circuit module, a first input terminal of the synchronization circuit module is connected to the first voltage detection terminal, a second input terminal of the synchronization circuit module is connected to the second voltage detection terminal, and an output terminal of the synchronization circuit module is connected to an input terminal of a control chip; and a control chip, an output terminal of the control chip is connected to a control terminal of the IGBT module.

[0012] Optionally, the control module further includes: a driving circuit module, one end of which is connected to the output end of the control chip, and the other end of which is connected to the control end of the IGBT module.

[0013] Optionally, the switch control circuit further includes: a rectifier circuit module, a first end of the rectifier circuit module is used to connect to the power supply, and a second end of the rectifier circuit module is connected to the first end of the oscillation circuit.

[0014] Optionally, the switch control circuit further includes: a filter module, one end of the filter module is used to connect to the power supply, and the other end of the filter module is connected to the first end of the rectifier circuit module.

[0015] Optionally, the switch control circuit further includes: a second inductor, one end of which is connected to the second end of the rectifier circuit module, and the other end of which is connected to the first end of the oscillation circuit.

[0016] Optionally, the switch control circuit further includes: a second capacitor, one end of which is connected to the first end of the oscillation circuit, and the other end of which is grounded.

[0017] An embodiment of the present invention further provides a cooking appliance, which includes: a voltage division ratio adjustment circuit as described in any of the above embodiments, and / or a switch control circuit as described in any of the above embodiments.

[0018] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0019] 1. An embodiment of the present invention provides a voltage division ratio adjustment circuit, which includes: an oscillation circuit, a first end of the oscillation circuit is used to connect to a power supply, and a second end of the oscillation circuit is used to connect to a resonance end of an IGBT module; a first voltage detection end is connected to the first end of the oscillation circuit through a first resistor; a second voltage detection end is connected to the second end of the oscillation circuit through a second resistor; the voltage division ratio adjustment circuit also includes: a first adjustable resistor, one end of which is connected to the first voltage detection end, and the other end is grounded; and / or, a second adjustable resistor, one end of which is connected to the second voltage detection end, and the other end is grounded.

[0020] With such a configuration, when the mains voltage is low, since the voltage detected by the first voltage detection terminal is low, when the voltage detected by the second voltage detection terminal is less than or equal to the voltage detected by the first voltage detection terminal, the IGBT module is delayed in turning on. By increasing the resistance value of the first adjustable resistor or decreasing the resistance value of the second adjustable resistor, the voltage detected by the first voltage detection terminal can be increased or the voltage detected by the second voltage detection terminal can be decreased, so that the IGBT module is turned on normally. Similarly, when the mains voltage is high, the voltage detected by the first voltage detection terminal is high, causing the IGBT module to turn on early. By decreasing the resistance value of the first adjustable resistor or increasing the resistance value of the second adjustable resistor, the voltage detected by the first voltage detection terminal can be decreased or the voltage detected by the second voltage detection terminal can be increased, so that the IGBT module is turned on normally.

[0021] 2. An embodiment of the present invention provides a switch control circuit, which includes: a control module, a first input end of the control module is connected to the first voltage detection end, and a second input end of the control module is connected to the second voltage detection end; a first output end of the control module is connected to the control end of the IGBT module; the control module is also provided with multiple second output ends, and the control module sends a control signal to the control end of the switch module in the multiple resistance modules through the second output end.

[0022] With such a configuration, when the control module detects that the mains voltage is low through the first voltage detection terminal, the control module can increase the number of connected resistor modules by controlling one side of the first voltage detection terminal, thereby increasing the resistance value of the first adjustable resistor; or the control module can reduce the number of connected resistor modules by controlling one side of the second voltage detection terminal, thereby reducing the resistance value of the second adjustable resistor, so that the IGBT module is normally turned on. Prevent the IGBT module from being reversely turned on, thereby preventing the IGBT module from being lost, and improving the service life and reliability of the IGBT module. When the control module detects that the mains voltage is high through the first voltage detection terminal, the control module can reduce the number of connected resistor modules by controlling one side of the first voltage detection terminal, thereby reducing the resistance value of the first adjustable resistor; or the control module can increase the number of connected resistor modules by controlling one side of the second voltage detection terminal, thereby increasing the resistance value of the second adjustable resistor, so that the IGBT module is normally turned on. Prevent the IGBT module from being turned on prematurely, prevent the IGBT module from being lost, improve the service life and reliability of the IGBT module, and reduce the problem of electromagnetic interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A circuit diagram of the prior art;

[0025] Figure 2 A circuit diagram of a first implementation of a voltage division ratio adjustment circuit according to an embodiment of the present invention;

[0026] Figure 3 A circuit diagram of a second implementation of a voltage division ratio adjustment circuit according to an embodiment of the present invention;

[0027] Figure 4 4 is a circuit diagram of a switch control circuit according to an embodiment of the present invention.

[0028] Reference numerals:

[0029] A first voltage-dividing resistor R1, a second voltage-dividing resistor R2, a first resistor R3, and a second resistor R4;

[0030] A first transistor Q1, a second transistor Q2;

[0031] A first filter capacitor C1, a second filter capacitor C2, a first capacitor C3, and a second capacitor C4;

[0032] The first inductor L1 and the second inductor L2. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] like Figure 1As shown, the zero voltage turn-on of the single-tube parallel resonant electromagnetic induction heating circuit is to judge whether the C pole of the IGBT is in a zero voltage state by comparing the voltages at the power supply end and the resonant end. In actual operation, the voltages at the power supply end POWER and the resonant end are divided by a resistor in a certain proportion, and then the voltages detected at the SUPPLY end and the RESONANCE end are input into the comparator of the synchronization circuit for processing. The function of the comparator is to compare the magnitudes of the two voltages. Here, it is used to compare the two voltages at the SUPPLY end and the RESONANCE end. The SUPPLY end changes according to the mains voltage, and the RESONANCE end changes according to the resonant end. When the resonant voltage drops to a certain voltage point that is just smaller than the SUPPLY end, the comparator will flip. When the mains voltage is small, that is, the SUPPLY end voltage becomes smaller, the resonant end needs to drop to a smaller voltage before the comparator flips, so there is a delay. When the IGBT is turned on with delay, the resonant end voltage continues to drop before it is turned on, and when it is lower than zero, the IGBT will conduct in the reverse direction.

[0038] A single synchronization circuit is generally calibrated to achieve zero voltage switching at a mains voltage of 220VAC. However, in actual use, when the actual mains voltage is low, the SUPPLY terminal voltage is lower than the calibrated voltage. Because the comparator will only flip when the RESONANCE terminal ≤ the SUPPLY terminal voltage, the RESONANCE terminal voltage needs to be lower to trigger the flip. Therefore, the synchronization signal is delayed, which will cause the IGBT to turn on later, and there may be a situation where the IGBT is reversed, which will cause large IGBT losses and excessive IGBT temperature rise, thereby affecting the device life and reliability.

[0039] Similarly, when the actual mains voltage is high, the SUPPLY voltage is higher than the calibrated voltage, and the resonant and RESONANCE voltages are high. Therefore, before the RESONANCE voltage drops to the normal SUPPLY voltage, the RESONANCE voltage ≤ SUPPLY voltage has already occurred. Therefore, the comparator flips in advance, and the synchronization signal is generated in advance, resulting in an early IGBT turn-on time. When the IGBT is turned on in advance, the C-pole voltage of the IGBT has not dropped to the zero voltage state, so zero voltage turn-on cannot be achieved, and thus a hard turn-on occurs. The hard turn-on of the IGBT will directly lead to large IGBT losses, causing the IGBT temperature to rise too high, thereby affecting the device life and reliability, and also causing serious EMI problems.

[0040] Example 1

[0041] like Figure 2As shown, an embodiment of the present invention provides a voltage division ratio adjustment circuit, which includes: an oscillation circuit, a first voltage detection terminal SUPPLY, a second voltage detection terminal RESONANCE, and a first adjustable resistor and a second adjustable resistor.

[0042] The first end of the oscillation circuit is used to connect to the power supply, and the second end of the oscillation circuit is used to connect to the resonant end of the IGBT module. The first voltage detection terminal SUPPLY is connected to the first end of the oscillation circuit through the first resistor R3, and the first voltage detection terminal SUPPLY is used to detect the voltage shared by the first adjustable resistor. The second voltage detection terminal RESONANCE is connected to the second end of the oscillation circuit through the second resistor R4, and the second voltage detection terminal RESONANCE is used to detect the voltage shared by the second adjustable resistor. One end of the first adjustable resistor is connected to the first voltage detection terminal SUPPLY, and the other end is grounded, and one end of the second adjustable resistor is connected to the second voltage detection terminal RESONANCE, and the other end is grounded.

[0043] In actual operation, when the mains voltage is low, since the voltage detected by the first voltage detection terminal SUPPLY is low, the voltage detected by the first voltage detection terminal SUPPLY can be increased by increasing the resistance value of the first adjustable resistor, so that the calibrated voltage of the first voltage detection terminal SUPPLY is stabilized at the voltage level when the mains is in a normal state, so that the IGBT module is normally turned on. Alternatively, the resistance value of the second adjustable resistor can be reduced to directly reduce the voltage detected by the second voltage detection terminal RESONANCE, so that the voltage detected by the second voltage detection terminal RESONANCE matches the actual calibrated voltage of the first voltage detection terminal SUPPLY, and when the voltage detected by the second voltage detection terminal RESONANCE is less than or equal to the actual calibrated voltage of the first voltage detection terminal SUPPLY, the IGBT module can be turned on normally.

[0044] When the mains voltage is high, since the voltage detected by the first voltage detection terminal SUPPLY is high, by reducing the resistance value of the first adjustable resistor or increasing the resistance value of the second adjustable resistor, the voltage detected by the first voltage detection terminal SUPPLY can be reduced, so that the calibrated voltage of the first voltage detection terminal SUPPLY is stabilized at the voltage level when the mains is in a normal state, so that the IGBT module is normally turned on. Alternatively, the resistance value of the second adjustable resistor can be increased to directly increase the voltage detected by the second voltage detection terminal RESONANCE, so that the voltage detected by the second voltage detection terminal RESONANCE matches the actual calibrated voltage of the first voltage detection terminal SUPPLY, and when the voltage detected by the second voltage detection terminal RESONANCE is less than or equal to the actual calibrated voltage of the first voltage detection terminal SUPPLY, the IGBT module can be turned on normally.

[0045] Of course, those skilled in the art may set the first adjustable resistor only on one side of the first voltage detection terminal SUPPLY, or set the second adjustable resistor only on one side of the second voltage detection terminal RESONANCE, according to actual conditions, or, when setting the first adjustable resistor and the second adjustable resistor at the same time, the first adjustable resistor and the second adjustable resistor may be adjusted at the same time. This embodiment is only an example for illustration and is not limited thereto, and the same technical effect can be achieved.

[0046] Specifically, the first adjustable resistor includes a plurality of resistor modules connected in parallel, and the second adjustable resistor includes a plurality of resistor modules connected in parallel. The resistor module includes a voltage-dividing resistor and a switch module. The control end of the switch module is used to receive a control signal, and the first end of the switch module is grounded. In the resistor module of the first adjustable resistor, the second end of the switch module is connected to the first voltage detection end SUPPLY through the voltage-dividing resistor; in the resistor module of the second adjustable resistor, the second end of the switch module is connected to the second voltage detection end RESONANCE through the voltage-dividing resistor.

[0047] In actual operation, when the mains voltage is too high or too low, the number of resistor modules in the first adjustable resistor connected to the circuit can be adjusted according to actual needs. A control signal is sent to the control end of the switch module to turn it on and off, so that the resistor module can be controlled to be connected and disconnected from the circuit. Alternatively, the number of resistor modules in the second adjustable resistor connected to the circuit can also be adjusted.

[0048] like Figure 3 As shown, in an embodiment of the present invention, as a second implementation, a second adjustable resistor may be provided only on one side of the second voltage detection terminal RESONANCE, and the second adjustable resistor includes a first resistor module and a second resistor module. The first resistor module includes a first voltage-dividing resistor R1, a first transistor Q1, and a first filter capacitor C1, and the second resistor module includes a second voltage-dividing resistor R2, a second transistor Q2, and a second filter capacitor C2. One end of the second filter capacitor C2 is connected to the second voltage detection terminal RESONANCE, and the other end is grounded.

[0049] Specifically, the first transistor Q1 and the second transistor Q2 are controlled respectively by two control signals, so that the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 can be connected to the circuit for voltage division. The resistance values ​​of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 are different, so that when any one of the first transistor Q1 and the second transistor Q2 is turned on or turned on at the same time, the size of the resistance in the connected circuit has three states, and three different proportions of voltage division are achieved at the resonant end. The three different proportions under low voltage, normal voltage and high voltage are calibrated according to actual conditions, and different voltage division ratios are selected according to the actual mains voltage, so that the synchronization signal will not lag when the mains is at a low voltage, and the synchronization signal will not advance when the mains is at a high voltage, thereby ensuring that zero voltage can be turned on in the entire voltage range, and can effectively solve the temperature rise problem of power devices and electromagnetic interference problems.

[0050] In the embodiment of the present invention, the first voltage-dividing resistor R1, the second voltage-dividing resistor R2, the first resistor R3, and the second resistor R4 are equivalent parameters of multiple devices, not single resistor values. The detection voltage range of the SUPPLY terminal and the RESONANCE terminal is 0-5V.

[0051] like Figure 3 As shown, in the embodiment of the present invention, the oscillation circuit includes a first inductor L1 and a first capacitor C3, the first end of the first inductor L1 is used to connect to the power supply, and the second end of the first inductor L1 is connected to the first end of the IGBT module. One end of the first capacitor C3 is connected to the first end of the first inductor L1, and the other end of the first capacitor C3 is connected to the second end of the first inductor L1.

[0052] Example 2

[0053] like Figure 4 As shown, an embodiment of the present invention further provides a switch control circuit, which includes a control module, an IGBT module and the voltage division ratio adjustment circuit described in the above embodiment.

[0054] The first input end of the control module is connected to the first voltage detection end SUPPLY, the second input end of the control module is connected to the second voltage detection end RESONANCE, the first output end of the control module is connected to the control end of the IGBT module, and the control module is also provided with multiple second output ends. The control module sends a control signal to the switch module of the multiple resistance modules in the voltage division ratio adjustment circuit through the second output end; the other end of the IGBT module is grounded, that is, the E pole of the IGBT module is grounded.

[0055] With such a configuration, when the control module detects that the mains voltage is low through the first voltage detection terminal SUPPLY, the control module can increase the number of connected resistor modules by controlling one side of the first voltage detection terminal SUPPLY, thereby increasing the resistance value of the first adjustable resistor; or the control module can reduce the number of connected resistor modules by controlling one side of the second voltage detection terminal RESONANCE, thereby reducing the resistance value of the second adjustable resistor, so that the IGBT module is normally turned on. Prevent the IGBT module from being reversely turned on, thereby preventing the IGBT module from having a large loss, and improving the service life and reliability of the IGBT module. When the control module detects that the mains voltage is high through the first voltage detection terminal SUPPLY, the control module can reduce the number of connected resistor modules by controlling one side of the first voltage detection terminal SUPPLY, thereby reducing the resistance value of the first adjustable resistor; or the control module can increase the number of connected resistor modules by controlling one side of the second voltage detection terminal RESONANCE, thereby increasing the resistance value of the second adjustable resistor, so that the IGBT module is normally turned on. Prevent the IGBT module from being turned on prematurely, prevent the IGBT module from having a large loss, improve the service life and reliability of the IGBT module, and reduce the problem of electromagnetic interference.

[0056] In the embodiment of the present invention, the control module further includes: a synchronization circuit module and a control chip.

[0057] The first input end of the synchronization circuit module is connected to the first voltage detection end SUPPLY, the second input end of the synchronization circuit module is connected to the second voltage detection end RESONANCE, the output end of the synchronization circuit module is connected to the input end of the control chip; the output end of the control chip is connected to the control end of the IGBT module.

[0058] A comparator is provided in the synchronization circuit, the first input terminal of the comparator is connected to the first voltage detection terminal SUPPLY, the second input terminal of the comparator is connected to the second voltage detection terminal RESONANCE, and the output terminal of the comparator is connected to the input terminal of the control chip. The first voltage detection terminal SUPPLY is a port after the AC power is divided by a resistor. The AC power voltage is relatively high and needs to be divided before it can be connected to the comparator. The second voltage detection terminal RESONANCE is a port after the resonance terminal is divided by a resistor. The voltage of the IGBT-C pole is relatively high and needs to be divided before it can be connected to the comparator.

[0059] In an embodiment of the present invention, the control module further includes: a driving circuit module, one end of the driving circuit module is connected to the output end of the control chip, and the other end of the driving circuit module is connected to the control end of the IGBT module.

[0060] In the embodiment of the present invention, the switch control circuit further includes: a rectifier circuit module, a filter module, a first inductor L1 and a first capacitor C3.

[0061] The first end of the rectifier circuit module is used to connect the power supply, and the second end of the rectifier circuit module is connected to the first end of the oscillation circuit. One end of the filter module is used to connect the power supply, and the other end of the filter module is connected to the first end of the rectifier circuit module.

[0062] One end of the second inductor L2 is connected to the second end of the rectifier circuit module, and the other end is connected to the first end of the oscillation loop. One end of the second capacitor C4 is connected to the first end of the oscillation loop, and the other end is grounded.

[0063] Example 3

[0064] An embodiment of the present invention further provides a cooking appliance, which includes: a voltage division ratio adjustment circuit as described in any of the above embodiments, and / or a switch control circuit as described in any of the above embodiments.

[0065] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A voltage division ratio adjustment circuit, characterized in that: include: An oscillation circuit, wherein a first end of the oscillation circuit is used to connect to a power supply, and a second end of the oscillation circuit is used to connect to a resonance end of an IGBT module; A first voltage detection terminal connected to the first end of the oscillation circuit via a first resistor (R3); A second voltage detection terminal connected to the second end of the oscillation circuit via a second resistor (R4); Also includes: A first adjustable resistor, one end of which is connected to the first voltage detection end, and the other end of which is grounded; And / or, a second adjustable resistor, one end of which is connected to the second voltage detection end, and the other end of which is grounded.

2. The voltage division ratio adjustment circuit according to claim 1, characterized in that: The first adjustable resistor and the second adjustable resistor each include a plurality of resistor modules connected in parallel, and the resistor modules include a voltage dividing resistor and a switch module; The control end of the switch module is used to receive a control signal, the first end of the switch module is grounded, the second end of the switch module is connected to the first voltage detection end through the voltage divider resistor, or the second end of the switch module is connected to the second voltage detection end through the voltage divider resistor.

3. The voltage division ratio adjustment circuit according to claim 1 or 2, characterized in that: The oscillation circuit comprises a first inductor (L1) and a first capacitor (C3); The first end of the first inductor (L1) is used to connect to the power supply, and the second end of the first inductor (L1) is connected to the first end of the IGBT module; One end of the first capacitor (C3) is connected to the first end of the first inductor (L1), and the other end of the first capacitor (C3) is connected to the second end of the first inductor (L1).

4. A switch control circuit, characterized in that: include: A voltage division ratio adjustment circuit as described in any one of claims 1 to 3.

5. The switch control circuit according to claim 4, characterized in that: Also includes: A control module, wherein a first input terminal of the control module is connected to the first voltage detection terminal, and a second input terminal of the control module is connected to the second voltage detection terminal; a first output terminal of the control module is connected to a control terminal of the IGBT module; the control module is further provided with a plurality of second output terminals, and the control module sends a control signal to a control terminal of a switch module in a plurality of resistance modules through the second output terminals; The IGBT module, the other end of the IGBT module is grounded.

6. The switch control circuit according to claim 5, characterized in that: The control module comprises: A synchronization circuit module, wherein a first input terminal of the synchronization circuit module is connected to the first voltage detection terminal, a second input terminal of the synchronization circuit module is connected to the second voltage detection terminal, and an output terminal of the synchronization circuit module is connected to an input terminal of a control chip; The control chip, the output end of the control chip is connected to the control end of the IGBT module.

7. The switch control circuit according to claim 6, characterized in that: The control module also includes: A driving circuit module has one end connected to the output end of the control chip and the other end connected to the control end of the IGBT module.

8. The switch control circuit according to any one of claims 4 to 7, characterized in that: Also includes: A rectifier circuit module, wherein a first end of the rectifier circuit module is used to connect to the power supply, and a second end of the rectifier circuit module is connected to a first end of the oscillation circuit.

9. The switch control circuit according to claim 8, characterized in that: Also includes: A filter module, one end of the filter module is used to connect to the power supply, and the other end of the filter module is connected to the first end of the rectifier circuit module.

10. The switch control circuit according to claim 8, characterized in that: Also includes: A second inductor (L2) has one end connected to the second end of the rectifier circuit module and the other end connected to the first end of the oscillation circuit.

11. The switch control circuit according to claim 9 or 10, characterized in that: Also includes: The second capacitor (C4) has one end connected to the first end of the oscillation circuit and the other end grounded.

12. A cooking utensil, characterized in that: include: A voltage division ratio adjustment circuit as described in any one of claims 1 to 3, and / or a switch control circuit as described in any one of claims 4 to 11.

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