CN206963115U - Electromagnetic oven - Google Patents

Abstract

The utility model provides an electromagnetic oven. The induction cooker comprises: the circuit comprises a control circuit, a driving circuit, an IGBT, a resonance circuit, a triode, a first voltage division circuit, a second voltage division circuit, a temperature sensor and a comparison circuit. The base of the triode is connected with the temperature sensor, and when the temperature sensor is abnormal (such as short circuit, open circuit and high temperature detection) and normal, the two input ends of the controllable comparison circuit have different size relations. The comparison circuit outputs low voltage when the temperature sensor is abnormal and outputs high resistance state when the temperature sensor works normally according to different size relations, so that the induction cooker can be protected at high temperature when working, the working state of the induction cooker is prevented from being adjusted by adopting a software mode, and the reliability of high-temperature protection of the induction cooker is improved.

Description

Electromagnetic oven

Technical Field

The utility model relates to a circuit structure technical field especially relates to an electromagnetic oven.

Background

The induction cooker is common household electrical equipment, has the advantages of safety, no open fire, high efficiency, energy conservation, cleanness and the like, and more people begin to use the induction cooker to heat various cookers and kettles for food processing.

In order to ensure the cooking effect and avoid overhigh temperature of the heated food, the induction cooker needs to be protected at high temperature. The existing induction cookers are usually provided with a temperature sensor under the microcrystalline panel. The temperature sensor is used for detecting the temperature of the cookware placed on the microcrystal panel and sending the temperature to the processing chip, and the processing chip adjusts the working state of the induction cooker according to the received temperature to realize high-temperature protection of the induction cooker.

However, the performance of the processing chip is unstable, the abnormal operation is easy to occur, and the risk of the temperature adjusting mode is large. Therefore, the reliability of the high-temperature protection mode of the existing induction cooker is lower.

SUMMERY OF THE UTILITY MODEL

In order to solve at least one problem mentioned in the background art, the utility model provides an electromagnetic oven for solve the lower problem of high temperature protection mode reliability of current electromagnetic oven.

An aspect of the present invention provides an induction cooker, including: the circuit comprises a control circuit, a driving circuit, an IGBT, a resonance circuit, a triode, a first voltage division circuit, a second voltage division circuit, a temperature sensor and a comparison circuit; wherein,

the control circuit is connected with the drive circuit, the drive circuit is also connected with the grid electrode of the IGBT, the collector electrode of the IGBT is connected with the first end of the resonance circuit, the second end of the resonance circuit is connected with a mains supply, and the emitter electrode of the IGBT is grounded and connected with the mains supply;

the base electrode of the triode is connected with the first input end of the comparison circuit through the temperature sensor;

the first end of the first voltage division circuit and the emitting electrode of the triode are both connected with a direct current power supply, and the first end of the second voltage division circuit is connected with the collector electrode of the triode; second ends of the first voltage division circuit and the second voltage division circuit are both grounded; the voltage division tap of the first voltage division circuit is connected with the first input end of the comparison circuit; a voltage division tap of the second voltage division circuit is connected with a second input end of the comparison circuit; and the output end of the comparison circuit is connected with the driving circuit.

By connecting the base of the triode with the temperature sensor, when the temperature sensor is abnormal (such as short circuit, open circuit and high temperature detection) and normal, the two input ends of the controllable comparison circuit have different size relations. The comparison circuit outputs low voltage when the temperature sensor is abnormal and outputs high resistance state when the temperature sensor works normally according to different size relations, so that the induction cooker can be protected at high temperature when working, the working state of the induction cooker is prevented from being adjusted by adopting a software mode, and the reliability of high-temperature protection of the induction cooker is improved.

The induction cooker as described above, further comprising: a first diode;

the first voltage dividing circuit includes a first voltage dividing element and a second voltage dividing element, and the second voltage dividing circuit includes a third voltage dividing element and a fourth voltage dividing element;

the emitting electrode of the triode is respectively connected with a direct-current power supply and the first end of the first voltage division element, and the base electrode of the triode is connected with the first end of the temperature sensor;

the second end of the first voltage division element is respectively connected with the first end of the second voltage division element, the second end of the temperature sensor and the first input end of the comparison circuit, and the second end of the second voltage division element is grounded;

a collector of the triode is connected with a first end of the third voltage division element, a second end of the third voltage division element is respectively connected with a first end of the fourth voltage division element and a second input end of the comparison circuit, and a second end of the fourth voltage division element is grounded;

the output end of the comparison circuit is connected with the cathode of the first diode, and the anode of the first diode is connected with the driving circuit.

The induction cooker as described above, further comprising: a fifth resistor and a second diode;

the first end of the fifth resistor is connected with the non-inverting input end of the comparison circuit, the second end of the fifth resistor is connected with the anode of the second diode, and the cathode of the second diode is connected with the output end of the comparison circuit.

The diode and the fifth resistor are additionally arranged between the phase-verifying input end and the output end of the comparison circuit to form a hysteresis comparison circuit, so that a certain difference value is formed between a high-temperature protection temperature point and a temperature point for recovering normal heating after the temperature is reduced, and the damage of the IGBT caused by frequent conduction and cut-off of the IGBT is avoided. Meanwhile, the voltage signal of the driving circuit of the IGBT is prevented from influencing the voltage of the positive phase input end of the comparison circuit, so that the comparison circuit works more stably.

The induction cooker as described above, further comprising: a sixth resistor;

and the first end of the sixth resistor is connected with the second end of the temperature sensor, and the second end of the sixth resistor is connected with the control circuit.

Through increasing the sixth resistance, be connected temperature sensor through sixth resistance and control circuit, can adopt hardware circuit and software control's mode to carry out high temperature protection to the electromagnetism stove simultaneously, have higher reliability.

The induction cooker as described above, further comprising: a voltage stabilizing tube;

the first end of the voltage-stabilizing tube is connected with the base electrode of the IGBT, and the second end of the voltage-stabilizing tube is grounded;

and the voltage-stabilizing tube is used for controlling the base voltage of the IGBT within a preset voltage range.

The induction cooker as described above, further comprising: a seventh resistor;

the first end of the seventh resistor is connected with the base electrode of the IGBT, and the second end of the seventh resistor is grounded.

The seventh resistor is used for shunting overcurrent to protect the IGBT.

The induction cooker as described above, the driving circuit includes a level conversion circuit and a push-pull driving circuit;

the level switching circuit is respectively connected with the control circuit and the push-pull driving circuit, and the push-pull driving circuit is also connected with the grid electrode of the IGBT.

The induction cooker as described above, further comprising: a capacitor;

the first end of the capacitor is connected with the push-pull driving circuit, and the second end of the capacitor is grounded.

The capacitor is a bypass filter capacitor and is used for filtering interference burr signals and avoiding the IGBT from being switched on due to the burr signals.

According to the induction cooker, the triode is a PNP type triode.

The induction cooker also comprises a rectification filter circuit;

the second end of the resonance circuit is connected with the mains supply through the rectification filter circuit of the rectification filter circuit, and the emitting electrode of the IGBT is connected with the mains supply through the rectification filter circuit.

The structure of the present invention and other objects and advantages thereof will be more clearly understood from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.

Drawings

Fig. 1 is a schematic structural diagram of an induction cooker according to the present invention;

fig. 2 is a schematic structural diagram of an induction cooker according to the present invention;

fig. 3 is a third schematic structural view of the induction cooker provided by the present invention;

fig. 4 is a schematic structural diagram of an induction cooker according to the present invention;

fig. 5 is a schematic structural diagram of an induction cooker according to the present invention;

fig. 6 is a schematic structural diagram six of the induction cooker provided by the present invention;

fig. 7 is a seventh schematic structural diagram of the induction cooker provided by the present invention;

fig. 8 is a schematic structural diagram eight of the induction cooker provided by the present invention;

fig. 9 is a schematic structural diagram nine of the induction cooker provided by the present invention.

Reference numerals:

11-a control circuit; 12-a drive circuit; 13-an IGBT;

14-a resonant circuit; 15-a triode; 16-a first voltage dividing circuit;

17-a second voltage divider circuit; 161-a first voltage dividing element; 162-a second voltage dividing element;

171-a third voltage dividing element; 172-fourth voltage dividing element; 18-a temperature sensor;

19-a comparison circuit; 20 — a first diode; 21-fifth resistance;

22 — a second diode; 23-sixth resistance; 24-a voltage stabilizing tube;

25-seventh resistance; 26-a level shift circuit; 27-push-pull drive circuit;

28-capacitor 29-rectifying and filtering circuit.

Detailed Description

Fig. 1 is a schematic structural diagram of an induction cooker according to the present invention. As shown in fig. 1, the utility model provides an induction cooker includes:

a control circuit 11, a drive circuit 12, an IGBT13, a resonance circuit 14, a transistor 15, a first voltage dividing circuit 16, a second voltage dividing circuit 17, a temperature sensor 18, and a comparison circuit 19; wherein,

the control circuit 11 is connected with the drive circuit 12, the drive circuit 12 is also connected with the grid of the IGBT13, the collector of the IGBT13 is connected with the first end of the resonance circuit 14, the second end of the resonance circuit 14 is connected with the mains supply, and the emitter of the IGBT13 is grounded and connected with the mains supply;

the base electrode of the triode 15 is connected with a first input end of a comparison circuit 19 through a temperature sensor 18;

a first end of the first voltage division circuit 16 and an emitting electrode of the triode 15 are both connected with a direct current power supply, and a first end of the second voltage division circuit 17 is connected with a collector electrode of the triode 15; second ends of the first voltage division circuit 16 and the second voltage division circuit 17 are both grounded; a voltage dividing tap of the first voltage dividing circuit 16 is connected to a first input terminal of the comparison circuit 19; a voltage division tap of the second voltage division circuit 17 is connected with a second input terminal of the comparison circuit 19; the output of the comparator circuit 19 is connected to the driver circuit 12.

Illustratively, the output port of the control circuit 11 is connected to the input terminal of the driving circuit 12, and the output terminal of the driving circuit 12 is connected to the gate of the IGBT 13. The collector of the IGBT13 is connected to a first end of the resonant circuit 14, a second end of the resonant circuit 14 is for connection to a mains supply, and the emitter of the IGBT13 is for connection to ground and to the mains supply. The mains supply is connected with the resonant circuit 14 and the IGBT13 to form a heating loop of the induction cooker. When the control circuit 11 provides a high level to the driving circuit 11, the driving circuit 12 controls the IGBT13 to be turned on, the resonant circuit 14 is charged, when the control circuit 11 provides a low level to the driving circuit 12, the driving circuit 12 controls the IGBT13 to be turned off, the resonant circuit 14 is discharged to generate an alternating magnetic field, and the alternating magnetic field cuts a pot placed on the induction cooker to heat the pot.

A temperature sensor is usually provided in the electromagnetic oven for detecting the temperature, and when the temperature is too high, the IGBT is controlled to turn off to stop the operation of the resonance circuit. However, in the conventional induction cooker, the control circuit generally outputs different driving signals according to the detected temperature of the temperature sensor, so that the driving circuit drives the IGBT to be turned on or off according to the different driving signals. Namely, the working state of the induction cooker is adjusted by adopting a software mode, so that the high-temperature protection of the induction cooker is realized. However, the performance of the processing chip is unstable, and the situation of abnormal work is easy to occur, so that the risk of a mode of adjusting the temperature by software is large. Therefore, the reliability of the high-temperature protection mode of the existing induction cooker is lower.

In order to solve the above problem, the present embodiment adds a transistor 15, a first voltage dividing circuit 16, a second voltage dividing circuit 17, a temperature sensor 18, and a comparison circuit 19 to the electromagnetic oven.

The first voltage divider 16 has a first end connected to a dc power supply and the other end grounded. The voltage dividing tap a of the first voltage dividing circuit 16 is connected to one input terminal of the comparison circuit 19. One end of the second voltage dividing circuit 17 is connected to the collector of the transistor 15, and the other end is grounded. The voltage dividing tap B of the second voltage dividing circuit 17 is connected to the other input terminal of the comparison circuit 19. The comparison circuit determines the output voltage according to the voltages input by the two input ends.

The base of the transistor 15 is connected to a first end of the temperature sensor 18, and the emitter of the transistor 15 is connected to a dc power supply. A second terminal of the temperature sensor 18 is connected to the voltage dividing tap a of the first voltage dividing circuit 16. The temperature sensor 18 is used for detecting the temperature of a pot placed on the induction cooker. The higher the temperature, the smaller the resistance value of the temperature sensor 18, and the lower the temperature, the larger the resistance value of the temperature sensor 18.

Illustratively, the temperature sensor 18 includes three states, short-circuit fault, open-circuit fault, and normal operation. When the temperature sensor 18 works normally or short-circuit faults occur, the triode 15 is conducted; when the temperature sensor 18 opens the fault, the transistor 15 is turned off. When the temperature sensor 18 fails, the IGBT13 needs to be controlled to not conduct any more. When the temperature sensor 18 is in normal operation, the temperature may be high, and temperature protection is required, and the IGBT13 is also controlled not to be turned on.

When the temperature sensor 18 is in open circuit fault and the triode 15 is turned off, the second voltage division circuit 17 has no power supply, and the voltage at the point B of the voltage division tap is 0. The first voltage dividing circuit 16 divides the dc power. At this time, the voltage at the point A of the voltage division tap is greater than the voltage at the point B of the voltage division tap. Illustratively, when the voltage dividing tap a is connected to the inverting input terminal of the comparing circuit 19, and the voltage dividing tap B is connected to the non-inverting input terminal of the comparing circuit 19, at this time, since the voltage dividing tap a is higher than the voltage dividing tap B, the output terminal of the comparing circuit 19 outputs a low level signal, and the driving circuit 12 receives the low level signal, and at this time, the driving circuit 12 drives the IGBT13 to turn off no matter the control circuit 11 outputs the low level signal or the high level signal. That is, when the temperature sensor 18 fails to detect the temperature due to an open circuit failure, the IGBT13 is not turned on, thereby protecting the induction cooker.

When the temperature sensor 18 is short-circuited or the temperature of the electromagnetic oven is high, the resistance value of the temperature sensor 18 is small, the triode 15 is conducted, and it can be considered that the temperature sensor 18 directly connects the voltage division tap a point with the direct-current power supply, and the voltage of the voltage division tap a point is the same as the voltage provided by the direct-current power supply. At this time, the transistor 15 operates normally, and the second voltage dividing circuit 17 divides the dc power. At this time, the voltage at the point A of the voltage division tap is greater than the voltage at the point B of the voltage division tap. As in the case of the open circuit of the transistor 15, the output terminal of the comparator circuit 19 outputs a low level signal, and the IGBT13 is driven to turn off by the driver circuit 12. Namely, when the temperature sensor 18 has a short-circuit fault or the temperature of the induction cooker is high, the IGBT13 is not conducted, and the high-temperature protection of the induction cooker is realized.

When the temperature sensor 18 works normally and the temperature of the electromagnetic oven is low, the resistance value of the temperature sensor 15 is large, at this time, the triode 15 is conducted, and the temperature sensor 18 is connected in parallel with part of voltage dividing elements of the first voltage dividing circuit 16, so that the voltage of the voltage dividing tap A is influenced. The second voltage dividing circuit 17 divides the dc power supply. For example, the voltage at the voltage dividing tap a is generally set according to the resistance ratio of each voltage dividing element in the second voltage dividing circuit 17, so that the voltage at the voltage dividing tap B is smaller than the voltage at the voltage dividing tap a. At this time, the output terminal of the comparator circuit 19 is in a leak-open state and outputs a high impedance state, and the driver circuit 12 receives only the level signal from the control circuit 11. That is, when the temperature sensor 18 is operating normally and the temperature is low, the control of the IGBT13 by the control circuit 11 is not affected.

For example, the voltage divider circuit may be composed of a voltage divider element, or may be a device having a voltage tap such as a sliding varistor. The voltage dividing element may exemplarily be a component having a certain resistance value, such as a resistor, a sliding varistor, a capacitor, an inductor, a diode, and a triode, and the resistor in this application may be a resistor, or a resistor structure obtained by connecting a plurality of resistors in series or in parallel, which is not limited in this application.

Optionally, the voltage dividing tap a may be connected to the positive phase input terminal of the comparison circuit 19, and the voltage dividing tap B may be connected to the negative phase input terminal of the comparison circuit 19, and correspondingly, the output terminal of the adjustable comparison circuit 19 may output a low level when the voltage at the positive phase input terminal is greater than the voltage at the negative phase input terminal; and when the voltage of the inverting input end is greater than that of the non-inverting input end, the high-resistance state is output in a leakage mode.

Illustratively, the transistor 15 may be a PNP transistor.

An embodiment of the utility model provides an induction cooker, including control circuit, drive circuit, IGBT, resonant circuit, triode, first voltage divider circuit, second voltage divider circuit, temperature sensor and comparison circuit. The base of the triode is connected with the temperature sensor, and when the temperature sensor is abnormal (such as short circuit, open circuit and high temperature detection) and normal, the base can control the potential of the A point of the voltage division tap of the first voltage division circuit and the potential of the B point of the voltage division tap of the second voltage division circuit to have different magnitude relations. The comparison circuit outputs low voltage when the temperature sensor is abnormal and outputs high resistance state when the temperature sensor works normally according to different size relations, so that the induction cooker can be protected at high temperature when working, the working state of the induction cooker is prevented from being adjusted by adopting a software mode, and the reliability of high-temperature protection of the induction cooker is improved.

Further, with reference to the embodiment shown in fig. 1, an embodiment of the present invention further provides an induction cooker. Fig. 2 is a schematic structural diagram of the induction cooker according to the present invention, and the structure of the first voltage dividing circuit 16 and the second voltage dividing circuit 17 is described in detail in this embodiment. As shown in fig. 2, in this embodiment, the induction cooker further includes: a first diode 20;

the first voltage dividing circuit 16 includes a first voltage dividing element 161 and a second voltage dividing element 162, and the second voltage dividing circuit 17 includes a third voltage dividing element 171 and a fourth voltage dividing element 172;

an emitter electrode of the triode 15 is respectively connected with the direct-current power supply and a first end of the first voltage division element 161, and a base electrode of the triode 15 is connected with a first end of the temperature sensor 18;

a second terminal of the first voltage divider 161 is connected to a first terminal of the second voltage divider 162, a second terminal of the temperature sensor 18, and an inverting input terminal of the comparator circuit 19, respectively, and a second terminal of the second voltage divider 162 is grounded;

a collector of the transistor 15 is connected to a first end of the third voltage dividing element 171, a second end of the third voltage dividing element 171 is respectively connected to a first end of the fourth voltage dividing element 172 and a second input end of the comparison circuit 19, and a second end of the fourth voltage dividing element 172 is grounded;

the output terminal of the comparator circuit 19 is connected to the cathode of the first diode 20, and the anode of the first diode 20 is connected to the driver circuit 12.

Illustratively, the first voltage dividing element 161 and the second voltage dividing element 162 constitute the first voltage dividing circuit 16, and the third voltage dividing element 171 and the fourth voltage dividing element 172 constitute the second voltage dividing circuit 17. A second end of the temperature sensor 18 is connected to a connection point a of two voltage dividing elements in the first voltage dividing circuit 16. The connection point B of the two voltage dividing elements in the second voltage dividing circuit 17 is connected to the other input terminal of the comparison circuit 19.

When the temperature sensor 18 fails to open the circuit and the transistor 15 is turned off, the third voltage division element 171 and the fourth voltage division element 172 do not supply power, and the voltage at the point B is 0. The first voltage dividing element 161 and the second voltage dividing element 162 divide the dc power. At this time, the voltage at point a is greater than the voltage at point B. Illustratively, when the point a is connected to the inverting input terminal of the comparator circuit 19 and the point B is connected to the non-inverting input terminal of the comparator circuit 19, since the point a voltage is higher than the point B voltage, the output terminal of the comparator circuit 19 outputs a low level signal, the positive electrode voltage of the first diode 20 is higher than the negative electrode voltage, the first diode 20 is turned on, and the driver circuit 12 receives the low level signal, at which time, the driver circuit 12 drives the IGBT13 to turn off regardless of whether the control circuit 11 outputs the low level signal or the high level signal. That is, when the temperature sensor 18 fails to detect the temperature due to an open circuit failure, the IGBT13 is not turned on, thereby protecting the induction cooker.

When the temperature sensor 18 is short-circuited or the temperature of the electromagnetic oven is high, the resistance value of the temperature sensor 18 is small, the transistor 15 is turned on, it can be considered that the temperature sensor 18 short-circuits the first voltage dividing element 161, and the voltage at the point a is the same as the voltage provided by the dc power supply. At this time, the transistor 15 normally operates, and the third voltage dividing element 171 and the third voltage dividing element 172 divide the dc power. At this time, the voltage at point a is greater than the voltage at point B. As in the case of the open circuit of the transistor 15, the output terminal of the comparator circuit 19 outputs a low level signal, and the IGBT13 is driven to turn off by the driver circuit 12. Namely, when the temperature sensor 18 has a short-circuit fault or the temperature of the induction cooker is high, the IGBT13 is not conducted, and the high-temperature protection of the induction cooker is realized.

When the temperature sensor 18 works normally and the temperature of the electromagnetic oven is low, the resistance value of the temperature sensor 15 is large, at this time, the triode 15 is conducted, the first voltage division element 161 is connected with the temperature sensor 18 in parallel, and then the voltage division element and the second voltage division element 162 divide the voltage of the direct-current power supply. The third voltage dividing element 171 and the third voltage dividing element 172 divide the voltage of the dc power. For example, a resistor having a specific resistance is generally selected as the second voltage divider 162 according to the ratio of the resistances of the third voltage divider 171 and the fourth voltage divider 172, so that the voltage at the point a is smaller than the voltage at the point B. At this time, the output terminal of the comparator circuit 19 is opened, the output terminal is in a high impedance state, the first diode 20 is turned off, and the driver circuit 12 receives only the level signal from the control circuit 11. That is, when the temperature sensor 18 is operating normally and the temperature is low, the control of the IGBT13 by the control circuit 11 is not affected.

The embodiment of the utility model provides an among the electromagnetism stove first voltage division circuit and second voltage division circuit simple structure, the cost is lower.

Further, with reference to the embodiment shown in fig. 2, an embodiment of the present invention further provides an induction cooker. Fig. 3 is a schematic structural diagram of the electromagnetic oven provided by the utility model, the electromagnetic oven further includes in this implementation: and the fifth resistor 21 and the second diode 22 are used for forming a hysteresis comparison circuit, so that a certain difference value exists between a high-temperature protection temperature point and a temperature point for recovering normal heating after the temperature is reduced, and the frequent conduction and cut-off of the IGBT are avoided. As shown in fig. 3, in this embodiment, the induction cooker further includes: a fifth resistor 21 and a second diode 22;

a first end of the fifth resistor 21 is connected to the non-inverting input terminal of the comparator circuit 19, a second end of the fifth resistor 21 is connected to the anode of the second diode 22, and the cathode of the second diode 22 is connected to the output terminal of the comparator circuit 19.

For example, referring to fig. 3, when the temperature of the temperature sensor 18 is higher than the high-temperature protection temperature point, the output terminal of the comparison circuit 19 outputs a low level, so that the IGBT13 cannot be turned on, and the temperature of the electromagnetic oven decreases, and when the temperature of the temperature sensor 18 is lower than the high-temperature protection temperature point, the output terminal of the comparison circuit 19 outputs a high resistance state, so that the IGBT13 can be turned on, and the temperature of the electromagnetic oven increases. Therefore, when the temperature of the temperature sensor 18 is in the vicinity of the high-temperature protection temperature point, there may be a case where the IGBT13 is frequently turned on and off, and the IGBT13 may be damaged.

In this embodiment, a fifth resistor 21 and a second diode 22 are added. A fifth resistor 21 is connected in series with the second diode 22 and is arranged between the non-inverting input of the comparison circuit 19 and the output of the comparison circuit 19. And the inverting input terminal of the second diode 22 is connected to the output terminal of the comparing circuit 19 to form a hysteresis comparing circuit, and at this time, the output state of the output terminal of the comparing circuit 19 depends on the current output state of the output terminal and the voltage magnitude of the non-inverting and inverting input terminals.

For example, when the temperature of the temperature sensor 18 is higher than the high temperature protection temperature point, the voltage at the positive input terminal of the comparison circuit 19 is lower than the voltage at the negative input terminal of the comparison circuit 19, the output terminal of the comparison circuit 19 outputs a low level, at this time, the IGBT13 is turned off, the induction cooker stops heating, the temperature of the temperature sensor 18 decreases, when the temperature decreases to a level that the voltage at the positive input terminal of the comparison circuit 19 is higher than the voltage at the negative input terminal of the comparison circuit 19, the state of the output terminal of the comparison circuit 19 is not immediately switched to the high resistance state, but the state of the output terminal of the comparison circuit 19 is switched to the high resistance state only when the voltage at the positive input terminal of the comparison circuit 19 is higher than the voltage at the negative input terminal of the comparison circuit. Similarly, when the output terminal of the comparison circuit 19 outputs a high impedance state, the IGBT13 may be turned on under the control of the control circuit 11, the induction cooker resumes heating, the temperature of the temperature sensor 18 increases, and when the temperature increases to a level that the voltage at the positive input terminal of the comparison circuit 19 is lower than the voltage at the negative input terminal of the comparison circuit 19, the state of the output terminal of the comparison circuit 19 does not immediately switch to the low level, but when the voltage at the positive input terminal of the comparison circuit 19 is lower than the voltage at the negative input terminal of the comparison circuit 19 by a predetermined value, the state of the output terminal of the comparison circuit 19 switches to the low level. A certain difference value is formed between the high-temperature protection temperature point and the temperature point which is recovered to be normally heated after the temperature is reduced, and the damage of the IGBT caused by frequent switching-on and switching-off of the IGBT is avoided.

Illustratively, the second diode 22 is unidirectionally conducted to prevent the voltage signal of the driving circuit 12 of the IGBT13 from affecting the voltage at the non-inverting input terminal of the comparator circuit 19, so that the comparator circuit 19 operates more stably.

In this embodiment, the diode and the fifth resistor are added between the phase-verifying input end and the output end of the comparison circuit to form a hysteresis comparison circuit, so that a certain difference value exists between the high-temperature protection temperature point and the temperature point at which normal heating is resumed after the temperature is reduced, and the damage of the IGBT caused by frequent switching-on and switching-off of the IGBT is avoided. Meanwhile, the voltage signal of the driving circuit of the IGBT is prevented from influencing the voltage of the positive phase input end of the comparison circuit, so that the comparison circuit works more stably.

Further, with reference to the embodiment shown in fig. 3, an embodiment of the present invention further provides an induction cooker. Fig. 4 is a schematic structural diagram of the induction cooker provided by the present invention. The electromagnetic oven in this embodiment further comprises a sixth resistor 23 for connecting the temperature sensor 18 and the control circuit 11. As shown in fig. 4, in this embodiment, the induction cooker further includes: a sixth resistor 23;

a first end of the sixth resistor 23 is connected to the second end of the temperature sensor 18, and a second end of the sixth resistor 23 is connected to the control circuit 11.

For example, referring to fig. 4, the temperature sensor 18 may be further connected to the control circuit 11 through a sixth resistor 23, so that the driving circuit 12 may still adjust the operating state of the induction cooker in a software manner when the comparing circuit 19 fails, thereby implementing high temperature protection of the induction cooker. The current resistor 23 is a current limiting resistor for protecting the control circuit 11.

The induction cooker provided by the embodiment can be subjected to high-temperature protection by adopting a hardware circuit and software control mode, and has higher reliability.

Further, with reference to the embodiment shown in fig. 4, an embodiment of the present invention further provides an induction cooker. Fig. 5 is a schematic structural diagram of the induction cooker provided by the present invention. In this embodiment, the induction cooker further includes a voltage regulator tube for controlling the base voltage of the IGBT within a preset voltage range. Referring to fig. 5, the induction cooker further includes: a voltage regulator tube 24;

the first end of the voltage regulator tube 24 is connected with the base electrode of the IGBT13, and the second end of the voltage regulator tube 24 is grounded;

and the voltage regulator tube 24 is used for controlling the base voltage of the IGBT13 within a preset voltage range.

Illustratively, referring to fig. 5, the cathode of the regulator tube 24 is connected to the base of the IGBT13, and the anode of the regulator tube 24 is grounded, so as to control the base voltage of the IGBT13 within a preset voltage range, and prevent the overvoltage signal in the driving circuit 12 from being applied to the base of the IGBT13, which may cause the IGBT13 to be damaged.

Further, with reference to the embodiment shown in fig. 5, an embodiment of the present invention further provides an induction cooker. Fig. 6 is a schematic structural diagram six of the induction cooker provided by the present invention. The electromagnetic oven in this embodiment further includes a seventh resistor. Referring to fig. 6, the induction cooker further includes: a seventh resistor 25;

a first terminal of the seventh resistor 25 is connected to the base of the IGBT13, and a second terminal of the seventh resistor 25 is grounded.

Illustratively, as shown in fig. 6, the base of the IGBT13 is further provided with a seventh resistor 25 for shunting the overcurrent.

Further, with reference to the embodiment shown in fig. 6, an embodiment of the present invention further provides an induction cooker. Fig. 7 is a seventh schematic structural diagram of the induction cooker provided by the present invention. The present embodiment will explain the drive circuit 12 in detail. As shown in fig. 7, in the present embodiment, the drive circuit 12 includes a level conversion circuit 26 and a push-pull drive circuit 27;

the level shift circuit 26 is connected to the control circuit 11 and the push-pull drive circuit 27, respectively, and the push-pull drive circuit 27 is also connected to the gate of the IGBT 13.

Illustratively, the level shift circuit 26 is configured to level-shift the driving voltage supplied from the control circuit 11. The operating voltage of the control circuit 11 is usually 5V, while the driving voltage of the IGBT13 and the operating voltage of the push-pull driving circuit 27 are usually 15-18V, so the control circuit 11 cannot directly send the driving signal to the push-pull driving circuit 27, and the level converting circuit 26 needs to convert the driving signal sent by the control circuit 11 from 0V and 5V to 0V and 15-18V.

The push-pull drive circuit 27 is used to shape the drive voltage polarity received from the level shift circuit 26. The push-pull driving circuit 27 has a simple structure and a low cost.

Illustratively, the anode of the first diode 20 may be connected to the level shift circuit 26 as shown in fig. 7, may be connected to a connection point of the control circuit 11 and the level shift circuit 26, and may be connected to a connection point of the push-pull drive circuit 27 and the level shift circuit 26.

Further, in combination with the embodiment shown in fig. 7, the embodiment of the present invention further provides an induction cooker. Fig. 8 is a schematic structural diagram eight of the induction cooker provided by the present invention. The induction cooker in the embodiment also comprises a capacitor for filtering the interference burr signal. Referring to fig. 8, the induction cooker further includes: a capacitor 28;

a first terminal of the capacitor 28 is connected to the push-pull driving circuit 27, and a second terminal of the capacitor 28 is grounded.

For example, referring to fig. 8, a capacitor 28 may be further disposed at an input end of the push-pull driving circuit 27, where the capacitor 28 is a bypass filter capacitor, and is used to filter an interference glitch signal and prevent the IGBT13 from being turned on by the glitch signal.

Further, with reference to the embodiment shown in fig. 8, the embodiment of the present invention further provides an induction cooker, wherein a rectifying and filtering circuit is disposed in the heating circuit. Fig. 9 is a schematic structural diagram nine of the induction cooker provided by the present invention. As shown in fig. 9, in the present embodiment, the induction cooker further includes a rectifying and filtering circuit 29;

the second terminal of the resonant circuit 14 is connected to the mains supply through the rectifying and filtering circuit 29, and the emitter of the IGBT13 is connected to the mains supply through the rectifying and filtering circuit 29.

Illustratively, the mains power supplies the heating loop formed by the IGBT13 and the resonant circuit 14 through the rectifier filter circuit 29. The rectifier and filter circuit 29 is specifically configured to rectify the 2018V ac mains supply into dc power, filter out possible resonances in the grid, and provide stable current and voltage to the resonant circuit 14. The rectifying and filtering module 29 may be composed of a rectifying bridge and a filtering device.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims (10)

1. An induction hob, comprising: the power supply comprises a control circuit (11), a driving circuit (12), an IGBT (13) and a resonance circuit (14), wherein the control circuit (11) is connected with the driving circuit (12), the driving circuit (12) is connected with the grid electrode of the IGBT (13), the collector electrode of the IGBT (13) is connected with the first end of the resonance circuit (14), the second end of the resonance circuit (14) is connected with a mains supply, and the emitter electrode of the IGBT (13) is grounded and connected with the mains supply; it is characterized by also comprising: the circuit comprises a triode (15), a first voltage division circuit (16), a second voltage division circuit (17), a temperature sensor (18) and a comparison circuit (19); wherein,

the base electrode of the triode (15) is connected with the first input end of the comparison circuit (19) through the temperature sensor (18);

the first end of the first voltage division circuit (16) and the emitting electrode of the triode (15) are both connected with a direct current power supply, and the first end of the second voltage division circuit (17) is connected with the collecting electrode of the triode (15); the second ends of the first voltage division circuit (16) and the second voltage division circuit (17) are both grounded; the voltage dividing tap of the first voltage dividing circuit (16) is connected with a first input end of the comparison circuit (19); the voltage dividing tap of the second voltage dividing circuit (17) is connected with a second input end of the comparison circuit (19); the output end of the comparison circuit (19) is connected with the drive circuit (12).

2. The induction cooking range according to claim 1, further comprising: a first diode (20);

the first voltage dividing circuit (16) includes a first voltage dividing element (161) and a second voltage dividing element (162), and the second voltage dividing circuit (17) includes a third voltage dividing element (171) and a fourth voltage dividing element (172);

the emitting electrode of the triode (15) is respectively connected with the direct current power supply and the first end of the first voltage division element (161), and the base electrode of the triode (15) is connected with the first end of the temperature sensor (18);

a second end of the first voltage division element (161) is respectively connected with a first end of the second voltage division element (162), a second end of the temperature sensor (18) and a first input end of the comparison circuit (19), and a second end of the second voltage division element (162) is grounded;

a collector of the triode (15) is connected with a first end of the third voltage division element (171), a second end of the third voltage division element (171) is respectively connected with a first end of the fourth voltage division element (172) and a second input end of the comparison circuit (19), and a second end of the fourth voltage division element (172) is grounded;

the output end of the comparison circuit (19) is connected with the cathode of the first diode (20), and the anode of the first diode (20) is connected with the driving circuit (12).

3. The induction cooking range according to claim 2, further comprising: a fifth resistor (21) and a second diode (22);

the first end of the fifth resistor (21) is connected with the non-inverting input end of the comparison circuit (19), the second end of the fifth resistor (21) is connected with the anode of the second diode (22), and the cathode of the second diode (22) is connected with the output end of the comparison circuit (19).

4. The induction cooking range according to claim 3, further comprising: a sixth resistor (23);

the first end of the sixth resistor (23) is connected with the second end of the temperature sensor (18), and the second end of the sixth resistor (23) is connected with the control circuit (11).

5. The induction cooking range according to claim 4, further comprising: a voltage regulator tube (24);

the first end of the voltage regulator tube (24) is connected with the base electrode of the IGBT (13), and the second end of the voltage regulator tube (24) is grounded;

and the voltage regulator tube (24) is used for controlling the base voltage of the IGBT (13) within a preset voltage range.

6. The induction cooking range according to claim 5, further comprising: a seventh resistor (25);

the first end of the seventh resistor (25) is connected with the base electrode of the IGBT (13), and the second end of the seventh resistor (25) is grounded.

7. The induction cooking hob according to claim 6, characterized in, that the drive circuit (12) comprises a level shift circuit (26) and a push-pull drive circuit (27);

the level conversion circuit (26) is respectively connected with the control circuit (11) and the push-pull drive circuit (27), and the push-pull drive circuit (27) is also connected with the grid electrode of the IGBT (13).

8. The induction cooking range according to claim 7, further comprising: a capacitor (28);

the first end of the capacitor (28) is connected with the push-pull driving circuit (27), and the second end of the capacitor (28) is grounded.

9. The induction hob according to claim 8, characterized in, that the transistor (15) is a PNP type transistor.

10. The induction hob according to claim 9, characterized in, that the induction hob further comprises a rectifier filter circuit (29);

the second end of the resonance circuit (14) is connected with a mains supply through the rectifying and filtering circuit (29) of the rectifying and filtering circuit (29), and the emitting electrode of the IGBT (13) is connected with the mains supply through the rectifying and filtering circuit (29).