CN215010759U - Electromagnetic cooking utensil and noise reduction circuit thereof - Google Patents

Abstract

The application discloses electromagnetism cooking utensil falls circuit and electromagnetism cooking utensil of making an uproar, fall the circuit of making an uproar including the rectification unit, the resonance unit that carry out the rectification to external power supply and with the IGBT that the resonance unit is connected, it still includes to fall the circuit of making an uproar: and two ends of the noise reduction unit are respectively connected with the rectification unit and the resonance unit, and the rectified pulsating direct current is filtered so as to reduce the envelope pressure difference generated by the IGBT. The arrangement of the noise reduction unit can carry out filtering processing on the pulsating direct current and reduce the envelope pressure difference generated by the IGBT, so that the amplitude energy of the envelope pressure difference is greatly reduced, and the noise of the electromagnetic cooking appliance is further reduced.

Description

Electromagnetic cooking utensil and noise reduction circuit thereof

Technical Field

The utility model belongs to the technical field of domestic appliance, especially, relate to an electromagnetism cooking utensil fall circuit of making an uproar and electromagnetism cooking utensil.

Background

Electromagnetic cooking utensil is because the mode through electromagnetic induction cooks food, and it is efficient to generate heat, and convenient to use safety, convenient to carry simultaneously easily uses, as long as there is the place of power all to use, compares with traditional firing equipment and has very big advantage, has been used by more and more people.

Specifically, because the high-frequency excitation coil inside the electromagnetic cooking utensil can generate an alternating magnetic field after being introduced with alternating current, when the metal cookware is placed on the surface of the electromagnetic cooking utensil, the surface of the cookware can cut the magnetic lines of force of the alternating magnetic field to generate a large amount of eddy currents at the bottom of the cookware, the eddy currents enable carriers at the bottom of the cookware to move irregularly at high speed, and the carriers collide with atoms and rub to generate heat energy, so that the purpose of heating food is achieved. However, the existing electromagnetic cooking appliances are often accompanied by buzzing noise during heating, and the noise becomes larger as the heating power increases, especially when water is boiled, thereby seriously affecting the use experience of users.

Through experimental analysis, the skilled person finds that the main components of the noise are low-frequency noise of 100Hz and resonance frequency (100Hz integer times frequency) noise, and the noise in the frequency range just falls within the frequency range of human auditory sense (the frequency range of human auditory sense is 20-20000 Hz). The noise is generated because the power frequency alternating current in China is 50Hz, and when the power frequency alternating current of 50Hz passes through a rectifying circuit in the electromagnetic cooking appliance, the power frequency alternating current can output pulsating direct current with the frequency of 100Hz and the peak voltage of 310V. Further, when an IGBT (Insulated Gate Bipolar Transistor) in the electromagnetic cooking appliance operates at an operating frequency (e.g., 20 to 35kHz), an envelope voltage difference formed by a pulsating direct current of 100Hz can reach 970V. This kind of envelope pressure differential has very big amplitude energy, and it can be along with electromagnetic cooking utensil's resonant frequency and act on the metal pan to make the pan produce a large amount of lorentz forces, and then produce above-mentioned noise.

It will thus be seen that the prior art is susceptible to further improvements and enhancements.

SUMMERY OF THE UTILITY MODEL

The utility model provides an electromagnetism cooking utensil's circuit of making an uproar and electromagnetism cooking utensil fall to solve above-mentioned technical problem's at least one technical problem.

The utility model discloses the technical scheme who adopts does:

in a first aspect, the utility model provides an electromagnetic cooking utensil fall circuit of making an uproar, include the rectification unit, the resonance unit that carry out the rectification to external power supply and with the IGBT that the resonance unit is connected, fall the circuit of making an uproar and still include: and two ends of the noise reduction unit are respectively connected with the rectification unit and the resonance unit, and the rectified pulsating direct current is filtered so as to reduce the envelope pressure difference generated by the IGBT.

As a preferred embodiment of the present invention, the noise reduction circuit further includes: and the access switch is connected with the noise reduction unit in series and is used for controlling the noise reduction unit to be accessed into the noise reduction circuit.

As a preferred embodiment of the present invention, the noise reduction circuit further includes a zero-crossing detection unit connected to the access switch, the zero-crossing detection unit is used for detecting a zero-crossing signal to control the connection and disconnection of the access switch.

As a preferred embodiment of the present invention, the access switch includes a thyristor or a relay.

As a preferred embodiment of the present invention, the noise reduction circuit further includes a voltage stabilizing unit connected to the IGBT to generate a stable voltage for the IGBT to switch on.

In a second aspect, the present invention further provides an electromagnetic cooking device, which includes a housing and a display panel disposed on the surface of the housing, and a circuit board disposed inside the housing, wherein the circuit board is provided with the noise reduction circuit.

As a preferred embodiment of the present invention, the display panel is provided with a mute function key, the mute function key is electrically connected to the noise reduction circuit.

As a preferred embodiment of the utility model, the electromagnetic cooking appliance comprises an electromagnetic oven, an electric ceramic oven, an electric rice cooker, an electric pressure cooker or a boiling water cooker.

Since the technical scheme is used, the utility model discloses the beneficial effect who gains does:

1. the utility model provides an electromagnetism cooking utensil's circuit of making an uproar falls, including rectification unit, resonance unit and IGBT to and the unit of making an uproar falls. The noise reduction unit is arranged to filter the pulsating direct current and reduce the envelope pressure difference generated by the IGBT, so that the amplitude energy of the envelope pressure difference is greatly reduced, and the noise of the electromagnetic cooking appliance is reduced.

2. As the utility model discloses a preferred embodiment, the setting of access switch can realize its selective control to the unit access of making an uproar falls the circuit of making an uproar to avoid falling the loss that probably produces after the unit long-time work of making an uproar, thereby do benefit to the life who prolongs the unit of making an uproar, and then promote user's use and experience.

3. As a preferred embodiment of the utility model, zero cross detection unit's setting can control switching on and breaking off of access switch to avoid causing the condition appearance that the access switch struck sparks the adhesion because of the instantaneous charge-discharge current of the unit of making an uproar falls too big, and then do benefit to the stability and the security of guaranteeing the access switch, with the even running of the circuit of making an uproar falls in the realization.

4. As the utility model discloses a preferred embodiment, the setting of steady voltage unit can make IGBT output stable voltage, reduces IGBT output voltage's fluctuation to the IGBT envelope pressure differential's that significantly reduces amplitude energy, and promote the stability of IGBT working process, and then further reduce electromagnetic cooking utensil's noise.

5. As an optimized implementation manner of the utility model, the silence function key that sets up on the display panel can make the user know the product characteristic more directly perceivedly, not only does benefit to the propaganda of product, also can convenience of customers operate electromagnetic cooking utensil in the in-service use process.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the application and not to limit the invention. In the drawings:

fig. 1 is a block diagram of a noise reduction circuit according to an embodiment of the present invention;

fig. 2 is a schematic circuit structure diagram of a noise reduction circuit according to an embodiment of the present invention;

fig. 3 is a block diagram of a noise reduction circuit according to an embodiment of the present invention;

fig. 4 is a voltage waveform diagram of a pulsating dc current according to an embodiment of the present invention;

fig. 5 is a waveform diagram of an envelope pressure difference generated by an IGBT according to an embodiment of the present invention;

fig. 6 is a schematic circuit structure diagram of another noise reduction circuit provided in the embodiment of the present invention;

fig. 7 is a schematic flow chart of a working process of an access switch according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a display panel according to an embodiment of the present invention.

The device comprises a 100 rectifying unit, a 200 resonant unit, a 300IGBT, a 400 noise reduction unit and a 500 voltage stabilizing unit.

Detailed Description

In order to more clearly explain the overall concept of the present application, the following detailed description is given by way of example in conjunction with the accompanying drawings.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.

In addition, in the description of the present invention, it is to be understood that the terms "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and to simplify the description, and do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

As shown in fig. 1, the utility model provides an electromagnetic cooking utensil's circuit of making an uproar falls, it includes carries out rectifier unit 100, resonance unit 200 and the IGBT300 that resonance unit 200 is connected of rectification to external power source. In addition, the noise reduction circuit further includes a noise reduction unit 400, and two ends of the noise reduction unit 400 are respectively connected to the rectification unit 100 and the resonance unit 200, and can filter rectified pulsating direct current to reduce the envelope voltage difference generated by the IGBT 300.

It should be noted that, the rectifying unit 100 in this embodiment is connected to an external power supply and is used for converting an alternating current into a pulsating direct current, and the embodiment is not limited to a specific type and structure of the rectifying unit 100, and may be a full-wave rectifying unit, a bridge rectifying unit, or even a half-wave rectifying unit if there is no requirement for power. As to what type of the rectifier unit 100 is selected, the design requirement, the use characteristics, the production cost, the stability, and the like of the product should be considered comprehensively.

Specifically, referring to fig. 2, the rectifying unit 100 in the present embodiment may include a FUSE1, a voltage dependent resistor CNR1, a capacitor C1, a first diode D1, and a second diode D2. The negative electrode of the second diode D2 is connected with the negative electrode of the first diode D1, the first diode D1 and the second diode D2 are connected in series and then are respectively connected in parallel with the piezoresistor CNR1 and the capacitor C1 to form a parallel unit, one end of the FUSE FUSE1 is connected with the live wire leading-out end of the external power supply, the other end of the FUSE FUSE1 is connected with the parallel unit, and the other end of the parallel unit is connected with the zero wire leading-out end of the external power supply. In addition, the rectifying unit 100 further includes a power supply VCC, and the power supply VCC is connected to cathodes of the first diode D1 and the second diode D2, respectively.

The resonant unit 200 in this embodiment can filter the pulsating dc power and convert it into smooth dc power for transmission to the IGBT 300. Preferably, the resonant unit 200 may include an inductor L1, a capacitor C4, and a resistor R1 connected in series, where the size of the series resistor R1 in the series resonant unit does not affect the natural frequency of the series resonant unit, but can control and adjust the amplitudes of the current and voltage at resonance, thereby facilitating to reduce the envelope voltage difference generated by the IGBT 300. It should also be understood that the circuit structure of the resonant unit 200 provided in the present embodiment is only one specific example, and does not constitute a limitation on the specific structure of the resonant unit 200, and the resonant unit 200 may be a parallel resonant circuit, a series-parallel resonant circuit, or the like, in addition to the series resonant circuit described above.

Further, referring to fig. 2 and fig. 3, the noise reduction circuit provided in this embodiment may further include a voltage stabilizing unit 500 connected to the IGBT300 to generate a stable voltage for the IGBT300 to conduct. The voltage stabilizing unit 500 may be formed by, for example, a resistor R2 and a third diode D3 connected in parallel, and the voltage stabilizing unit 500 may enable the IGBT300 to output a stable voltage, so as to reduce the fluctuation of the output voltage of the IGBT300, thereby greatly reducing the amplitude energy of the envelope voltage difference of the IGBT300, improving the stability of the IGBT300 in the working process, and further reducing the noise of the electromagnetic cooking appliance.

In one embodiment, the noise reduction unit 400 may be an electrolytic capacitor, and the capacitance value of the electrolytic capacitor ranges from 100 μ F to 1000 μ F. When the capacitance value of the electrolytic capacitor is in the above range, the electromagnetic cooking appliance has less noise. It should be noted that, in the present embodiment, there may be a plurality of types of the noise reduction unit 400, and besides the electrolytic capacitor, for example, a mica capacitor, a ceramic capacitor, and the like may also be used, which is not limited in the present embodiment.

Specifically, when the capacitance value of the connected electrolytic capacitor is greater than 100 muF, the noise of the electromagnetic cooking appliance in an actual test is already improved, and the larger the capacitance value of the electrolytic capacitor is, the more obvious the noise improvement is; when the capacity value reaches 330 muF, the electromagnetic noise is obviously improved; when the capacity value reaches 680 mu F, the noise of the electromagnetic cooking appliance is greatly eliminated; when the capacity value reaches 1000 muF, the noise of the electromagnetic cooking utensil is basically eliminated. For a clear understanding of the relationship between the capacitance value of the electrolytic capacitor and the envelope voltage difference generated by the IGBT300, reference may be made to table 1:

TABLE 1 volume-envelope pressure difference comparison table

Volume (uF)	Maximum back pressure (V)	Minimum back pressure (V)	Envelope pressure difference (V)	Difference value of capacitor not connected (V)	Percentage of reduction
						0	970	0	970	0	0.00％
100	976	256	720	250	25.77％
						220	964	456	508	462	47.63％
330	928	552	376	594	61.24％
						470	912	620	292	678	69.90％
680	884	688	196	774	79.79％
						820	884	670	184	786	81.03％
1000	880	704	176	794	81.86％

Further, when the capacitance value of the connected electrolytic capacitor is 1000 μ F, the waveform of the pulsating direct current and the operating waveform curve of the IGBT300 are as shown in fig. 4 and 5, compared with the prior art in which no electrolytic capacitor is provided (the maximum differential voltage of the pulsating direct current waveform is 310V, the envelope differential voltage generated by the IGBT300 is 976V), the maximum differential voltage of the pulsating direct current waveform after the connection of the electrolytic capacitor is only 60V, and the envelope differential voltage generated by the IGBT300 is only 176V. It is found that the provision of the electrolytic capacitor can greatly reduce the envelope voltage difference generated by the IGBT300 and the noise of the electromagnetic cooking appliance.

It should be noted thatSince the rectified voltage is the input voltage

The external power supply is usually the commercial power, the domestic commercial power voltage can reach 1.1 times of the rated voltage, so the maximum voltage after rectification is as follows:

therefore, the electrolytic capacitance is preferably 350V or more.

The utility model provides an electromagnetism cooking utensil's circuit of making an uproar falls carries out filtering process and reduces the produced envelope pressure differential of IGBT300 to the pulsation direct current through the setting of the unit of making an uproar 400 that falls to reduce envelope pressure differential's amplitude energy by a wide margin, and then reduce electromagnetism cooking utensil's noise.

It should be understood that the capacitor with a large capacitance value is accompanied by attenuation during long-term operation, and the charging and discharging processes of the capacitor generate a large instantaneous current, and the electromagnetic cooking appliance has a possibility of generating noise only after reaching a certain temperature. Therefore, in order to protect each electrical component in the noise reduction circuit and prolong the service life of the electrolytic capacitor, as a preferred embodiment of the present invention, referring to fig. 6, the noise reduction circuit may further include an access switch K connected in series with the noise reduction unit 400, wherein the access switch K is used for controlling the noise reduction unit 400 to access the noise reduction circuit. The access switch K may be, for example, a thyristor or a relay.

Specifically, the workflow regarding the access switch K can be illustrated with reference to fig. 7, and includes the following steps:

s1, heating is started.

And S2, judging whether the electromagnetic cooking utensil reaches the preset temperature. If yes, go to step S3; if not, step S4 is executed.

And S3, heating is suspended, and the access switch K is turned on.

And S4, continuing heating, and turning off the switch K.

And S5, restarting the IGBT.

And S6, finishing heating.

It should be noted that, since the heating power of the electromagnetic cooking appliance can reach 2000W or even higher, and through experimental tests, the average charging and discharging current of the electrolytic capacitor is 15A, and the peak current can reach 40A. Therefore, when selecting the type of the access switch K, electrical components such as thyristors or relays having shock resistance should be selected. For example, for a relay, a model which is higher than the rated current 20A and can resist the current surge instantly can be selected; for the thyristor, a model with a rated current of 20A or more can be selected.

The setting of access switch K in this embodiment can realize its selective control to the circuit of making an uproar is fallen in the unit 400 access of falling of making an uproar to avoid falling the loss that probably produces after the unit 400 works for a long time of making an uproar, thereby do benefit to the life that the unit 400 was made an uproar of falling in the extension, and then promote user's use and experience.

In one embodiment, the noise reduction circuit may further include a zero-crossing detection unit (not shown in the figure) connected to the access switch K, and the zero-crossing detection unit is configured to detect a zero-crossing signal to control the access switch K to be turned on and off. The setting of zero cross detection unit can control access switch K and switch on and break off when crossing the zero point to avoid causing access switch K to strike sparks the condition of adhesion to appear because of the too big condition of instantaneous charge-discharge current of unit 400 of making an uproar, and then do benefit to the stability and the security that guarantee access switch K, in order to realize the even running of circuit of making an uproar.

The utility model also provides an electromagnetic cooking utensil, it include the casing (not shown in the figure) with set up in housing face's display panel (as shown in FIG. 8), and set up in the inside circuit board of casing (not shown in the figure), just the circuit board is provided with as above the circuit of making an uproar falls.

Preferably, the display panel is provided with a mute function key, and the mute function key is electrically connected with the noise reduction circuit. The specific structure of the mute function key is not limited in this embodiment, and the mute function key may be a touch type case, a mechanical type case, a toggle switch, an encoder, or the like. The mute function key arranged on the display panel can enable a user to know the characteristics of the product more intuitively, not only is beneficial to the propaganda of the product, but also can facilitate the user to operate the electromagnetic cooking appliance in the actual use process.

As a preferred embodiment of the present invention, the electromagnetic cooking device may include an induction cooker, an electric ceramic cooker, an electric rice cooker, an electric pressure cooker, or a water boiler.

The utility model can be realized by adopting or using the prior art for reference in places which are not mentioned in the utility model.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments.

The above description is only an example of the present invention, and is not intended to limit the present invention. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (10)

1. The utility model provides an electromagnetism cooking utensil's circuit of making an uproar falls, includes rectifier unit, the resonance unit that carries out the rectification to external power supply and with the IGBT that the resonance unit is connected, its characterized in that, the circuit of making an uproar still includes:

and two ends of the noise reduction unit are respectively connected with the rectification unit and the resonance unit, and the rectified pulsating direct current is filtered so as to reduce the envelope pressure difference generated by the IGBT.

2. The noise reduction circuit of claim 1, further comprising: and the access switch is connected with the noise reduction unit in series and is used for controlling the noise reduction unit to be accessed into the noise reduction circuit.

3. The noise reduction circuit of claim 2, further comprising a zero-crossing detection unit coupled to the access switch, the zero-crossing detection unit to detect a zero-crossing signal to control the on and off of the access switch.

4. The noise reduction circuit of claim 2, wherein the access switch comprises a thyristor or a relay.

5. The noise reduction circuit of claim 1, further comprising a voltage stabilization unit coupled to the IGBT to generate a stabilized voltage for the IGBT to conduct.

6. The noise reduction circuit according to any one of claims 1 to 5, wherein the noise reduction unit is an electrolytic capacitor.

7. The noise reduction circuit of claim 6, wherein the electrolytic capacitor has a capacitance in a range of 100 μ F to 1000 μ F.

8. An electromagnetic cooking appliance comprising a housing and a display panel provided on a surface of the housing, and a circuit board provided inside the housing, and the circuit board is provided with the noise reduction circuit according to any one of claims 1 to 7.

9. The electromagnetic cooking appliance according to claim 8, wherein said display panel is provided with a mute function key electrically connected to said noise reduction circuit.

10. The electromagnetic cooking appliance of claim 9, wherein the electromagnetic cooking appliance comprises an induction cooker, an electric ceramic cooker, an electric rice cooker, an electric pressure cooker, or a water boiler.

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