CN112555925B

CN112555925B - Noise reduction method for induction cooker with more than two wire coils

Info

Publication number: CN112555925B
Application number: CN202110034484.1A
Authority: CN
Inventors: 杜建鸿; 张耀; 蹇福权
Original assignee: Foshan Shunde Bravo Electric Co ltd
Current assignee: Foshan Shunde Bravo Electric Co ltd
Priority date: 2021-01-12
Filing date: 2021-01-12
Publication date: 2023-06-06
Anticipated expiration: 2041-01-12
Also published as: CN112555925A

Abstract

The invention relates to the technical field of induction cookers, in particular to a noise reduction method of an induction cooker with more than two wire coils, which comprises the following steps: a step of discharging before work, wherein a main control module connected with each wire coil detects a zero crossing point of alternating current input before each wire coil enters a working state, and discharges a capacitor connected with the wire coil before the zero crossing point, and the wire coil enters the working state again when the zero crossing point after the discharging is completed; a time-sharing preheating step, wherein the master controller controls each wire coil to be in a working state in different time periods, and obtains the heating power and the working frequency information of each wire coil; and the same-frequency switching heating step, namely controlling each wire coil to work at the same frequency by the master controller according to the acquired heating power and working frequency information of each wire coil, and switching and heating at least part of the wire coils, wherein the switching and heating are that part of the wire coils are in a working state and part of the wire coils are in a stopping state in a certain time period.

Description

Noise reduction method for induction cooker with more than two wire coils

Technical Field

The invention relates to the technical field of induction cookers, in particular to a noise reduction method of an induction cooker with more than two wire coils.

Background

The induction cooker heats by utilizing the electromagnetic induction principle, namely, when alternating current passes through the wire coil, the wire coil generates an alternating magnetic field, when the metal cooker is placed on the wire coil, the cutting magnetic field generates eddy current, free electrons in iron materials at the bottom of the cooker are in vortex-like alternating motion, and the eddy current and the cooker resistor generate heat energy, so that the heating purpose is realized. The induction cooker is popular with consumers due to the advantages of environmental protection, energy saving, high heating efficiency, safety and the like.

In the prior art, induction cooker noise is a common problem. In the starting process of the induction cooker, an alternating current power supply can form 300-volt direct current voltage under the action of a capacitor after being rectified by a bridge rectifier, and energy cannot be released due to high collector voltage of an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT), so that noise is high during wire coil starting. And to the electromagnetism stove that is provided with more than two drum, set up more than two drum in some single-end kitchen, perhaps be provided with a plurality of drum in the bull kitchen, in the aforesaid circumstances, when the distance between the drum is comparatively little, and different drum is when the operating frequency of during operation, also can produce the harshness noise. The above problems lead to noise generated by the induction cookers with more than two wire coils in the prior art, both in the starting process and the heating process, and greatly influence the use experience of users.

Disclosure of Invention

The invention aims to provide a noise reduction method for an induction cooker with more than two wire coils, which aims to solve the problem that the induction cooker with more than two wire coils generates noise in the starting process and the heating process.

In order to achieve the above purpose, the invention provides a noise reduction method for an induction cooker with more than two wire coils, each wire coil is respectively controlled by a main control module connected with the wire coil, each main control module is connected with a control panel and is controlled by a master controller of the induction cooker control panel, and the method comprises the following steps: a step of discharging before work, wherein a main control module connected with each wire coil detects a zero crossing point of alternating current input before each wire coil enters a working state, and discharges a capacitor connected with the wire coil before the zero crossing point, and the wire coil enters the working state again when the zero crossing point after the discharging is completed; a time-sharing preheating step, wherein the master controller controls each wire coil to be in a working state in different time periods, and obtains the heating power and the working frequency information of each wire coil; and the same-frequency switching heating step, namely controlling each wire coil to work at the same frequency by the master controller according to the acquired heating power and working frequency information of each wire coil, and switching and heating at least part of the wire coils, wherein the switching and heating are that part of the wire coils are in a working state and part of the wire coils are in a stopping state in a certain time period.

Further, in the same-frequency switching heating step, at least one wire coil is continuously in a working state at a first frequency, and other wire coils are switched and heated.

Further, before the time-sharing preheating step, the method further comprises a heating wire coil number judging step, if only one wire coil is needed to work, the needed wire coil is controlled to enter a working state, otherwise, the method enters an interference judging step for judging whether interference exists between the wire coils, if the interference exists, the needed wire coil is controlled to enter the time-sharing preheating step and the same-frequency switching heating step, otherwise, the needed wire coil is controlled to enter the working state.

Further, in the interference judging step, if more than two wire coils are required to work and the intervals of the wire coils required to work are all larger than an interference threshold value, the required wire coils are controlled to enter a working state, and if the intervals of at least part of the wire coils required to work are smaller than the interference threshold value, the wire coils with the intervals smaller than the interference threshold value are controlled to enter the time-sharing preheating step and the same-frequency switching heating step.

Further, the interference threshold is less than 150mm.

Further, in the pre-operation discharging step, the discharging process is a fixed PWM output mode, and the first voltage is used for driving the IGBT, wherein the first voltage is larger than or equal to the turn-on threshold voltage of the IGBT and smaller than 15V.

Further, in the discharging process, the PWM output time is 1ms or more and 8ms or less.

Further, in the discharging process, the PWM output frequency is greater than or equal to 50KHz and less than or equal to 100KHz.

Further, in the discharging process, the pulse width time for controlling the IGBT to be turned on in a single PWM period is smaller than 2us.

Further, after the discharging process is completed, the output mode is PPG at the zero crossing point, and the IGBT is driven with a second voltage, which is 15V or 18V.

Compared with the prior art, the noise reduction method for the induction cooker with more than two wire coils provided by the invention has the advantages that the discharge treatment is carried out before the wire coils enter the working state each time, so that the capacitance energy is released, and then the wire coils enter the working state when the wire coils are in zero crossing points, so that the noise generated when the wire coils are started can be effectively avoided; meanwhile, a time-sharing preheating step and a same-frequency switching heating step are carried out in formal heating, in the time-sharing preheating step, the working states are in time-sharing mode, so that even if the working frequencies of the wire coils are different, the wire coils cannot interfere with each other, heating power and working frequency information of each wire coil are obtained in the time-sharing preheating step so as to match power in the subsequent same-frequency output working state, in the same-frequency switching step, part of wire coils are subjected to switching heating, so that the power of each wire coil can be considered under the precondition of same-frequency output, the total power required to be output by an electromagnetic oven is kept unchanged, and the frequency of each wire coil in the working state is consistent by virtue of the switching heating mode, so that noise caused by interference among the wire coils can be avoided; in conclusion, the noise reduction method of the induction cooker with more than two wire coils can enable the wire coils of the induction cooker to be noiseless when being started and when being heated during working, and can greatly improve the use experience of users.

Drawings

FIG. 1 is a schematic diagram of a pre-operation discharge step in a noise reduction method of an induction cooker of more than two wire reels of the present invention;

FIG. 2 is a schematic diagram of the operation of a preferred embodiment of the noise reduction method of the induction cooker of the present invention with more than two wire reels;

fig. 3 is a control flow chart of the noise reduction method of the induction cooker of the more than two wire coils of the invention.

Detailed Description

The present invention will be described in detail with reference to specific examples.

The electromagnetic ovens with two upper wire reels can be single-head electromagnetic ovens or multi-head electromagnetic ovens, and if the electromagnetic ovens with single heads are the electromagnetic ovens with single heads, the electromagnetic ovens with multiple heads are provided with more than two wire reels in one furnace head, and if the electromagnetic ovens with multiple heads are provided with more than one wire reel in each furnace head, the electromagnetic ovens with multiple heads are provided with more than one wire reel in each furnace head. The noise reduction method of the electromagnetic oven with more than two wire coils is applicable to any electromagnetic oven which comprises more than two wire coils and has the possibility of mutual interference or mutual interference between the wire coils. The term "two or more" as used herein means two or more. The invention provides a noise reduction method of an induction cooker with more than two wire coils, as shown in figures 1 to 3, each wire coil is respectively controlled by a main control module connected with the wire coil, each main control module is connected with a control panel and is controlled by a master controller of the induction cooker control panel, and the method comprises the following steps: a step of discharging before work, wherein a main control module connected with each wire coil detects a zero crossing point of alternating current input before each wire coil enters a working state, and discharges a capacitor connected with the wire coil before the zero crossing point, and the wire coil enters the working state again when the zero crossing point after the discharge is completed; a time-sharing preheating step, wherein the master controller controls each wire coil to be in a working state in different time periods, and obtains the heating power and the working frequency information of each wire coil; and the same-frequency switching heating step, wherein the master controller controls each wire coil to work at the same frequency according to the acquired heating power and working frequency information of each wire coil, at least part of the wire coils are switched and heated, and the switching heating is that part of the wire coils are in a working state and part of the wire coils are in a stopping state in a certain time period.

According to the noise reduction method of the induction cooker based on the more than two wire coils, the wire coils are discharged before each time the wire coils enter the working state, so that the capacitance energy is released, and then the wire coils enter the working state at zero crossing points, so that the noise generated when the wire coils are started can be effectively avoided; meanwhile, a time-sharing preheating step and a same-frequency switching heating step are carried out in formal heating, in the time-sharing preheating step, the working states are in time-sharing mode, so that even if the working frequencies of the wire coils are different, the wire coils cannot interfere with each other, heating power and working frequency information of each wire coil are obtained in the time-sharing preheating step so as to match power in the subsequent same-frequency output working state, in the same-frequency switching step, part of wire coils are subjected to switching heating, so that the power of each wire coil can be considered under the precondition of same-frequency output, the total power required to be output by an electromagnetic oven is kept unchanged, and the frequency of each wire coil in the working state is consistent by virtue of the switching heating mode, so that noise caused by interference among the wire coils can be avoided; in conclusion, the noise reduction method of the induction cooker with more than two wire coils can enable the wire coils of the induction cooker to be noiseless when being started and when being heated during working, and can greatly improve the use experience of users.

As shown in fig. 1, which is a schematic diagram of a discharging step before operation, a process indicated by T1 is a discharging process, in which the discharging process is a pulse width modulation (Pulse width modulation, PWM) output mode, and meanwhile, a first voltage U1 is used to drive the IGBT, where the first voltage U1 is greater than or equal to an on threshold voltage of the IGBT and less than 15V, the first voltage U1 preferably uses 6V, and the first voltage U1 can make the IGBT operate in an amplified state, so as to effectively inhibit a pulse current that is turned on in a high frequency state of the power tube. Preferably, during the discharging, the PWM output time T1 is 1ms or more and 8ms or less. Preferably, during discharge, the PWM output frequency is greater than or equal to 50KHz and less than or equal to 100KHz. Preferably, the pulse width time for controlling the turn-on of the IGBT in a single PWM period is less than 2us during the discharge. After the discharging process is finished, the grid-connected wire coil is in a PPG output mode when the zero crossing point is achieved, meanwhile, the IGBT is driven by the second voltage U2, the second voltage U2 is 15V or 18V, and after the IGBT is driven by 15V or 18V (specifically, the normal driving voltage required by the IGBT is used as a standard), the wire-coil enters a working state.

Based on the setting of the discharging step before operation, as shown in fig. 2, each wire coil needs to be discharged before the wire coil enters the working state in the preheating, continuous heating or switching heating process, particularly, in the switching heating process, as part of the wire coil is in the working state and part of the wire coil is in the stopping state, the capacitor stores energy in the stopping state, if the energy is not released, the wire coil starting noise is periodically generated in the switching heating process, and because of the discharging step before operation, the wire coil is discharged before entering the working state each time, so that the effect of no starting noise in the switching heating process can be realized.

In this embodiment, schematic diagrams of the time-sharing preheating step and the same-frequency switching heating step are shown in fig. 2. In the time-sharing preheating step, although the working frequencies of different wire coils are possibly different, the wire coils enter the working state in different time periods, so that the condition of noise generated by mutual interference does not exist, and meanwhile, the wire coils have a discharging process before entering the working state, so that the noise does not occur in the whole preheating step. In the preheating step, the master controller acquires heating power information and working frequency information of each wire coil, calculates the working frequency which each wire coil should output and the working time under the same frequency according to the power requirement to be output, and controls each wire coil to work according to the calculation result. Because the operating frequency of the wire coil is related to the heating power and is influenced by the cooker, the heating area of the wire coil and the like, the operating frequencies of different wire coils are inconsistent. At this time, the working frequency and the working time of each wire coil are coordinated through the preheating treatment, so that the problem of heating noise caused by the factors can be effectively solved. For example, if the coil in the induction cooker is interfered with each other, the output power of the coil 1 is 1000W, the operating frequency is a, the output power of the coil 2 is 500W, and the operating frequency is B, the two coils are inconsistent in operating frequency, so that noise is generated due to mutual interference. After the method provided by the invention is adopted, the wire coil 1 continuously works at the working frequency A, the output power is 1000W, the wire coil 2 is switched and heated, the working frequency in the working state is A, and the aim of 500W of output power is achieved by controlling the working time of the wire coil 2 in a certain period. Because both wire reels work with the same frequency A, the difference frequency noise when working is avoided. Of course, the wire coil 1 and the wire coil 2 can also be switched and heated simultaneously by adopting the working frequency C, and the requirement of output power can be met only by adjusting the corresponding working time. Therefore, in a preferred scheme, at least one wire coil is continuously in an operating state at a first frequency, and other wire coils are heated in a switching mode.

In this embodiment, before the time-sharing preheating step, the method further includes a heating wire coil number judging step, if only one wire coil is needed to work, the needed wire coil is controlled to enter a working state, otherwise, an interference judging step for judging whether interference exists between the wire coils is entered, if the interference exists, the needed wire coil is controlled to enter the time-sharing preheating step and the same-frequency switching heating step, otherwise, the needed wire coil is controlled to enter the working state. In the actual use process, for example, more than two wire coils are arranged in a single-head furnace, and the current power output requirement can be met by starting only one wire coil, or each furnace end in a multi-head furnace only has one wire coil, and only needs one wire coil to work, so that the situation of interference does not exist, and the master controller can directly enable the required wire coil to enter the working state without entering a time-sharing preheating step and a same-frequency switching heating step. Of course, before the single wire coil enters the working state, the discharging step before the working is also needed to be carried out, so that no noise is generated when the wire coil is started.

In this embodiment, in the interference judging step, if more than two wire coils are required to work and the intervals between the wire coils required to work are all greater than the interference threshold, the required wire coils are controlled to enter the working state, and if the intervals between at least part of the wire coils required to work and the wire coils required to work are less than the interference threshold, the wire coils with the intervals less than the interference threshold are controlled to enter the time-sharing preheating step and the same-frequency switching heating step. In the actual use process, if the space between the wire coils is large enough, the interference condition does not exist, and the master controller directly enables the wire coils with the large enough space to enter the working state without entering the time-sharing preheating step and the same-frequency switching heating step. For example, three wire coils need to be started, but the distance between the first wire coil and the other two wire coils is large enough, the first wire coil cannot be interfered, the distance between the other two wire coils is small, the interference exists, the master controller directly enables the first wire coil to enter a working state, and the other two wire coils enter a time-sharing preheating step and a same-frequency switching heating step. Of course, before the single wire coil enters the working state, the discharging step before the working is also needed to be carried out, so that no noise is generated when the wire coil is started. Preferably, the interference threshold is less than 150mm.

In conclusion, the noise reduction method of the induction cooker with more than two wire coils can enable the wire coils of the induction cooker to be noiseless when being started and when being heated during working, and can greatly improve the use experience of users.

The above-described embodiments and features of the embodiments may be combined with each other without conflict.

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 scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. The method for reducing noise of the induction cooker with more than two wire coils is characterized in that each wire coil is respectively controlled by a main control module connected with the wire coils, each main control module is connected with a control panel and is controlled by a master controller of the control panel of the induction cooker, and the method comprises the following steps:

a step of discharging before work, wherein a main control module connected with each wire coil detects a zero crossing point of alternating current input before each wire coil enters a working state, and discharges a capacitor connected with the wire coil before the zero crossing point, and the wire coil enters the working state again when the zero crossing point after the discharging is completed;

a time-sharing preheating step, wherein the master controller controls each wire coil to be in a working state in different time periods, and obtains the heating power and the working frequency information of each wire coil;

and the same-frequency switching heating step, namely controlling each wire coil to work at the same frequency by the master controller according to the acquired heating power and working frequency information of each wire coil, and switching and heating at least part of the wire coils, wherein the switching and heating are that part of the wire coils are in a working state and part of the wire coils are in a stopping state in a certain time period.

2. The method for reducing noise in an induction cooker with more than two wire coils according to claim 1, wherein: in the same-frequency switching heating step, at least one wire coil is continuously in a working state at a first frequency, and other wire coils are switched and heated.

3. The method for reducing noise in an induction cooker with more than two wire coils according to claim 1, wherein: before the time-sharing preheating step, the method further comprises a heating wire coil number judging step, if only one wire coil is needed to work, the needed wire coil is controlled to enter a working state, otherwise, the method enters an interference judging step for judging whether interference exists between the wire coils, if the interference exists, the needed wire coil is controlled to enter the time-sharing preheating step and the same-frequency switching heating step, otherwise, the needed wire coil is controlled to enter the working state.

4. A method of reducing noise in an induction cooker having more than two wire coils as defined in claim 3, wherein: in the interference judging step, if more than two wire coils are required to work and the spacing of the wire coils required to work is larger than an interference threshold value, the required wire coils are controlled to enter a working state, and if the spacing of at least part of the wire coils required to work is smaller than the interference threshold value, the wire coils with the spacing smaller than the interference threshold value are controlled to enter the time-sharing preheating step and the same-frequency switching heating step.

5. The method for reducing noise in an induction cooker with more than two wire coils as set forth in claim 4, wherein: the interference threshold is less than 150mm.

6. The method for reducing noise in an induction cooker having two or more reels as set forth in any one of claims 1 to 5, wherein: in the discharging step before working, the discharging process is in a fixed PWM output mode, and meanwhile, a first voltage is used for driving the IGBT, wherein the first voltage is larger than or equal to the turn-on threshold voltage of the IGBT and smaller than 15V.

7. The method for reducing noise in an induction cooker with more than two wire coils as set forth in claim 6, wherein: during the discharging, the PWM output time is 1ms or more and 8ms or less.

8. The method for reducing noise in an induction cooker with more than two wire coils as set forth in claim 6, wherein: in the discharging process, the PWM output frequency is more than or equal to 50KHz and less than or equal to 100KHz.

9. The method for reducing noise in an induction cooker with more than two wire coils as set forth in claim 6, wherein: in the discharging process, the pulse width time for controlling the IGBT to be turned on in a single PWM period is less than 2us.

10. The method for reducing noise in an induction cooker with more than two wire coils as set forth in claim 6, wherein: after the discharging process is completed, the PPG output mode is set at the zero crossing point, and meanwhile, the IGBT is driven by a second voltage which is 15V or 18V.