CN102548077B - Power supply power adjusting method of microwave oven - Google Patents
Power supply power adjusting method of microwave oven Download PDFInfo
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- CN102548077B CN102548077B CN201210011298.7A CN201210011298A CN102548077B CN 102548077 B CN102548077 B CN 102548077B CN 201210011298 A CN201210011298 A CN 201210011298A CN 102548077 B CN102548077 B CN 102548077B
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Abstract
The invention discloses a power supply power adjusting method of a microwave oven. The power supply power adjusting method comprises a mode of combining pulse frequency modulation and pulse width modulation, wherein driving levels of an upper pipe and a lower pipe of a resonance half-bridge are complementary on the time sequence and are unequal in pulse width. According to the power supply power adjusting method disclosed by the invention, the gain of a converter under a light load condition is reduced, and the power adjusting performance under the light load condition is improved.
Description
[technical field]
The present invention relates to frequency-conversion microwave oven, relate in particular to a kind of power regulating method of microwave oven supply power.
[background technology]
Frequency-conversion microwave oven is high with its efficiency, homogeneous heating in unit interval and be subject to increasing user's favor. compare with traditional microwave oven supply power, frequency-conversion microwave oven power acquisition used power within the specific limits continuously adjustable Switching Power Supply replaced the power output cannot continuously adjustable Industrial Frequency Transformer.
But existing microwave oven supply power also has its deficiency, microwave oven variable frequency power supply consists of resonance oscillation semi-bridge, as shown in Figure 1, H is that upper pipe drives sequential chart, L is that lower pipe drives sequential chart, and in figure, t1-t2, t3-t4, t5-t6, t7-t8 are Dead Time, and t2-t3, t6-t7 are upper pipe service time, t4-t5, t8-t9 are lower pipe service time, and the drive level of the top tube and down tube of the half-bridge that shakes is not only complementary in sequential.And time wide equate, the service time of going up pipe equals the service time of lower pipe.This single frequency modulation control mode has determined to design when circuit is worked in wide-voltage range complicated, cannot continuous operation when underloading.Its power regulating range is limited, can only partly be downloaded between fully loaded adjustablely continuously, and below semi-load, its power is adjusted with conventional microwave oven power supply similar, can only obtain required power by the time of startup-shutdown is set.
[summary of the invention]
The technical problem to be solved in the present invention is to provide that a kind of circuit structure is simple, underloading power can continuously adjustable microwave oven supply power power regulating method.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is that a kind of microwave oven supply power power regulating method, comprises pulse frequency and the mode of adjusting pulse duration to combine adjusted, the drive level of the top tube and down tube of resonance oscillation semi-bridge is complementary in sequential, and pulsewidth is not etc.
Above-described microwave oven supply power power regulating method, in described top tube and down tube, the duty ratio of a power tube changes between 20-50%, the changing between 80-50% of the duty ratio of another power tube.
Above-described microwave oven supply power power regulating method, microprocessor is adjusted the duty ratio of power tube according to the power/duty ratio corresponding data table prestoring, and described power/duty ratio corresponding data table stores the duty ratio numerical value that microwave oven is corresponding with every 1 power section.
Above-described microwave oven supply power power regulating method, described adjustment microwave oven supply power comprises: power signal reference cell, error signal unit, pulse-frequency modulation are adjusted wide unit and resonance oscillation semi-bridge:
Power signal reference cell reads the power reference signal that control board sends, and converts the control signal that pwm unit can be identified to;
Error signal unit sends the actual power inputing or outputing of variable-frequency electric source plate power reference signal with control board is compared, and produces error signal, and this error signal input pulse modulating frequency and width unit is used for adjusting the frequency of pulse;
Pulse-frequency modulation adjusts the control signal that represents different capacity grade that power signal reference cell is sent in wide unit to convert corresponding pulse width information to, and the error signal of error signal unit is converted to corresponding FM signal, the pulse duration of output is corresponding with power setting grade, the modulating frequency and width signal that pulse frequency and instantaneous power or voltage or electric current are relevant;
The control signal that resonance oscillation semi-bridge adjusts wide unit to send here pulse-frequency modulation is separated, amplifies, and controls correct phase relation, and drives upper and lower bridge, the power of setting in the output output of transformer.
The drive level of the top tube and down tube of resonance oscillation semi-bridge of the present invention is complementary in sequential, and pulsewidth not etc., has not reduced the gain of underloading condition downconverter, and the power having improved under underloading condition is adjusted performance.
[accompanying drawing explanation]
Below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.
Fig. 1 is that prior art microwave oven supply power is managed driving sequential chart up and down.
Fig. 2 is that embodiment of the present invention microwave oven supply power is managed driving sequential chart up and down.
Fig. 3 is the theory diagram of embodiment of the present invention microwave oven supply power control circuit.
Fig. 4 is the gain curve figure of embodiment of the present invention microwave oven supply power input voltage within the scope of 1 π.
Fig. 5 is the gain curve comparison diagram under embodiment of the present invention microwave oven supply power different output power.
Fig. 6 is the partial enlarged drawing of Fig. 5 figure line intersection area.
[embodiment]
Microwave oven variable frequency power supply is a single-stage controlled resonant converter in most cases, and the power that should meet output setting drives the demand of microwave tube, and this is equivalent to a DC/DC converter; Meet again the requirement of certain harmonic wave, to reduce the pollution to electrical network, this is equivalent to a pfc circuit.It all requires microwave oven variable frequency power supply converter normally to work and in most scope, exports corresponding power in the voltage range of the whole sine wave of electrical network input, and the operating voltage of microwave tube is relatively fixing.This just needs converter within the scope of whole sine voltage, to have the gain of answering in contrast, as shown in Figure 4.
When converter is operated under different power output conditions, gain also changes relatively, during underloading gain larger, and when heavy duty gain can decline relatively, but converter can only work in certain frequency range,
Gain contrast when accompanying drawing 5 is output as 200W and 1000W for converter.As can be seen from the figure, served as resonance frequency fo (in figure, gain is 1 point), change in gain is very slow; particularly particularly outstanding under underloading condition, in order to obtain 0.1 change in gain amount, when underloading; more than frequency need to change 10KHZ, as shown in Figure 6.But the frequency limited of converter can not infinitely raise in components and parts, and in the time of therefore can causing underloading, power is out of control.
Embodiments of the invention adopt pulse frequency and the mode of adjusting pulse duration to combine adjusted, as shown in Figure 2, H is that upper pipe drives sequential chart, L is that lower pipe drives sequential chart, in figure, t1-t2, t3-t4, t5-t6, t7-t8 are Dead Time, and t2-t3, t6-t7 are upper pipe service time, and t4-t5, t8-t9 are lower pipe service time, the drive level of top tube and down tube of half-bridge of shaking is not only complementary in sequential, and pulsewidth is not etc.
In top tube and down tube, the duty ratio of a power tube can change between 20-50, and the duty ratio of another power tube can change between 80-50%.
Microprocessor is adjusted the duty ratio of power tube according to the power/duty ratio corresponding data table prestoring, and power/duty ratio corresponding data table stores the duty ratio numerical value that microwave oven is corresponding with every 1 power section.
Adjustment microwave oven supply power comprises: power signal reference cell, error signal unit, pulse-frequency modulation are adjusted wide unit and resonance oscillation semi-bridge.
Power signal reference cell reads the power reference signal that control panel of microwave oven sends, and converts the digital controlled signal that pwm unit can be identified to;
Error signal unit sends the actual power inputing or outputing of variable frequency power supply power reference signal with control board is compared, and produces error signal, and this error signal input pulse modulating frequency and width unit is used for adjusting the frequency of pulse;
Pulse-frequency modulation adjusts the control signal that represents different capacity grade that power signal reference cell is sent in wide unit to convert corresponding pulse width information to according to above-mentioned power/duty ratio corresponding data table, and the error signal of error signal unit is converted to corresponding FM signal through Digital Control loop (PI loop), is converted to corresponding FM signal (PI loop is prior art, can consult < < Advanced PID control and MATLAB emulation > > thereof, Liu Jinkun work); Output pulse width is corresponding with power setting grade, the modulating frequency and width signal that pulse frequency and instantaneous power or voltage or electric current are relevant.
The control signal that resonance oscillation semi-bridge adjusts wide unit to send here pulse-frequency modulation is separated, amplifies, and controls correct phase relation, and drives upper and lower bridge, the power of setting in the output output of transformer.
Converter of the present invention, when setting power declines, as shown in Figure 2, dwindles the duty ratio of a power tube, amplify the duty ratio of another power tube simultaneously, limited the energy that flows into converter, gain controlled, from accompanying drawing 6, can see, converter, when low power run, reduces after duty ratio, and gain curve approaches former full load gain curve very much, that is to say, in equal frequency range, power output has obtained effective control, and power output is adjustable continuously.
Claims (3)
1. a microwave oven supply power power regulating method, is characterized in that, comprises and adjusts pulse frequency and the mode of adjusting pulse duration to combine, and the drive level of the top tube and down tube of resonance oscillation semi-bridge is complementation in sequential, and pulsewidth is not etc.; Duty ratio is controlled by power instruction, and when power instruction is constant, duty ratio remains unchanged;
Described microwave oven supply power comprises: power signal reference cell, error signal unit, pulse-frequency modulation are adjusted wide unit and resonance oscillation semi-bridge:
Power signal reference cell reads the power reference signal that control board sends, and converts the control signal that pwm unit can be identified to;
Error signal unit sends the actual power inputing or outputing of variable frequency power supply power reference signal with control board is compared, and produces error signal, and this error signal input pulse modulating frequency and width unit is used for adjusting the frequency of pulse;
Pulse-frequency modulation adjusts the control signal that represents different capacity grade that power signal reference cell is sent in wide unit to convert corresponding pulse width information to according to power/duty ratio corresponding data table, and the error signal of error signal unit is converted to corresponding FM signal through Digital Control loop, output pulse width is corresponding with power setting grade, the modulating frequency and width signal that pulse frequency and instantaneous power or voltage or electric current are relevant;
The control signal that resonance oscillation semi-bridge adjusts wide unit to send here pulse-frequency modulation is separated, amplifies, and controls correct phase relation, and drives upper and lower bridge, the power of setting in the output output of transformer.
2. microwave oven supply power power regulating method according to claim 1, is characterized in that, in described top tube and down tube, the duty ratio of a power tube changes between 20-50%, the changing between 80-50% of the duty ratio of another power tube.
3. microwave oven supply power power regulating method according to claim 1, it is characterized in that, microprocessor is adjusted the duty ratio of power tube according to the power/duty ratio corresponding data table prestoring, and described power/duty ratio corresponding data table stores the duty ratio numerical value that microwave oven is corresponding with every 1 power section.
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| CN201210011298.7A CN102548077B (en) | 2012-01-13 | 2012-01-13 | Power supply power adjusting method of microwave oven |
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| CN105142253B (en) * | 2015-07-24 | 2018-07-10 | 石铁峰 | A kind of microwave generating apparatus, microwave heating equipment and heating means |
| CN108605391B (en) | 2016-01-28 | 2020-11-17 | 松下电器产业株式会社 | Method and apparatus for transmitting radio frequency electromagnetic energy for cooking food products |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004304869A (en) * | 2003-03-28 | 2004-10-28 | Sanken Electric Co Ltd | Inverter device |
| CN102313307A (en) * | 2011-09-13 | 2012-01-11 | 深圳麦格米特电气股份有限公司 | Method of switching power for variable frequency microwave oven |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004304869A (en) * | 2003-03-28 | 2004-10-28 | Sanken Electric Co Ltd | Inverter device |
| CN102313307A (en) * | 2011-09-13 | 2012-01-11 | 深圳麦格米特电气股份有限公司 | Method of switching power for variable frequency microwave oven |
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Effective date of registration: 20170608 Address after: 412000 No. 1728, Taishan Road, Tianyuan District, Hunan, Zhuzhou Patentee after: Zhuzhou Megmeet Electrical Co., Ltd. Address before: 518000 Shenzhen science and technology zone, Nanshan District Province, North District, road, No. 13, Thunis science and Technology Park, layer 5 Patentee before: Shenzhen Megmeet Electrical Co., Ltd. |
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