CN210518903U

CN210518903U - Low-power standby circuit and induction cooker

Info

Publication number: CN210518903U
Application number: CN201921561573.6U
Authority: CN
Inventors: 孙鹏刚; 赵礼荣
Original assignee: Zhejiang Shaoxing Supor Domestic Electrical Appliance Co Ltd
Current assignee: Zhejiang Shaoxing Supor Domestic Electrical Appliance Co Ltd
Priority date: 2019-09-19
Filing date: 2019-09-19
Publication date: 2020-05-12
Anticipated expiration: 2029-09-19

Abstract

The utility model provides a low-power standby circuit and electromagnetism stove, this low-power standby circuit, include: EMC filter circuit (20), switching power supply circuit (30), little the control unit (40), first rectifier circuit (51), drive circuit (70) and main heating circuit (60), still include: a second rectifying circuit (52), a third rectifying circuit (53), a VCC switching circuit (10), and a controllable switch (80); the micro control unit (40) is used for controlling the VCC switch circuit (10) to be switched off in a standby state, so that the controllable switch (80) is switched off, and the first rectifying circuit (51) and the second rectifying circuit (52) are switched on; the micro control unit (40) is also used for controlling the conduction of the VCC switch circuit (10) in a working state, so that the controllable switch (80) is conducted, and the EMC filter circuit (20), the first rectifying circuit (51) and the third rectifying circuit (53) are conducted, thereby overcoming the problems of large circuit debugging difficulty and high component cost.

Description

Low-power standby circuit and induction cooker

Technical Field

The utility model relates to a household electrical appliances technical field especially relates to a low-power standby circuit and electromagnetism stove.

Background

An induction cooker is a common household appliance for heating. When the induction cooker works, high-frequency alternating current passes through the coil panel to enable the bottom of a pot placed on the induction cooker to generate eddy current, so that the pot arranged on the induction cooker is heated.

In the prior art, in order to prevent the mutual interference between the induction cooker and the power grid when the induction cooker works, the induction cooker must pass the national electromagnetic compatibility (EMC) mandatory standard, and meanwhile, the problem of low standby power of the induction cooker is considered, and chinese patent publication No. CN205946222U discloses a low power standby circuit, wherein fig. 1 is a schematic structural diagram of the low power standby circuit provided in the prior art. As shown in fig. 1, the main heating circuit of the rectifier filter resonant circuit 30 has a first EMC filter circuit 20, and the switching power supply circuit 40 has a second EMC filter circuit 43. In order to avoid charging and discharging of the capacitor in the first EMC filter circuit 20 when the induction cooker is in the standby state, thereby increasing the standby power consumption of the circuit, the first EMC filter circuit 20 is turned off and the rectifying-filtering resonant circuit 30 is turned off by the controllable switch circuit 50 during standby, so as to reduce the standby power consumption.

However, in the prior art, the switching power supply circuit and the main heating circuit are respectively provided with the EMC filter circuit, which not only causes great difficulty in debugging the circuit, but also causes higher cost due to more components.

SUMMERY OF THE UTILITY MODEL

An embodiment of the utility model provides a low-power standby circuit and electromagnetism stove to it is big to overcome the circuit debugging degree of difficulty, and the many problems with high costs of component.

In a first aspect, the present invention provides a low power standby circuit, comprising: EMC filter circuit, switching power supply circuit, little the control unit, first rectifier circuit, drive circuit and main heating circuit still include: the second rectifying circuit, the third rectifying circuit, the VCC switch circuit and the controllable switch; wherein

The controllable switch is respectively connected with a mains supply, the EMC filter circuit and the VCC switch circuit, and the first rectifying circuit is respectively connected with the EMC filter circuit and the main heating loop;

the second rectifying circuit is respectively connected with the commercial power at the upstream of the controllable switch, the switching power supply circuit and the third rectifying circuit, and the third rectifying circuit is respectively connected with the second rectifying circuit, the switching power supply circuit, the EMC filter circuit and the first rectifying circuit;

the micro control unit is respectively connected with the driving circuit, the switching power supply circuit and the VCC switch circuit, and the driving circuit is also respectively connected with the main heating circuit and the VCC switch circuit;

the micro control unit is used for controlling the VCC switch circuit to be switched off when in a standby state, so that the controllable switch is switched off, and the first rectifying circuit and the second rectifying circuit are switched on;

the micro control unit is also used for controlling the conduction of the VCC switch circuit in a working state, so that the controllable switch is conducted, and the EMC filter circuit, the first rectifying circuit and the third rectifying circuit are conducted.

The low-power standby circuit and the induction cooker provided by the embodiment comprise a micro control unit, a first rectifying circuit, a driving circuit, a main heating loop, a second rectifying circuit, a third rectifying circuit, a VCC switch circuit and a controllable switch; the micro control unit controls the disconnection of the VCC switch circuit in a standby state to disconnect the controllable switch, the EMC filter circuit and the main heating circuit to reduce energy consumption, the second rectifier circuit and part of the rectifier devices of the first rectifier circuit are conducted to form half-wave rectification to maintain the load output of the switching power supply circuit, when the VCC switch circuit is disconnected, other VCC circuits such as a driving circuit, a fan and the like can not obtain VCC voltage, thereby further reducing energy consumption in standby state, the micro control unit controls the conduction of the VCC switch circuit in a working state to conduct the controllable switch, the third rectifier circuit and part of the rectifier devices of the first rectifier circuit are conducted to form half-wave or full-bridge rectification to maintain the load output of the switching power supply circuit, and simultaneously the main heating circuit and the switching power supply circuit are subjected to electromagnetic compatibility processing through the EMC filter circuit to meet the requirements of the whole machine, because an EMC filter circuit is reduced, the debugging of the circuit is simple, and the cost is reduced.

In one possible implementation, the VCC switch circuit is a triode-type switch circuit, and the controllable switch is a relay, so that the VCC switch circuit is simple in structure and easy to implement and control.

In a possible implementation, the VCC switch circuit includes triode Q1 and triode Q2, triode Q1 with triode Q2 connects, triode Q1 still with the little the control unit connects, triode Q2 still respectively with switching power supply circuit with the relay with drive circuit connects.

The VCC switch circuit is formed by the triode Q1 and the triode Q2, so that the VCC switch circuit is simple in structure and easy to realize. Meanwhile, the two triodes Q1 and Q2 can protect the micro-control unit and prevent the influence of large current on the micro-control unit.

In one possible implementation, the transistor Q1 is an NPN-type transistor, and the transistor Q2 is a PNP-type transistor;

the base electrode of the triode Q1 is connected with the micro control unit, the emitting electrode of the triode Q1 is grounded, the collector electrode of the triode Q2 is connected with the base electrode of the triode Q2, the collector electrode of the triode Q2 is respectively connected with the relay and the driving circuit, and the emitting electrode of the triode Q2 is connected with the switching power supply circuit.

In one possible implementation, the relay is a normally open relay.

In one possible implementation, the first rectifying circuit is a bridge rectifying circuit.

In one possible implementation, the second rectification circuit includes a diode D1 and a diode D2 connected in series;

the positive pole of the diode D1 is connected with the live wire of the commercial power, the negative pole of the diode D1 is connected with the positive pole of the diode D2, and the negative pole of the diode D2 is connected with the switching power supply circuit and the third rectifying circuit respectively.

In one possible implementation, the third rectification circuit includes a diode D3;

the positive pole of the diode D3 is connected with the live wire of the commercial power, and the negative pole of the diode D3 is connected with the second rectifying circuit and the switching power supply circuit respectively.

Because the switching power supply circuit adopts half-wave rectification, compared with full-bridge rectification in the prior art, only two diodes are needed, the input voltage is reduced, and the power consumption is further reduced in a standby state.

In a possible implementation manner, the third rectification circuit further includes a diode D4, an anode of the diode D4 is connected to a zero line of the commercial power, and a cathode of the diode D4 is connected to the second rectification circuit and the switching power supply circuit, respectively.

When the induction cooker is in a working state, the diode D4 is added, so that full-bridge rectification can be realized, and the loading capacity of the switching power supply circuit is larger.

In a second aspect, the present invention provides an induction hob including a low power standby circuit as described above in the first aspect or in various possible designs of the first aspect.

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 diagram of a low power standby circuit provided in the prior art;

fig. 2 is a first schematic structural diagram of a low-power standby circuit provided by the present invention;

fig. 3 is a schematic structural diagram of a low power standby circuit according to the present invention;

fig. 4 is a schematic structural diagram of a low power standby circuit provided by the present invention;

fig. 5 is a fourth schematic diagram of the low power standby circuit provided by the present invention;

fig. 6 is a fifth schematic structural diagram of the low power standby circuit provided by the present invention.

Description of reference numerals:

a 10-VCC switching circuit;

20-an EMC filter circuit;

30-a switching power supply circuit;

40-a micro control unit;

51-a first rectifying circuit;

52-a second rectifying circuit;

53-a third rectifier circuit;

60-a primary heating loop;

70-a drive circuit;

80-controllable switch.

Detailed Description

Fig. 2 is a first schematic structural diagram of a low power standby circuit provided by the present invention. As shown in fig. 2, the low power standby circuit provided in the present embodiment includes: EMC filter circuit 20, switching power supply circuit 30, little the control unit 40, first rectifier circuit 51, drive circuit 70 and main heating circuit 60, its characterized in that still includes: a second rectifying circuit 52, a third rectifying circuit 53, a VCC switch circuit 10, and a controllable switch 80; wherein

The controllable switch 80 is respectively connected with the commercial power, the EMC filter circuit 20 and the VCC switch circuit 10, and the first rectifying circuit 51 is respectively connected with the EMC filter circuit 20 and the main heating loop 60;

the second rectifying circuit 52 is connected to the commercial power, the switching power supply circuit 30, and the third rectifying circuit 53 is connected to the second rectifying circuit 52, the switching power supply circuit 30, the EMC filter circuit 20, and the first rectifying circuit 51;

the micro control unit 40 is connected to the driving circuit 70, the switching power supply circuit 30 and the VCC switch circuit 10, respectively, and the driving circuit 70 is further connected to the main heating circuit and the VCC switch circuit 10, respectively.

In the present embodiment, the Electromagnetic Compatibility (EMC) filter circuit 20 can eliminate or reduce Electromagnetic interference between the switching power supply circuit 30 and the main heating circuit 60 during Electromagnetic heating. This EMC filter circuit 20 can be for the circuit that has electromagnetic filter including inductance and electric capacity, and this embodiment does not do special restriction to EMC filter circuit 20's concrete implementation, and all can realize EMC's filter circuit, all belong to the utility model discloses a protection category.

The switching power supply circuit 30 mainly supplies electric energy to the weak current devices, for example, can convert high voltage into low voltage required by the weak current devices, and supplies power to the weak current devices, for example, various control chips, various sensors, and the like.

The first rectifying circuit 51, the second rectifying circuit 52, and the third rectifying circuit 53 may be rectifying circuits including diodes, and the number and the form of the diodes included in the rectifying circuits are not particularly limited in the present embodiment.

The second rectifier circuit 52 is connected to the mains upstream of the controllable switch 80, for example, it may be connected downstream of the FUSE 1. Therefore, when the controllable switch 80 is turned off, the second rectification circuit 52 can be switched into a circuit.

The voltage drop of the second rectifying circuit 52 is larger than that of the third rectifying circuit 53, when the controllable switch 80 is turned on, the second rectifying circuit 52 is disconnected, and the third rectifying circuit 53 can be connected into the circuit.

The controllable switch 80 is a switch capable of being controlled to be turned on and off, the controllable switch 80 may be a relay, the controllable switch 80 may also be a switch formed by a device such as a triode, and the like, and the implementation manner of the controllable switch 80 is not particularly limited in this embodiment.

The VCC switch circuit 60 may be a circuit capable of controlling the circuit on and off, for example, a triode-type switch circuit.

Where Vcc is abbreviated as Volt Current concentrator, it means the power supply voltage of the circuit, power supply voltage.

The main heating circuit 60 may include a resonant circuit, an Insulated Gate Bipolar Transistor (IGBT), wherein the resonant circuit is connected to the first rectifying circuit 51 and the IGBT, respectively, and the driving circuit 70 is connected to the IGBT and the micro control unit 40, respectively.

The working process of the main heating loop 60 mainly comprises: the first rectifying circuit 51 converts commercial power into pulsating direct current, the resonant circuit can convert the pulsating direct current into resonant current, so that a coil panel of the resonant circuit generates a periodically-changed magnetic field, magnetic lines of force penetrate through a furnace surface through a magnetic loop formed by a coil and the bottom of a metal utensil and act on the bottom of a pot, heat is generated by using a short-circuit heat effect of small resistance and large current, eddy current is formed at the bottom of the pot to generate heat, and the effect of heating food in the utensil is achieved. The Micro Control Unit (MCU) 40 may control the driving circuit to operate, so that the driving circuit controls the on/off of the IGBT, and the IGBT is turned on/off to generate the resonant current.

In this embodiment, a detailed description is given by taking an example that the low power standby circuit is applied to an electromagnetic oven, and the implementation manner of applying the low power standby circuit to other devices is similar, and the description of this embodiment is omitted here.

After the power supply is plugged in the induction cooker, the working state of the induction cooker mainly comprises two working states, namely a working state and a standby state. Under operating condition, the electromagnetism stove can heat the pan. In the standby state, the main heating loop of the induction cooker does not work any more. Most of the time, the induction cooker is in a standby state.

In this embodiment, a low-power standby circuit is improved, so that the switching power supply circuit and the main heating circuit share the EMC filter circuit, the circuit structure is optimized, components are reduced, and development difficulty and cost are reduced.

When the induction cooker is in the working state, the micro control unit 40 controls the conduction of the VCC switch circuit 10 in the working state, so that the controllable switch 80 is conducted, and the EMC filter circuit 20, a part of the rectifying devices of the first rectifying circuit 51 and the third rectifying circuit 53 are conducted.

The mcu 40 can control the VCC switch circuit 10 to be turned on, and the VCC switch circuit 10 is a switch circuit for providing a VCC voltage, and when the VCC switch circuit 10 is turned on, the switching power supply circuit 30 can provide the VCC voltage to the outside and turn on the controllable switch 80. When the controllable switch 80 is turned on, the EMC filter circuit 20 is turned on, the main heating circuit 60 and the switching power supply circuit 30 both pass through the EMC filter circuit 20, and the whole machine meets EMC requirements.

Meanwhile, the main heating circuit 60 is rectified by the first rectifying circuit 51, and for the switching power supply circuit 30, a half-wave rectifying circuit or a full-bridge rectifying circuit, which can rectify the switching power supply circuit 30, may be formed by a part of the rectifying devices in the first rectifying circuit 51 and the second rectifying circuit 52. The switching power supply circuit 30 can ensure the output power of the switching power supply under the condition of adjusting the parameters of the switching power supply.

Specifically, the switching power supply circuit 30 and the main Heating circuit 60 share the EMC filter circuit, and in the field of electromagnetic Heating (IH), a main interference source is the main Heating circuit 60, and the power of the switching power supply circuit 30 as the interference source is much smaller than that of the main Heating circuit 60, so that the EMC filter circuit sharing the main Heating circuit 60 can debug the interference of the main Heating circuit 60 and the switching power supply circuit 30 during debugging, that is, debug the EMC filter circuit, and can have the electromagnetic compatibility characteristic.

Furthermore, in a standby state, the output power of the switching power supply circuit is very low, and the interference to the outside is very small; when the IH product is heated, the switching power supply circuit outputs high power, and the switching power supply circuit shares the EMC filter circuit of the main heating loop so as to reduce the interference to the outside.

When the induction cooker is in the standby state, the micro control unit 40 is used for controlling the VCC switch circuit 10 to be switched off in the standby state, so that the controllable switch 80 is switched off, and the first rectification circuit 51 and the second rectification circuit 52 are switched on. When the controllable switch 80 is open, the EMC filter circuit 20 as well as the main heating circuit 60 are open, thereby reducing the energy consumption. Part of the rectifying devices of the first rectifying circuit 51 and the second rectifying circuit 52 are conducted to form half-wave rectification, and the load output of the switching power supply is maintained.

As will be understood by those skilled in the art, in the standby state, the current supplied by the switching power supply circuit 30 is very small, and mainly supplies power to some weak current devices, such as some function keys and micro control units. Thus, the electromagnetic compatibility characteristics of the switching power supply circuit 30 can satisfy the respective standards and the use requirements.

When the VCC switch circuit 10 is turned off, the switch power supply circuit 30 can supply power to the micro control unit 40, and other VCC circuits such as a driving circuit, a fan, etc. cannot obtain a VCC voltage, thereby further reducing power consumption in standby.

The low-power standby circuit provided by the embodiment comprises a micro control unit, a first rectifying circuit, a driving circuit, a main heating loop, a second rectifying circuit, a third rectifying circuit, a VCC switch circuit and a controllable switch; the micro control unit controls the disconnection of the VCC switch circuit in a standby state to disconnect the controllable switch, the EMC filter circuit and the main heating circuit to reduce energy consumption, the second rectifier circuit and part of the rectifier devices of the first rectifier circuit are conducted to form half-wave rectification to maintain the load output of the switching power supply circuit, when the VCC switch circuit is disconnected, other VCC circuits such as a driving circuit, a fan and the like can not obtain VCC voltage, thereby further reducing energy consumption in standby state, the micro control unit controls the conduction of the VCC switch circuit in a working state to conduct the controllable switch, the third rectifier circuit and part of the rectifier devices of the first rectifier circuit are conducted to form half-wave or full-bridge rectification to maintain the load output of the switching power supply circuit, and simultaneously the main heating circuit and the switching power supply circuit are subjected to electromagnetic compatibility processing through the EMC filter circuit to meet the requirements of the whole machine, because an EMC filter circuit is reduced, the debugging of the circuit is simple, and the cost is reduced.

Fig. 3 is a schematic structural diagram of a low power standby circuit according to the present invention, and as shown in fig. 3, the first rectification circuit 51 is a rectifier bridge. The rectifier bridge comprises 4 diodes, and is obtained by butt joint of four diodes in pairs.

The second rectifying circuit 52 includes a diode D1 and a diode D2 connected in series; the anode of the diode D1 is connected to the live wire of the commercial power, the cathode of the diode D1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the switching power supply circuit 30 and the third rectifying circuit 53, respectively.

The third rectifying circuit 53 includes a diode D3; the anode of the diode D3 is connected to the live line of the commercial power, and the cathode of the diode D3 is connected to the second rectifier circuit 52 and the switching power supply circuit 30, respectively.

It will be understood by those skilled in the art that when the anode of the diode D3 is connected to the hot line of the utility power, it suffices that the anode of the diode D3 is connected to the EMC filter circuit 20.

In this embodiment, the controllable switch 80 is a relay, for example, the relay is a normally open relay RLY 1. That is, the relay is in the off state when no voltage is applied to the relay RLY 1. A current limiting resistor R1 is also provided between the VCC switch circuit 10 and the relay RLY1 to protect the relay RLY1 and prevent an excessive current from flowing through the relay RLY 1.

When the induction cooker is in a standby state, the relay is in an off state, the EMC filter circuit 20 and the main heating circuit 60 are not powered on, and power consumption is not generated. The switching power supply circuit 30 maintains the load output of the switching power supply circuit 30 by forming half-wave rectification by one of the diodes of the rectifying diode D1, the rectifying diode D2, and the rectifying bridge DB 1. When the main heating loop is required to work, the micro control unit 40 outputs a control signal to the VCC switch circuit 10, so that the coil of the relay RY1 is loaded with voltage, the relay RY1 is switched to a closed state, the EMC filter circuit 20 and the main heating loop 60 are powered on, and the work can be started; since the voltage drop of the diode D1+ the diode D2 is greater than that of the diode D3, the two branches are located in the same phase of the input power, the diode D3 is turned on, the diode D1 and the diode D2 are turned off, and the switching power supply circuit 30 forms a half-wave rectifier circuit through the rectifier diode D3 and 1 diode of the rectifier bridge DB1, so as to meet the load output of the switching power supply circuit.

Since the switching power supply circuit 30 employs half-wave rectification, only two diodes are required, and the input voltage is reduced, compared to full-bridge rectification in the prior art, and the power consumption is further reduced in the standby state.

Fig. 4 is a schematic structural diagram of a low power standby circuit according to the present invention. As shown in fig. 4, based on the embodiment shown in fig. 3, the third rectification circuit 53 further includes a diode D4, an anode of the diode D4 is connected to the zero line of the commercial power, and a cathode of the diode D4 is connected to the second rectification circuit 52 and the switching power supply circuit 30, respectively. It will be understood by those skilled in the art that when the anode of the diode D4 is connected to the neutral line of the utility power, it suffices that the anode of the diode D4 is connected to the EMC filter circuit 20.

In the standby state, the embodiment shown in fig. 4 is the same as the embodiment shown in fig. 3. When the induction cooker is in a working state, full-bridge rectification can be realized by adding the diode D4.

The micro control unit 40 outputs a control signal to the VCC switch circuit 10, so that the coil of the relay RY1 is loaded with voltage, the relay RY1 is switched to be in a closed state, the EMC filter circuit 20 and the main heating loop 60 are powered on, and the work can be started; in one half-wave, diode D3 is on, and diode D1 and diode D2 are off, switching power supply circuit 30 forms a half-wave rectifier circuit by rectifying diode D3 and 1 diode of rectifier bridge DB1, in the other half-wave, diode D4 is on, and diode D1 and diode D2 are off, and switching power supply circuit 30 forms a half-wave rectifier circuit by rectifying diode D4 and the other 1 diode of rectifier bridge DB 1. Thus, the diode D3 and the diode D4 form full-bridge rectification, and the load capacity of the switching power supply circuit is increased.

Fig. 5 is a fourth schematic diagram of the operation of the low power standby circuit provided by the present invention, and fig. 6 is a fifth schematic diagram of the structure of the low power standby circuit provided by the present invention. As shown in fig. 5, the VCC switch circuit 10 includes a transistor Q1 and a transistor Q2, the transistor Q1 is connected to the transistor Q2, the transistor Q1 is further connected to the micro control unit 40, and the transistor Q2 is further connected to the switching power supply circuit 30 and the relay and drive circuit 70, respectively.

The VCC switch circuit 10 is formed by the transistor Q1 and the transistor Q2, so that the VCC switch circuit is simple in structure and easy to implement. Meanwhile, the two triodes Q1 and Q2 can protect the micro control unit 40 and prevent the influence of large current on the micro control unit 40.

In one possible implementation, the transistor Q1 is an NPN-type transistor, and the transistor Q2 is a PNP-type transistor; the base electrode of the triode Q1 is connected with the micro control unit 40, the emitter electrode of the triode Q1 is grounded, the collector electrode of the triode Q2 is connected with the base electrode of the triode Q2, the collector electrode of the triode Q2 is respectively connected with the relay and the drive circuit 70, and the emitter electrode of the triode Q2 is connected with the switching power supply circuit 30.

As shown in fig. 5 and 6, the protection circuit further includes a resistor R2, a resistor R3, and a resistor R4, and these resistors are protection resistors capable of achieving voltage division, current limiting, and the like. In a specific implementation process, the resistance may also be increased or decreased according to actual needs, which is not described herein.

When the induction cooker is in a working state and the micro control unit 40 outputs a high level, the triode Q1 is conducted, so that the triode Q2 is conducted, the coil of the relay RY1 is loaded with voltage, the relay RY1 is turned into a closed state, and the EMC filter circuit 20 is conducted and can work.

When the induction cooker is in a standby state, the micro control unit 40 outputs a low level, the triode Q1 is closed, the triode Q2 is closed, no voltage is loaded on the coil of the relay RY1, the relay RY1 is turned into an open state, and the EMC filter circuit 20 is opened and cannot work.

As shown in fig. 5 and 6, the EMC filter circuit 20 includes: common mode inductance L1 and capacitor C1, differential mode inductance L2 and capacitor C2. Two ends of the capacitor C1 are respectively connected with the live wire and the zero wire, and the common mode inductor L1 is arranged between the capacitor C1 and the differential mode inductor L2. The differential mode inductor L2 and the capacitor C2 are arranged between the common mode inductor L1 and the rectifier bridge; two ends of the capacitor C2 are respectively connected with the live wire and the zero wire, and the differential mode inductor L2 is arranged on the live wire or the zero wire and is positioned between the capacitor C2 and the common mode inductor L1. In the present embodiment, the differential-mode inductor L2 is drawn by way of example as being disposed on a fire line.

The anode of the diode D3 may be disposed between the common mode inductor L1 and the differential mode inductor L2, or may be connected to the differential mode inductor L2 and the capacitor C2. The anode of the diode D4 may be disposed between the common mode inductor L1 and the differential mode inductor L2, or may be connected to the differential mode inductor L2 and the capacitor C2.

It will be appreciated by those skilled in the art that when the differential mode inductor L2 and the capacitor C2 are disposed between the common mode inductor L1 and the rectifier bridge, i.e., the differential mode inductor L2 and the second capacitor C2 are disposed upstream of the rectifier bridge, the differential mode inductor L2 and the capacitor C2 may be part of the EMC filter circuit 20, or both, thereby enhancing the electromagnetic compatibility without adding devices.

As shown in fig. 5, when the induction cooker is in the standby state, the relay is in the off state, and the commercial power passes through one of the diodes of the rectifier diode D1, the rectifier diode D2, and the rectifier bridge DB1, so that half-wave rectification is performed to maintain the load output of the switching power supply circuit 30. When the induction cooker is in a working state, the relay is closed, the diode D3 is conducted, the diode D1 and the diode D2 are cut off, and the commercial power passes through the rectifier diode D3 and 1 diode of the rectifier bridge DB1 to carry out half-wave rectification so as to meet the load output of the switching power supply circuit.

As shown in fig. 6, on the basis of fig. 5, when the induction cooker is in the operating state, during another half wave, the commercial power passes through the rectifier diode D4, the rectifier diode D2 and another diode of the rectifier bridge DB1, so as to form full-bridge rectification.

The embodiment also provides an induction cooker which comprises the low-power standby circuit.

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

1. A low power standby circuit comprising: EMC filter circuit (20), switching power supply circuit (30), little the control unit (40), first rectifier circuit (51), drive circuit (70) and main heating circuit (60), its characterized in that still includes: a second rectifying circuit (52), a third rectifying circuit (53), a VCC switching circuit (10), and a controllable switch (80); wherein

The controllable switch (80) is respectively connected with a mains supply, the EMC filter circuit (20) and the VCC switch circuit (10), and the first rectifying circuit (51) is respectively connected with the EMC filter circuit (20) and the main heating loop (60);

the second rectifying circuit (52) is respectively connected with the commercial power at the upstream of the controllable switch (80), the switching power supply circuit (30) and the third rectifying circuit (53), and the third rectifying circuit (53) is respectively connected with the second rectifying circuit (52), the switching power supply circuit (30), the EMC filtering circuit (20) and the first rectifying circuit (51);

the micro control unit (40) is respectively connected with the driving circuit (70), the switching power supply circuit (30) and the VCC switch circuit (10), and the driving circuit (70) is also respectively connected with the main heating circuit and the VCC switch circuit (10);

the micro control unit (40) is used for controlling the VCC switch circuit (10) to be switched off in a standby state, so that the controllable switch (80) is switched off, and the first rectifying circuit (51) and the second rectifying circuit (52) are switched on;

the micro control unit (40) is further used for controlling the conduction of the VCC switch circuit (10) in an operating state, so that the controllable switch (80) is conducted, and the EMC filter circuit (20), the first rectifying circuit (51) and the third rectifying circuit (53) are conducted.

2. The circuit according to claim 1, characterized in that the VCC switch circuit (10) is a triode-type switch circuit and the controllable switch (80) is a relay.

3. The circuit of claim 2, wherein said VCC switch circuit (10) comprises a transistor Q1 and a transistor Q2, said transistor Q1 being connected to said transistor Q2, said transistor Q1 being further connected to said micro control unit (40), said transistor Q2 being further connected to said switching power supply circuit (30) and said relay and said driver circuit (70), respectively.

4. The circuit of claim 3, wherein the transistor Q1 is an NPN transistor, and the transistor Q2 is a PNP transistor;

the base electrode of the triode Q1 is connected with the micro control unit (40), the emitting electrode of the triode Q1 is grounded, the collecting electrode of the triode Q2 is connected with the base electrode of the triode Q2, the collecting electrode of the triode Q2 is respectively connected with the relay and the driving circuit (70), and the emitting electrode of the triode Q2 is connected with the switching power supply circuit (30).

5. The circuit of claim 2, wherein the relay is a normally open relay.

6. A circuit according to claim 1, characterized in that the first rectifier circuit (51) is a bridge rectifier circuit.

7. The circuit of claim 1, wherein the second rectification circuit (52) comprises a diode D1 and a diode D2 in series;

the positive pole of the diode D1 is connected with the live wire of the commercial power, the negative pole of the diode D1 is connected with the positive pole of the diode D2, and the negative pole of the diode D2 is respectively connected with the switching power supply circuit (30) and the third rectifying circuit (53).

8. A circuit according to claim 1, characterized in that the third rectifying circuit (53) comprises a diode D3;

the anode of the diode D3 is connected with the live wire of the commercial power, and the cathode of the diode D3 is respectively connected with the second rectifying circuit (52) and the switch power supply circuit (30).

9. The circuit according to claim 8, wherein the third rectifying circuit (53) further comprises a diode D4, the anode of the diode D4 being connected to the neutral line of the mains supply, and the cathode of the diode D4 being connected to the second rectifying circuit (52) and the switching power supply circuit (30), respectively.

10. An induction hob, characterized in, that it comprises a low power standby circuit according to any one of the claims 1 to 9.