CN209806111U

CN209806111U - Electromagnetic heating circuit and electromagnetic heating appliance

Info

Publication number: CN209806111U
Application number: CN201822075812.9U
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: 2018-12-11
Filing date: 2018-12-11
Publication date: 2019-12-17
Anticipated expiration: 2028-12-11

Abstract

The utility model provides an electromagnetic heating circuit (100) and electromagnetic heating utensil (10). The electromagnetic heating circuit (100) comprises a main loop (100'), a micro-processing unit (101), a level conversion circuit (102), a waveform conversion circuit (103), a push-pull circuit (104) and an IGBT module (105). The first output end of the microprocessing unit (101) is connected with the level conversion circuit (102), the second output end of the microprocessing unit (101) is connected with the waveform conversion circuit (103), the input end of the push-pull circuit (104) is respectively connected with the level conversion circuit (102) and the waveform conversion circuit (103), the output end of the push-pull circuit (104) is connected with the input end of the IGBT module (105), the output end of the IGBT module (105) is connected with the main loop (100'), and the microprocessing unit (101) controls the on-off of the waveform conversion circuit (103), so that the instantaneous current of the IGBT module (105) is greatly reduced when the electromagnetic heating appliance (10) works at low power, and the working condition of the IGBT module (105) is improved.

Description

electromagnetic heating circuit and electromagnetic heating appliance

Technical Field

The utility model relates to an electromagnetism stove technical field especially relates to an electromagnetic heating circuit and electromagnetic heating utensil.

Background

the electromagnetic heating circuit can convert electric energy into heat energy by utilizing the electromagnetic induction principle, and heat the equipment to be heated. The electromagnetic heating circuit has a wide application field, such as various electromagnetic heating appliances needing heating functions, such as electric cookers, electric pressure cookers, soybean milk makers, coffee makers, mixers and the like.

Generally, when an electromagnetic heating appliance is heated at a high power, in a conventional electromagnetic heating circuit, when a voltage across a drain of an Insulated Gate Bipolar Transistor (IGBT) module crosses zero, the IGBT module is turned on, and a current of the IGBT module is small. However, when the electromagnetic heating device is heated at a low power, in the conventional electromagnetic heating circuit, if the drain of the IGBT module still has a certain voltage, the IGBT module is turned on, the current of the IGBT module is large, which easily causes the loss of the IGBT module, and increases the device cost of the electromagnetic heating device.

SUMMERY OF THE UTILITY MODEL

The utility model provides an electromagnetic heating circuit and electromagnetic heating utensil to solve current electromagnetic heating circuit because the electromagnetic heating utensil switches on the instantaneous drain-source electrode current of IGBT module under the miniwatt state and too big and cause the problem of IGBT module damage.

In a first aspect, the present invention provides an electromagnetic heating circuit, including: the device comprises a main loop, a micro-processing unit, a level conversion circuit, a waveform conversion circuit, a push-pull circuit and an insulated gate bipolar transistor IGBT module;

The first output end of the micro-processing unit is connected with the input end of the level conversion circuit, the second output end of the micro-processing unit is connected with the input end of the waveform conversion circuit, the input end of the push-pull circuit is respectively connected with the output end of the level conversion circuit and the output end of the waveform conversion circuit, the output end of the push-pull circuit is connected with the input end of the IGBT module, and the output end of the IGBT module is connected with the main loop;

The micro-processing unit is used for acquiring and detecting the actual power and the target voltage of the electromagnetic heating appliance;

The micro-processing unit is further used for controlling the waveform conversion circuit to be in a conducting state when the actual power of the electromagnetic heating appliance is smaller than a preset power and the target voltage is not a preset threshold value, so that the push-pull circuit drives the IGBT module to be in an amplification area;

The micro-processing unit is further used for controlling the waveform conversion circuit to be in a turn-off state when the actual power of the electromagnetic heating appliance is smaller than a preset power and the target voltage is a preset threshold value, so that the push-pull circuit drives the IGBT module to be in a saturated conduction region;

The target voltage is the power supply voltage of the electromagnetic heating circuit, and the preset threshold is the valley value of the power supply voltage of the electromagnetic heating circuit, or the target voltage is the rectified voltage of the power supply voltage of the electromagnetic heating circuit, and the preset threshold is the valley value of the rectified voltage of the power supply voltage of the electromagnetic heating circuit.

optionally, the microprocessor unit is configured to send a conduction signal to the waveform conversion circuit and send a first pulse signal to the level conversion circuit when it is determined that the actual power is less than a preset power and it is determined that the target voltage is not a preset threshold, where the conduction signal is used to conduct the waveform conversion circuit and communicate the connection between the waveform conversion circuit and the push-pull circuit, the first pulse signal is used to enable the push-pull circuit to send a first driving signal to the IGBT module, and the first driving signal is used to drive the IGBT module to be in an amplification region.

optionally, the microprocessor is further configured to send a turn-off signal to the waveform conversion circuit and send a second pulse signal to the level conversion circuit when it is determined that the actual power is smaller than a preset power and that the target voltage is a preset threshold, where the turn-off signal is used to turn off the waveform conversion circuit and disconnect the waveform conversion circuit from the push-pull circuit, the second pulse signal is used to enable the push-pull circuit to send a second driving signal to the IGBT module, the second driving signal is used to drive the IGBT module to be in a saturated conduction region, and an amplitude of the second driving signal is greater than an amplitude of the first driving signal, and/or a high pulse width of the second driving signal is greater than a high pulse width of the first driving signal.

Optionally, the microprocessor is further configured to send a turn-off signal to the waveform converting circuit and send a third pulse signal to the level converting circuit when it is determined that the actual power is greater than or equal to a preset power, where the turn-off signal is used to turn off the waveform converting circuit and disconnect the waveform converting circuit from the push-pull circuit, the third pulse signal is used to enable the push-pull circuit to send a third driving signal to the IGBT module, the third driving signal is used to drive the IGBT module to be in a saturated conduction region, and an amplitude of the third driving signal is greater than an amplitude of the first driving signal, and/or a high pulse width of the third driving signal is greater than a high pulse width of the first driving signal.

alternatively,

A first input end of the micro-processing unit (101) is connected with a power supply end of the main loop (100 ') or a first input end of the micro-processing unit (101) is connected with a rectification output end of a power supply voltage of the main loop (100') and is used for acquiring the target voltage;

A second input end of the micro-processing unit (101) is connected with the main loop (100') and is used for obtaining a target current, wherein the target current is an actual current of the electromagnetic heating appliance;

The micro-processing unit is further used for determining the actual power of the electromagnetic heating appliance according to the target voltage and the target current.

optionally, the micro-processing unit comprises: the micro control unit MCU, the voltage detection circuit and the current detection circuit;

the input end of the voltage detection circuit is the input end of the micro-processing unit and is used for acquiring the target voltage;

the current detection circuit is used for acquiring the target current;

The first input end of the MCU is connected with the output end of the voltage detection circuit, the second input end of the MCU is connected with the output end of the current detection circuit, the first output end of the MCU is connected with the input end of the level conversion circuit, and the second output end of the MCU is connected with the input end of the waveform conversion circuit.

optionally, the waveform conversion circuit includes: the circuit comprises a first switch module, a diode and a first capacitor;

A first end of the first switch module is connected with a second output end of the microprocessor unit, a second end of the first switch module is respectively connected with a first end of the first capacitor and a negative electrode of the diode, a second end of the first capacitor is connected with an input end of the push-pull circuit, and a third end of the first switch module and a positive electrode of the diode are grounded;

the micro-processing unit is used for sending the conducting signal to the first switch module so as to close the first switch module;

The micro-processing unit is further configured to send the turn-off signal to the first switch module, so that the first switch module is turned off.

Optionally, the first switch module is a triode and a sixth resistor, or an electronic switch.

optionally, the level shift circuit includes: the circuit comprises a first resistor, a second resistor and a second switch module;

The first end of the first resistor is connected with a first level, the second end of the first resistor is connected with the first end of the second resistor, the first end of the second switch module is connected between the first resistor and the second resistor, the second end of the second switch module is connected with the input end of the push-pull circuit, and the third end of the second switch module is grounded with the second end of the second resistor.

optionally, the push-pull circuit comprises: the circuit comprises a third resistor, a third switch module, a fourth resistor and a fifth resistor;

The first end of the third resistor is connected with a first level, the second end of the third resistor is respectively connected with the output end of the level conversion circuit, the output end of the waveform conversion circuit, the first end of the third switch module and the first end of the fourth switch module, the second end of the third switch module is connected with the first level, the third end of the third switch module is connected with the first end of the fourth resistor, the second end of the fourth resistor is respectively connected with the second end of the fourth switch module and the first end of the fifth resistor, the third end of the fourth switch module is grounded, and the second end of the fifth resistor is connected with the input end of the IGBT module.

optionally, the push-pull circuit further comprises: a second capacitor;

And the first end of the second capacitor is connected with the second end of the third resistor, and the second end of the second capacitor is grounded.

Optionally, the main loop comprises: a rectifier circuit, a filter circuit and a resonant circuit;

The rectifier circuit is used for rectifying the power supply voltage of the electromagnetic heating circuit, the positive output end of the rectifier circuit is connected with the first input end of the filter circuit, the first output end of the filter circuit is connected with the input end of the resonance circuit, the output end of the resonance circuit is connected with the first output end of the IGBT module, the negative output end of the rectifier circuit is connected with the second input end of the filter circuit, and the second output end of the filter circuit and the second output end of the IGBT module are both grounded.

Optionally, a first input end of the voltage detection circuit is connected to a positive input end of the rectification circuit, and a second input end of the voltage detection circuit is connected to a negative input end of the rectification circuit, so as to obtain the target voltage; or,

And the first input end of the voltage detection circuit is connected with the positive input end of the rectification circuit, and the second input end of the voltage detection circuit is connected with the first input end of the filter circuit and used for acquiring the target voltage.

Optionally, a first input end of the current detection circuit is connected to a second output end of the filter circuit, and a second input end of the current detection circuit is connected to a second output end of the IGBT module, so as to obtain the target current.

In a second aspect, the present invention provides an electromagnetic heating device, comprising: the electromagnetic heating circuit of the first aspect.

In a third aspect, the present invention provides a current regulation method, including:

Acquiring the actual power of the electromagnetic heating appliance;

When the actual power of the electromagnetic heating appliance is determined to be smaller than the preset power and the target voltage is determined not to be the preset threshold value, inputting a first pulse signal to the level conversion circuit, and controlling the waveform conversion circuit to be in a conducting state, so that the current of the IGBT module driven by the push-pull circuit is in an amplification area;

when the actual power of the electromagnetic heating appliance is determined to be smaller than the preset power and the target voltage is determined to be the preset threshold value, inputting a second pulse signal to the level conversion circuit, and controlling the waveform conversion circuit to be in a turn-off state, so that the push-pull circuit drives the IGBT module to be in a saturated conduction region;

the target voltage is a power supply voltage of the electromagnetic heating circuit, and the preset threshold is a valley value of the power supply voltage of the electromagnetic heating circuit, or the target voltage is a rectified voltage of the power supply voltage of the electromagnetic heating circuit, and the preset threshold is a valley value of the rectified voltage of the power supply voltage of the electromagnetic heating circuit 0.

Optionally, when it is determined that the actual power of the electromagnetic heating appliance is less than the preset power and it is determined that the target voltage is not the preset threshold, inputting a first pulse signal to the level conversion circuit, and controlling the waveform conversion circuit to be in a conducting state, so that the push-pull circuit drives the IGBT module to be in the amplification region, including:

Sending a conducting signal to the waveform conversion circuit, wherein the conducting signal is used for conducting the waveform conversion circuit and communicating the waveform conversion circuit with the push-pull circuit;

and sending a first pulse signal to the level conversion circuit, wherein the first pulse signal is used for enabling the push-pull circuit to send a first driving signal to the IGBT module, and the first driving signal is used for driving the IGBT module to be in an amplification area.

optionally, when it is determined that the actual power of the electromagnetic heating appliance is smaller than the preset power and it is determined that the target voltage is the preset threshold, inputting a second pulse signal to the level conversion circuit, and controlling the waveform conversion circuit to be in an off state, so that the push-pull circuit drives the IGBT module to be in the saturated conduction region, including:

Sending a turn-off signal to the waveform conversion circuit, wherein the turn-off signal is used for turning off the waveform conversion circuit and disconnecting the waveform conversion circuit from the push-pull circuit;

And sending a second pulse signal to the level conversion circuit, wherein the second pulse signal is used for enabling the push-pull circuit to send a second driving signal to the IGBT module, the second driving signal is used for driving the IGBT module to be in a saturated conduction region, the amplitude of the second driving signal is larger than that of the first driving signal, and/or the high pulse width of the second driving signal is larger than that of the first driving signal.

optionally, when it is determined that the actual power is greater than or equal to the preset power, the method further includes:

And sending a third pulse signal to the level conversion circuit, wherein the third pulse signal is used for enabling the push-pull circuit to send a third driving signal to the IGBT module, the third driving signal is used for driving the IGBT module to be in a saturated conduction region, the amplitude of the third driving signal is larger than that of the first driving signal, and/or the high pulse width of the third driving signal is larger than that of the first driving signal.

Optionally, the obtaining the actual power of the electromagnetic heating appliance includes:

Acquiring the target voltage and the target current, wherein the target current is the actual current of the electromagnetic heating appliance;

And determining the actual power of the electromagnetic heating appliance according to the target voltage and the target current.

The utility model provides an electromagnetic heating circuit and electromagnetic heating utensil can acquire electromagnetic heating utensil's actual power and target voltage in real time through the microprocessing unit. When the actual power of the electromagnetic heating appliance is determined to be smaller than the preset power and the target voltage is determined not to be the preset threshold value, the micro-processing unit can control the waveform conversion circuit to be conducted, and sends a first pulse signal to the level conversion circuit, so that the waveform conversion circuit participates in the work of the push-pull circuit, further, the driving voltage sent by the push-pull circuit to the IGBT module is reduced, the IGBT module is located in the amplification area, the current of the IGBT module located in the amplification area is small, and the loss of the IGBT module is reduced. The voltage on the drain electrode of the IGBT module is changed to be the minimum value along with the fact that the target voltage is continuously close to the preset threshold value, at the moment, when the actual power of the electromagnetic heating appliance is determined to be smaller than the preset power and the target voltage is determined to be the preset threshold value, the micro-processing unit can control the waveform conversion circuit to be turned off and send a second pulse signal to the level conversion circuit, the waveform conversion circuit does not participate in the work of the push-pull circuit any more, then the drive voltage sent to the IGBT module by the push-pull circuit is not changed, the IGBT module can be in saturated conduction, and the normal work of the electromagnetic heating appliance in a low-power state is achieved. The utility model provides a current electromagnetic heating circuit because the electromagnetic heating utensil switches on under the low power state that IGBT module instantaneous current is too big and cause the problem of IGBT module damage, through the driving voltage who reduces the IGBT module under the low power state at the electromagnetic heating utensil, make the IGBT module be in the amplification area, reduce the electric current of IGBT module, thereby the loss of IGBT module has been reduced, the life of IGBT module has been prolonged, the reliability of IGBT module has been improved, make the electromagnetic heating utensil can normal heating, the components and parts cost of electromagnetic heating utensil has been practiced thrift.

drawings

in order to clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.

fig. 1 is a schematic structural diagram of an electromagnetic heating circuit provided by the present invention;

Fig. 2a is a schematic diagram of an envelope waveform of a voltage on a drain electrode of an IGBT module in an electromagnetic heating circuit provided by the present invention;

Fig. 2b is a schematic waveform diagram of the first driving signal and the second driving signal sent by the push-pull circuit to the IGBT module in the electromagnetic heating circuit provided by the present invention;

Fig. 3a is a schematic structural diagram of an electromagnetic heating circuit provided by the present invention;

fig. 3b is a schematic structural diagram of an electromagnetic heating circuit provided by the present invention;

Fig. 4a is a schematic circuit diagram of an electromagnetic heating circuit provided by the present invention;

Fig. 4b is a schematic circuit diagram of an electromagnetic heating circuit provided by the present invention;

fig. 5a is a schematic structural diagram of an electromagnetic heating circuit provided by the present invention;

fig. 5b is a schematic circuit diagram of an electromagnetic heating circuit provided by the present invention;

Fig. 6 is a schematic structural diagram of an electromagnetic heating device provided by the present invention;

fig. 7 is a schematic flow chart of a current adjusting method provided by the present invention.

Reference numerals:

100-an electromagnetic heating circuit; 100' -a main loop;

101-a microprocessing unit; 102-a level conversion circuit;

103-a waveform conversion circuit; 104-push-pull circuit;

105-an IGBT module; 106-MCU;

107-voltage detection circuit 108-current detection circuit;

109-a rectifier circuit; 110-a filter circuit;

111-a resonant circuit; 10-electromagnetic heating appliance.

Detailed Description

in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the scope protected by the embodiments of the present invention.

at present, when the electromagnetic heating appliance 10 is heated at a low power, in the existing electromagnetic heating circuit, if the drain of the IGBT module 105 still has a certain voltage, the IGBT module 105 is turned on, and the transient current of the turn-on is large, which easily causes the loss of the IGBT module 105, and increases the device cost of the electromagnetic heating appliance 10. In this embodiment, the power value ranges specifically corresponding to the low power and the high power are not limited. Typically, low power levels range from 0 to 1000 watts (W) and high power levels range from 1000W to 2200W.

In view of the above problem, the electromagnetic heating circuit 100 of the present embodiment can reduce the current of the IGBT module 105 by reducing the driving voltage of the IGBT module 105 when the electromagnetic heating appliance 10 is in low power heating, thereby reducing the loss of the IGBT module 105.

next, a detailed description will be given of a specific structure of the electromagnetic heating circuit 100 by way of a specific example. Fig. 1 is a schematic structural diagram of an electromagnetic heating circuit provided by the present invention, as shown in fig. 1, the electromagnetic heating circuit 100 of the present embodiment may include: the circuit comprises a main loop 100', a micro-processing unit 101, a level conversion circuit 102, a waveform conversion circuit 103, a push-pull circuit 104 and an insulated gate bipolar transistor IGBT module 105.

the first output end of the micro-processing unit 101 is connected with the input end of the level conversion circuit 102, the second output end of the micro-processing unit 101 is connected with the input end of the waveform conversion circuit 103, the input end of the push-pull circuit 104 is respectively connected with the output end of the level conversion circuit 102 and the output end of the waveform conversion circuit 103, the initial state of the waveform conversion circuit 103 is a turn-off state, the output end of the push-pull circuit 104 is connected with the input end of the IGBT module 105, and the output end of the IGBT module 105 is connected with the main loop 100'.

A microprocessor unit 101 for obtaining the actual power and the target voltage of the detected electromagnetic heating appliance 10.

the micro-processing unit 101 is further configured to control the waveform converting circuit 103 to be in a conducting state when the actual power of the electromagnetic heating appliance 10 is less than the preset power and the target voltage is not a preset threshold, so that the push-pull circuit 104 drives the IGBT module 105 to be in the amplification region.

The micro-processing unit 101 is further configured to control the waveform converting circuit 103 to be in an off state when the actual power of the electromagnetic heating appliance 10 is less than the preset power and the target voltage is a preset threshold, so that the push-pull circuit 104 drives the IGBT module 105 to be in a saturated conduction region.

the target voltage is a power supply voltage of the electromagnetic heating circuit 100, and the preset threshold is a valley value of the power supply voltage of the electromagnetic heating circuit 100, or the target voltage is a rectified voltage of the power supply voltage of the electromagnetic heating circuit 100, and the preset threshold is a valley value of the rectified voltage of the power supply voltage of the electromagnetic heating circuit 100.

In order to monitor the working state of the electromagnetic heating apparatus 10 in real time, in the present embodiment, the microprocessor 101 may detect the actual power of the electromagnetic heating apparatus 10. Furthermore, the microprocessor 101 can compare the actual power with the preset power to determine the current working state of the electromagnetic heating device 10.

the preset power may be set according to the actual situation of the electromagnetic heating apparatus 10, may be preset in the microprocessor unit 101, or may be set by a user according to an expectation and manually input into the microprocessor unit 101, which is not limited in this embodiment.

For convenience of description, the low power in the present embodiment refers to a case that the actual power of the electromagnetic heating appliance 10 is smaller than the preset power, and the high power refers to a case that the actual power of the electromagnetic heating appliance 10 is greater than or equal to the preset power.

Those skilled in the art can understand that when the actual power of the electromagnetic heating appliance 10 is a small power, and the drain voltage of the IGBT module 105 is zero, turning on the IGBT module 105 can play a role of protecting the IGBT module 105, but in an actual situation, a certain voltage still exists on the drain of the IGBT module 105, and when the drain of the IGBT module 105 has a voltage, the impact current generated by saturation and turn on of the IGBT module 105 is very large, which easily causes the current that instantaneously flows through the drain source of the IGBT module 105 to be too large, even exceeding the safe working range thereof, not only the IGBT module 105 may generate noise, but also components may be easily damaged by long-time working, and therefore, in this embodiment, the electromagnetic heating appliance 10 may be normally in a small power by reducing the current of the IGBT module 105 at this time.

Since the voltage on the drain of the IGBT module 105 is easily affected by the surrounding environment and the like, the microprocessing unit 101 does not directly detect the voltage on the drain of the IGBT module 105. Since the magnitude of the bottom of the power supply voltage of the electromagnetic heating circuit 100 is predetermined and the voltage of the bottom is easily obtained, the microprocessor 101 can set the target voltage to the power supply voltage of the electromagnetic heating circuit 100, and in this case, the preset threshold value is the bottom of the power supply voltage of the electromagnetic heating circuit 100. The microprocessor 101 may set the target voltage to be a rectified voltage of the power supply voltage of the electromagnetic heating circuit 100, and at this time, the preset threshold value may be a valley value of the rectified voltage of the power supply voltage of the electromagnetic heating circuit 100.

Further, the micro-processing unit 101 may obtain the actual power and the target voltage of the electromagnetic heating appliance 10 in real time, so that the micro-processing unit 101 may determine whether the electromagnetic heating appliance 10 is in a low-power state according to the magnitude between the actual power and the preset power of the electromagnetic heating appliance 10, and may also determine whether the voltage on the drain of the IGBT module 105 exists and determine the magnitude of the voltage according to the magnitude between the target voltage and the preset threshold.

Specifically, a first output terminal of the microprocessing unit 101 is connected to an input terminal of the level shift circuit 102 to transmit a pulse signal to the level shift circuit 102, and a second output terminal of the microprocessing unit 101 is connected to an input terminal of the waveform conversion circuit 103 to transmit a signal to the waveform conversion circuit 103.

Further, when it is determined that the actual power of the electromagnetic heating appliance 10 is smaller than the preset power and that the target voltage is not the preset threshold, the microprocessor 101 inputs the first pulse signal to the level shifter circuit 102, and controls the waveform shifter circuit 103 to be turned on, and the turned-on waveform shifter circuit 103 participates in the operation of the push-pull circuit 104, so that the amplitude of the first pulse signal input to the push-pull circuit 104 by the level shifter circuit 102 may be reduced, and the amplitude of the driving voltage input to the IGBT module 105 by the push-pull circuit 104 is reduced, so that the IGBT module 105 is in the amplification region.

As will be understood by those skilled in the art, when the IGBT module 105 is in the amplification region, the turn-on voltage of the IGBT module 105 is in a linear relationship with the current of the IGBT module 105, and the current of the IGBT module 105 rises slowly, and after crossing this region, the IGBT module 105 is in the saturation region, and the IGBT is turned on in saturation, and the current of the IGBT module 105 rises very quickly to the maximum. Therefore, the current through the source and drain when the IGBT module 105 is amplified will be less than the current through the source and drain when the IGBT module 105 is in saturation conduction.

further, compared with the IGBT module 105 in the conventional electromagnetic heating circuit 100, since the IGBT module 105 in this embodiment is not in saturation conduction but in the amplification region, the current of the IGBT module 105 in this embodiment is smaller than the current of the conventional electromagnetic heating circuit 100 when the IGBT module 105 is in conduction, so that the consumption of the IGBT module 105 is reduced, and the component cost of the electromagnetic heating device 10 is saved.

Further, after a period of time (the period of time is usually within a range of half cycle of the power supply voltage), the target voltage gradually becomes the preset threshold, and at this time, the micro processing unit 101 may still determine that the actual power of the electromagnetic heating appliance 10 is still less than the preset power, input the second pulse signal to the level conversion circuit 102, and controls the waveform converting circuit 103 to be switched off, the switched-off waveform converting circuit 103 does not participate in the work of the push-pull circuit 104, so that the amplitude of the second pulse signal input to the push-pull circuit 104 by the level shift circuit 102 is not changed, so that the driving voltage input to the IGBT module 105 by the push-pull circuit 104 is constant, and at this time, the IGBT module 105 may be in a saturated conduction region, therefore, the heating process of the electromagnetic heating appliance 10 in a low-power state is realized, the heat productivity of the IGBT module 105 is reduced, and the loss and the noise of the IGBT module 105 are reduced.

The first pulse signal and the second pulse signal are different pulse signals, and the first driving signal and the second driving signal are different pulse signals. Generally, the low-middle pulse width in the first pulse signal is smaller than the low-middle pulse width in the second pulse signal, the low-middle pulse amplitude in the first pulse signal is smaller than the low-middle pulse amplitude in the second pulse signal, the high-middle pulse width in the first drive signal is smaller than the high-middle pulse width in the second drive signal, and the high-middle pulse amplitude in the first drive signal is smaller than the high-middle pulse amplitude in the second drive signal. The microprocessor 101 may be an integrated chip or a circuit built by a plurality of components, which is not limited in this embodiment.

Further, in this embodiment, the electromagnetic heating circuit 100 may change the driving voltage sent by the push-pull circuit 104 to the IGBT module 105 by controlling whether the waveform converting circuit 103 is connected between the level converting circuit 102 and the push-pull circuit 104 according to whether the electromagnetic heating appliance 10 is in a low-power operating state, so that the operating condition of the IGBT module 105 is changed, and thus the current passing through the drain and the source of the IGBT module 105 is adjusted.

When it is determined that the electromagnetic heating appliance 10 is in a low-power state where the actual power is smaller than the preset power and the target voltage is not the preset threshold, under the control action of the microprocessor unit 101, the waveform conversion circuit 103 is turned on, so that the waveform conversion circuit 103 participates in the operation of the push-pull circuit 104, the driving voltage sent by the push-pull circuit 104 to the IGBT module 105 is reduced, the driving voltage received by the IGBT module 105 is smaller than the voltage required when the IGBT is in a saturation conduction region, such as generally 13 volts V, at this time, the IGBT module 105 is in an amplification region, the current of the IGBT module 105 can be greatly reduced, the operating condition of the IGBT module 105 is improved, and the service life of the IGBT module 105 is prolonged.

In the above process, the target voltage gradually changes to the preset threshold, that is, the voltage on the drain of the IGBT module 105 gradually changes until the target voltage becomes the minimum value. When the micro-processing unit 101 still determines that the electromagnetic heating appliance 10 is still in a low-power state in which the actual power is smaller than the preset power, under the control of the micro-processing unit 101, the waveform conversion circuit 103 is turned off, so that the waveform conversion circuit 103 does not participate in the work of the push-pull circuit 104 any more, the push-pull circuit 104 can send a driving voltage for saturated conduction of the IGBT module 105 to the IGBT module 105, and the low-power heating process of the electromagnetic heating appliance 10 is realized.

The electromagnetic heating circuit provided by the embodiment can acquire the actual power and the target voltage of the electromagnetic heating appliance in real time through the micro-processing unit. When the actual power of the electromagnetic heating appliance is determined to be smaller than the preset power and the target voltage is determined not to be the preset threshold value, the micro-processing unit can control the waveform conversion circuit to be conducted, and sends a first pulse signal to the level conversion circuit, so that the waveform conversion circuit participates in the work of the push-pull circuit, further, the driving voltage sent by the push-pull circuit to the IGBT module is reduced, the IGBT module is located in the amplification area, the current of the IGBT module located in the amplification area is small, and the loss of the IGBT module is reduced. The voltage on the drain electrode of the IGBT module is changed to be the minimum value along with the fact that the target voltage is continuously close to the preset threshold value, at the moment, when the actual power of the electromagnetic heating appliance is determined to be smaller than the preset power and the target voltage is determined to be the preset threshold value, the micro-processing unit can control the waveform conversion circuit to be turned off and send a second pulse signal to the level conversion circuit, the waveform conversion circuit does not participate in the work of the push-pull circuit any more, then the drive voltage sent to the IGBT module by the push-pull circuit is not changed, the IGBT module can be in saturated conduction, and the normal work of the electromagnetic heating appliance in a low-power state is achieved. The embodiment solves the problem that the IGBT module is damaged because the instantaneous current of the IGBT module is excessively high when the electromagnetic heating device is in a low-power state in the existing electromagnetic heating circuit, the driving voltage of the IGBT module is reduced when the electromagnetic heating device is in the low-power state, the IGBT module is in an amplification area, the current of the IGBT module is reduced, the loss of the IGBT module is reduced, the service life of the IGBT module is prolonged, the reliability of the IGBT module is improved, the electromagnetic heating device can normally heat, and the component cost of the electromagnetic heating device is saved.

For convenience of illustration, in this embodiment, the first output terminal of the micro processing unit 101 may be a PPG port, and the second output terminal of the micro processing unit 101 may be a CON port.

optionally, the micro processing unit 101 is configured to send a turn-on signal to the waveform converting circuit 103 and send a first pulse signal to the level converting circuit 102 when it is determined that the actual power is less than the preset power and it is determined that the target voltage is not the preset threshold, where the turn-on signal is used to turn on the waveform converting circuit 103 and connect the waveform converting circuit 103 and the push-pull circuit 104, the first pulse signal is used to enable the push-pull circuit 104 to send a first driving signal to the IGBT module 105, and the first driving signal is used to drive the IGBT module 105 to be in the amplification region.

specifically, when determining that the actual power of the electromagnetic heating appliance 10 is less than the preset power and that the target voltage is not the preset threshold, the micro processing unit 101 may send a turn-on signal to the waveform conversion circuit 103 through the CON port, and send a first pulse signal to the level conversion circuit 102 through the PPG port, at this time, the turn-on signal may control the waveform conversion circuit 103 to turn on, so that the waveform conversion circuit 103 communicates with the push-pull circuit 104, and the first pulse signal may cause the push-pull circuit 104 to send the first driving signal to the IGBT module 105.

further, when the IGBT module 105 receives the first driving signal, the driving voltage received by the IGBT module 105 is small, so that the IGBT module 105 can be in the amplification region, and at this time, the current of the IGBT module 105 is smaller than the current of the IGBT module 105 when the IGBT module 105 is in saturation conduction.

Optionally, the micro processing unit 101 is further configured to send a turn-off signal to the waveform converting circuit 103 and send a second pulse signal to the level converting circuit 102 when it is determined that the actual power is smaller than the preset power and the target voltage is the preset threshold, where the turn-off signal is used to turn off the waveform converting circuit 103 and disconnect the waveform converting circuit 103 from the push-pull circuit 104, the second pulse signal is used to enable the push-pull circuit 104 to send a second driving signal to the IGBT module 105, the second driving signal is used to drive the IGBT module 105 to be in a saturated conduction region, and an amplitude of the second driving signal is larger than an amplitude of the first driving signal, and/or a high pulse width of the second driving signal is larger than a high pulse width of the first driving signal.

Specifically, when the micro-processing unit 101 determines that the actual power of the electromagnetic heating appliance 10 is less than the preset power and the target voltage is the preset threshold value, a shutdown signal may be sent to waveform transformation circuit 103 via the CON port and a second pulse signal may be sent to level translation circuit 102 via the PPG port, at which point, the turn-off signal may control the waveform transformation circuit 103 to turn off, such that the waveform transformation circuit 103 and the push-pull circuit 104 are no longer in communication, since the amplitude of the second pulse signal is greater than the amplitude of the first pulse signal, and/or the low pulse width of the second pulse signal is greater than the low pulse width of the first pulse signal, therefore, the second pulse signal may cause the push-pull circuit 104 to transmit the second driving signal to the IGBT module 105, the amplitude of the second drive signal is thus greater than the amplitude of the first drive signal and/or the high pulse width of the second drive signal is greater than the high pulse width of the first drive signal.

Further, when the IGBT module 105 receives the second driving signal, the second driving signal may drive the IGBT module 105 to be in saturation conduction, so as to implement a heating process of the electromagnetic heating appliance 10 in a low power state, reduce the heat generation amount of the IGBT module 105, and reduce the loss and noise of the IGBT module 105.

optionally, the micro processing unit 101 is further configured to send a turn-off signal to the waveform converting circuit 103 and send a third pulse signal to the level converting circuit 102 when it is determined that the actual power is greater than or equal to the preset power, where the turn-off signal is used to turn off the waveform converting circuit 103 and disconnect the waveform converting circuit 103 from the push-pull circuit 104, the third pulse signal is used to enable the push-pull circuit 104 to send a third driving signal to the IGBT module 105, the third driving signal is used to drive the IGBT module 105 to be in a saturated conduction region, and an amplitude of the third driving signal is greater than an amplitude of the first driving signal, and/or a high pulse width of the third driving signal is greater than a high pulse width of the first driving signal.

specifically, the micro processing unit 101, upon determining that the actual power is greater than or equal to the preset power, may transmit a shutdown signal to the waveform conversion circuit 103 through the CON port, and sends a third pulse signal to the level shift circuit 102 through the PPG port, at this time, the turn-off signal ensures that the waveform conversion circuit 103 is turned off, so that the waveform conversion circuit 103 and the push-pull circuit 104 are no longer connected, since the amplitude of the third pulse signal is greater than the amplitude of the first pulse signal, and/or the low pulse width of the third pulse signal is greater than the low pulse width of the first pulse signal, therefore, the third pulse signal may enable the push-pull circuit 104 to transmit the third driving signal to the IGBT module 105, thus, the amplitude of the third drive signal is greater than the amplitude of the first drive signal, and/or the high pulse width of the third drive signal is greater than the high pulse width of the first drive signal.

The first pulse signal and the third pulse signal are different pulse signals, and the first driving signal and the third driving signal are different pulse signals. Generally, the low-middle pulse width in the first pulse signal is smaller than the low-middle pulse width in the third pulse signal, the low-middle pulse amplitude in the first pulse signal is smaller than the low-middle pulse amplitude in the third pulse signal, the high-middle pulse width in the first drive signal is smaller than the high-middle pulse width in the third drive signal, and the high-middle pulse amplitude in the first drive signal is smaller than the high-middle pulse amplitude in the third drive signal. The second pulse signal and the third pulse signal may be the same pulse signal or different pulse signals, and it is only necessary to ensure that the low pulse amplitudes of the second pulse signal and the third pulse signal are the same. When the second pulse signal and the third pulse signal are different pulse signals, the low-middle pulse width in the second pulse signal is smaller than the low-middle pulse width in the third pulse signal, the low-middle pulse amplitude in the second pulse signal is equal to the low-middle pulse amplitude in the third pulse signal, the high-middle pulse width in the second driving signal is smaller than the high-middle pulse width in the third driving signal, and the high-middle pulse amplitude in the second driving signal is equal to the high-middle pulse amplitude in the third driving signal.

Further, when the IGBT module 105 receives the third driving signal, the third driving signal may drive the IGBT module 105 to be in saturation conduction, so as to implement a heating process of the electromagnetic heating appliance 10 in a high-power operating state.

The settings of the first driving signal, the second driving signal, and the third driving signal may include multiple settings, which is not limited in this embodiment. Generally, the first driving signal may be a driving pulse with a narrow high level and a narrow width to ensure that the voltage on the drain of the IGBT module 105 is finally minimized. The second driving signal and the third driving signal may be high-level driving pulses to ensure that the IGBT module 105 may be turned on in saturation.

further, the electromagnetic heating circuit 100 may change the driving voltage sent by the push-pull circuit 104 to the IGBT module 105 by controlling whether the waveform converting circuit 103 is connected between the level converting circuit 102 and the push-pull circuit 104 according to the operating state of the electromagnetic heating appliance 10 with low power or high power, so that the operating state of the IGBT module 105 is changed, and the current of the IGBT module 105 is adjusted.

When it is determined that the electromagnetic heating appliance 10 is in a low-power state where the actual power is smaller than the preset power and the target voltage is not the preset threshold, under the control action of the micro-processing unit 101, the waveform conversion circuit 103 is turned on, so that the waveform conversion circuit 103 participates in the operation of the push-pull circuit 104, the push-pull circuit 104 can send a first driving signal to the IGBT module 105, the first driving signal enables the driving voltage received by the IGBT module 105 to be smaller than the voltage required when the IGBT is in saturation conduction, at this time, the IGBT module 105 is in an amplification region, the current of the IGBT module 105 can be greatly reduced, the operating condition of the IGBT module 105 is improved, and the service life of the IGBT module 105 is prolonged. In the above process, the target voltage gradually changes to the preset threshold, when the micro processing unit 101 still determines that the electromagnetic heating appliance 10 is in a low-power state where the actual power is smaller than the preset power at this time, under the control action of the micro processing unit 101, the waveform converting circuit 103 is turned off, so that the waveform converting circuit 103 does not participate in the operation of the push-pull circuit 104 any more, at this time, the push-pull circuit 104 may send a second driving signal to the IGBT module 105, and the second driving signal makes the IGBT module 105 saturated and turned on, thereby implementing the low-power heating process of the electromagnetic heating appliance 10.

when it is determined that the electromagnetic heating appliance 10 is in a high-power state where the actual power is greater than or equal to the preset power, under the control action of the micro-processing unit 101, the waveform conversion circuit 103 is turned off, the level conversion circuit 102 can realize the conversion process of the voltage sent by the micro-processing unit 101, generally, 5V can be converted into 13V, and further, the push-pull circuit 104 can send a third driving signal to the IGBT module 105, so that the IGBT module 105 is saturated and turned on, thereby realizing the high-power heating process of the electromagnetic heating appliance 10.

the preset threshold is different, and the voltage change process on the drain of the IGBT module 105 is different. The following describes a specific implementation process in detail with reference to fig. 2a and 2 b.

when the micro-processing unit 101 determines that the actual power of the electromagnetic heating appliance 10 is less than the preset power and the target voltage is not the valley value of the supply voltage or the rectified supply voltage of the electromagnetic heating circuit 100, at this time, as shown in fig. 2a, the voltage at the drain of the IGBT module 105 will gradually decrease from a certain value until the valley value of the drain voltage, which is generally zero, wherein the time period during which the voltage at the drain of the IGBT module 105 gradually decreases corresponds to t1-t 2. Correspondingly, as shown in fig. 2b, the amplitude Va of the first driving signal is smaller than the amplitude VCC of the second driving signal, and the duty ratio of the first driving signal is higher than the duty ratio of the second driving signal.

Further, the micro-processing unit 101 may control the IGBT module 105 to receive the second driving signal, so that the IGBT module 105 is in the saturation conduction region, wherein the envelope waveform of the drain voltage of the IGBT module 105 is as the waveform corresponding to the time period t2-t3 in fig. 2 b.

The electromagnetic heating circuit provided by the embodiment can acquire the actual power and the target voltage of the electromagnetic heating appliance in real time through the micro-processing unit. When the actual power of the electromagnetic heating appliance is determined to be smaller than the preset power and the target voltage is determined not to be the preset threshold value, the micro-processing unit can send a conducting signal to the waveform conversion circuit and send a first pulse signal to the level conversion circuit to enable the waveform conversion circuit to be conducted, and the push-pull circuit can send a first driving signal to the IGBT module to enable the IGBT module to be located in the amplification area, so that the current of the IGBT module is reduced, and the loss of the IGBT module is reduced. The voltage on the drain electrode of the IGBT module is changed to be the minimum value along with the fact that the target voltage is continuously close to the preset threshold value, at the moment, when the actual power of the electromagnetic heating appliance is determined to be smaller than the preset power and the target voltage is determined to be the preset threshold value, the micro-processing unit can send a turn-off signal to the waveform conversion circuit and send a second pulse signal to the level conversion circuit, the waveform conversion circuit is turned off, the push-pull circuit can send a second driving signal to the IGBT module, the IGBT module is in saturated conduction, and the electromagnetic heating appliance can normally work under the low-power state. When the actual power of the electromagnetic heating appliance is determined to be larger than or equal to the preset power, the micro-processing unit can send a turn-off signal to the waveform conversion circuit and send a third pulse signal to the level conversion circuit, so that the waveform conversion circuit is turned off, and the push-pull circuit can send a third driving signal to the IGBT module, so that the IGBT module is in saturated conduction, and the electromagnetic heating appliance can normally work in a high-power state. In this embodiment, the problem of current electromagnetic heating circuit cause the IGBT module to damage because the electromagnetic heating utensil switches on IGBT module instantaneous current under the low power state too big is solved, through reduce the driving voltage of IGBT module under the low power state at the electromagnetic heating utensil, make the IGBT module be in the amplification area, reduce the electric current of IGBT module, thereby the loss of IGBT module has been reduced, the life of IGBT module has been prolonged, the reliability of IGBT module has been improved, make the electromagnetic heating utensil not only can normally heat under the low power state, also can normally heat under high-power operating condition, the components and parts cost of electromagnetic heating utensil has been practiced thrift.

On the basis of the above embodiment of fig. 1, since the preset threshold may include various implementation forms, the micro processing unit 101 may detect and obtain the target voltage and may also detect and obtain the target current in various ways. Next, a specific process of the micro-processing unit 101 obtaining the target voltage and the actual current of the electromagnetic heating appliance 10 will be described in detail with reference to fig. 3 a.

Fig. 3a is a schematic structural diagram of the electromagnetic heating circuit provided by the present invention, as shown in fig. 3a, on the basis of the electromagnetic heating circuit 100 shown in fig. 1, optionally, the first input terminal of the micro processing unit 101 is connected to the power supply terminal of the main circuit 100 'or the first input terminal of the micro processing unit 101 is connected to the rectification output terminal of the power supply voltage of the main circuit 100' for obtaining the target voltage.

a second input of the microprocessor 101 is connected to the main circuit 100' for obtaining a target current, which is the actual current of the electromagnetic heating appliance 10.

The microprocessor unit 101 is further configured to determine an actual power of the electromagnetic heating appliance 10 according to the target voltage and the target current.

Specifically, the first input terminal of the micro processing unit 101 may be connected to the power supply terminal of the main circuit 100 ', or may be connected to the rectified output terminal of the power supply voltage of the main circuit 100', so as to obtain the target voltage, which is not limited in this embodiment. The second input of the micro-processing unit 101 may also obtain the target current through the connection with the main loop 100'.

further, the micro-processing unit 101 determines the actual power of the electromagnetic heating appliance 10 by the acquired target voltage and the actual current of the electromagnetic heating appliance 10. The specific implementation manner of the micro processing unit 101 for obtaining the target current is not limited in this embodiment.

further, the micro processing unit 101 may be divided into a plurality of components depending on the function of the micro processing unit 101. The detailed structure of the micro-processing unit 101 will be described in detail below with reference to fig. 3 b. Fig. 3b is a schematic structural diagram of an electromagnetic heating circuit provided by the present invention, as shown in fig. 3b, on the basis of the electromagnetic heating circuit 100 shown in fig. 3a, optionally, the microprocessor 101 may include: a Micro Controller Unit (MCU) 106, a voltage detection circuit 107, and a current detection circuit 108.

The input terminal of the voltage detection circuit 107 is the input terminal of the micro processing unit 101, and is used for obtaining the target voltage.

And a current detection circuit 108 for obtaining the target current.

A first input end of the MCU106 is connected to an output end of the voltage detection circuit 107, a second input end of the MCU106 is connected to an output end of the current detection circuit 108, a first output end of the MCU106 is connected to an input end of the level shift circuit 102, and a second output end of the MCU106 is connected to an input end of the waveform conversion circuit 103.

In order to monitor the operating state of the electromagnetic heating appliance 10 in real time, in this embodiment, the voltage detection circuit 107 may detect the target voltage and send the target voltage to the microprocessor unit 101, so that the microprocessor unit 101 may obtain the target voltage in real time. The current detection circuit 108 can detect the target current and send the target current to the microprocessor unit 101, so that the microprocessor unit 101 can obtain the target current in real time, and the microprocessor unit 101 can calculate the actual power of the electromagnetic heating appliance 10 according to the target voltage and the target current. Furthermore, the microprocessor 101 can compare the actual power of the electromagnetic heating device 10 with the preset power to determine the current working state of the electromagnetic heating device.

further, the voltage detection circuit 107 may obtain the supply voltage of the electromagnetic heating circuit 100, that is, the target voltage, by connecting to the supply terminal of the electromagnetic heating circuit 100, or may obtain the voltage of the supply voltage of the electromagnetic heating circuit 100 after rectification, that is, the target voltage, by connecting to the rectified output terminal of the supply voltage of the electromagnetic heating circuit 100. Further, the micro-processing unit 101 may compare the magnitude between the target voltage and a preset threshold value, thereby determining whether there is a voltage on the drain of the IGBT module 105 and determining the magnitude of the voltage on the drain of the IGBT module 105.

the voltage detection circuit 107 and the current detection circuit 108 may be integrated chips, or may be circuits built by a plurality of components, which is not limited in this embodiment.

Based on the embodiment shown in fig. 1, fig. 3a, or fig. 3b, the specific structure of the waveform converting circuit 103 in the electromagnetic heating circuit 100 will be described in detail with reference to fig. 4a and fig. 4 b. Fig. 4a is a circuit schematic diagram of the electromagnetic heating circuit provided by the present invention, and fig. 4b is a circuit schematic diagram of the electromagnetic heating circuit provided by the present invention, as shown in fig. 4a and fig. 4b, optionally, the waveform converting circuit 103 may include: the circuit comprises a first switch module, a diode and a first capacitor.

The first end of the first switch module is connected to the second output end of the microprocessor unit 101, the second end of the first switch module is connected to the first end of the first capacitor and the negative electrode of the diode, the second end of the first capacitor is connected to the input end of the push-pull circuit 104, and the third end of the first switch module and the positive electrode of the diode are grounded.

The micro processing unit 101 is configured to send a conducting signal to the first switch module, so that the first switch module is closed. The micro processing unit 101 is further configured to send a turn-off signal to the first switch module, so that the first switch module is turned off.

In this embodiment, the first switch module may function as a switch, and the specific form of the first switch module may include multiple types, as shown in fig. 4a, the first switch module may be a transistor Q1 and a sixth resistor R6, as shown in fig. 4b, and the first switch module may be an electronic switch K. For convenience of illustration, in fig. 4a and 4b, the diode is labeled D1, the first capacitor is labeled C2, and the micro-processing unit 101 is labeled as the MCU 106.

specifically, when the actual power of the electromagnetic heating appliance 10 is less than the preset power and the target voltage is not the preset threshold, the waveform conversion circuit 103 is turned on and participates in the operation of the push-pull circuit 104, therefore, the micro processing unit 101 may send a turn-on signal to the first switch module through the CON port, so that the first capacitor may be connected to the push-pull circuit 104, and further, under the driving action of the push-pull circuit 104, the driving voltage received by the IGBT module 105 is less than the driving voltage when the IGBT module 105 is saturated and turned on, thereby reducing the instantaneous current of the IGBT module 105 and playing a role in protecting the IGBT module 105.

further, since the waveform converting circuit 103 is turned off and does not participate in the operation of the push-pull circuit 104 when the actual power of the electromagnetic heating appliance 10 is greater than or equal to the preset power or the target voltage is the preset threshold, the micro processing unit 101 may transmit a turn-off signal to the first switching module through the CON port, so that the first capacitor may be disconnected from the push-pull circuit 104.

Further, when the first capacitor is connected to the push-pull circuit 104, the diode is turned off in the reverse direction. When the first capacitor is disconnected from the push-pull circuit 104, one end of the diode is grounded, so that a loop can be provided for discharging of the first capacitor, and the current on the component connected with the first capacitor is prevented from reversely flowing to the first switch module, so that the first switch module is protected.

Next, with reference to fig. 4a or 4b, a detailed description will be given of a specific configuration of the level shift circuit 102 in the electromagnetic heating circuit 100. As shown in fig. 4a or fig. 4b, the level shift circuit 102 may optionally include: the circuit comprises a first resistor, a second resistor and a second switch module.

The first end of the first resistor is connected with a first level, the second end of the first resistor is connected with the first end of the second resistor, the first end of the second switch module is connected between the first resistor and the second resistor, the second end of the second switch module is connected with the input end of the push-pull circuit 104, and the third end of the second switch module is grounded with the second end of the second resistor.

For convenience of illustration, in fig. 4a and 4b, the second switch module is illustrated as a transistor Q2, the first resistor is labeled as R1, and the second resistor is labeled as R2.

specifically, the micro-processing unit 101 may send different pulse signals to the level conversion circuit 102 according to the current working state of the electromagnetic heater. When the actual power of the electromagnetic heating appliance 10 is less than the preset power and the target voltage is not the preset threshold, the micro-processing unit 101 may send a first pulse signal to the level conversion circuit 102; when the actual power of the electromagnetic heating appliance 10 is less than the preset power and the target voltage is a preset threshold, the micro-processing unit 101 may send a second pulse signal to the level conversion circuit 102; when the actual power of the electromagnetic heating appliance 10 is greater than or equal to the preset power, the micro-processing unit 101 may send a third pulse signal to the level conversion circuit 102.

Further, the level shifter circuit 102 may perform level shifting on the received pulse signal, and transmit the level shifted pulse signal to the push-pull circuit 104, so that the push-pull circuit 104 may obtain a driving voltage according with the current operating state of the IGBT module 105.

Next, with reference to fig. 4a or fig. 4b, a detailed description will be given of a specific structure of the push-pull circuit 104 in the electromagnetic heating circuit 100. As shown in fig. 4a or fig. 4b, optionally, the push-pull circuit 104 may include: the circuit comprises a third resistor, a third switch module, a fourth resistor and a fifth resistor.

the first end of the third resistor is connected to the first level, the second end of the third resistor is connected to the output end of the level conversion circuit 102, the output end of the waveform conversion circuit 103, the first end of the third switch module and the first end of the fourth switch module, the second end of the third switch module is connected to the first level, the third end of the third switch module is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the second end of the fourth switch module and the first end of the fifth resistor, the third end of the fourth switch module is grounded, and the second end of the fifth resistor is connected to the gate of the IGBT module 105.

In this embodiment, for convenience of illustration, the third resistor is labeled as R3, the third switching module is illustrated as a transistor Q3, the fourth switching module is illustrated as a transistor Q4, the fourth resistor is labeled as R4, and the fifth resistor is labeled as R5.

specifically, when the actual power of the electromagnetic heating appliance 10 is less than the preset power and the target voltage is not the preset threshold, the micro processing unit 101 may send the first pulse signal to the level conversion circuit 102 through the PPG port, and the micro processing unit 101 may also send the conducting signal to the waveform conversion circuit 103 through the CON port, so that the first capacitor in the waveform conversion circuit 103 may be connected to the push-pull circuit 104, that is, under the effect of the first level, the first capacitor may be in a charging state, and as the voltage across the first capacitor gradually increases, the third switch module may be turned on.

Further, by setting the charging time constant of the first capacitor to be greater than the time width of the first pulse signal sent by the micro processing unit 101 to the level shifter circuit 102 through the PPG port, the voltage at two ends of the first capacitor is controlled to be less than the first level, but not equal to the first voltage, and the amplitude of the first level is equal to that of the second driving signal, so that the driving voltage output by the push-pull circuit 104 to the IGBT module 105 is less than the driving voltage when the IGBT module 105 is in saturation conduction, thereby reducing the instantaneous current of the IGBT module 105, and playing a role in protecting the IGBT module 105 and prolonging the service life of the IGBT module 105.

Further, when the actual power of the electromagnetic heating appliance 10 is less than the preset power and the target voltage is the preset threshold, after a period of time, the second pulse signal is sent to the level shifter circuit 102 through the PPG port, and the micro-processing unit 101 may also send a shut-off signal to the waveform converter circuit 103 through the CON port, so that the first capacitor in the waveform transformation circuit 103 is not connected to the push-pull circuit 104, the second switch module in the level shift circuit 102 is turned off, the second switch module in the level shift circuit 102 operates normally, so that the third switching module and the fourth switching module can work normally, and the amplitude of the second pulse signal is equal to the first level, therefore, the driving voltage output by the push-pull circuit 104 to the IGBT module 105 may make the IGBT module 105 conduct in saturation, so that the electromagnetic heating appliance 10 may be heated normally in a low-power operating state.

Further, when the actual power of the electromagnetic heating appliance 10 is greater than or equal to the preset power, the micro processing unit 101 may send a third pulse signal to the level conversion circuit 102 through the PPG port, and the micro processing unit 101 may also send an off signal to the waveform conversion circuit 103 through the CON port, so that the first capacitor in the waveform conversion circuit 103 is not connected to the push-pull circuit 104, the second switch module in the level conversion circuit 102 operates normally, so that the third switch module and the fourth switch module operate normally, and the amplitude of the third pulse signal is equal to the first level, therefore, the drive voltage output by the push-pull circuit 104 to the IGBT module 105 may make the IGBT module 105 conduct in saturation, so that the electromagnetic heating appliance 10 may heat normally in a low-power operating state.

in addition, with continuing reference to fig. 4a or fig. 4b, optionally, the push-pull circuit 104 may further include: a second capacitance. For ease of illustration, the second capacitor is labeled C1 in fig. 4a and 4 b.

In this embodiment, when the waveform converting circuit 103 is connected to the push-pull circuit 104, the first capacitor is connected in parallel with the second capacitor, the voltage transmitted to the third switching module and the fourth switching module is the voltage across the first capacitor and the second capacitor, this voltage needs to be smaller than the first level, and therefore, the voltage across the first capacitor and the second capacitor can be controlled to be smaller than the first level by setting the charging time constant of the first capacitor and the second capacitor to be larger than the time width of the first pulse signal sent by the micro processing unit 101 to the level shift circuit 102 through the PPG port, but not equal to the first voltage, and the first level is equal to the amplitude of the second driving signal, so that the driving voltage output by the push-pull circuit 104 to the IGBT module 105 is smaller than the driving voltage when the IGBT module 105 is in saturated conduction, thereby reducing the instantaneous drain-source current of the IGBT module 105 and playing a role in protecting the IGBT module 105 and prolonging the service life of the IGBT module 105.

next, a specific configuration included in the electromagnetic heating circuit 100 of the present embodiment will be described in detail with reference to fig. 5a and 5 b. Fig. 5a is a schematic structural diagram of the electromagnetic heating circuit provided by the present invention, and fig. 5b is a schematic circuit diagram of the electromagnetic heating circuit provided by the present invention. As shown in fig. 5a, the electromagnetic heating circuit 100 of the present embodiment is based on fig. 1 or fig. 3a or fig. 3b, and the main circuit 100' may include: a rectifier circuit 109, a filter circuit 110, and a resonant circuit 111.

The rectifying circuit 109 is used for rectifying the power supply voltage of the electromagnetic heating circuit 100, a positive output end of the rectifying circuit 109 is connected with a first input end of the filter circuit 110, a first output end of the filter circuit 110 is connected with an input end of the resonant circuit 111, an output end of the resonant circuit 111 is connected with a drain electrode of the IGBT module 105, a negative output end of the rectifying circuit 109 is connected with a second input end of the filter circuit 110, and a second output end of the filter circuit 110 and a source electrode of the IGBT module 105 are both grounded.

In this embodiment, the rectifying circuit 109 may rectify an input power supply voltage, such as a commercial power, into a pulsating dc voltage, which is convenient for supplying a working voltage to the resonant circuit 111. The power supply voltage can be 220V, 50HZ single-phase sinusoidal alternating current voltage, and can also be mains supply after transformation, and this embodiment does not limit this, and only the type of the power supply voltage can satisfy various working requirements. The rectifying circuit 109 may be a full-bridge rectifier or a half-bridge rectifier, which is not limited in this embodiment.

In this embodiment, the filter circuit 110 plays a role of filtering. In addition, optionally, the voltage detection circuit 107 is connected to a positive input end of the rectification circuit 109, and a second input end of the voltage detection circuit 107 is connected to a negative input end of the rectification circuit 109, so as to obtain the target voltage; or,

A first input terminal of the voltage detection circuit 107 is connected to the positive input terminal of the rectifying circuit 109, and a second input terminal of the voltage detection circuit 107 is connected to a first input terminal of the filter circuit 110, for obtaining the target voltage.

In this embodiment, since the power supply voltage of the electromagnetic heating device 10 does not differ greatly from the time corresponding to the valley value of the drain voltage of the IGBT module 105, in this embodiment, the voltage detection circuit 107 may be connected to the input terminal of the rectifier circuit 109, and the voltage detection circuit 107 may determine the presence or absence and the magnitude of the drain voltage of the IGBT module 105 by detecting whether the target voltage is the valley value of the power supply voltage of the electromagnetic heating device 10.

Further, since the supply voltage-conditioned voltage of the electromagnetic heating appliance 10 does not differ greatly from the timings corresponding to the valleys of the drain voltage of the IGBT module 105, in this embodiment, the voltage detection circuit 107 may be connected between the rectifier circuit 109 and the filter circuit 110, and the voltage detection circuit 107 may determine the presence or absence and magnitude of the drain voltage of the IGBT module 105 by detecting whether or not the target voltage is the valley of the supply voltage-conditioned voltage of the electromagnetic heating appliance 10.

In this embodiment, the specific implementation manner of the voltage detection circuit 107 is not limited, and it is only necessary that the micro processing unit 101 can compare the target voltage received from the voltage detection circuit 107 with a preset threshold to quickly determine whether the drain of the IGBT module 105 has a voltage, which is convenient for subsequent corresponding operations.

for example, when the voltage detection circuit 107 is directly connected to the power supply voltage, since the power supply voltage is an alternating current, the voltage detection circuit 107 may be provided with two backward diodes connected in parallel, and may detect the target voltage using a device such as a voltage sensor. When the voltage detection circuit 107 is connected between the rectifier circuit 109 and the filter circuit 110, a device such as a voltage sensor may be used as it is to detect the target voltage.

Optionally, a first input end of the current detection circuit 108 is connected to a second output end of the filter circuit 110, and a second input end of the current detection circuit 108 is connected to a second output end of the IGBT module 105, so as to obtain the target current.

Specifically, the current detection circuit 108 can acquire the target current by being connected between the resonance circuit 111 and the IGBT module 105. Since the current is not well obtained, the current detection circuit 108 can obtain the target current by obtaining the voltage across the small resistor, and since the voltage across the small resistor is not large, the current detection circuit 108 can input the voltage into an amplifier in the MCU106, thereby obtaining an accurate target current.

In a specific embodiment, as shown in fig. 5b, the main circuit 100' is not shown, and the voltage detection circuit 107 may include two diodes D1 and D2, two resistors R7 and R8, and a capacitor C5, wherein an anode of D1 is connected to the positive input terminal of the rectifying circuit 109, an anode of D2 is connected to the negative input terminal of the rectifying circuit 109, a cathode of D1 and a cathode of D2 are both connected to one end of R7, the other end of R7 is connected to the first input terminal of the MCU106, one end of R8 and one end of C5, and the other end of R8 and the other end of C5 are both grounded. The current detection circuit 108 may include a resistor RZ1, a resistor R9, a resistor R10, and a capacitor C6, wherein one end of the RZ1 is connected to the negative output terminal of the rectifying circuit 109 and one end of the R9, the other end of the RZ1 is connected to the source of the IGBT module 105, the other end of the R9 is connected to the input terminal of the amplifier in the MCU106, one end of the R10 is connected to the power supply voltage of the MCU106, the other end of the R10 is connected to one end of the C6 and the other end of the R9, and the other end of the C6 is grounded.

In this embodiment, the push-pull circuit 104 may drive the IGBT module 105 to turn on and off through the output driving voltage, so that the resonant circuit 111 may emit electromagnetic energy according to the switching state of the IGBT module 105 to heat the device to be heated, and may control the power state of the electromagnetic heating circuit 100 through the switching state of the IGBT module 105.

alternatively, the resonance circuit 111 may include: a heating coil and a resonant capacitor. Wherein, a heating coil is connected in series between the first output end of the filter circuit 110 and the drain of the IGBT module 105, and a resonant capacitor is connected in parallel at both ends of the heating coil. Optionally, the magnetic material of the heating coil is ferrite, iron silicon, or iron silicon aluminum.

Further, in the present embodiment, the filter circuit 110 includes multiple implementation forms, and only the requirement that the filter circuit 110 has an energy storage function is satisfied. In a specific implementation form of the filter circuit 110, optionally, the filter circuit 110 may include: a filter inductor and a filter capacitor;

The positive output end of the rectifying circuit 109 is connected to the input end of the filter inductor, the first end and the second end of the filter capacitor are connected in parallel between the output end of the filter inductor and the negative output end of the rectifying circuit 109, and the first end of the filter capacitor is further connected to the input end of the resonant circuit 111.

in this embodiment, the filter inductor and the filter capacitor play a role in filtering, and when the IGBT module 105 is not turned on, since the filter capacitor is connected in parallel to the trimming circuit, the voltage of the filter capacitor changes synchronously with the change of the ac voltage. The number and the numerical value of the filter inductors and the filter capacitors can be selected according to actual conditions.

it should be noted that: the filter circuit 110 may be configured such that the filter circuit 110 includes only a filter capacitor, in addition to the above-described configuration.

Fig. 6 is a schematic structural diagram of an electromagnetic heating device provided by the present invention, and as shown in fig. 6, an electromagnetic heating device 10 of the present embodiment includes: such as the electromagnetic heating circuit 100 described above.

The electromagnetic heating appliance 10 provided in this embodiment includes the electromagnetic heating circuit 100 as described above, and the above embodiments can be implemented, and specific implementation principles and technical effects thereof can be seen in the technical solutions of the embodiments shown in fig. 1 to fig. 5b, which are not described herein again.

fig. 7 is a schematic flow chart of the current adjusting method provided by the present invention, as shown in fig. 7, the current adjusting method of the present embodiment may include:

s101, acquiring the actual power of the electromagnetic heating appliance 10.

S102, when it is determined that the actual power of the electromagnetic heating appliance 10 is smaller than the preset power and it is determined that the target voltage is not the preset threshold, inputting a first pulse signal to the level shift circuit 102, and controlling the waveform conversion circuit 103 to be in a conducting state, so that the current of the IGBT module 105 driven by the push-pull circuit 104 is in an amplification region.

S103, when it is determined that the actual power of the electromagnetic heating appliance 10 is smaller than the preset power and the target voltage is the preset threshold, inputting a second pulse signal to the level conversion circuit 102, and controlling the waveform conversion circuit 103 to be in an off state, so that the push-pull circuit 104 drives the IGBT module 105 to be in a saturated conduction region.

With reference to fig. 1 to 5b, the current adjusting method of the present embodiment may use the microprocessor 101 in the electromagnetic heating circuit 100 as an execution main body, and the specific process may execute the above embodiments, and the specific implementation principle and technical effect thereof may refer to the technical solutions of the embodiments shown in fig. 1 to 5b, which are not described herein again.

Based on the embodiment in fig. 7, a specific implementation manner of S102 may be: optionally, a conducting signal is sent to the waveform converting circuit 103, the conducting signal is used for conducting the waveform converting circuit 103, and the connection between the waveform converting circuit 103 and the push-pull circuit 104 is connected;

and sending a first pulse signal to the level shift circuit 102, wherein the first pulse signal is used for enabling the push-pull circuit 104 to send a first driving signal to the IGBT module 105, and the first driving signal is used for driving the IGBT module 105 to be in an amplification region.

On the basis of the embodiment of fig. 7, a specific implementation manner of S103 is: optionally, a turn-off signal is sent to the waveform conversion circuit 103, the turn-off signal is used for turning off the waveform conversion circuit 103, and the connection between the waveform conversion circuit 103 and the push-pull circuit 104 is disconnected;

And sending a second pulse signal to the level shift circuit 102, where the second pulse signal is used to enable the push-pull circuit 104 to send a second driving signal to the IGBT module 105, the second driving signal is used to drive the IGBT module 105 to be in a saturated conduction region, and an amplitude of the second driving signal is greater than an amplitude of the first driving signal, and/or a high pulse width of the second driving signal is greater than a high pulse width of the first driving signal.

on the basis of the embodiment of fig. 7, optionally, when it is determined that the actual power is greater than or equal to the preset power, the current adjusting method of this embodiment may further include:

Sending a turn-off signal to the waveform conversion circuit 103, wherein the turn-off signal is used for turning off the waveform conversion circuit 103 and disconnecting the waveform conversion circuit 103 from the push-pull circuit 104;

And sending a third pulse signal to the level shift circuit 102, where the third pulse signal is used to enable the push-pull circuit 104 to send a third driving signal to the IGBT module 105, the third driving signal is used to drive the IGBT module 105 to be in a saturated conduction region, and an amplitude of the third driving signal is greater than an amplitude of the first driving signal, and/or a high pulse width of the third driving signal is greater than a high pulse width of the first driving signal.

On the basis of the embodiment of fig. 7, a specific implementation manner of S101 is as follows: optionally, a target voltage and a target current are obtained, wherein the target current is an actual current of the electromagnetic heating appliance 10;

from the target voltage and the target current, the actual power of the electromagnetic heating appliance 10 is determined.

the current adjusting method of this embodiment may implement the embodiment of the electromagnetic heating circuit 100, and the specific implementation principle and technical effect thereof may refer to the technical solutions of the embodiments shown in fig. 1 to fig. 5b, which are not described herein again.

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. an electromagnetic heating circuit (100), comprising: the device comprises a main loop (100'), a micro-processing unit (101), a level conversion circuit (102), a waveform conversion circuit (103), a push-pull circuit (104) and an insulated gate bipolar transistor IGBT module (105);

Wherein a first output end of the micro-processing unit (101) is connected with an input end of the level conversion circuit (102), a second output end of the micro-processing unit (101) is connected with an input end of the waveform conversion circuit (103), input ends of the push-pull circuit (104) are respectively connected with an output end of the level conversion circuit (102) and an output end of the waveform conversion circuit (103), an output end of the push-pull circuit (104) is connected with an input end of the IGBT module (105), and an output end of the IGBT module (105) is connected with the main loop (100');

The micro-processing unit (101) is used for acquiring the actual power and the target voltage of the electromagnetic heating appliance (10);

the micro-processing unit (101) is further used for controlling the waveform conversion circuit (103) to be in a conducting state when the actual power of the electromagnetic heating appliance (10) is smaller than a preset power and the target voltage is not a preset threshold value, so that the push-pull circuit (104) drives the IGBT module (105) to be in an amplification region;

The micro-processing unit (101) is further configured to control the waveform conversion circuit (103) to be in an off state when the actual power of the electromagnetic heating appliance (10) is smaller than a preset power and the target voltage is a preset threshold value, so that the push-pull circuit (104) drives the IGBT module (105) to be in a saturated conduction region;

The target voltage is the power supply voltage of the electromagnetic heating circuit (100), and the preset threshold is a valley value of the power supply voltage of the electromagnetic heating circuit (100), or the target voltage is a rectified voltage of the power supply voltage of the electromagnetic heating circuit (100), and the preset threshold is a valley value of the rectified voltage of the power supply voltage of the electromagnetic heating circuit (100).

2. The electromagnetic heating circuit (100) of claim 1,

a second input of the microprocessor unit (101) is connected to the main circuit (100') for obtaining a target current, which is an actual current of the electromagnetic heating appliance (10);

The micro-processing unit (101) is further used for determining the actual power of the electromagnetic heating appliance (10) according to the target voltage and the target current.

3. The electromagnetic heating circuit (100) according to claim 2, characterized in that said micro-processing unit (101) comprises: the device comprises a micro control unit MCU (106), a voltage detection circuit (107) and a current detection circuit (108);

wherein, the input end of the voltage detection circuit (107) is the input end of the micro-processing unit (101) and is used for obtaining the target voltage;

The current detection circuit (108) is used for acquiring the target current;

The first input end of the MCU (106) is connected with the output end of the voltage detection circuit (107), the second input end of the MCU (106) is connected with the output end of the current detection circuit (108), the first output end of the MCU (106) is connected with the input end of the level conversion circuit (102), and the second output end of the MCU (106) is connected with the input end of the waveform conversion circuit (103).

4. the electromagnetic heating circuit (100) of claim 1, wherein the waveform transformation circuit (103) comprises: the circuit comprises a first switch module, a diode and a first capacitor;

A first end of the first switch module is connected with a second output end of the micro-processing unit (101), a second end of the first switch module is respectively connected with a first end of the first capacitor and a negative electrode of the diode, a second end of the first capacitor is connected with an input end of the push-pull circuit (104), and a third end of the first switch module and a positive electrode of the diode are grounded;

The micro-processing unit (101) is used for sending a conducting signal to the first switch module when the actual power of the electromagnetic heating appliance (10) is smaller than the preset power and the target voltage is not a preset threshold value, so that the first switch module is in a conducting state;

the micro-processing unit (101) is further configured to send a turn-off signal to the first switch module when the actual power of the electromagnetic heating appliance (10) is less than a preset power and the target voltage is a preset threshold value, so that the first switch module is in a turn-off state.

5. The electromagnetic heating circuit (100) of claim 4, wherein the first switching module is a transistor and a sixth resistor, or an electronic switch.

6. The electromagnetic heating circuit (100) of claim 1, wherein the level shifting circuit (102) comprises: the circuit comprises a first resistor, a second resistor and a second switch module;

The first end of the first resistor is connected with a first level, the second end of the first resistor is connected with the first end of the second resistor, the first end of the second switch module is connected between the first resistor and the second resistor, the second end of the second switch module is connected with the input end of the push-pull circuit (104), and the third end of the second switch module is grounded with the second end of the second resistor.

7. The electromagnetic heating circuit (100) of claim 1, wherein the push-pull circuit (104) comprises: the circuit comprises a third resistor, a third switch module, a fourth resistor and a fifth resistor;

The first end of the third resistor is connected with a first level, the second end of the third resistor is respectively connected with the output end of the level conversion circuit (102), the output end of the waveform conversion circuit (103), the first end of the third switch module and the first end of the fourth switch module, the second end of the third switch module is connected with the first level, the third end of the third switch module is connected with the first end of the fourth resistor, the second end of the fourth resistor is respectively connected with the second end of the fourth switch module and the first end of the fifth resistor, the third end of the fourth switch module is grounded, and the second end of the fifth resistor is connected with the input end of the IGBT module (105).

8. The electromagnetic heating circuit (100) of claim 7, wherein the push-pull circuit (104) further comprises: a second capacitor;

9. The electromagnetic heating circuit (100) according to claim 3, characterized in that the main circuit (100') comprises: a rectifier circuit (109), a filter circuit (110), and a resonance circuit (111);

the rectifying circuit (109) is used for rectifying the power supply voltage of the electromagnetic heating circuit (100), the positive output end of the rectifying circuit (109) is connected with the first input end of the filter circuit (110), the first output end of the filter circuit (110) is connected with the input end of the resonance circuit (111), the output end of the resonance circuit (111) is connected with the first output end of the IGBT module (105), the negative output end of the rectifying circuit (109) is connected with the second input end of the filter circuit (110), and the second output end of the filter circuit (110) and the second output end of the IGBT module (105) are both grounded.

10. the electromagnetic heating circuit (100) according to claim 9, wherein a first input terminal of the voltage detection circuit (107) is connected to a positive input terminal of the rectification circuit (109), and a second input terminal of the voltage detection circuit (107) is connected to a negative input terminal of the rectification circuit (109) for obtaining the target voltage; or,

and a first input end of the voltage detection circuit (107) is connected with a positive input end of the rectifying circuit (109), and a second input end of the voltage detection circuit (107) is connected with a first input end of the filter circuit (110) and is used for acquiring the target voltage.

11. The electromagnetic heating circuit (100) according to claim 9, wherein a first input of the current detection circuit (108) is connected to a second output of the filter circuit (110), and a second input of the current detection circuit (108) is connected to a second output of the IGBT module (105) for obtaining the target current.

12. An electromagnetic heating appliance (10), characterized by comprising: the electromagnetic heating circuit (100) of any of claims 1-11.