Electric kettle and control circuit

Abstract

The utility model relates to an electric kettle and a control circuit, the control circuit comprises a control unit, a power control module, a temperature detection module and a heating wire, one end of the heating wire is electrically connected with a live wire, the other end of the heating wire is electrically connected with the output end of a power switch of the power control module, and the temperature detection module comprises a precision resistor and a comparison unit. One end of the precision resistor is electrically connected with a zero line and a first input end of the comparison unit, the other end of the precision resistor is electrically connected with an input end of the power switch and a second input end of the comparison unit, and an output end of the comparison unit is electrically connected with a temperature detection port of the control unit. The controlled end of the power switch is coupled and electrically connected with the power regulation control port of the control unit; and the heating wire, the power switch and the precision resistor form a series loop of which two ends are electrically connected with a live wire and a zero wire respectively. According to the application, the precision resistor is connected in series in the series loop corresponding to the heating wire, the water temperature is calculated and controlled by detecting the voltage of the precision resistor, and NTC-free water temperature measurement is realized.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to an electric kettle and a control circuit. Background Art

[0002] Small appliances like electric kettles have become a frequently used part of everyday life. Currently, electric kettles typically use a Negative Temperature Coefficient (NTC) thermistor (NTC) temperature sensor installed on the bottom of the kettle. The NTC temperature sensor measures the water temperature, and the microcontroller (MCU) controls the heater based on the feedback from the NTC temperature sensor, thereby controlling the water temperature. However, using the NTC temperature sensor on the bottom of the kettle for water temperature control requires riveting wires to the NTC temperature sensor pins and connecting them to the circuit board terminals. This can lead to poor contact and / or open circuits in the NTC temperature sensor wires, causing water temperature control failures and affecting the kettle's performance.

[0003] Currently, no effective solution has been proposed for the problem that electric kettles using NTC in related technologies are prone to poor contact of wire components, resulting in water temperature control failure. Utility Model Content

[0004] In view of this, it is necessary to provide an electric kettle and a control circuit to at least solve the problem in the related art that electric kettles using NTC are prone to poor contact of wire components and cause water temperature control failure.

[0005] In a first aspect, the present application provides a technical solution as follows: a control circuit for an electric kettle, comprising a control unit, a power control module, a temperature detection module, and a heating wire, wherein one end of the heating wire is electrically connected to the live wire of the mains power grid, and the other end is electrically connected to the output end of the power switch of the power control module; the temperature detection module comprises a precision resistor and a comparison unit, wherein one end of the precision resistor is electrically connected to the neutral wire of the mains power grid and the first input end of the comparison unit, respectively, and the other end is electrically connected to the input end of the power switch and the second input end of the comparison unit, respectively; the output end of the comparison unit is electrically connected to the temperature detection port of the control unit; the controlled end of the power switch is coupled and electrically connected to the power regulation control port of the control unit; the heating wire, the power switch, and the precision resistor form a series circuit with two ends electrically connected to the live wire and the neutral wire, respectively; wherein the comparison unit is used to detect the voltage across the precision resistor and generate a feedback voltage reflecting the temperature change of the heating wire based on the detected voltage across the precision resistor;

[0006] The control unit is used to control the switching of the power switch based on the current water temperature determined according to the received feedback voltage, so as to control the on-off of the series circuit, and to control the on-off of the heating wire and the neutral line through the series circuit, so as to correspondingly control the heating of the heating wire and control the water temperature.

[0007] In one embodiment, the comparison unit includes a non-inverting proportional amplifier, a first optocoupler isolator, and a first RC filter circuit. The non-inverting proportional amplifier includes a first negative input terminal, a first positive input terminal, and a first output terminal. The first negative input terminal is connected to the first input terminal, and the first positive input terminal is connected to the second input terminal. The first output terminal is electrically connected to the anode of the light emitter of the first optocoupler isolator via a first resistor in series. The cathode of the light emitter of the first optocoupler isolator is connected to ground. The collector of the light receiver of the first optocoupler isolator is electrically connected to a first power supply via a second resistor in series. The emitter of the light receiver of the first optocoupler isolator is electrically connected to the first RC filter circuit and the first coupling resistor, respectively. The other end of the first coupling resistor, which is away from the electrical connection with the emitter of the light receiver of the first optocoupler isolator, is electrically connected to the output terminal of the comparison unit. The non-inverting proportional amplifier is used to compare the voltages across the precision resistor and generate a first comparison signal based on the detected voltages across the precision resistor. The first optocoupler is used to convert the first comparison signal into the feedback voltage and output it along the output terminal of the comparison unit. The first RC filter circuit is used to perform signal filtering on the feedback voltage.

[0008] In one embodiment, the power control module further includes a power switch drive circuit, which includes an optocoupler thyristor relay and a first switch tube, the first switch tube including a first port, a second port, and a third port, the first port being electrically connected to a third resistor and a fourth resistor, respectively, the other end of the third resistor away from the electrical connection to the first port being electrically connected to the power regulation control port and the fifth resistor, respectively, the other end of the fourth resistor away from the electrical connection to the first port being electrically connected to the third port and to ground, the other end of the fifth resistor away from the electrical connection to the third resistor being electrically connected to a first power supply, the second port being electrically connected to the cathode of the light emitter of the optocoupler thyristor relay, the anode of the light emitter of the optocoupler thyristor relay being electrically connected to the first power supply via a seventh resistor in series, the first electrode of the light receiver of the optocoupler thyristor relay being connected in series with a second coupling resistor to the output end of the power switch, the second electrode of the light receiver of the optocoupler thyristor relay being connected in series with a third coupling resistor to the controlled end of the power switch, In the embodiment, the control unit is configured to output a corresponding power control signal; the first switching tube is configured to control the connection and disconnection of the second port and the third port according to the level of the power control signal received by the first port; the optocoupler-controlled silicon relay is configured to generate a first control signal output along the second electrode of the light receiver of the optocoupler-controlled silicon relay when the second port is connected to the third port, and to generate a second control signal output along the first electrode of the light receiver of the optocoupler-controlled silicon relay when the second port is disconnected from the third port; the power switch is configured to control the connection between the input terminal and the output terminal of the power switch upon receiving the first control signal output by the optocoupler-controlled silicon relay, and to control the disconnection between the input terminal and the output terminal of the power switch upon receiving the second control signal output by the optocoupler-controlled silicon relay; the series circuit is configured to control the connection or disconnection between the heating wire and the neutral line according to the connection and disconnection of the input terminal and the output terminal of the power switch, so that the heating wire generates heat accordingly.

[0009] In one embodiment, the power control module further includes a zero-crossing detection circuit, which includes a first sampling circuit and a second optocoupler. The first sampling circuit includes a first diode, a first voltage-dividing resistor, and a second voltage-dividing resistor electrically connected in series. The anode of the first diode is electrically connected to the live wire, the electrical connection point between the first voltage-dividing resistor and the second voltage-dividing resistor is electrically connected to the anode of the light emitter of the second optocoupler, and the other end of the second voltage-dividing resistor away from the electrical connection with the first voltage-dividing resistor is electrically connected to the neutral wire and the cathode of the light emitter of the second optocoupler, respectively. The collector of the light receiver of the second optocoupler is electrically connected to the first power supply through a first pull-up resistor, and the emitter of the light receiver of the second optocoupler is electrically connected to the first power supply through a first pull-up resistor. They are electrically connected to the second RC filter circuit and the fourth coupling resistor respectively, the other end of the second RC filter circuit away from the electrical connection with the emitter of the light receiver of the second optocoupler is connected to the ground, and the other end of the fourth coupling resistor away from the electrical connection with the emitter of the light receiver of the second optocoupler is electrically connected to the zero-crossing detection port of the control unit, wherein the first sampling circuit is used to sample a DC detection signal representing the voltage magnitude of the AC power of the mains power grid; the second optocoupler is used to convert the DC detection signal into a corresponding zero-crossing detection signal; the control unit is used to generate a corresponding zero-crossing control signal according to the magnitude of the level of the zero-crossing detection signal, and control the switching of the power switch based on the corresponding zero-crossing control signal.

[0010] In one embodiment, the control circuit also includes an alarm circuit, the alarm circuit includes a buzzer and a buzzer drive circuit, the buzzer drive circuit includes a second switch tube, the second switch tube includes a fourth port, a fifth port and a sixth port, the fourth port is electrically connected to the alarm control port of the control unit through a fifth coupling resistor in series, the fourth port is also electrically connected to the fifth port through an RC bypass circuit composed of a first capacitor and a sixth resistor, the fifth port is also connected to the ground, the sixth port is respectively electrically connected to the first pole and the seventh resistor of the buzzer, the other end of the seventh resistor away from the electrical connection with the sixth port is respectively electrically connected to the second pole and the eighth resistor of the buzzer, and the other end of the eighth resistor away from the electrical connection with the seventh resistor is electrically connected to the first power supply.

[0011] In one embodiment, the control circuit also includes a water adding module, the water adding module includes a water pump and a water pump driving circuit, the water pump driving circuit includes a third switch tube, the third switch tube includes a seventh port, an eighth port and a ninth port, the positive electrode of the water pump is electrically connected to the second power supply, the negative electrode of the water pump is electrically connected to the seventh port, the eighth port is electrically connected to the water supply control port of the control unit through a sixth coupling resistor in series, and the ninth port is electrically connected to the ground through the seventh coupling resistor, wherein the third switch tube is used to control the connection and disconnection of the seventh port and the ninth port according to the water supply control signal received by the eighth port, so as to control the water pump to perform corresponding pumping operation by enabling the connection and disconnection of the negative electrode of the water pump and the ground.

[0012] In one embodiment, the control circuit further includes a weighing module and a display module electrically connected to the control unit, wherein:

[0013] The weighing module includes an electronic scale unit composed of an HX711 analog-to-digital conversion chip and peripheral resistors and capacitors;

[0014] The display module includes a liquid crystal display unit composed of a TM1640 display chip, peripheral capacitors, resistors and inductors, and multiple LED indicator lights. The control unit controls the electrical connection between the liquid crystal display unit and the multiple LED indicator lights.

[0015] In one embodiment, the control circuit further includes a power supply module, and the power supply module includes:

[0016] A rectifier circuit comprising a varistor, a filter capacitor, and a rectifier bridge stack. The varistor and filter capacitor constitute a front-end filter unit. The input of the front-end filter unit is connected to the mains power grid, and the output of the front-end filter unit is connected to the input of the rectifier bridge stack. The output of the rectifier bridge stack is connected to the primary winding of the inverter transformer. The rectifier circuit is used to rectify the AC power input from the mains power grid into a DC voltage. The inverter transformer also includes a secondary winding and an auxiliary winding.

[0017] A control circuit includes a switching power supply control chip, wherein the power supply port of the switching power supply control chip is electrically coupled to the output end of the rectifier circuit via a voltage divider circuit composed of multiple resistors connected in series, the power supply port is also electrically connected to the same-name end of the auxiliary winding via a voltage stabilization circuit composed of a second diode and a current-limiting resistor connected in series, the feedback port of the switching power supply control chip is also electrically connected to the same-name end of the auxiliary winding via a positive feedback circuit composed of multiple sampling resistors connected in series, the power switch control port of the switching power supply control chip is electrically connected to the same-name end of the primary winding, and the secondary winding is electrically connected to the output end of the power module via an output rectifier circuit and a step-down circuit electrically connected in sequence, the output rectifier circuit includes a parallel rectifier diode and an RC absorption network, and the step-down circuit includes a DC step-down unit composed of a three-terminal voltage regulator tube and surrounding capacitors and inductors, wherein:

[0018] The rectifier circuit is used to provide power for starting the switching power supply control chip;

[0019] The auxiliary winding is used to supply power to the switching power supply control chip after it is started;

[0020] The switching power supply control chip is used to obtain a state signal reflecting the DC voltage output by the rectifier circuit through the positive feedback circuit to control the on / off of the internal power switch, so that the inverter transformer converts the DC voltage rectified by the rectifier circuit into a high-frequency square wave pulse voltage and outputs it along the secondary winding;

[0021] The output rectifier circuit is used to rectify the high-frequency square wave pulse voltage into a second voltage corresponding to the second power supply;

[0022] The step-down circuit is used to step down the second voltage to a first voltage corresponding to the first power supply.

[0023] In one embodiment, the control unit includes one of the following: a single chip microcomputer MCU, a digital signal processor DSP, and a programmable logic device FPGA.

[0024] In a second aspect, an embodiment of the present application further provides an electric kettle, comprising a kettle body, on which is provided a control circuit for controlling the operation of the electric kettle, wherein the control circuit is the control circuit of the electric kettle described in the first aspect.

[0025] Compared with the related art, the present embodiment provides an electric kettle and a control circuit, which includes a control unit, a power control module, a temperature detection module and a heating wire, one end of the heating wire is electrically connected to the live wire of the mains power grid, and the other end is electrically connected to the output end of the power switch of the power control module, the temperature detection module includes a precision resistor and a comparison unit, one end of the precision resistor is electrically connected to the neutral wire of the mains power grid and the first input end of the comparison unit respectively, and the other end is electrically connected to the input end of the power switch and the second input end of the comparison unit respectively, the output end of the comparison unit is electrically connected to the temperature detection port of the control unit, and the reception end of the power switch is electrically connected to the temperature detection port of the comparison unit. The control end is coupled and electrically connected with the power regulation control port of the control unit, and the heating wire, the power switch and the precision resistor form a series circuit with the two ends electrically connected to the live wire and the neutral wire respectively. By connecting the precision resistor in series in the series circuit corresponding to the heating wire and detecting the voltage of the corresponding precision resistor to calculate and control the water temperature, the water temperature is measured without NTC, so that the electric kettle can achieve temperature control and heat preservation functions, avoiding the use failure caused by poor contact and / or open circuit caused by the installation of NTC components, and solving the problem that the electric kettle using NTC in the related art is prone to poor contact of wire components and water temperature control failure.

[0026] The details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention, and together with the description, serve to explain the principles of the present invention.

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 This is a structural block diagram of a control circuit of an electric kettle provided in an embodiment of the present application;

[0030] Figure 2 A topological diagram of a control unit according to an embodiment of the present application;

[0031] Figure 3 A topological diagram of a series circuit consisting of a heating wire, a power control module, and a precision resistor according to an embodiment of the present application;

[0032] Figure 4 A topological diagram of a comparison unit according to an embodiment of the present application;

[0033] Figure 5 This is a structural block diagram of a control circuit of another electric kettle according to an embodiment of the present application;

[0034] Figure 6 A topological diagram of the alarm circuit according to an embodiment of the present application;

[0035] Figure 7 This is a topological diagram of the water adding module according to an embodiment of the present application;

[0036] Figure 8 A topological diagram of a weighing module according to an embodiment of the present application;

[0037] Figure 9 A topological diagram of a display module according to an embodiment of the present application;

[0038] Figure 10 This is a topological diagram of the power module according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] The electric kettle and control circuit of the present application will be described below with reference to the drawings in the embodiments of the present application and through specific embodiments.

[0041] refer to Figures 1 to 10 The control circuit of the electric kettle provided in the embodiment of the present application includes a control unit 100, a power control module 200, a temperature detection module 300 and a heating wire 400, one end of the heating wire 400 is electrically connected to the live wire L of the mains power grid, and the other end is electrically connected to the power switch 21 of the power control module 200 (reference Figure 3 Output terminal 201 (reference Figure 3 The temperature detection module 300 includes a precision resistor 31 (reference Figure 3 R66 in) and the comparison unit 32, one end of the precision resistor 31 is respectively connected to the neutral line N of the mains and the first input terminal 301 (reference Figure 3 、 Figure 4 The network label CS_A in FIG is electrically connected, and the other end is respectively connected to the input terminal 202 of the power switch 21 (reference Figure 3 T2 of TR1) and the second input terminal 302 of the comparison unit 32 (reference Figure 3 、 Figure 4 The output terminal 303 of the comparison unit 32 is electrically connected to the temperature detection port 101 of the control unit 100 ( Figure 4 In the figure, the controlled terminal 203 of the power switch 21 (reference Figure 3 G of TR1) and the power regulation control port 102 of the control unit 100 (reference Figure 2 The heating wire 400, the power switch 21 and the precision resistor 31 form a series circuit with the live wire L and the neutral wire N electrically connected at both ends, wherein:

[0042] The comparison unit 32 is used to detect the voltage across the precision resistor 31 and generate a feedback voltage that reflects the temperature change of the heating wire 400 according to the detected voltage across the precision resistor 31 .

[0043] In this embodiment, when the electric kettle is started, the comparison unit 32 detects the voltage across the precision resistor 31 and provides the detected feedback voltage (corresponding to the voltage loaded on the precision resistor 31) to the control unit 100. When the heating wire is heating, the comparison unit 32 intermittently detects the voltage across the precision resistor 31 and feeds back the corresponding feedback voltage to the control unit 100. The control unit 100 determines the current water temperature corresponding to the current feedback voltage according to the preset voltage and water temperature parameter table, thereby realizing temperature detection.

[0044] It should be understood that the preset voltage and water temperature parameter table is generated in advance based on experimental measurements. That is, under the set conditions, the voltage corresponding to the precision resistor 31 is measured when the heating wire 400 is heated, and the corresponding water temperature is measured using a temperature detector. In this way, the corresponding voltage and water temperature parameter table is generated.

[0045] The control unit 100 is used to control the switching of the power switch 21 based on the current water temperature determined according to the received feedback voltage, so as to control the on-off of the series circuit, and to control the on-off of the heating wire 400 and the neutral line N through the series circuit, so as to correspondingly control the heating of the heating wire 400 and control the water temperature.

[0046] In this embodiment, when the power switch 21 is disconnected, the series circuit is disconnected, the heating wire 400 is disconnected from the neutral line N, and the heating wire 400 cannot form a power-on circuit, and thus cannot conduct electricity, that is, the heating wire 400 stops heating; when the power switch 21 is controlled to connect its input end 202 with the output end 201, the electrode corresponding to the heating wire 400 is connected to the neutral line N, thereby connecting the heating wire 400 to the live wire L and the neutral line N, that is, forming a power-on circuit, and the heating wire 400 is powered on and works.

[0047] In this embodiment, the control unit 100 can be a single-chip microcomputer MCU, a digital signal processor DSP, or a programmable logic device FPGA. In some optional implementation schemes, the control unit 100 preferably uses one of the following MCUs: STC15F204 single-chip microcomputer, AT89S52 single-chip microcomputer, and EN8F677E main control chip.

[0048] The control circuit of the above-mentioned electric kettle adopts a method of connecting a precision resistor 31 in series in the series circuit corresponding to the heating wire 400, and calculating and controlling the water temperature by detecting the voltage of the corresponding precision resistor 31, thereby realizing water temperature measurement without NTC, so that the electric kettle can achieve temperature control and heat preservation functions, avoiding the use failure caused by poor contact and / or open circuit caused by the installation of NTC components, and solving the problem in the related art that electric kettles using NTC are prone to poor contact of wire components and cause water temperature control failure.

[0049] In some of these embodiments, reference Figures 1 to 4 The comparison unit 32 includes a non-inverting proportional amplifier U5A, a first optocoupler isolator UG6, and a first RC filter circuit. The non-inverting proportional amplifier U5A includes a first negative input terminal, a first positive input terminal, and a first output terminal. The first negative input terminal is connected to the first input terminal 301, and the first positive input terminal is connected to the second input terminal 302. The first output terminal is electrically connected to the anode of the light emitter of the first optocoupler isolator U6G through a first resistor R35 connected in series. The cathode of the light emitter of the first optocoupler isolator U6G is connected to the ground (that is, electrically connected to the signal ground, reference Figure 4 The collector of the light receiver of the first optocoupler isolator U6G is electrically connected to the first power supply (in this embodiment, the first power supply represents a power supply with a corresponding voltage value of +5V, and in this embodiment, the first power supply is represented by +5V) through a second resistor R91 in series, and the emitter of the light receiver of the first optocoupler isolator U6G is electrically connected to the first RC filter circuit and the first coupling resistor R98 respectively. The other end of the first coupling resistor R98, which is away from the electrical connection with the emitter of the light receiver of the first optocoupler isolator U6G, is connected to the output end 303 of the comparison unit 32 (corresponding to the reference Figure 3 The network label CS_AD in the figure is electrically connected, where

[0050] The non-inverting proportional amplifier U5A is used to compare the voltages across the precision resistor and generate a first comparison signal according to the detected voltages across the precision resistor.

[0051] In this embodiment, the inverse proportional amplifier includes an LM393 operational amplifier chip (refer to Figure 3 At the same time, the inverting input terminal of the operational amplifier chip corresponding to the proportional amplifier U5A is electrically connected to the output terminal of the operational amplifier chip through the resistor R23, thus forming a corresponding proportional amplifier.

[0052] The first optical coupler isolator U6G is used to convert the first comparison signal into a feedback voltage and output it along the output end of the comparison unit 32 .

[0053] In this embodiment, the first optocoupler isolator U6G includes one of the following: TL431 optocoupler, PC817 optocoupler, TLP521 optocoupler.

[0054] The first RC filter circuit is used to perform signal filtering on the feedback voltage.

[0055] In this embodiment, the first RC filter circuit is composed of a resistor R92 and a capacitor C88.

[0056] In this embodiment, the control unit 100 receives the filtered feedback voltage and determines the current water temperature based on the corresponding feedback voltage. If the current water temperature (for example, 61°C) is not less than the preset water temperature value (for example, the insulation water temperature corresponding to warm boiled water is set to 60°C), the control signal for controlling the power switch 21 to be disconnected is output. Specifically, refer to Figure 2 and Figure 3 , the main control chip U6 corresponding to the control unit 100 along its power regulation control port (reference Figure 2 The P62 pin of the main control chip U6 outputs a low-level Triac1 signal, which is transmitted to the controlled end 203 of the power switch 21 through the corresponding power switch drive circuit 22 (refer to Figure 3 G terminal of TR1 in the middle), the input terminal 202 and the output terminal 201 of the power switch 21 are disconnected, the corresponding series circuit is open, and the heating wire 400 stops heating; when the current water temperature is lower than the preset water temperature value, the control unit 100 continuously outputs the control signal to enable the power switch 21 to be turned on, that is, the input terminal 202 and the output terminal 201 of the power switch 21 are connected, the corresponding series circuit is connected, and the heating wire 400 continues to be energized and heating.

[0057] In some of these embodiments, reference Figures 1 to 4 The power control module 200 further includes a power switch driving circuit 22, which includes an optocoupler thyristor relay UA and a first switch tube Q1. The first switch tube Q1 includes a first port, a second port, and a third port. The first port is electrically connected to a third resistor R114 and a fourth resistor R116, respectively. The other end of the third resistor R114, which is away from the electrical connection to the first port, is electrically connected to the power regulation control port 102 (reference Figure 2The P62 pin of the main control chip U6 in the middle is electrically connected to the fifth resistor R137, the other end of the fourth resistor R116 away from the electrical connection with the first port is electrically connected to the third port and is grounded, the other end of the fifth resistor R137 away from the electrical connection with the third resistor R114 is electrically connected to the first power supply, the second port is electrically connected to the cathode of the light emitter of the optocoupler-controllable silicon relay UA, the anode of the light emitter of the optocoupler-controllable silicon relay UA is electrically connected to the first power supply through the seventh resistor R113 in series, the first electrode of the light receiver of the optocoupler-controllable silicon relay UA is connected in series with the second coupling resistor (composed of the resistor R111 and the resistor R110 in series) and connected to the power switch 21 (reference Figure 3 The output terminal of TR Figure 3 The optocoupler can control the second electrode of the light receiver of the silicon relay UA in series with the third coupling resistor R112 and the controlled end of the power switch 21 (reference Figure 3 The G end of TR1 is electrically connected, wherein

[0058] The control unit 100 is configured to output a corresponding power control signal.

[0059] The first switch tube Q1 is used to control the on and off of the second port and the third port according to the level of the power control signal received by the first port.

[0060] In this embodiment, when the level of the power control signal received by the first port is a preset high level, the second port and the third port are connected; when the level of the power control signal received by the first port is a preset low level, the second port and the third port are disconnected.

[0061] It should be noted that the first switch tube Q1 in the embodiment of the present application includes but is not limited to a triode, a MOS tube, and a field-effect transistor. Moreover, based on the content disclosed in the present application, a person skilled in the art can easily think of modifying the first switch tube disclosed in the present application into a power switch drive circuit that is suitable for the selection of the switch tube according to the specific selection of the first switch tube. Therefore, whether the switch tube is an NPN-type or PNP-type triode, an N-channel or P-channel switch MOS tube, or an N-type or P-type field-effect transistor, the present application can be implemented and is not limited in the embodiments of the present application; in some optional implementation schemes, the first switch tube is preferably a PNP triode of the MMBT5401 model.

[0062] The optocoupler-controlled silicon relay UA is used to generate a first control signal output along the second electrode of the light receiver of the optocoupler-controlled silicon relay UA when the second port is connected to the third port, and to generate a second control signal output along the first electrode of the light receiver of the optocoupler-controlled silicon relay when the second port is disconnected from the third port.

[0063] In this embodiment, the optocoupler-controllable silicon relay UA includes one of the following: MOC3063 optocoupler, MOC3021 optocoupler, and IL420 optocoupler.

[0064] The power switch 21 is used to control the input end and the output end of the power switch 21 to be connected when receiving the first control signal output by the optocoupler controllable silicon relay UA, and to control the input end and the output end of the power switch to be disconnected when receiving the second control signal output by the optocoupler controllable silicon relay UA.

[0065] The series circuit is used to control the connection or disconnection between the heating wire 400 and the neutral line N according to the connection and disconnection of the input terminal 202 and the output terminal 201 of the power switch 21, so that the heating wire 400 generates heat accordingly.

[0066] In this embodiment, when the input end 202 and the output end 201 of the power switch 21 are disconnected, the corresponding series circuit is open and the heating wire 400 stops heating; when the input end 202 and the output end 201 of the power switch 21 are connected, the corresponding series circuit is connected and the heating wire 400 is energized to heat.

[0067] In some of these embodiments, reference Figures 1 to 4 The power control module 200 also includes a zero-crossing detection circuit 23, which includes a first sampling circuit and a second optocoupler UE. The first sampling circuit includes a first diode D4, a first voltage-dividing resistor (composed of a resistor RX1 and a resistor RX2 connected in series), and a second voltage-dividing resistor RX3 electrically connected in series. The anode of the first diode D4 is electrically connected to the live wire L, and the electrical connection point between the first voltage-dividing resistor and the second voltage-dividing resistor RX3 (corresponding to the electrical connection point between RX2 and RX3, which is also the corresponding sampling point) is electrically connected to the anode of the light emitter of the second optocoupler UE. The other end of the second voltage-dividing resistor RX3, which is away from the electrical connection with the first voltage-dividing resistor, is electrically connected to the neutral wire N and the cathode of the light emitter of the second optocoupler UE (reference Figure 3 The collector of the light receiver of the second optocoupler UE is electrically connected to the first power supply (corresponding to a +5V power supply) through the first pull-up resistor R27, and the emitter of the light receiver of the second optocoupler UE is electrically connected to the second RC filter circuit (composed of a resistor R28 and a capacitor C12) and the fourth coupling resistor R130, respectively. The other end of the second RC filter circuit away from the electrical connection to the emitter of the light receiver of the second optocoupler UE is connected to the ground, and the other end of the fourth coupling resistor R130 away from the electrical connection to the emitter of the light receiver of the second optocoupler UE is connected to the zero-crossing detection port (reference port) of the control unit 100. Figure 2 The P137 pin of U6 in the figure and the corresponding connection and signal transmission can be referred to Figure 2 and Figure 3 The network label ZERO in the figure is electrically connected, wherein:

[0068] The first sampling circuit is used to sample a DC detection signal representing the voltage of the AC power of the mains grid.

[0069] In this embodiment, the input end of the first sampling circuit is connected to the resistor R133 that couples the mains power grid to the control circuit of the electric kettle. The AC signal of the mains power grid is converted into a DC signal after passing through the first diode D4, and then the signal is sampled by a voltage dividing circuit composed of a first voltage dividing resistor and a second voltage dividing resistor RX3. Based on the sampled signal, the voltage of the AC power of the mains power grid is determined; in this embodiment, the DC detection signal is a pulsating DC voltage.

[0070] The second optical coupler UE is configured to convert the DC detection signal into a corresponding zero-crossing detection signal.

[0071] In this embodiment, the second optocoupler UE includes but is not limited to one of the following: PC817, EL817, TLP781. In this embodiment, PC817 is preferred. A linear optocoupler is used to achieve strong and weak electrical isolation and improve circuit safety.

[0072] In this embodiment, when the level corresponding to the DC detection signal is 0V, the light emitting device of the second optocoupler UE does not work, the second optocoupler UE is cut off, and the output terminal ZERO of the zero-crossing detection circuit outputs a low level. When the level corresponding to the DC detection signal is not 0, the light emitting device of the second optocoupler UE works, the second optocoupler UE is turned on, and the output terminal ZERO of the zero-crossing detection circuit outputs a high level.

[0073] The control unit 100 is configured to generate a corresponding zero-crossing control signal according to the level of the zero-crossing detection signal, and control the switching of the power switch 21 based on the corresponding zero-crossing control signal.

[0074] In this embodiment, within one cycle of the DC detection signal, the second optocoupler UE is in the on state most of the time. The zero-crossing control signal is a very narrow rectangular pulse. After the P137 pin of the main control chip U6 corresponding to the control unit 100 receives the rectangular pulse, the power output is controlled according to the time when the rectangular pulse appears.

[0075] In some of these embodiments, reference Figures 1 to 6 The control circuit of the embodiment of the present application further includes an alarm circuit 500, which includes a buzzer SP1 and a buzzer drive circuit. The buzzer drive circuit includes a second switch tube Q14. The second switch tube Q14 includes a fourth port, a fifth port, and a sixth port. The fourth port is connected to the alarm control port of the control unit 100 (see FIG. 1 ) via a fifth coupling resistor R38 in series. Figure 3The fourth port is also electrically connected to the fifth port through an RC bypass circuit composed of a first capacitor C34 and a sixth resistor R39. The fifth port is also grounded. The sixth port is respectively electrically connected to the first electrode of the buzzer SP1 and the seventh resistor R37. The other end of the seventh resistor R37 away from the electrical connection with the sixth port is respectively electrically connected to the second electrode of the buzzer SP1 and the eighth resistor R36. The other end of the eighth resistor R36 away from the electrical connection with the seventh resistor R37 is connected to the first power supply (corresponding to a +5V power supply).

[0076] In this embodiment, the control unit 100 judges the corresponding working status of the electric kettle during operation based on the corresponding module connected to it, for example: whether the water temperature reaches the boiling point, whether the water temperature reaches the water temperature threshold of the set mode, whether there is water in the electric kettle, abnormal boiling of water, abnormal pumping of water, etc. When it is determined that an abnormality occurs or exceeds the normal working state, the alarm module 500 is controlled to alarm.

[0077] In this embodiment, when an alarm is needed, the main control chip U6 corresponding to the control unit 100 outputs a high level along its alarm control port. After the fourth port of the second switch tube Q14 receives the high level, it controls its fifth port and sixth port to be connected, so that the fifth port is pulled down to the ground, and the buzzer SP1 is powered on and works, thereby realizing an alarm.

[0078] It should be noted that the second switch tube Q14 in the embodiment of the present application includes but is not limited to a triode, a MOS tube, and a field-effect transistor. Moreover, based on the content disclosed in the present application, a person skilled in the art can easily think of modifying the second switch tube disclosed in the present application into an alarm circuit 500 that is compatible with the selection of the switch tube according to the specific selection of the second switch tube. Therefore, whether the switch tube is an NPN-type or PNP-type triode, an N-channel or P-channel switch MOS tube, or an N-type or P-type field-effect transistor, the present application can be implemented and is not limited in the embodiment of the present application.

[0079] In some of these embodiments, reference Figures 1 to 9 The control circuit of the embodiment of the present application further includes a water adding module 600, a weighing module 700 and a display module 800 electrically connected to the control unit 100, wherein:

[0080] refer to Figure 2 、 Figure 5 and Figure 7 , the water adding module 600 includes a water pump (refer to Figure 7 CN11 interface in) and a water pump driving circuit, the water pump driving circuit includes a third switch tube Q12, the third switch tube Q12 includes a seventh port, an eighth port and a ninth port, the positive electrode of the water pump is connected to the second power supply (corresponding to a +12V power supply, reference Figure 7The negative electrode of the water pump is electrically connected to the seventh port, and the eighth port is electrically connected to the water supply control port (reference port) of the control unit 100 via the sixth coupling resistor R1 in series. Figure 2 The ninth port is electrically connected to the ground via a seventh coupling resistor (including resistors R43 and R44 connected in parallel), wherein:

[0081] The third switch tube Q12 is used to control the connection and disconnection of the seventh port and the ninth port according to the water supply control signal received by the eighth port, so as to control the water pump to perform corresponding pumping work by enabling the connection and disconnection of the negative electrode of the water pump and the ground.

[0082] In this embodiment, when water needs to be added to the electric kettle, the main control chip U6 corresponding to the control unit 100 outputs a high-level water supply control signal along its water supply control port, so that the third switch tube Q12 connects its seventh port with the ninth port, thereby pulling the negative electrode of the water pump down to the ground through the seventh coupling resistor, and the water pump is powered on to pump water into the electric kettle; when the water level in the electric kettle reaches the set water level, the main control chip U6 corresponding to the control unit 100 outputs a low-level water supply control signal along its water supply control port, so that the third switch tube Q12 is cut off and the water pump stops pumping water.

[0083] In this embodiment, the amount of water pumped in is measured by the weighing module 700 to determine whether the amount of water in the electric kettle reaches the set amount of water. It can be understood that the capacity of the pumped water can be calculated by the weight of the pumped water and the density of the water; of course, other metering methods can also be used to measure the amount of water pumped in, for example: calculating the capacity of the pumped water based on the flow rate and pumping time of the water pump; at the same time, the operation of the water pump can also be controlled by controlling its pumping time. After the working time is reached, the water pump stops pumping water, and the pumping control work can also be achieved.

[0084] It should be noted that the third switch tube in the embodiment of the present application includes but is not limited to a triode, a MOS tube, and a field-effect transistor. Moreover, based on the content disclosed in the present application, those skilled in the art can easily think of modifying the third switch tube disclosed in the present application into a water pump drive circuit that is compatible with the selection of the switch tube according to the specific selection of the third switch tube. Therefore, whether the switch tube is an NPN-type or PNP-type triode, an N-channel or P-channel switch MOS tube, or an N-type or P-type field-effect transistor, the present application can be implemented. This is not limited in the embodiment of the present application. In one optional embodiment, the third switch tube Q12 is preferably a PAN2060P model MOS tube.

[0085] refer to Figure 2 、 Figure 5 and Figure 8The weighing module 700 includes an electronic scale unit composed of an HX711 analog-to-digital conversion chip U1 and peripheral resistors (resistor R101, resistor R47, resistor R48, resistor R49, resistor R50, resistor R51) and capacitors (capacitor C25, capacitor C26, capacitor C27, capacitor C28, capacitor C30, capacitor C31); To adapt the operation of the electronic scale unit, refer to Figure 8 In the embodiment of the present application, the weighing module 700 further includes a push-pull voltage conversion circuit composed of a fourth switch tube Q15 and a fifth switch tube Q16, in conjunction with surrounding resistors and capacitors. Specifically, the input end of the fourth switch tube Q15 is electrically connected to a first power supply (corresponding to +5V), and the output end of the fourth switch tube Q15 is a power supply port (+5-ECO) of the electronic scale unit. The input end of the fourth switch tube Q15 is also electrically connected to a controlled end of the fourth switch tube Q15 and a resistor R56 via a bypass resistor R57. The other end of the resistor R56 is electrically connected to the input end of the fifth switch tube Q16. The controlled end of the fifth switch tube Q16 is connected to an I / O port of the main control chip U6 corresponding to the control unit 100 via a resistor R54 (see FIG. 2 ). Figure 2 The P10 pin of U6 in the circuit is connected to the P10 pin of U6 in the circuit, and is connected using the network label wifi). The controlled end of the fifth switch tube Q16 is connected to the output end of the fifth switch tube Q16 and ground via a bypass resistor R55. During weighing operation, the control unit 100 outputs a high-level control signal through the corresponding I / O port. The controlled end of the fifth switch tube Q16 receives the corresponding control signal and controls its input end and output end to be conductive, thereby pulling the controlled end of the fourth switch tube Q15 down to ground. The input end and output end of the fourth switch tube Q15 are conductive, and the fourth switch tube Q15 converts the first power supply (+5V) into the corresponding power supply voltage (+5-ECO), thereby starting the electronic scale unit.

[0086] The fourth switch tube and the fifth switch tube in the embodiment of the present application include but are not limited to triodes, MOS tubes, and field-effect transistors. Moreover, based on the content disclosed in the present application, those skilled in the art can easily think of modifying the third switch tube disclosed in the present application into a push-pull voltage conversion circuit that is compatible with the selection of the switch tube according to the specific selection of the fourth switch tube and the fifth switch tube. Therefore, whether the switch tube is an NPN-type or PNP-type triode, an N-channel or P-channel switch MOS tube, or an N-type or P-type field-effect transistor, the present application can be implemented. This is not limited in the embodiment of the present application. In the present embodiment, the fourth switch tube Q15 is preferably a MOS tube, and the fifth switch tube Q16 is preferably a triode.

[0087] refer to Figure 5 and Figure 9The display module 800 includes a liquid crystal display unit and multiple LED indicators composed of a TM1640 display chip IC1, peripheral capacitors (C2, C3, C36, C40), resistors (R67, R68, R69, R71, R72) and inductors (L5, L6). The control unit 100 controls the electrical connection between the liquid crystal display unit and the multiple LED indicators.

[0088] Figure 10 This is a topological circuit diagram of the power supply module of the preferred embodiment of the present application. In order to realize power supply to the control unit 100, the power control module 200, the temperature control module 300, the alarm module 500, the water adding module 600, the weighing module 700 and the display module 800, so as to form a first power supply (outputting a first voltage of +5V) and a second voltage (outputting a second voltage of +12V), reference is made to FIG. Figure 5 、 Figure 10 The control circuit of the embodiment of the present application further includes a power supply module 900, which includes:

[0089] A rectifier circuit includes a varistor VR1, a filter capacitor X1, and a rectifier bridge BD1. The varistor VR1 and filter capacitor X1 form a front-end filter unit. The input of the front-end filter unit is connected to the mains (live wire L and neutral wire N), and the output is connected to the input of the rectifier bridge BD1. The output of the rectifier bridge BD1 is connected to the primary winding of the inverter transformer TF1. The rectifier circuit is used to rectify the AC power input from the mains into a DC voltage. The inverter transformer TF1 also includes a secondary winding and an auxiliary winding.

[0090] The control circuit includes a switching power supply control chip U9. The power supply port VDD of the switching power supply control chip U9 is electrically coupled to the output end of the rectifier circuit through a voltage divider circuit composed of multiple resistors (R5, R6) connected in series. The power supply port VDD is also electrically connected to the same-name end of the auxiliary winding through a voltage stabilizing circuit composed of a second diode D3 and a current-limiting resistor R9 connected in series. The feedback port FB of the switching power supply control chip U9 is also electrically connected to the same-name end of the auxiliary winding through a positive feedback circuit composed of multiple sampling resistors (R10, R11) connected in series. The power switch control port of the switching power supply control chip U8 (reference Figure 10 Pins 5-8 of U9 in the circuit are electrically connected to the same-named terminals of the primary winding. The secondary winding is electrically connected to the output terminal of the power module 900 through an output rectifier circuit and a step-down circuit that are electrically connected in sequence. The output rectifier circuit includes a parallel rectifier diode D1 and an RC absorption network (composed of R14 and C4). The step-down circuit includes a DC step-down unit composed of a three-terminal voltage regulator U8 and surrounding capacitors and inductors.

[0091] In this embodiment, the switching power supply control chip U8 includes but is not limited to a VIPER22A chip, and the three-terminal voltage regulator U8 includes but is not limited to an AMS1117-5.0V linear voltage regulator.

[0092] In this embodiment, the rectifier circuit is used to provide power for starting the switching power supply control chip U9; the auxiliary winding is used to supply power to the switching power supply control chip U9 after it is started.

[0093] In this embodiment, the switching power supply control chip U9 is used to obtain a state signal reflecting the DC voltage output by the rectifier circuit through a positive feedback circuit to control the on / off of the internal power switch, so that the inverter transformer TF1 converts the DC voltage rectified by the rectifier circuit into a high-frequency square wave pulse voltage and outputs it along the secondary winding.

[0094] In this embodiment, the output rectifier circuit is used to rectify the high-frequency square wave pulse voltage into a second voltage (+12V) corresponding to the second power supply; the step-down circuit is used to step down the second voltage into a first voltage (+5V) corresponding to the first power supply.

[0095] It can be understood that the power supply module 900 of the embodiment of the present application can be a switching power supply built based on the VIPER22A chip in the prior art, or can be other existing switching power supply modules.

[0096] An embodiment of the present application further provides an electric kettle, comprising a kettle body, on which is provided a control circuit for controlling the operation of the electric kettle, the control circuit being the control circuit of the electric kettle in the above embodiment.

[0097] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive and also include other elements not explicitly listed, or also include elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0098] The foregoing description is intended only to provide specific embodiments of the present invention, intended to enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but rather to be construed in the broadest manner consistent with the principles and novel features claimed herein.

Claims

1. A control circuit for an electric kettle, characterized in that: It includes a control unit, a power control module, a temperature detection module and a heating wire, one end of the heating wire is electrically connected to the live wire of the mains power grid, and the other end is electrically connected to the output end of the power switch of the power control module. The temperature detection module includes a precision resistor and a comparison unit, one end of the precision resistor is electrically connected to the neutral wire of the mains power grid and the first input end of the comparison unit respectively, and the other end is electrically connected to the input end of the power switch and the second input end of the comparison unit respectively. The output end of the comparison unit is electrically connected to the temperature detection port of the control unit, the controlled end of the power switch is coupled and electrically connected to the power regulation control port of the control unit, and the heating wire, the power switch and the precision resistor form a series circuit with two ends electrically connected to the live wire and the neutral wire respectively, wherein, The comparison unit is used to detect the voltage across the precision resistor and generate a feedback voltage reflecting the temperature change of the heating wire according to the detected voltage across the precision resistor; The control unit is used to control the switching of the power switch based on the current water temperature determined according to the received feedback voltage, so as to control the on-off of the series circuit, and to control the on-off of the heating wire and the neutral line through the series circuit, so as to correspondingly control the heating of the heating wire and control the water temperature.

2. The control circuit of the electric kettle according to claim 1, characterized in that: The comparison unit includes a non-inverting proportional amplifier, a first optocoupler isolator, and a first RC filter circuit. The non-inverting proportional amplifier includes a first negative input terminal, a first positive input terminal, and a first output terminal. The first negative input terminal is connected to the first input terminal, and the first positive input terminal is connected to the second input terminal. The first output terminal is electrically connected to the anode of the light emitter of the first optocoupler isolator via a first resistor in series. The cathode of the light emitter of the first optocoupler isolator is connected to the ground. The collector of the light receiver of the first optocoupler isolator is electrically connected to the first power supply via a second resistor in series. The emitter of the light receiver of the first optocoupler isolator is electrically connected to the first RC filter circuit and the first coupling resistor, respectively. The other end of the first coupling resistor, which is away from the end electrically connected to the emitter of the light receiver of the first optocoupler isolator, is electrically connected to the output terminal of the comparison unit. The non-inverting proportional amplifier is used to compare the voltages across the precision resistor and generate a first comparison signal according to the detected voltages across the precision resistor; The first optical coupler isolator is used to convert the first comparison signal into the feedback voltage and output it along the output end of the comparison unit; The first RC filter circuit is used to perform signal filtering on the feedback voltage.

3. The control circuit of the electric kettle according to claim 1, characterized in that: The power control module also includes a power switch drive circuit, which includes an optocoupler thyristor relay and a first switch tube. The first switch tube includes a first port, a second port, and a third port. The first port is electrically connected to a third resistor and a fourth resistor respectively. The other end of the third resistor away from the electrical connection with the first port is electrically connected to the power regulation control port and the fifth resistor respectively. The other end of the fourth resistor away from the electrical connection with the first port is electrically connected to the third port and to ground. The other end of the fifth resistor away from the electrical connection with the third resistor is electrically connected to a first power supply. The second port is electrically connected to the cathode of the light emitter of the optocoupler thyristor relay. The anode of the light emitter of the optocoupler thyristor relay is electrically connected to the first power supply via a seventh resistor in series. The first electrode of the light receiver of the optocoupler thyristor relay is connected in series with a second coupling resistor to the output end of the power switch. The second electrode of the light receiver of the optocoupler thyristor relay is connected in series with a third coupling resistor to the controlled end of the power switch. The control unit is configured to output a corresponding power control signal; The first switch tube is used to control the on / off of the second port and the third port according to the level of the power control signal received by the first port; The optocoupler-controlled silicon relay is configured to generate a first control signal output along a second electrode of a light receiver of the optocoupler-controlled silicon relay when the second port is connected to the third port, and to generate a second control signal output along a first electrode of the light receiver of the optocoupler-controlled silicon relay when the second port is disconnected from the third port; The power switch is configured to control the input end and the output end of the power switch to be connected when receiving the first control signal output by the optocoupler-controllable silicon relay, and to control the input end and the output end of the power switch to be disconnected when receiving the second control signal output by the optocoupler-controllable silicon relay; The series circuit is used to control the connection or disconnection of the heating wire and the neutral line according to the on-off of the input end and the output end of the power switch, so that the heating wire generates heat accordingly.

4. The control circuit of the electric kettle according to claim 1, characterized in that: The power control module also includes a zero-crossing detection circuit, which includes a first sampling circuit and a second optocoupler. The first sampling circuit includes a first diode, a first voltage-dividing resistor, and a second voltage-dividing resistor electrically connected in series. The anode of the first diode is electrically connected to the live wire, and the electrical connection point between the first voltage-dividing resistor and the second voltage-dividing resistor is electrically connected to the anode of the light emitter of the second optocoupler. The other end of the second voltage-dividing resistor, which is away from the electrical connection with the first voltage-dividing resistor, is electrically connected to the neutral wire and the cathode of the light emitter of the second optocoupler, respectively. The collector of the light receiver of the second optocoupler is electrically connected to the first power supply through a first pull-up resistor. The emitter of the light receiver of the second optocoupler is electrically connected to a second RC filter circuit and a fourth coupling resistor, respectively. The other end of the second RC filter circuit, which is away from the electrical connection with the emitter of the second optocoupler, is connected to ground. The other end of the fourth coupling resistor, which is away from the electrical connection with the emitter of the second optocoupler, is electrically connected to the zero-crossing detection port of the control unit. The first sampling circuit is used to sample a DC detection signal representing the voltage of the AC power of the mains grid; The second optocoupler is used to convert the DC detection signal into a corresponding zero-crossing detection signal; The control unit is configured to generate a corresponding zero-crossing control signal according to the level of the zero-crossing detection signal, and control the switching of the power switch based on the corresponding zero-crossing control signal.

5. The control circuit of the electric kettle according to claim 1, characterized in that: The control circuit also includes an alarm circuit, which includes a buzzer and a buzzer drive circuit. The buzzer drive circuit includes a second switching tube, and the second switching tube includes a fourth port, a fifth port and a sixth port. The fourth port is electrically connected to the alarm control port of the control unit through a fifth coupling resistor in series. The fourth port is also electrically connected to the fifth port through an RC bypass circuit composed of a first capacitor and a sixth resistor. The fifth port is also connected to the ground. The sixth port is respectively electrically connected to the first pole and the seventh resistor of the buzzer. The other end of the seventh resistor is away from the electrical connection with the sixth port and is respectively electrically connected to the second pole and the eighth resistor of the buzzer. The other end of the eighth resistor is away from the electrical connection with the seventh resistor and is electrically connected to the first power supply.

6. The control circuit of the electric kettle according to claim 1, characterized in that: The control circuit further includes a water adding module, the water adding module includes a water pump and a water pump driving circuit, the water pump driving circuit includes a third switch tube, the third switch tube includes a seventh port, an eighth port and a ninth port, the positive electrode of the water pump is electrically connected to the second power supply, the negative electrode of the water pump is electrically connected to the seventh port, the eighth port is electrically connected to the water supply control port of the control unit via a sixth coupling resistor in series, and the ninth port is electrically connected to the ground via the seventh coupling resistor, wherein, The third switch tube is used to control the connection and disconnection of the seventh port and the ninth port according to the water supply control signal received by the eighth port, so as to control the water pump to perform corresponding pumping work by enabling the connection and disconnection between the negative electrode of the water pump and the ground.

7. The control circuit of the electric kettle according to claim 1, characterized in that: The control circuit further includes a weighing module and a display module electrically connected to the control unit, wherein: The weighing module includes an electronic scale unit composed of an HX711 analog-to-digital conversion chip and peripheral resistors and capacitors; The display module includes a liquid crystal display unit composed of a TM1640 display chip, peripheral capacitors, resistors and inductors, and multiple LED indicator lights. The control unit controls the electrical connection between the liquid crystal display unit and the multiple LED indicator lights.

8. The control circuit of the electric kettle according to claim 1, characterized in that: The control circuit further includes a power supply module, which includes: A rectifier circuit comprising a varistor, a filter capacitor, and a rectifier bridge stack. The varistor and filter capacitor constitute a front-end filter unit. The input of the front-end filter unit is connected to the mains power grid, and the output of the front-end filter unit is connected to the input of the rectifier bridge stack. The output of the rectifier bridge stack is connected to the primary winding of the inverter transformer. The rectifier circuit is used to rectify the AC power input from the mains power grid into a DC voltage. The inverter transformer also includes a secondary winding and an auxiliary winding. A control circuit includes a switching power supply control chip, wherein the power supply port of the switching power supply control chip is electrically coupled to the output end of the rectifier circuit via a voltage divider circuit composed of multiple resistors connected in series, the power supply port is also electrically connected to the same-name end of the auxiliary winding via a voltage stabilization circuit composed of a second diode and a current-limiting resistor connected in series, the feedback port of the switching power supply control chip is also electrically connected to the same-name end of the auxiliary winding via a positive feedback circuit composed of multiple sampling resistors connected in series, the power switch control port of the switching power supply control chip is electrically connected to the same-name end of the primary winding, and the secondary winding is electrically connected to the output end of the power module via an output rectifier circuit and a step-down circuit electrically connected in sequence, the output rectifier circuit includes a parallel rectifier diode and an RC absorption network, and the step-down circuit includes a DC step-down unit composed of a three-terminal voltage regulator tube and surrounding capacitors and inductors, wherein: The rectifier circuit is used to provide power for starting the switching power supply control chip; The auxiliary winding is used to supply power to the switching power supply control chip after it is started; The switching power supply control chip is used to obtain a state signal reflecting the DC voltage output by the rectifier circuit through the positive feedback circuit to control the on / off of the internal power switch, so that the inverter transformer converts the DC voltage rectified by the rectifier circuit into a high-frequency square wave pulse voltage and outputs it along the secondary winding; The output rectifier circuit is used to rectify the high-frequency square wave pulse voltage into a second voltage corresponding to the second power supply; The step-down circuit is used to step down the second voltage to a first voltage corresponding to the first power supply.

9. The control circuit of the electric kettle according to any one of claims 1 to 8, characterized in that: The control unit includes one of the following: a single chip microcomputer MCU, a digital signal processor DSP, and a programmable logic device FPGA.

10. An electric kettle, characterized in that: The invention comprises a kettle body, wherein the kettle body is provided with a control circuit for controlling the operation of the electric kettle, and the control circuit comprises the control circuit of the electric kettle according to any one of claims 1 to 9.

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