CN107396476B - Method for reducing EMI interference and electromagnetic heating device using same - Google Patents
Method for reducing EMI interference and electromagnetic heating device using same Download PDFInfo
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- CN107396476B CN107396476B CN201710604958.5A CN201710604958A CN107396476B CN 107396476 B CN107396476 B CN 107396476B CN 201710604958 A CN201710604958 A CN 201710604958A CN 107396476 B CN107396476 B CN 107396476B
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- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000010438 heat treatment Methods 0.000 title claims abstract description 23
- 239000006185 dispersion Substances 0.000 claims abstract description 7
- 238000001514 detection method Methods 0.000 claims description 28
- 238000010586 diagram Methods 0.000 description 3
- 230000006698 induction Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/02—Induction heating
- H05B6/06—Control, e.g. of temperature, of power
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B2206/00—Aspects relating to heating by electric, magnetic, or electromagnetic fields covered by group H05B6/00
- H05B2206/02—Induction heating
Abstract
The method for reducing EMI interference and the electromagnetic heating device using the method utilize an energy dispersion method to reduce EMI interference, namely, energy near the peak value of alternating current is dispersed to a wider area, in the working process, when a circuit works near the zero crossing point of the alternating current, the turn-on time of a power switch tube is increased, and when the circuit works near the peak value of the alternating current, the turn-on time of the power switch tube is reduced, and the electromagnetic heating device uses the energy dispersion method. The invention reduces the instantaneous impact current of the switch when the alternating current peak value is ensured to be stable under the condition of power stability, and disperses the concentrated interference generated when the alternating current peak value is carried out to a wider interval, thereby reducing the electromagnetic EMI interference and noise and ensuring that the power switch tube works in a safe current range.
Description
Technical Field
The invention relates to the field of electromagnetic heating, in particular to a method for reducing EMI interference.
Background
At present, due to the reasons of high power, high frequency and the like, the electromagnetic heating device can generate great electromagnetic interference in the working process, is difficult to be qualified when an EMI test is carried out, and even if the electromagnetic heating device can be qualified, the electromagnetic heating device is realized by adding an EMI filtering component, so the cost is increased.
Generally, the frequency point which is easy to exceed the standard is the multiple of the working main frequency of the electromagnetic heating product, and as the voltage is higher when the alternating current is at the peak value and the impulse current is also higher when the alternating current is in work, most of interference is concentrated near the peak value of the alternating current, so that the EMI test is unqualified.
Disclosure of Invention
The present invention is directed to solving the above problems, and provides a method for reducing EMI interference and an electromagnetic heating apparatus using the same.
In order to solve the technical problem, the embodiment of the invention provides a method for reducing EMI interference, which is characterized in that concentrated interference generated at the time of an alternating current peak is dispersed to a wider interval by adopting an energy dispersion method.
Further, the working steps are as follows:
1) under a normal working state, the PPG of the control module controls the power switch tube driving circuit module to drive the power switch tube to be periodically switched on and switched off in a width of x microseconds;
2) the time when the zero-crossing detection module detects the zero-crossing point of the alternating current for the first time is t0, the PPG at the time of t0 increases y microseconds every time by taking x microseconds as a reference, the opening width of the PPG is increased, and the time after the PPG is increased for N times is t 1;
3) stopping increasing the opening width of the PPG at the time t1, reducing the opening width of the PPG by z microseconds every time by taking the PPG width at the time t1 as a reference, and reducing the opening width of the PPG by t2 at the time after M times of reduction;
4) stopping reducing the opening width of the PPG at t2, and waiting for the next alternating current zero crossing point;
5) the zero-crossing detection module detects the zero-crossing time of the alternating current as t4 again, and then returns to the step 2);
wherein t 0< t1 < t2 < t3 < t4, and t3 is the peak time of the alternating current.
Further, the value ranges of M and N are M >0 and N > 0; the value ranges of x, y and z are 0< x <40, 0< y <10 and 0< z <10 in sequence.
Further, when the operating frequency of the single chip microcomputer is 24MHz and the circuit power is 1800W, 20< x <25, y-z-1/6 and M-N-25.
The electromagnetic heating device is characterized by comprising a control module, a power switch tube driving circuit module, a power switch tube, a zero-crossing detection module and a power supply module, wherein the power supply module is connected to the zero-crossing detection module, the control module receives a signal of the zero-crossing detection module and controls the power switch tube by driving the power switch tube driving circuit module, and the electromagnetic heating device adopts the method for reducing the EMI interference.
Further, the zero crossing detection module may be disposed inside or outside the control module.
Compared with the prior art, the invention has the following beneficial effects: the method for reducing the EMI interference reduces the EMI interference by using an energy dispersion method, namely, energy near the peak value of alternating current is dispersed to a wider area, so that the aim of reducing the EMI interference is fulfilled. In the working process, the on-time of the power switch tube is prolonged when the circuit works near the zero crossing point of the alternating current, the on-time of the power switch tube is shortened when the circuit works near the peak value of the alternating current, the instantaneous impact current of the switch at the peak value of the alternating current is reduced under the condition of ensuring stable power, and the concentrated interference generated at the peak value of the alternating current is dispersed to a wider interval, so that the electromagnetic EMI interference and noise are reduced, and the power switch tube is ensured to work in a safe current range.
The electromagnetic heating device comprises a control module, a power switch tube driving circuit module, a power switch tube, a zero-crossing detection module and a power supply module, wherein the power supply module is connected to the zero-crossing detection module, the control module receives a signal of the zero-crossing detection module and controls the power switch tube by driving the power switch tube driving circuit module, the electromagnetic heating device adopts the method for reducing the EMI interference, the EMI test result is stable, the effect is good, and the cost is not increased.
Drawings
FIG. 1 is a waveform diagram of voltage variation in a method for reducing EMI interference;
FIG. 2 is a flow chart of PPG turn-on width variation in a method for reducing EMI interference;
FIG. 3 is a block diagram of a first embodiment of an electromagnetic heating apparatus;
FIG. 4 is a block diagram of a second embodiment of an electromagnetic heating apparatus;
FIG. 5 is an EMI test chart of an induction cooker without adding EMI components;
FIG. 6 is an EMI test chart of an induction cooker with additional filtering components;
FIG. 7 is an EMI test chart of an induction cooker using the present solution.
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.
A method for reducing EMI interference adopts an energy dispersion method to disperse concentrated interference generated in the process of alternating current peak value to a wider interval.
The waveform change is shown in fig. 1, the change process of the PPG is shown in fig. 2, and the specific steps are as follows:
1) under a normal working state, the PPG of the control module controls the power switch tube driving circuit module to drive the power switch tube to be periodically switched on and switched off in a width of x microseconds;
2) the time when the zero-crossing detection module detects the zero-crossing point of the alternating current for the first time is t0, the PPG at the time of t0 increases y microseconds every time by taking x microseconds as a reference, the opening width of the PPG is increased, and the time after the PPG is increased for N times is t 1;
3) stopping increasing the opening width of the PPG at the time t1, reducing the opening width of the PPG by z microseconds every time by taking the PPG width at the time t1 as a reference, and reducing the opening width of the PPG by t2 at the time after M times of reduction;
4) stopping reducing the opening width of the PPG at t2, and waiting for the next alternating current zero crossing point;
5) the zero-crossing detection module detects the zero-crossing time of the alternating current as t4 again, and then returns to the step 2);
wherein t 0< t1 < t2 < t3 < t4, and t3 is the peak time of the alternating current.
In the actual operation process, x, y, z, M and N can be set independently according to needs, and the values of x, y, z, M and N are related to the selection of the working frequency of the singlechip and the selection of the power range of the product in the actual operation process. the PPG on width at time t2 is approximately equal to x microseconds. The value ranges of M and N are M >0 and N > 0; the value ranges of x, y and z are 0< x <40, 0< y <10 and 0< z <10 in sequence. Preferably, y is equal to z, M is equal to N, and since the amplitude and the number of times of increasing and decreasing the PPG opening width are the same, the PPG opening width at the time of t2 is x microseconds.
Taking an electromagnetic oven as an example, when the working frequency of the singlechip is 24MHz and the maximum power of the circuit is 1800W, the optimal range of x is 20-25, the optimal values of y and z are 1/6, and the optimal values of M and N are 25, at this time, the working state is the most stable, and the working state is normal. As shown in fig. 3 and 4, the electromagnetic heating device includes a control module, a power switching tube driving circuit module, a power switching tube, a zero-crossing detection module, and a power supply module. The zero-crossing detection module can be arranged inside or outside the control module, namely, the zero-crossing detection module can be an independent module and can also be integrated inside the control module. The electromagnetic heating device uses the method for reducing EMI interference.
In the first embodiment of the electromagnetic heating device, when the zero-crossing detection module is arranged outside the control module, the zero-crossing detection module is an independent module, and the power supply module is connected to the zero-crossing detection module to supply power to the zero-crossing detection module; the control module receives a signal of the zero-crossing detection module and then sends out a PPG signal to drive the power switch tube driving circuit module to control the power switch tube to be switched on or switched off, wherein the power switch tube generally refers to an IGBT.
In the second embodiment of the electromagnetic heating device, when the zero-crossing detection module is arranged in the control module, the zero-crossing detection module is integrated in the control module, and the power supply module is connected to the control module to supply power to the control module; when a zero-crossing detection module in the control module detects a zero-crossing signal, a PPG signal is sent out to drive a power switch tube driving circuit module to control the power switch tube to be switched on or switched off, and the power switch tube generally refers to an IGBT.
Taking a certain type of electromagnetic oven as an example, as shown in fig. 5, when an EMI interference test is performed on a common electromagnetic oven, a main frequency peak exceeds a national standard specified value, and a double frequency peak occasionally exceeds the national standard specified value, so that the EMI interference test cannot be passed. In order to solve the above problems, a method of adding a filter component is usually used, as shown in fig. 6, when an electromagnetic oven with the filter component is used for an EMI interference test, a main frequency peak margin is about 10dB, and a double frequency peak margin is sufficient, which can pass the EMI interference test, but the cost is increased by adding the filter component, which is not in line with the original purpose of cost reduction. The scheme adopts an energy dispersion method to disperse concentrated interference generated at a main frequency peak value to a wider interval, and the specific implementation mode is that the opening time of a power switch tube is increased when a circuit is near an alternating current zero crossing point, and the opening time of the power switch tube is reduced when the circuit is near the alternating current peak value, as shown in fig. 7, when an electromagnetic oven using the scheme is used for carrying out an EMI interference test, the main frequency peak margin is more than 20dB, the frequency doubling peak margin is sufficient, the top energy of all frequency points is relatively dispersed, the phenomenon of sudden high jump can not be generated, the test result of the scheme is stable, the working state of the electromagnetic oven is normal, additional components are not added, the implementation mode is simple, and the cost can not be increased.
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice.
Claims (5)
1. A method for reducing EMI interference is characterized in that an energy dispersion method is adopted to disperse concentrated interference generated in the process of alternating current peak value to a wider interval, and specifically comprises the steps of increasing the turn-on time of a power switch tube when a circuit is near an alternating current zero crossing point, and reducing the turn-on time of the power switch tube when the circuit is near the alternating current peak value;
the working steps are as follows:
1) under a normal working state, the PPG of the control module controls the power switch tube driving circuit module to drive the power switch tube to be periodically switched on and switched off in a width of x microseconds;
2) the time when the zero-crossing detection module detects the zero-crossing point of the alternating current for the first time is t0, the PPG at the time of t0 increases y microseconds every time by taking x microseconds as a reference, the opening width of the PPG is increased, and the time after the PPG is increased for N times is t 1;
3) stopping increasing the opening width of the PPG at the time t1, reducing the opening width of the PPG by z microseconds every time by taking the PPG width at the time t1 as a reference, and reducing the opening width of the PPG by t2 at the time after M times of reduction;
4) stopping reducing the opening width of the PPG at t2, and waiting for the next alternating current zero crossing point;
5) the zero-crossing detection module detects the zero-crossing time of the alternating current as t4 again, and then returns to the step 2);
wherein t 0< t1 < t2 < t3 < t4, and t3 is the peak time of the alternating current.
2. The method of reducing EMI interference of claim 1, wherein M and N have values in a range of M >0, N > 0; the value ranges of x, y and z are 0< x <40, 0< y <10 and 0< z <10 in sequence.
3. The method of claim 2, wherein when the operating frequency of the single chip is 24MHz and the circuit power is 1800W, 20< x <25, y-z-1/6, and M-N-25.
4. The electromagnetic heating device is characterized by comprising a control module, a power switch tube driving circuit module, a power switch tube, a zero-crossing detection module and a power supply module, wherein the power supply module is connected to the zero-crossing detection module, the control module receives a signal of the zero-crossing detection module and controls the power switch tube by driving the power switch tube driving circuit module, and the electromagnetic heating device uses the method for reducing EMI interference according to any one of claims 1 to 3.
5. Electromagnetic heating device according to claim 4, characterized in that the zero-crossing detection module can be arranged inside or outside the control module.
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| CN112888099B (en) * | 2019-11-29 | 2022-08-30 | 浙江绍兴苏泊尔生活电器有限公司 | IGBT control method of half-bridge electromagnetic appliance and half-bridge electromagnetic heating appliance |
| CN112351535B (en) * | 2020-11-06 | 2023-05-02 | 广东瑞德智能科技股份有限公司 | Heating control method and device of electromagnetic heating circuit and electrical equipment |
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| CN103763803A (en) * | 2014-01-23 | 2014-04-30 | 美的集团股份有限公司 | Electromagnetic resonance control circuit, electromagnetic heating device and method for controlling transistor |
| CN106686785A (en) * | 2015-11-11 | 2017-05-17 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating apparatus and control method therefor |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103763803A (en) * | 2014-01-23 | 2014-04-30 | 美的集团股份有限公司 | Electromagnetic resonance control circuit, electromagnetic heating device and method for controlling transistor |
| CN106686785A (en) * | 2015-11-11 | 2017-05-17 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating apparatus and control method therefor |
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Effective date of registration: 20231010 Address after: No. 2977, Jingliu Road, Linjiang Street, Qiantang District, Hangzhou City, Zhejiang Province 311228 Patentee after: Hangzhou yinglete Intelligent Technology Co.,Ltd. Address before: 313300 Tangpu Industrial Park, Anji Economic Development Zone, Anji County, Huzhou City, Zhejiang Province Patentee before: ANJI SINODOD INTELLIGENT TECHNOLOGY CO.,LTD. |
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