CN112449452B

CN112449452B - Method for reducing noise of electromagnetic heating circuit, electromagnetic heating circuit and apparatus

Info

Publication number: CN112449452B
Application number: CN201910812602.XA
Authority: CN
Inventors: 孙鹏刚; 赵礼荣
Original assignee: Zhejiang Shaoxing Supor Domestic Electrical Appliance Co Ltd
Current assignee: Zhejiang Shaoxing Supor Domestic Electrical Appliance Co Ltd
Priority date: 2019-08-30
Filing date: 2019-08-30
Publication date: 2023-05-02
Anticipated expiration: 2039-08-30
Also published as: CN112449452A

Abstract

The invention provides a method for reducing noise of an electromagnetic heating circuit (100), the electromagnetic heating circuit (100) and an appliance (10). The method is applied to an electromagnetic heating circuit (100), the method comprising: when the to-be-heated appliance is magnetic and the electromagnetic heating circuit (100) meets the first condition, the current working frequency of the electromagnetic heating circuit (100) is obtained. The first condition is that the output power of the electromagnetic heating circuit (100) reaches the maximum output power or the width of the PPG signal reaches the maximum width. The width of the PPG signal is used for adjusting the conduction time of the IGBT module (102) in the induction cooker heating circuit (100). And judging whether the current working frequency is smaller than a preset frequency threshold value. If so, the width of the PPG signal is reduced until the current working frequency is greater than the preset frequency threshold value, and the maximum width of the PPG signal is updated to be the current width of the PPG signal. If not, the electromagnetic heating circuit (100) is adjusted to satisfy the first condition.

Description

Method for reducing noise of electromagnetic heating circuit, electromagnetic heating circuit and apparatus

Technical Field

The invention relates to the technical field of electromagnetic ovens, in particular to a method for reducing noise of an electromagnetic heating circuit, the electromagnetic heating circuit and an appliance.

Background

The electromagnetic heating circuit can convert electric energy into heat energy by utilizing an electromagnetic induction principle and heat the to-be-heated appliance. The electromagnetic heating circuit has wide application field and is suitable for various appliances needing heating functions, such as electromagnetic ovens, electric rice cookers, electric pressure cookers, soymilk makers, coffee makers, mixers and the like.

At present, the electromagnetic heating appliance can be freely selected by users of the used appliance to be heated. Therefore, when designing electromagnetic heating appliances, it is necessary to be compatible with various materials. Taking an electromagnetic heating device as an electromagnetic oven for example, the electromagnetic oven needs to be matched with cookers compatible with various materials such as 430 stainless steel, 410 stainless steel, 304 stainless steel, 202 stainless steel, composite bottom and the like. In general, the material characteristics of the heating devices are different, and the maximum output power of the electromagnetic heating devices is greatly different. In order to ensure the consistency of the maximum output power of the electromagnetic heating device under the to-be-heated devices of various materials, the pulse program generator (program pulse generator, PPG) signals in the electromagnetic heating device need to be automatically adjusted.

However, some materials of the heating device have certain magnetism, such as 430 stainless steel, 410 stainless steel, and other materials of the pot. When the to-be-heated appliances made of these materials are placed on the electromagnetic heating appliances, the inductance of the wire coil in the electromagnetic heating appliances increases. It will be appreciated by those skilled in the art that the resonant frequency is inversely proportional to the inductance of the wire coil. Therefore, the resonance frequency is lowered at this time. In order to meet the power requirement, the width of the PPG signal needs to be increased, namely the on-time of the IGBT module in the electromagnetic heating appliance is increased, so that the frequency of the PPG signal is reduced, the heating frequency of the appliance to be heated is lower than 20HZ and can fall into the frequency range of the human ear of a user, the user can hear the nourishing noise, and poor use experience is brought to the user.

Disclosure of Invention

The invention provides a method for reducing noise of an electromagnetic heating circuit, the electromagnetic heating circuit and an appliance, which are used for avoiding the problem that the nourishing sound emitted by the traditional technology due to the frequency reduction of a PPG signal falls into the frequency range of human ears, and improving the use experience of users.

In a first aspect, the present invention provides a method for reducing noise of an electromagnetic heating circuit, applied to the electromagnetic heating circuit, the method comprising:

when the to-be-heated appliance is magnetic and the electromagnetic heating circuit meets a first condition, acquiring the current working frequency of the electromagnetic heating circuit; the first condition is that the output power of the electromagnetic heating circuit reaches the maximum output power or the width of a Pulse Program Generator (PPG) signal reaches the maximum width, wherein the width of the PPG signal is used for adjusting the on-time of an IGBT module (102) in the electromagnetic oven heating circuit; judging whether the current working frequency is smaller than a preset frequency threshold value or not; if yes, the width of the PPG signal is reduced until the current working frequency is greater than the preset frequency threshold value, and the maximum width of the PPG signal is updated to be the current width of the PPG signal; if not, the electromagnetic heating circuit is adjusted to meet the first condition.

Optionally, determining that the appliance to be heated is a magnetic material includes: acquiring the current output power of the electromagnetic heating circuit under the reference working frequency; judging whether the current output power is smaller than a preset power threshold value or not; if yes, determining that the to-be-heated device is made of magnetic materials.

Optionally, the preset power threshold is larger than the output power of the electromagnetic heating circuit (100) at the reference working frequency when the to-be-heated appliance with the magnetic material is placed, and the preset power threshold is smaller than the rated output power of the electromagnetic heating circuit (100).

Optionally, when the current output power is greater than the preset power threshold, the method further includes: determining that the to-be-heated appliance is made of nonmagnetic or diamagnetic materials, and adjusting the electromagnetic heating circuit to meet the first condition.

In a second aspect, the present invention provides an electromagnetic heating circuit comprising: the device comprises a main loop, an insulated gate bipolar transistor IGBT module, a driving circuit and a micro-processing unit;

the main loop is used for emitting electromagnetic energy converted by input power supply voltage, the output end of the main loop is electrically connected with the drain electrode of the IGBT module and the first input end of the micro-processing unit respectively, the second input end of the micro-processing unit is electrically connected with the grid electrode of the IGBT module or the output end of the driving circuit, the output end of the micro-processing unit is electrically connected with the input end of the driving circuit and is used for outputting a PPG signal to the driving circuit, the width of the PPG signal is used for adjusting the conduction duration of the IGBT module, and the output end of the driving circuit is electrically connected with the grid electrode of the IGBT module;

The micro-processing unit is used for acquiring the current working frequency of the electromagnetic heating circuit when the to-be-heated appliance is determined to be made of a magnetic material and the electromagnetic heating circuit meets a first condition; the first condition is that the output power of the electromagnetic heating circuit reaches the maximum output power or the width of the PPG signal of the pulse program generator reaches the maximum width;

the micro-processing unit is further used for judging whether the current working frequency is smaller than a preset frequency threshold value; when the current working frequency is smaller than the preset frequency threshold value, reducing the width of the PPG signal until the current working frequency is larger than the preset frequency threshold value, and updating the maximum width of the PPG signal to the current width of the PPG signal; and when the current working frequency is greater than or equal to the preset frequency threshold, adjusting the electromagnetic heating circuit to meet the first condition.

Optionally, the micro-processing unit is specifically configured to obtain a current output power of the electromagnetic heating circuit at the reference working frequency; judging whether the current output power is smaller than a preset power threshold value or not; and when the current output power is smaller than the preset power threshold, determining that the to-be-heated appliance is made of a magnetic material.

Optionally, the micro-processing unit is further specifically configured to determine that the to-be-heated device is a nonmagnetic or diamagnetic material when the current output power is greater than the preset power threshold, and adjust the electromagnetic heating circuit to meet the first condition.

Optionally, the micro-processing unit includes: the micro control unit MCU, the synchronous circuit and the frequency detection circuit;

the input end of the synchronous circuit is electrically connected with the output end of the main loop, the output end of the synchronous circuit is electrically connected with the first input end of the MCU, the output end of the MCU is electrically connected with the input end of the driving circuit, the input end of the frequency detection circuit is electrically connected with the grid electrode of the IGBT module or the output end of the driving circuit, and is used for acquiring the current working frequency, and the output end of the frequency detection circuit is electrically connected with the second input end of the MCU;

the MCU is used for receiving the current working frequency from the frequency detection circuit when the to-be-heated appliance is determined to be made of magnetic materials and the electromagnetic heating circuit meets a first condition;

the MCU is further used for judging whether the current working frequency is smaller than the preset frequency threshold value; when the current working frequency is smaller than the preset frequency threshold value, reducing the width of the PPG signal until the current working frequency is larger than the preset frequency threshold value, and updating the maximum width of the PPG signal to the current width of the PPG signal; and when the current working frequency is greater than or equal to the preset frequency threshold, adjusting the electromagnetic heating circuit to meet the first condition.

Optionally, the input end of the micro-processing unit is electrically connected with the power supply end of the main loop, and is used for acquiring the current working voltage of the electromagnetic heating circuit; or the input end of the micro-processing unit is electrically connected with the rectification output end of the power supply voltage of the electromagnetic heating circuit and is used for obtaining the current working voltage of the electromagnetic heating circuit;

the micro-processing unit is also used for acquiring the current working current of the electromagnetic heating circuit;

the micro-processing unit is further used for calculating the current output power according to the current working voltage and the current working current under the reference working frequency.

Optionally, the micro-processing unit further comprises: a voltage sampling circuit and a current sampling circuit; the main circuit includes: the output end of the resonance circuit is electrically connected with the drain electrode of the IGBT module;

the first input end of the voltage sampling circuit is electrically connected with the first input end of the rectifying circuit, and the second input end of the voltage sampling circuit is electrically connected with the second input end of the rectifying circuit and is used for acquiring the current working voltage of the electromagnetic heating circuit;

The third input end of the MCU is electrically connected with the output end of the voltage sampling circuit and is used for receiving the current working voltage from the voltage sampling circuit;

the first input end of the current sampling circuit is electrically connected with the negative output end of the rectifying circuit, and the second input end of the current sampling circuit is electrically connected with the source electrode of the IGBT module and is used for obtaining the current working current of the electromagnetic heating circuit;

the fourth input end of the MCU is electrically connected with the output end of the current sampling circuit and is used for receiving the current working current from the voltage sampling circuit;

and the MCU is also used for calculating the current output power according to the current working voltage and the current working current under the reference working frequency.

Optionally, the current sampling circuit includes: a first resistor, a second resistor, a third resistor and a first capacitor;

the first end of the first resistor is electrically connected with the negative output end of the rectifying circuit and the first end of the second resistor respectively, the second end of the first resistor is electrically connected with the source electrode of the IGBT module, the second end of the second resistor is electrically connected with the fourth input end of the MCU, the first end of the third resistor and the first end of the first capacitor respectively, the second end of the third resistor is connected with a first level, and the second end of the first capacitor is grounded.

Optionally, the micro-processing unit further comprises: a voltage sampling circuit and a current sampling circuit; the main circuit includes: a rectifying circuit, a filter circuit and a resonant circuit;

the positive input end of the rectifying circuit is electrically connected with the first input end of the filtering circuit, the negative input end of the rectifying circuit is electrically connected with the second input end of the filtering circuit, and the output end of the resonant circuit is electrically connected with the drain electrode of the IGBT module;

the input end of the voltage sampling circuit is electrically connected with the input end of the rectifying circuit and is used for acquiring the current working voltage of the electromagnetic heating circuit;

the first input end of the current sampling circuit is electrically connected with the output end of the filter circuit, and the second input end of the current sampling circuit is electrically connected with the input end of the resonant circuit and is used for obtaining the current working current of the electromagnetic heating circuit;

Optionally, the current sampling circuit includes: the transformer, the fourth resistor, the first diode, the fifth resistor, the sixth resistor and the second capacitor;

the first input end of the transformer is connected with the output end of the filter circuit, the second output end of the transformer is connected with the input end of the resonant circuit, the first output end of the transformer is respectively connected with the first end of the fourth resistor and the positive electrode of the first diode, the negative electrode of the first diode is connected with the first end of the fifth resistor, the second end of the fifth resistor is respectively connected with the first end of the sixth resistor, the first end of the second capacitor and the fourth input end of the MCU, and the second output end of the transformer, the second end of the fourth resistor, the second end of the sixth resistor and the second end of the second capacitor are all grounded.

Optionally, the voltage sampling circuit includes: a second diode, a third diode, a fourth diode, a seventh resistor, an eighth resistor, and a third capacitor;

The positive electrode of the second diode is electrically connected with the first input end of the rectifying circuit, the positive electrode of the third diode is electrically connected with the second input end of the rectifying circuit, the negative electrode of the second diode and the negative electrode of the third diode are electrically connected with the first end of the seventh resistor, the second end of the seventh resistor is electrically connected with the first end of the eighth resistor, the positive electrode of the fourth diode, the third input end of the MCU and the first end of the third capacitor respectively, the negative electrode of the fourth diode is connected with a second level, and the second end of the eighth resistor and the second end of the third capacitor are grounded.

Optionally, the voltage sampling circuit includes: comprising the following steps: a fifth diode, a sixth diode, a ninth resistor, a tenth resistor, an eleventh resistor, a third capacitor, a triode, and a twelfth resistor;

the positive pole of the fifth diode is electrically connected with the first input end of the rectifying circuit, the positive pole of the sixth diode is electrically connected with the second input end of the rectifying circuit, the negative pole of the fifth diode and the negative pole of the sixth diode are electrically connected with the first end of the ninth resistor, the second end of the ninth resistor is respectively electrically connected with the first end of the third capacitor, the first end of the tenth resistor and the first end of the eleventh resistor, the second end of the eleventh resistor is electrically connected with the base electrode of the triode, the collector electrode of the triode is respectively electrically connected with the third input end of the MCU and the first end of the twelfth resistor, the second end of the twelfth resistor is electrically connected with a third level, and the second end of the third capacitor, the second end of the tenth resistor and the emitter electrode of the triode are all grounded.

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

According to the method for reducing the noise of the electromagnetic heating circuit, the electromagnetic heating circuit and the device, when the device to be heated is determined to be made of the magnetic material, in order to keep the same judging condition of the devices to be heated of different types which are made of the magnetic material, the electromagnetic heating circuit 100 can be made to meet the first condition. The first condition is that the output power of the electromagnetic heating circuit reaches the maximum output power or the width of the PPG signal reaches the maximum width, wherein the width of the PPG signal is used for adjusting the on-time of the IGBT module in the electromagnetic oven heating circuit. Therefore, in order to avoid that the working frequency of the PPG signal falls into the frequency range of the human ear of the user, the current working frequency of the electromagnetic heating circuit can be obtained, and whether the current working frequency is smaller than a preset frequency threshold value or not is judged. And when the current working frequency is smaller than the preset frequency threshold, reducing the width of the PPG signal until the current working frequency is larger than the preset frequency threshold, and updating the maximum width of the PPG signal to the current width of the PPG signal so as to ensure that the working frequency of the electromagnetic heating circuit cannot be adjusted below the preset frequency threshold. When the current working frequency is greater than or equal to a preset frequency threshold, the electromagnetic heating circuit is adjusted to meet a first condition so as to ensure a good heating environment of the electromagnetic heating circuit. According to the invention, the material of the to-be-heated appliance is identified, and the working state of the electromagnetic heating circuit can be adjusted when the to-be-heated appliance is made of a magnetic material, so that a good electromagnetic heating environment is provided for the to-be-heated appliance made of the magnetic material, the problem that the nourishing sound emitted by the reduction of the frequency of the PPG signal falls into the frequency range of the human ear in the traditional technology is avoided, and the use experience of a user is improved.

Drawings

In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description of the embodiments or the drawings used in the description of the prior art will be given in brief, it being obvious that the drawings in the description below are some embodiments of the invention and that other drawings can be obtained from them without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart of a method for reducing noise of an electromagnetic heating circuit according to the present invention;

FIG. 2 is a schematic diagram of an electromagnetic heating circuit according to the present invention;

FIG. 3 is a schematic diagram of an electromagnetic heating circuit according to the present invention;

FIG. 4 is a schematic diagram of an electromagnetic heating circuit according to the present invention;

FIG. 5 is a schematic diagram of an electromagnetic heating circuit according to the present invention;

fig. 6 is a schematic circuit diagram of a current sampling circuit in the electromagnetic heating circuit provided by the invention;

FIG. 7 is a schematic diagram of an electromagnetic heating circuit according to the present invention;

fig. 8 is a schematic circuit diagram of a current sampling circuit in an electromagnetic heating circuit according to the present invention;

fig. 9 is a schematic circuit diagram of a voltage sampling circuit in the electromagnetic heating circuit provided by the invention;

Fig. 10 is a schematic circuit diagram of a voltage sampling circuit in the electromagnetic heating circuit provided by the invention;

fig. 11 is a schematic structural view of an electromagnetic heating device provided by the invention.

Reference numerals illustrate:

100—an electromagnetic heating circuit; 101-a main loop;

102-an IGBT module; 103-a driving circuit;

104-a microprocessor unit; 1041-MCU;

1042-a synchronization circuit; 1043-a frequency detection circuit;

1044-a voltage sampling circuit; 1045-a current sampling circuit;

1011—a rectifying circuit; 1012-a filter circuit;

1013-a resonant circuit; 10-electromagnetic heating appliance.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Fig. 1 is a flow chart of a method for reducing noise of an electromagnetic heating circuit according to the present invention. As shown in fig. 1, the method for reducing noise of an electromagnetic heating circuit of the present embodiment is applied to an electromagnetic heating circuit 100. The method for reducing noise of the electromagnetic heating circuit 100 of the present embodiment may include:

s101, when the to-be-heated appliance is magnetic and the electromagnetic heating circuit 100 meets the first condition, the current working frequency of the electromagnetic heating circuit 100 is obtained. The first condition is that the output power of the electromagnetic heating circuit 100 reaches the maximum output power or the width of the PPG signal reaches the maximum width, wherein the width of the PPG signal is used for adjusting the on-time of the IGBT module 102 in the electromagnetic heating circuit 100.

In this embodiment, the electromagnetic heating circuit 100 may be implemented in various ways to determine the material of the appliance to be heated. When it is determined that the to-be-heated tool is made of a magnetic material, since the to-be-heated tool made of the same magnetic material also includes a plurality of types, the present embodiment can adjust the electromagnetic heating circuit 100 to satisfy the first condition, so that different types of to-be-heated tools maintain the same judgment condition.

In this way, the electromagnetic heating circuit 100 can adjust the output power of the electromagnetic heating circuit 100 at this time so that the output power of the electromagnetic heating circuit 100 reaches the maximum output power. The maximum output power is the maximum value that can be reached by the output power of the electromagnetic heating circuit 100, and is generally related to the material of the appliance to be heated. In general, the material of the heating device is different, and the maximum output power of the electromagnetic heating circuit 100 is different.

Alternatively, electromagnetic heating circuit 100 may adjust the width of the PPG signal at this time so that the width of the PPG signal reaches a maximum width. The maximum width of the PPG signal may be set according to an empirical value in this embodiment, which is not limited in this embodiment.

Accordingly, in order to prevent the electromagnetic heating circuit 100 from buzzing up and entering the ear frequency range of the user due to the operation frequency of the electromagnetic heating circuit 100 at this time, the present embodiment needs to acquire the current operation frequency of the electromagnetic heating circuit 100.

S102, judging whether the current working frequency is smaller than a preset frequency threshold value.

In this embodiment, by comparing the magnitude relation between the current operating frequency and the preset frequency threshold, it may be determined whether the current operating frequency may cause the electromagnetic heating circuit 100 to buzzing and enter the ear frequency range of the user.

The magnitude of the preset frequency threshold is not limited in this embodiment. In general, since the human ear frequency is typically up to 18KHz, some people can hear frequencies below 20KHz, and thus the preset frequency threshold may be set to the maximum achievable for the human ear frequency, e.g., 20KHz.

Thus, if the current operating frequency is less than the preset frequency threshold, determining the current operating frequency causes the electromagnetic heating circuit 100 to buzzing into the ear frequency range of the user, thereby executing S1031. If the current operating frequency is equal to or greater than the preset frequency threshold, it is determined that the current operating frequency does not cause the electromagnetic heating circuit 100 to buzzing into the ear frequency range of the user, thereby executing S1032.

S1031, reducing the width of the PPG signal until the current working frequency is larger than a preset frequency threshold value, and updating the maximum width of the PPG signal to the current width of the PPG signal.

In this embodiment, when the current operating frequency is smaller than the preset frequency threshold, the width of the PPG signal may be continuously reduced to reduce the output power of the electromagnetic heating circuit 100 until the current operating frequency is greater than the preset frequency threshold. At this time, the current width of the PPG signal is recorded, and the maximum width of the PPG signal is updated to the current width of the PPG signal, so as to ensure that the operating frequency of the electromagnetic heating circuit 100 is not adjusted below the preset frequency threshold.

S1032, the electromagnetic heating circuit 100 is adjusted to satisfy the first condition.

In this embodiment, when the current operating frequency is greater than the preset frequency threshold, the electromagnetic heating circuit 100 may be adjusted to satisfy the first condition, so as to ensure that the operating frequency of the electromagnetic heating circuit 100 is not adjusted to be below the preset frequency threshold, so that the electromagnetic heating circuit 100 has a good heating environment.

In this way, the present embodiment can determine whether the output power of the electromagnetic heating circuit 100 reaches the maximum output power at this time based on the present operating voltage of the electromagnetic heating circuit 100 and the present operating current of the electromagnetic heating circuit 100. If not, the output power of the electromagnetic heating circuit 100 is continuously increased, so that the output power of the electromagnetic heating circuit 100 reaches the maximum output power.

Alternatively, the present embodiment may acquire the current width of the PPG signal, and determine whether the current width of the PPG signal reaches the maximum width. If not, the width of the PPG signal is continuously increased, so that the width of the PPG signal reaches the maximum width.

In a specific embodiment, taking the electromagnetic heating apparatus 10 as an electromagnetic oven, the apparatus to be heated as a cooker, and the preset frequency threshold taking 22KHz as an example, the specific process of adopting the electromagnetic oven including the electromagnetic heating circuit 100 of the embodiment to ensure consistent maximum output power under the cookers of different materials is as follows:

step 1, when it is determined that the pan is made of a magnetic material and the electromagnetic heating circuit 100 meets a first condition, sampling a current working frequency f of the electromagnetic heating circuit 100.

And step 2, judging whether the current working frequency f is smaller than 22KHz.

Step 21, if f <22KHz, continuously reducing the width of the PPG signal to reduce the output power of the induction cooker until f >22 KHz. At this time, the maximum width of the PPG signal is updated to the current width of the PPG signal, so as to ensure that the operating frequency of the electromagnetic heating circuit 100 is not adjusted to be below 22KHz.

And 22, if f is more than or equal to 22KHz, sampling the current working voltage and current working current of the electromagnetic heating circuit 100, and determining whether the output power of the electromagnetic heating circuit 100 reaches the maximum output power at the moment. If not, the output power of the electromagnetic heating circuit 100 is continuously increased until the output power of the electromagnetic heating circuit 100 reaches the maximum output power. Alternatively, a judgment width of the PPG signal is obtained, and a current width of the PPG signal is determined so that the maximum width is reached. If not, the width of the PPG signal is continuously increased until the width of the PPG signal reaches the maximum width. Thereby, the heating environment of the electromagnetic heating circuit 100 is ensured.

In the electromagnetic heating circuit provided in this embodiment, when it is determined that the to-be-heated appliance is made of a magnetic material, in order to keep the same judgment conditions for the to-be-heated appliances of different types that are made of the magnetic material, the electromagnetic heating circuit 100 may be made to satisfy the first condition. The first condition is that the output power of the electromagnetic heating circuit reaches the maximum output power or the width of the PPG signal reaches the maximum width, wherein the width of the PPG signal is used for adjusting the on-time of the IGBT module in the electromagnetic oven heating circuit. Therefore, in order to avoid that the working frequency of the PPG signal falls into the frequency range of the human ear of the user, the current working frequency of the electromagnetic heating circuit can be obtained, and whether the current working frequency is smaller than a preset frequency threshold value or not is judged. And when the current working frequency is smaller than the preset frequency threshold, reducing the width of the PPG signal until the current working frequency is larger than or equal to the preset frequency threshold, and updating the maximum width of the PPG signal to the current width of the PPG signal so as to ensure that the working frequency of the electromagnetic heating circuit cannot be adjusted below the preset frequency threshold. When the current working frequency is greater than or equal to a preset frequency threshold, the electromagnetic heating circuit is adjusted to meet a first condition so as to ensure a good heating environment of the electromagnetic heating circuit. According to the invention, the material of the to-be-heated appliance is identified, and the working state of the electromagnetic heating circuit can be adjusted when the to-be-heated appliance is made of a magnetic material, so that a good electromagnetic heating environment is provided for the to-be-heated appliance made of the magnetic material, the problem that the nourishing sound emitted by the reduction of the frequency of the PPG signal falls into the frequency range of the human ear in the traditional technology is avoided, and the use experience of a user is improved.

Since the materials of the to-be-heated appliances on the electromagnetic heating appliance 10 including the electromagnetic heating circuit 100 are different, and the output frequencies of the electromagnetic heating circuit 100 are different, in a feasible implementation manner of determining that the to-be-heated appliance is made of a magnetic material in S101, optionally, the embodiment may fix a reference working frequency, and obtain the current output power of the electromagnetic heating circuit 100 at the reference working frequency, so as to determine whether the current output power is less than the preset power threshold.

The preset power threshold may be set according to an empirical value, which is not limited in this embodiment. Optionally, the preset power threshold is greater than the output power of the electromagnetic heating circuit 100 at the reference operating frequency when the magnetic material to be heated is placed on the electromagnetic heating apparatus 10, and the preset power threshold is less than the rated output power of the electromagnetic heating circuit 100. In addition, the preset power threshold may be smaller than the output power of the electromagnetic heating circuit 100 at the reference operating frequency when the non-magnetic or diamagnetic material to be heated is placed on the electromagnetic heating device 10.

Thus, when the current output power is smaller than the preset power threshold value, the to-be-heated appliance is determined to be made of magnetic materials. When the current output power is greater than the preset power threshold, it may be determined that the to-be-heated appliance is made of a nonmagnetic or diamagnetic material, and the embodiment may adjust the electromagnetic heating circuit 100 to satisfy the first condition. The specific process of the electromagnetic heating circuit 100 to meet the first adjustment can be referred to in the foregoing, and will not be described herein.

When the current output power is equal to the preset power threshold, the embodiment can determine that the to-be-heated device is made of a magnetic material, or determine that the to-be-heated device is made of a nonmagnetic or diamagnetic material, and the setting of the preset power threshold is relevant.

In this embodiment, through the material that discerns the utensil of waiting to heat, can adjust electromagnetic heating circuit's operating condition to waiting to heat the utensil for different materials and provide good electromagnetic heating environment, avoided among the conventional art because the frequency of PPG signal decline and the problem that the sound of sending falls into human ear frequency range, improved user's use experience.

Illustratively, the present embodiment also provides an electromagnetic heating circuit 100. Fig. 2 is a schematic structural diagram of an electromagnetic heating circuit provided in the present invention, as shown in fig. 2, an electromagnetic heating circuit 100 of the present embodiment may include: a main loop 101, an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT) module 102, a drive circuit 103, and a microprocessor unit 104.

The main circuit 101 is configured to emit electromagnetic energy converted by an input power supply voltage, an output end of the main circuit 101 is electrically connected to a drain electrode of the IGBT module 102 and a first input end of the micro processing unit 104, a second input end of the micro processing unit 104 is electrically connected to a gate electrode of the IGBT module 102 or an output end of the driving circuit 103, an output end of the micro processing unit 104 is electrically connected to an input end of the driving circuit 103, and is configured to output a PPG signal to the driving circuit 103, and an output end of the driving circuit 103 is electrically connected to the gate electrode of the IGBT module 102.

In this embodiment, the output end of the driving circuit 103 is electrically connected to the gate of the IGBT module 102, so that the IGBT module 102 can be driven to be turned on and off based on the PPG signal output by the micro processing unit 104. The width of the PPG signal is used to adjust the on-time of the IGBT module 102. Based on the electrical connection between the output end of the main circuit 101 and the drain electrode of the IGBT module 102, the main circuit 101 may convert the received power supply voltage into electromagnetic energy according to the on state or the off state of the IGBT module 102, and emit electromagnetic energy to heat an appliance to be heated (such as a pot), or stop emitting electromagnetic energy to heat the appliance to be heated, and may also control the power state of the electromagnetic heating circuit 100.

The power supply voltage can be 220V and 50HZ single-phase sinusoidal ac voltage, or can be a transformed mains supply, which is not limited in this embodiment, and only the type of the power supply voltage is required to meet various working requirements. And the specific number of IGBT modules 102 is not limited in this embodiment.

The micro-processing unit 104 may learn the material of the appliance to be heated in a variety of ways. Alternatively, in order to know the material of the electromagnetic heating device 10 to be heated, in this embodiment, the micro-processing unit 104 may obtain the current output power of the electromagnetic heating circuit 100 at the reference operating frequency. Further, the micro-processing unit 104 may compare the magnitude relation between the current output power and the preset power threshold to determine the material of the appliance to be heated.

In this embodiment, the material of the to-be-heated device may be distinguished by a preset power threshold, where the preset power threshold may be expressed as the minimum output power of the electromagnetic heating circuit 100 when the to-be-heated device is a non-magnetic material or a diamagnetic material, or the preset power threshold may be expressed as the maximum output power of the electromagnetic heating circuit 100 when the to-be-heated device is a magnetic material. The setting content of the preset power threshold may be referred to the description in fig. 1, and will not be described herein.

In addition, the preset power threshold may be set according to the actual situation of the electromagnetic heating circuit 100, may be set in the micro-processing unit 104 in advance, or may be manually input into the micro-processing unit 104 by the user's expectation, which is not limited in this embodiment.

Thus, when the current output power is smaller than the preset power threshold, the micro-processing unit 104 may determine that the appliance to be heated is a magnetic material. In order to ensure that the same judgment criteria are maintained for different types of appliances to be heated, which are magnetic materials, the micro-processing unit 104 may adjust the electromagnetic heating circuit 100 to satisfy the first condition. The adjustment process for the electromagnetic heating circuit 100 to satisfy the first condition may be described with reference to fig. 1, and will not be described herein.

Thus, based on the electrical connection relationship between the second input terminal of the micro-processing unit 104 and the gate of the IGBT module 102, the micro-processing unit 104 may acquire the frequency of the voltage on the gate of the IGBT module 102, and take the frequency as the current operating frequency of the electromagnetic heating circuit 100. Alternatively, based on the electrical connection relationship between the second input terminal of the micro-processing unit 104 and the output terminal of the driving circuit 103, the micro-processing unit 104 may acquire the frequency of the driving signal output by the driving circuit 103. Since the frequency of the driving signal is equivalent to the frequency of the voltage on the gate of the IGBT module 102 (especially in the high power state), the micro processing unit 104 can use the frequency of the driving signal as the current operating frequency of the electromagnetic heating circuit 100.

Based on the above description, the micro-processing unit 104 may acquire the current operating frequency of the electromagnetic heating circuit 100, and determine, through the magnitude relation between the current operating frequency and the preset frequency threshold, whether the current operating frequency may cause the electromagnetic heating circuit 100 to buzzing into the ear frequency range of the user.

The magnitude of the preset frequency threshold is not limited in this embodiment. In general, since the human ear frequency is typically up to 18KHz, some people can hear frequencies below 20KHz, and thus the preset frequency threshold may be set to the maximum achievable for the human ear frequency, e.g., 20KHz. The preset frequency threshold may be set in the micro-processing unit 104 in advance, or may be manually input into the micro-processing unit 104 by the user's expectation, which is not limited in this embodiment.

If the current operating frequency is less than the preset frequency threshold, the micro-processing unit 104 may continuously decrease the width of the PPG signal to decrease the output power of the electromagnetic heating circuit 100 until the current operating frequency is greater than or equal to the preset frequency threshold. At this time, the micro-processing unit 104 records the current width of the PPG signal, and updates the maximum width of the PPG signal to the current width of the PPG signal, so as to ensure that the operating frequency of the electromagnetic heating circuit 100 is not adjusted below the preset frequency threshold.

If the current operating frequency is greater than or equal to the preset frequency threshold, the micro-processing unit 104 may adjust the electromagnetic heating circuit 100 to satisfy the first condition, so as to ensure that the operating frequency of the electromagnetic heating circuit 100 is not adjusted to be below the preset frequency threshold, so that the electromagnetic heating circuit 100 has a good heating environment. The adjustment process for the electromagnetic heating circuit 100 to satisfy the first condition may be described with reference to fig. 1, and will not be described herein.

The PPG signal is a pulse signal output by the micro processing unit 104 to the driving circuit 103, so that the driving circuit 103 can drive the IGBT module 102 to be turned on or turned off based on the PPG signal. The specific implementation form of the PPG signal is not limited in this embodiment.

Additionally, optionally, when the current output power is greater than the preset power threshold, the micro-processing unit 104 may determine that the appliance to be heated is a non-magnetic material or a diamagnetic material. Thus, the micro-processing unit 104 may adjust the electromagnetic heating circuit 100 to satisfy the first condition. The adjustment process for the electromagnetic heating circuit 100 to satisfy the first condition may be described with reference to fig. 1, and will not be described herein.

In a specific embodiment, based on the structure of the electromagnetic heating circuit 100 shown in fig. 2, taking the electromagnetic heating apparatus 10 as an electromagnetic oven, the apparatus to be heated as a cooker, and the preset frequency threshold value as 22KHz as an example, the specific process of adopting the electromagnetic oven including the electromagnetic heating circuit 100 of the embodiment to ensure consistent maximum output power under the cookers of different materials is as follows:

step 1, the micro-processing unit 104 may fix a reference operating frequency and obtain the current output power P of the electromagnetic heating circuit 100 at the reference operating frequency.

Step 2, the micro-processing unit 104 determines a magnitude relation between the current output power P and a preset power threshold.

Step 3, when the current output power P is smaller than a preset power threshold, the micro-processing unit 104 can determine that the pan is made of a magnetic material; when the current output power P is larger than the preset power threshold, the cookware can be determined to be made of nonmagnetic materials or diamagnetic materials.

In step 41, if the pan is made of magnetic material, the micro-processing unit 104 may adjust the output power of the electromagnetic heating circuit 100 to reach the maximum output power or adjust the width of the PPG signal to reach the maximum width. At this time, the micro-processing unit 104 may sample the current operating frequency f of the induction cooker. If f <22KHz, the micro-processing unit 104 may continuously decrease the width of the PPG signal to decrease the output power of the induction cooker until f is greater than or equal to 22 KHz. At this time, the micro-processing unit 104 may record the current width of the PPG signal, and use the current width as the maximum width of the PPG signal in the power adjustment process, so as to ensure that the operating frequency of the induction cooker is not adjusted to be below 22 KHz.

In step 42, if the pan is made of non-magnetic material or diamagnetic material, the micro-processing unit 104 can adjust the output power of the electromagnetic heating circuit 100 to reach the maximum output power or adjust the width of the PPG signal to reach the maximum width, so as to ensure a good heating environment of the electromagnetic heating circuit 100.

The electromagnetic heating circuit provided by the embodiment is electrically connected with the drain electrode of the IGBT module through the output end of the main circuit, the output end of the main circuit is electrically connected with the first input end of the micro-processing unit, the output end of the micro-processing unit is electrically connected with the input end of the driving circuit and is used for outputting a pulse program generator PPG signal to the driving circuit, the output end of the driving circuit is electrically connected with the grid electrode of the IGBT module, so that the main circuit can emit electromagnetic energy converted by the input power supply voltage when the IGBT module is conducted, and the main circuit can stop emitting electromagnetic energy converted by the input power supply voltage when the IGBT module is turned off. The micro-processing unit is configured to, when determining that the to-be-heated appliance is made of a magnetic material, enable the electromagnetic heating circuit 100 to satisfy the first condition in order to keep the same judgment condition for different types of to-be-heated appliances that are made of the magnetic material. The first condition is that the output power of the electromagnetic heating circuit reaches the maximum output power or the width of the PPG signal reaches the maximum width, wherein the width of the PPG signal is used for adjusting the on-time of the IGBT module in the electromagnetic oven heating circuit. Therefore, in order to avoid that the working frequency of the PPG signal falls into the frequency range of the human ear of the user, the second input end of the micro-processing unit is electrically connected with the grid electrode of the IGBT module or the output end of the driving circuit, the current working frequency of the electromagnetic heating circuit can be obtained, when the current working frequency is smaller than the preset frequency threshold value, the width of the PPG signal is reduced until the current working frequency is larger than or equal to the preset frequency threshold value, and the maximum width of the PPG signal is updated to the current width of the PPG signal, so that the working frequency of the electromagnetic heating circuit cannot be adjusted to be lower than the preset frequency threshold value. When the current output power is greater than or equal to a preset frequency threshold, the micro-processing unit can adjust the electromagnetic heating circuit to meet a first condition so as to ensure a good heating environment of the electromagnetic heating circuit. In this embodiment, through the material that discerns the utensil of waiting to heat, can adjust electromagnetic heating circuit's operating condition to waiting to heat the utensil for different materials and provide good electromagnetic heating environment, avoided among the conventional art because the frequency of PPG signal decline and the problem that the sound of sending falls into human ear frequency range, improved user's use experience.

Next, a specific structure included in the electromagnetic heating circuit 100 of the present embodiment will be described in detail with reference to fig. 3 to 10 on the basis of the embodiment of fig. 2.

Based on the foregoing functional description of the micro-processing unit, the micro-processing unit 104 may be divided into a plurality of constituent parts. Next, a specific structure of the micro processing unit 104 will be described in detail with reference to fig. 3.

Fig. 3 is a schematic structural diagram of an electromagnetic heating circuit provided in the present invention, as shown in fig. 3, the micro-processing unit 104 of the present embodiment may include: a micro control unit (Microcontroller Unit, MCU 1041), a synchronization circuit 1042 and a frequency detection circuit 1043.

The input end of the synchronization circuit 1042 is electrically connected with the output end of the main circuit 101, the output end of the synchronization circuit 1042 is electrically connected with the first input end of the MCU 1041, the output end of the MCU 1041 is electrically connected with the input end of the driving circuit 103, the input end of the frequency detection circuit 1043 is electrically connected with the gate of the IGBT module 102 or the output end of the driving circuit 103, for obtaining the current working frequency, and the output end of the frequency detection circuit 1043 is electrically connected with the second input end of the MCU 1041.

In this embodiment, the synchronization circuit 1042 is electrically connected to the output end of the main circuit 101 to detect the operation state of the main circuit 101. The synchronization circuit 1042 is electrically connected to the first input terminal of the MCU 1041, and can transmit the signal detected by the synchronization circuit 1042 to the MCU 1041, so that the MCU 1041 can output the PPG signal according to the signal detected by the synchronization circuit 1042.

The signal detected by the synchronization circuit 1042 may represent the characteristics of the current or voltage at the output of the main loop 101, so that the operating state of the main loop 101 may be detected to determine parameters such as the width and frequency of the PPG signal. The synchronization circuit 1042 may be an integrated chip or a circuit built up of a plurality of components, and is not limited to this embodiment.

In this embodiment, the frequency detection circuit 1043 is electrically connected to the gate of the IGBT module 102, so as to obtain the voltage on the gate of the IGBT module 102, thereby detecting the frequency of the voltage on the gate of the IGBT module 102. The frequency detection circuit 1043 is electrically connected to the MCU 1041, and may send the frequency of the voltage on the gate of the IGBT module 102 to the MCU 1041, so that when the MCU 1041 determines that the to-be-heated device is made of a magnetic material and the electromagnetic heating circuit 100 meets the first condition, the frequency of the voltage on the gate of the IGBT module 102 may be used as the current operating frequency of the electromagnetic heating circuit 100.

Alternatively, the frequency detection circuit 1043 is electrically connected to the output terminal of the driving circuit 103, and thereby can acquire the driving signal output from the driving circuit 103, and detect the frequency of the driving signal. Since the frequency of the driving signal is equivalent to the frequency of the voltage on the gate of the IGBT module 102 (especially in a high power state), the frequency detection circuit 1043 is electrically connected to the MCU 1041, and can send the frequency of the driving signal to the MCU 1041, so that the frequency of the driving signal can be used as the current operating frequency of the electromagnetic heating circuit 100 when the MCU 1041 determines that the appliance to be heated is made of a magnetic material and the electromagnetic heating circuit 100 satisfies the first condition.

The frequency detection circuit 1043 may be an integrated chip or a circuit built up of a plurality of components, which is not limited in this embodiment.

Thus, the MCU 104 may also determine whether the current operating frequency is less than a preset frequency threshold. When the current operating frequency is less than the preset frequency threshold, the MCU 104 may decrease the width of the PPG signal until the current operating frequency is greater than or equal to the preset frequency threshold, and update the maximum width of the PPG signal to the current width of the PPG signal. When the current operating frequency is greater than or equal to the preset frequency threshold, the MCU 104 may adjust the electromagnetic heating circuit 100 to satisfy the first condition.

Optionally, in this embodiment, the MCU 1041 may acquire the current output power of the electromagnetic heating circuit 100 at the reference operating frequency, and compare the magnitude relation between the current output power and the preset power threshold to determine the material of the to-be-heated appliance.

When the current output power is smaller than the preset power threshold, the MCU 1041 may determine that the appliance to be heated is a magnetic material, and adjust the electromagnetic heating circuit 100 to satisfy the first condition. Thus, the MCU 1041 may receive the current operating frequency from the frequency detection circuit 1043. If the current operating frequency is less than the preset frequency threshold, the MCU 1041 may decrease the width of the PPG signal until the current operating frequency is greater than or equal to the preset frequency threshold, and the MCU 1041 may determine the current width of the PPG signal as the maximum width of the PPG signal, so as to ensure that the operating frequency of the electromagnetic heating circuit 100 is not adjusted below the preset frequency threshold.

When the current output power is greater than or equal to the preset frequency threshold, the MCU 1041 may adjust the electromagnetic heating circuit 100 to satisfy the first condition, so that the electromagnetic heating circuit 100 has a good heating environment.

In order to determine the material of the electromagnetic heating device 10 to be heated, the micro-processing unit 104 may also have the function of detecting the operating current and the operating voltage of the electromagnetic heating circuit 100 in real time.

Next, a description will be given of an implementation procedure in which the micro-processing unit 104 can sample the operation current and the operation voltage of the electromagnetic heating circuit 100, with reference to fig. 4.

In a possible implementation, as shown in fig. 4, alternatively, the input terminal of the micro-processing unit 104 may obtain the current operating voltage of the electromagnetic heating circuit 100 by being electrically connected to the power supply terminal of the main circuit 101. Alternatively, the input of the micro-processing unit 104 may obtain the current operating voltage of the electromagnetic heating circuit 100 by being electrically connected to the rectified output of the power supply voltage of the electromagnetic heating circuit 100 (not shown in fig. 4).

In this embodiment, the micro-processing unit 104 may also acquire the current operating current of the electromagnetic heating circuit 100. The micro-processing unit 104 thus fixes a reference operating frequency, based on the principle that the current multiplied by the voltage is equal to the power, at which the current output power can be calculated from the current operating voltage and the current operating current.

The implementation of the micro-processing unit 104 using the current operating current and the current operating voltage may be implemented by a software program or may be implemented by a hardware circuit, which is not limited in this embodiment.

Next, an implementation in which the micro processing unit 104 of the present embodiment samples the present operation current and the present operation voltage will be described with reference to fig. 5 and 6.

In a possible implementation manner, based on the embodiments shown in fig. 3 to fig. 4, as shown in fig. 5, the micro processing unit 104 of this embodiment may further include: a voltage sampling circuit 1044 and a current sampling circuit 1045. The main circuit 101 may include: the rectifying circuit 1011, the filter circuit 1012, and the resonant circuit 1013 which are sequentially connected, and an output terminal of the resonant circuit 1013 is electrically connected to a drain of the IGBT module 102.

In this embodiment, the rectifying circuit 1011 can rectify the power supply voltage into a pulsating dc voltage, so as to conveniently supply the operating voltage to the resonant circuit 1013. The power supply voltage may refer to the foregoing description, and will not be described herein. The rectifying circuit 1011 may be a full-bridge rectifier or a half-bridge rectifier, which is not limited in this embodiment.

In this embodiment, the filter circuit 1012 is electrically connected to the rectifier circuit 1011, so that the pulsating direct current voltage rectified by the rectifier circuit 1011 can be filtered. The filter circuit 1012 is electrically connected to the resonant circuit 1013, so that an operating voltage can be provided to the resonant circuit 1013, which is convenient for the resonant circuit 1013 to start heating, so that the electromagnetic heating circuit 100 operates normally. The specific implementation form of the filter circuit 1012 is not limited in this embodiment, and it is only required that the filter circuit 1012 has the functions of filtering and energy storage.

Optionally, the filter circuit 1012 may include: filter inductance and filter capacitance. The positive output end of the rectifying circuit 1011 is connected with 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 1011, and the first end of the filter capacitor is also connected with the input end of the resonant circuit 1013 and the first input end of the micro-processing unit 104, respectively.

In this embodiment, the filter inductor and the filter capacitor play roles in filtering and energy storage, and when the IGBT module 102 is not turned on, the voltage of the filter capacitor changes synchronously with the change of the supply voltage because the filter capacitor is connected in parallel with the rectifying circuit 1011. The number and the numerical value of the filter inductor and the filter capacitor can be selected according to actual conditions.

It should be noted that: the filter circuit 1012 may include only a filter capacitor in addition to the above-described configuration, and the embodiment is not limited thereto.

In this embodiment, a first input terminal of the voltage sampling circuit 1044 is electrically connected to a first input terminal of the rectifying circuit 1011, and a second input terminal of the voltage sampling circuit 1044 is electrically connected to a second input terminal of the rectifying circuit 1011, so as to obtain a current operating voltage of the electromagnetic heating circuit 100.

The voltage sampling circuit 1044 may be an integrated chip or a circuit built up of a plurality of components, which is not limited in this embodiment.

In this embodiment, a first input end of the current sampling circuit 1045 is electrically connected to a negative output end of the rectifying circuit 1011, and a second input end of the current sampling circuit 1045 is electrically connected to a source electrode of the IGBT module 102, so as to obtain a current operating current of the electromagnetic heating circuit 100.

The current sampling circuit 1045 may be an integrated chip or a circuit built up of a plurality of components, which is not limited in this embodiment.

In this embodiment, the third input terminal of the MCU 1041 is electrically connected to the output terminal of the voltage sampling circuit 1044, and can receive the current operating voltage from the voltage sampling circuit 1044. A fourth input of the MCU 1041 is electrically connected to an output of the current sampling circuit 1045, and may receive the present operating current from the voltage sampling circuit 1044. Thus, the MCU 1041 fixes a reference operating frequency, and at the reference operating frequency, a current output power may be calculated according to a current operating voltage and a current operating current.

The specific structure of the current sampling circuit 1045 is not limited in this embodiment. In a possible implementation structure, as shown in fig. 6, optionally, the current sampling circuit 1045 of this embodiment may include: the first resistor R1, the second resistor R2, the third resistor R3 and the first capacitor C1.

The first end of the first resistor R1 is electrically connected to the negative output end of the filter circuit 1012 and the first end of the second resistor R2, the second end of the first resistor R1 is electrically connected to the source of the IGBT module 102, the second end of the second resistor R2 is electrically connected to the fourth input end of the MCU 1041, the first end of the third resistor R3, and the first end of the first capacitor C1, the second end of the third resistor R3 is connected to the first level V1, and the second end of the first capacitor C1 is grounded.

In another possible implementation manner, based on the embodiments shown in fig. 3 to fig. 4, as shown in fig. 7, the micro processing unit 104 of this embodiment may further include: a voltage sampling circuit 1044 and a current sampling circuit 1045. The main circuit 101 may include: a rectifying circuit 1011, a filter circuit 1012, and a resonant circuit 1013.

The positive input terminal of the rectifying circuit 1011 is electrically connected to the first input terminal of the filter circuit 1012, the negative input terminal of the rectifying circuit 1011 is electrically connected to the second input terminal of the filter circuit 1012, and the output terminal of the resonant circuit 1013 is electrically connected to the drain of the IGBT module 102.

The input terminal of the voltage sampling circuit 1044 is electrically connected to the input terminal of the rectifying circuit 1011, so as to obtain the current operating voltage of the electromagnetic heating circuit 100.

In the present embodiment, the working principles of the rectifying circuit 1011, the filtering circuit 1012, the resonant circuit 1013, and the voltage sampling circuit 1044 can be seen in the embodiment shown in fig. 5, and the description thereof is omitted herein.

Unlike the embodiment shown in fig. 5, the voltage sampling circuit 1044 is electrically connected between the filter circuit 1012 and the resonant circuit 1013. The first input end of the current sampling circuit 1045 is electrically connected to the output end of the filter circuit 1012, and the second input end of the current sampling circuit 1045 is electrically connected to the input end of the resonant circuit 1013, so as to obtain the current operating current of the electromagnetic heating circuit 100.

In this embodiment, the third input terminal of the MCU 1041 is electrically connected to the output terminal of the voltage sampling circuit 1044, and can receive the current operating voltage from the voltage sampling circuit 1044. A fourth input of the MCU 1041 is electrically connected to an output of the current sampling circuit 1045, and may receive the present operating current from the voltage sampling circuit 1044. Thus, the MCU 1041 may fix a reference operating frequency, and at the reference operating frequency, a current output power may be calculated according to a current operating voltage and a current operating current.

The specific structure of the current sampling circuit 1045 is not limited in this embodiment. In a possible implementation structure, as shown in fig. 8, optionally, the current sampling circuit 1045 of this embodiment may include: transformer CT, fourth resistor R4, first diode D1, fifth resistor R5, sixth resistor R6, and second capacitor C2.

The first input end of the transformer CT is connected to the output end of the filter circuit 1012, the second output end of the transformer CT is connected to the input end of the resonant circuit 1013, the first output end of the transformer CT is connected to the first end of the fourth resistor R4 and the positive electrode of the first diode D1, the negative electrode of the first diode D1 is connected to the first end of the fifth resistor R5, the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6, the first end of the second capacitor C2 and the fourth input end of the MCU 1041, and the second output end of the transformer CT, the second end of the fourth resistor R4, the second end of the sixth resistor R6 and the second end of the second capacitor C2 are all grounded.

Based on the embodiments shown in fig. 5-8, the specific implementation of the voltage sampling circuit 1044 is not limited in this embodiment. Next, a specific structure of the voltage sampling circuit 1044 will be described in detail with reference to fig. 9 and 10.

In a possible implementation structure, as shown in fig. 9, optionally, the voltage sampling circuit 1044 of this embodiment may include: the second diode D2, the third diode D3, the fourth diode D4, the seventh resistor R7, the eighth resistor R8, and the third capacitor C3.

The positive electrode of the second diode D2 is electrically connected to the first input end of the rectifying circuit 1011, the positive electrode of the third diode D3 is electrically connected to the second input end of the rectifying circuit 1011, the negative electrode of the second diode D2 and the negative electrode of the third diode D3 are both electrically connected to the first end of the seventh resistor R7, the second end of the seventh resistor R7 is electrically connected to the first end of the eighth resistor R8, the positive electrode of the fourth diode D4, the third input end of the MCU 1041 and the first end of the third capacitor C3, the negative electrode of the fourth diode D4 is connected to the second level V2, and the second end of the eighth resistor R8 and the second end of the third capacitor C3 are both grounded.

In another possible implementation structure, as shown in fig. 10, the voltage sampling circuit 1044 of this embodiment may optionally include: fifth diode D5, sixth diode D6, ninth resistor R9, tenth resistor R10, eleventh resistor R11, third capacitor C3, transistor Q1, and twelfth resistor R12.

The positive electrode of the fifth diode D5 is electrically connected to the first input end of the rectifying circuit 1011, the positive electrode of the sixth diode D6 is electrically connected to the second input end of the rectifying circuit 1011, the negative electrode of the fifth diode D5 and the negative electrode of the sixth diode D6 are both electrically connected to the first end of the ninth resistor R9, the second end of the ninth resistor R9 is electrically connected to the first end of the third capacitor C3, the first end of the tenth resistor R10, the first end of the eleventh resistor R11, the second end of the eleventh resistor R11 is electrically connected to the base of the triode Q1, the collector of the triode Q1 is electrically connected to the third input end of the MCU 1041 and the first end of the twelfth resistor R12, the second end of the twelfth resistor R12 is electrically connected to the third level V3, and the second end of the third capacitor C3, the second end of the tenth resistor R10, and the emitter of the triode Q1 are all grounded.

Illustratively, the present embodiment also provides an electromagnetic heating appliance 10. Fig. 11 is a schematic structural diagram of an electromagnetic heating apparatus provided by the present invention, and as shown in fig. 11, the electromagnetic heating apparatus 10 of the present embodiment may include: the electromagnetic heating circuit 100 described above.

Wherein electromagnetic heating appliance 10 may include, but is not limited to, various appliances requiring heating such as induction cookers, electric autoclaves, soymilk makers, coffee makers, blenders, and the like.

The electromagnetic heating apparatus 10 provided in this embodiment includes the electromagnetic heating circuit 100, and the above embodiment may be implemented, and the specific implementation principle and technical effects thereof may be referred to the technical solutions of the above embodiments of fig. 2-10, which are not described herein again.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. A method of reducing noise in an electromagnetic heating circuit, applied to an electromagnetic heating circuit (100), the method comprising:

when the to-be-heated appliance is determined to be made of a magnetic material and the electromagnetic heating circuit (100) meets a first condition, acquiring the current working frequency of the electromagnetic heating circuit (100); the first condition is that the output power of the electromagnetic heating circuit (100) reaches the maximum output power or the width of a Pulse Program Generator (PPG) signal reaches the maximum width, wherein the width of the PPG signal is used for adjusting the on-time of an IGBT module (102) in the electromagnetic heating circuit (100);

Judging whether the current working frequency is smaller than a preset frequency threshold value or not;

if yes, the width of the PPG signal is reduced until the current working frequency is greater than the preset frequency threshold value, and the maximum width of the PPG signal is updated to be the current width of the PPG signal;

if not, adjusting the electromagnetic heating circuit (100) to meet the first condition;

determining that the appliance to be heated is a magnetic material, comprising:

acquiring the current output power of the electromagnetic heating circuit (100) at a reference working frequency;

judging whether the current output power is smaller than a preset power threshold value or not;

if yes, determining that the to-be-heated device is made of magnetic materials.

2. The method according to claim 1, characterized in that the preset power threshold is greater than the output power of the electromagnetic heating circuit (100) at the reference operating frequency when the appliance to be heated is placed with magnetic material, and the preset power threshold is smaller than the rated output power of the electromagnetic heating circuit (100).

3. The method according to claim 1 or 2, wherein when the current output power is greater than the preset power threshold, the method further comprises:

Determining that the appliance to be heated is a nonmagnetic or diamagnetic material, and adjusting the electromagnetic heating circuit (100) to meet the first condition.

4. An electromagnetic heating circuit (100), characterized by comprising: the device comprises a main loop (101), an insulated gate bipolar transistor IGBT module (102), a driving circuit (103) and a micro-processing unit (104);

the main loop (101) is used for emitting electromagnetic energy converted by input power supply voltage, the output end of the main loop (101) is electrically connected with the drain electrode of the IGBT module (102) and the first input end of the micro-processing unit (104) respectively, the second input end of the micro-processing unit (104) is electrically connected with the grid electrode of the IGBT module (102) or the output end of the driving circuit (103), the output end of the micro-processing unit (104) is electrically connected with the input end of the driving circuit (103) and is used for outputting a PPG signal to the driving circuit (103), the width of the PPG signal is used for adjusting the conduction duration of the IGBT module (102), and the output end of the driving circuit (103) is electrically connected with the grid electrode of the IGBT module (102).

The micro-processing unit (104) is used for acquiring the current working frequency of the electromagnetic heating circuit (100) when the to-be-heated appliance is determined to be made of a magnetic material and the electromagnetic heating circuit (100) meets a first condition; the first condition is that the output power of the electromagnetic heating circuit (100) reaches the maximum output power or the width of the pulse program generator PPG signal reaches the maximum width;

The micro-processing unit (104) is further used for judging whether the current working frequency is smaller than a preset frequency threshold value; when the current working frequency is smaller than the preset frequency threshold value, reducing the width of the PPG signal until the current working frequency is larger than the preset frequency threshold value, and updating the maximum width of the PPG signal to the current width of the PPG signal; when the current working frequency is greater than or equal to the preset frequency threshold value, adjusting the electromagnetic heating circuit (100) to meet the first condition;

the micro-processing unit (104) is specifically configured to obtain a current output power of the electromagnetic heating circuit (100) at a reference working frequency; judging whether the current output power is smaller than a preset power threshold value or not; and when the current output power is smaller than the preset power threshold, determining that the to-be-heated appliance is made of a magnetic material.

5. The electromagnetic heating circuit (100) according to claim 4, wherein the micro-processing unit (104) is further specifically configured to determine that the appliance to be heated is a non-magnetic or a diamagnetic material when the current output power is greater than the preset power threshold, and adjust the electromagnetic heating circuit (100) to satisfy the first condition.

6. The electromagnetic heating circuit (100) according to claim 4 or 5, wherein the micro-processing unit (104) comprises: the micro control unit MCU (1041), the synchronous circuit (1042) and the frequency detection circuit (1043);

the input end of the synchronization circuit (1042) is electrically connected with the output end of the main circuit (101), the output end of the synchronization circuit (1042) is electrically connected with the first input end of the MCU (1041), the output end of the MCU (1041) is electrically connected with the input end of the driving circuit (103), the input end of the frequency detection circuit (1043) is electrically connected with the grid of the IGBT module (102) or the output end of the driving circuit (103) for obtaining the current working frequency, and the output end of the frequency detection circuit (1043) is electrically connected with the second input end of the MCU (1041);

the MCU (1041) is configured to receive the current operating frequency from the frequency detection circuit (1043) when it is determined that the appliance to be heated is magnetic and the electromagnetic heating circuit (100) satisfies a first condition;

the MCU (1041) is further configured to determine whether the current operating frequency is less than the preset frequency threshold; when the current working frequency is smaller than the preset frequency threshold value, reducing the width of the PPG signal until the current working frequency is larger than the preset frequency threshold value, and updating the maximum width of the PPG signal to the current width of the PPG signal; and when the current working frequency is greater than or equal to the preset frequency threshold value, adjusting the electromagnetic heating circuit (100) to meet the first condition.

7. The electromagnetic heating circuit (100) of claim 6, wherein,

the input end of the micro-processing unit (104) is electrically connected with the power supply end of the main loop (101) and is used for acquiring the current working voltage of the electromagnetic heating circuit (100); or, the input end of the micro-processing unit (104) is electrically connected with the rectification output end of the power supply voltage of the electromagnetic heating circuit (100) and is used for obtaining the current working voltage of the electromagnetic heating circuit (100);

the micro-processing unit (104) is further used for acquiring the current working current of the electromagnetic heating circuit (100);

the micro-processing unit (104) is further configured to calculate, at a reference operating frequency, the current output power according to the current operating voltage and the current operating current.

8. The electromagnetic heating circuit (100) of claim 7, wherein the micro-processing unit (104) further comprises: a voltage sampling circuit (1044) and a current sampling circuit (1045); the main circuit (101) comprises: a rectifying circuit (1011), a filter circuit (1012) and a resonant circuit (1013) which are connected in sequence, wherein the output end of the resonant circuit (1013) is electrically connected with the drain electrode of the IGBT module (102);

The first input end of the voltage sampling circuit (1044) is electrically connected with the first input end of the rectifying circuit (1011), and the second input end of the voltage sampling circuit (1044) is electrically connected with the second input end of the rectifying circuit (1011) for obtaining the current working voltage of the electromagnetic heating circuit (100);

a third input end of the MCU (1041) is electrically connected with an output end of the voltage sampling circuit (1044) and is used for receiving the current working voltage from the voltage sampling circuit (1044);

a first input end of the current sampling circuit (1045) is electrically connected with a negative output end of the rectifying circuit (1011), and a second input end of the current sampling circuit (1045) is electrically connected with a source electrode of the IGBT module (102) and is used for obtaining the current working current of the electromagnetic heating circuit (100);

a fourth input end of the MCU (1041) is electrically connected with an output end of the current sampling circuit (1045) and is used for receiving the current working current from the voltage sampling circuit (1044);

the MCU (1041) is further configured to calculate the current output power according to the current operating voltage and the current operating current at the reference operating frequency.

9. The electromagnetic heating circuit (100) of claim 8, wherein the current sampling circuit (1045) comprises: a first resistor, a second resistor, a third resistor and a first capacitor;

the first end of the first resistor is electrically connected with the negative output end of the filter circuit (1012) and the first end of the second resistor respectively, the second end of the first resistor is electrically connected with the source electrode of the IGBT module (102), the second end of the second resistor is electrically connected with the fourth input end of the MCU (1041), the first end of the third resistor and the first end of the first capacitor respectively, the second end of the third resistor is connected with a first level, and the second end of the first capacitor is grounded.

10. The electromagnetic heating circuit (100) of claim 7, wherein the micro-processing unit (104) further comprises: a voltage sampling circuit (1044) and a current sampling circuit (1045); the main circuit (101) comprises: a rectifier circuit (1011), a filter circuit (1012), and a resonant circuit (1013);

the positive input end of the rectifying circuit (1011) is electrically connected with the first input end of the filtering circuit (1012), the negative input end of the rectifying circuit (1011) is electrically connected with the second input end of the filtering circuit (1012), and the output end of the resonant circuit (1013) is electrically connected with the drain electrode of the IGBT module (102);

The input end of the voltage sampling circuit (1044) is electrically connected with the input end of the rectifying circuit (1011) and is used for acquiring the current working voltage of the electromagnetic heating circuit (100);

a first input end of the current sampling circuit (1045) is electrically connected with an output end of the filter circuit (1012), and a second input end of the current sampling circuit (1045) is electrically connected with an input end of the resonant circuit (1013) for obtaining the current working current of the electromagnetic heating circuit (100);

11. The electromagnetic heating circuit (100) of claim 10, wherein the current sampling circuit (1045) comprises: the transformer, the fourth resistor, the first diode, the fifth resistor, the sixth resistor and the second capacitor;

The first input end of the transformer is connected with the output end of the filter circuit (1012), the second output end of the transformer is connected with the input end of the resonant circuit (1013), the first output end of the transformer is respectively connected with the first end of the fourth resistor and the positive electrode of the first diode, the negative electrode of the first diode is connected with the first end of the fifth resistor, the second end of the fifth resistor is respectively connected with the first end of the sixth resistor, the first end of the second capacitor and the fourth input end of the MCU (1041), and the second output end of the transformer, the second end of the fourth resistor, the second end of the sixth resistor and the second end of the second capacitor are all grounded.

12. The electromagnetic heating circuit (100) according to any one of claims 8-11, wherein the voltage sampling circuit (1044) comprises: a second diode, a third diode, a fourth diode, a seventh resistor, an eighth resistor, and a third capacitor;

the positive electrode of the second diode is electrically connected with the first input end of the rectifying circuit (1011), the positive electrode of the third diode is electrically connected with the second input end of the rectifying circuit (1011), the negative electrode of the second diode and the negative electrode of the third diode are both electrically connected with the first end of the seventh resistor, the second end of the seventh resistor is respectively electrically connected with the first end of the eighth resistor, the positive electrode of the fourth diode, the third input end of the MCU (1041) and the first end of the third capacitor, the negative electrode of the fourth diode is connected with a second level, and the second end of the eighth resistor and the second end of the third capacitor are both grounded.

13. The electromagnetic heating circuit (100) according to any one of claims 8-11, wherein the voltage sampling circuit (1044) comprises: comprising the following steps: a fifth diode, a sixth diode, a ninth resistor, a tenth resistor, an eleventh resistor, a third capacitor, a triode, and a twelfth resistor;

the positive electrode of the fifth diode is electrically connected with the first input end of the rectifying circuit (1011), the positive electrode of the sixth diode is electrically connected with the second input end of the rectifying circuit (1011), the negative electrode of the fifth diode and the negative electrode of the sixth diode are both electrically connected with the first end of the ninth resistor, the second end of the ninth resistor is respectively electrically connected with the first end of the third capacitor, the first end of the tenth resistor and the first end of the eleventh resistor, the second end of the eleventh resistor is electrically connected with the base electrode of the triode, the collector electrode of the triode is respectively electrically connected with the third input end of the MCU (1041) and the first end of the twelfth resistor, the second end of the twelfth resistor is electrically connected with a third level, and the second end of the third capacitor, the second end of the tenth resistor and the emitter electrode of the triode are all grounded.

14. An electromagnetic heating appliance (10), characterized by comprising: the electromagnetic heating circuit (100) of any of claims 4-13.