CN105485731B - Microwave oven circuit and micro-wave oven - Google Patents
Microwave oven circuit and micro-wave oven Download PDFInfo
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- CN105485731B CN105485731B CN201511030511.9A CN201511030511A CN105485731B CN 105485731 B CN105485731 B CN 105485731B CN 201511030511 A CN201511030511 A CN 201511030511A CN 105485731 B CN105485731 B CN 105485731B
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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
- H05B6/64—Heating using microwaves
- H05B6/66—Circuits
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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
- H05B6/64—Heating using microwaves
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- Electromagnetism (AREA)
- Control Of High-Frequency Heating Circuits (AREA)
- Inverter Devices (AREA)
Abstract
The invention provides a kind of microwave oven circuit and micro-wave oven, microwave oven circuit, including：Electric-controlled plate and high-frequency heating circuit；Wherein, the electric-controlled plate includes：Relay drive circuit, for being transmitted electric power signal to the high-frequency heating circuit；Power driving circuit, for conveying power signal to the high-frequency heating circuit；First filter circuit, is connected to the signal feedback end of the high-frequency heating circuit, and processing is filtered for the magnetron current signal to the high-frequency heating electronic feedback；Analog to digital conversion circuit, is connected to first filter circuit, and the signal for being exported to first filter circuit carries out analog-to-digital conversion process；Controller, it is connected to analog-digital conversion circuit as described, the relay drive circuit and the power driving circuit, electric power signal for controlling the relay drive circuit conveying, and the signal exported according to analog-digital conversion circuit as described controls the power signal that the power driving circuit is conveyed.
Description
Technical field
The present invention relates to micro-wave oven technical field, in particular to a kind of microwave oven circuit and a kind of micro-wave oven.
Background technology
Inverter in microwave oven circuit is for transformer frequency response, with light and handy, power factor is high, power is continuous
Adjustable the advantages of, receive the extensive favor of user.With a large amount of utilizations of frequency converter, the repair rate of in the market generally increases,
From the point of view of the data reprocessed, IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) and
The damage of rectifier bridge stack is in the great majority, and present control mode has received stern challenge.
As shown in figure 1, existing variable frequency microwave furnace control system, including electric-controlled plate and thermatron.Wherein, it is automatically controlled
Plate includes MCU, relay driving module and PWM (pulsewidth modulation) drive module, and relay driving module transmits electric power signal
To the inverter in thermatron, PWM drive circuit passes to power signal the inverter in thermatron, inverse
Become device and microwave is produced according to the signal driving magnetron received, reach the purpose of heating food.
It is the structural representation of the inverter in existing microwave oven circuit as shown in Figure 2, the operation principle of inverter is：City
Electricity by the filter circuit 2 ' being made up of inductance L1 ' and electric capacity C1 ', then accesses resonance electricity after the rectification of rectifier bridge stack 1 '
Hold the resonant network of 3 ' and the composition of high-frequency step-up transformer 4 ', and control resonant energy to feed back to height by IGBT 5 ' break-make
The secondary of frequency step-up transformer 4 ', then the voltage-multiplying circuit by being made up of high-voltage capacitance C2 ', C3 ' and high-voltage diode D1 ', D2 '
6 ', the high pressure of driving magnetron is produced, magnetron is then sent to, driving magnetron produces microwave.
Wherein, the size of resonance current can be changed by changing IGBT 5 ' switching frequency, so as to change magnetron
Power.
As shown in figure 3, in the control sequential that correlation technique is proposed, when microwave relay is opened, electricity can be provided to inverter
Force signal, while conveying target power signal PWM to inverter, reaches desired power.But, in microwave relay conducting
When, if the voltage at the electric capacity C2 ' two ends in inverter is not zero, if at this moment line voltage is higher, it can cause in peak value
The two ends of rectifier bridge stack 1 ' produce higher abnormal voltage, up to more than 1,000 volt, easily damage bridge heap.It is specific as shown in Figure 4：
Fig. 4 shows the control of inverter voltage waveform, microwave relay of city's electric signal when opening in correlation technique
The voltage waveform (i.e. Vab waveforms) at signal waveform and the two ends of rectifier bridge stack 1 '.Assuming that civil power exchanges for 220V, if at city's electric signal
In peak value 310V, and during microwave relay conducting, the voltage at electric capacity C2 ' two ends is 0, then microwave relay turn on moment due to
The voltage at electric capacity C2 ' two ends can not be mutated, and civil power peak value 310V is applied directly to inductance L1 ' above, because the characteristic of inductance is (i.e. electric
Stream can not be mutated), then it can produce very big backward voltage and prevent electric current from increasing, therefore in the port of front end, i.e. rectifier bridge stack 1 ',
Larger voltage can be produced, up to 1000V easily damages rectifier bridge stack 1 '.The theory analysis is also with the feedback data one in market
Cause, i.e., the maintenance rate of rectifier bridge stack 1 ' remains high.
Meanwhile, another maintenance rate it is higher be IGBT 5 ' because IGBT G pole tensions are no more than 25V, still
Under existing control mode, when microwave relay is opened, more than 33V voltage occurs in IGBT G poles once in a while.
Therefore, how when inverter is opened, the voltage at reduction rectifier bridge stack two ends, it is to avoid rectifier bridge stack two ends
Overtension and damage rectifier bridge stack, while avoid IGBT G poles due to voltage is excessive and damaging turns into technology urgently to be resolved hurrily
Problem.
The content of the invention
It is contemplated that at least solving one of technical problem present in prior art or correlation technique.
Therefore, it is an object of the present invention to propose a kind of new microwave oven circuit, can when inverter is opened,
Reduce the voltage at rectifier bridge stack two ends, it is to avoid the overtension at rectifier bridge stack two ends and damage rectifier bridge stack, while can avoid
IGBT G poles are damaged because voltage is excessive.
It is another object of the present invention to propose a kind of micro-wave oven.
To achieve the above object, a kind of embodiment according to the first aspect of the invention, it is proposed that microwave oven circuit, bag
Include：Electric-controlled plate and high-frequency heating circuit；Wherein, the electric-controlled plate includes：Relay drive circuit, for the high-frequency heating
Circuit transmits electric power signal；Power driving circuit, for conveying power signal to the high-frequency heating circuit；First filtered electrical
Road, is connected to the signal feedback end of the high-frequency heating circuit, for the magnetron current to the high-frequency heating electronic feedback
Signal is filtered processing；Analog to digital conversion circuit, is connected to first filter circuit, for defeated to first filter circuit
The signal gone out carries out analog-to-digital conversion process；Controller, is connected to analog-digital conversion circuit as described, the relay drive circuit and institute
Power driving circuit is stated, the electric power signal for controlling the relay drive circuit conveying, and according to analog-to-digital conversion electricity
The signal of road output controls the power signal of the power driving circuit conveying.
Microwave oven circuit, passes through the magnetron current signal to high-frequency heating electronic feedback according to an embodiment of the invention
Processing is filtered, and analog-to-digital conversion process is carried out by analog to digital conversion circuit, after by controller according to analog-to-digital conversion process
Signal control power driving circuit conveying power signal, enabling avoid inverter circuit from occurring work(in start-up course
The problem of rate is overshooted, while interference signal of the inverter circuit in unlatching, such as reduction inverter circuit can be reduced as far as possible
Open when IGBT G pole tensions and the backward voltage at rectifier bridge stack two ends, it is to avoid the overtension at rectifier bridge stack two ends and damage
Bad rectifier bridge stack, while avoiding IGBT G pole tensions excessive and damaging.
Specifically, the control process of the controller in electric-controlled plate is as follows：
When receiving the instruction for starting micro-wave oven, if detecting civil power signal zero-crossing, in control microwave oven circuit
Fan circuit and rotating disk circuit turn-on, when controlling fan circuit and after rotating disk circuit turn-on certain time length, when detecting civil power
When signal reaches zero crossing, electricity on control inverter circuit.On inverter circuit after electricity, after one section of time delay, to
Inverter circuit incoming frequency is less than the power signal of target frequency；When the electric current in magnetron reaches predetermined current value, if
Detect the city's electric signal powered to microwave oven circuit and reach zero crossing, be then equal to target frequency to inverter circuit incoming frequency
Power signal.
In above-mentioned control process, because fan and rotating disk are inductive loads, therefore electromagnetism spoke can be produced when opening
Penetrate and voltage disturbance, and then influence whether IGBT G pole tensions, therefore by when receiving the instruction for starting micro-wave oven,
And when detecting city electric signal and reaching zero crossing, control fan circuit and rotating disk circuit turn-on, and after certain time length,
And when detecting city's electric signal arrival zero crossing, then control (determining to need to start inverter circuit) electric on inverter circuit,
The interference of fan circuit and rotating disk circuit in conducting to IGBT G pole tensions can effectively be reduced, it is to avoid IGBT G poles due to
Voltage is excessive and damages, and improves IGBT service life.
And by when detecting city's electric signal arrival zero crossing, it is electric on control inverter circuit so that in inverter electricity
During Lu Shang electricity, the backward voltage at rectifier bridge stack two ends can be effectively reduced, the reliability of microwave oven circuit is improved, extended whole
Flow the service life of bridge heap.
After the electricity on inverter circuit, and not directly to inverter circuit input power signal, but passing through one
Inputted again after section time delay, enabling reserve the power-up initializing time to the electronic device in inverter circuit, it is ensured that inverse
Become the stability of device circuit work.
It is less than the power signal of target frequency to inverter circuit incoming frequency by elder generation, and in magnetron is detected
It is mesh to inverter circuit incoming frequency when electric current reaches predetermined current value (predetermined current value illustrates that magnetron is started working)
Mark the power signal of frequency so that inverter circuit can be with less energetic start up, and when magnetron is started working, then with complete
The power power signal of target frequency (input) operation, it is to avoid what inverter circuit emergent power in start-up course was overshooted
Problem.
Microwave oven circuit according to the abovementioned embodiments of the present invention, can also have following technical characteristic：
According to one embodiment of present invention, the high-frequency heating circuit includes：Magnetron, for producing microwave；Inversion
Device circuit, is connected to the magnetron, and the electric power signal and the power for receiving the relay drive circuit conveying drive
The power signal of dynamic circuit conveying, and drive the magnetron to produce microwave according to the electric power signal and the power signal；
Sampling feedback circuit, for being sampled to the electric current in the magnetron, and the magnetron current signal that sampling is obtained is anti-
It is fed to the electric-controlled plate.
According to one embodiment of present invention, the inverter circuit includes：Rectification circuit, is connected to AC power, uses
Rectification processing is carried out in the alternating current inputted to the AC power；Second filter circuit, is connected to the rectification circuit, is used for
Processing is filtered to the signal that the rectification circuit is exported；Resonance circuit, including resonant capacitance and high-frequency step-up transformer, institute
State the two ends that second filter circuit is connected in parallel on after resonant capacitance is connected with IGBT, the primary line of the high-frequency step-up transformer
Circle is connected in parallel with the resonant capacitance；Voltage-multiplying circuit, is connected to the secondary coil of the high-frequency step-up transformer, for producing
Drive the voltage of the magnetron.
According to one embodiment of present invention, the rectification circuit includes rectifier circuit.
According to one embodiment of present invention, second filter circuit includes LC filter circuits.
According to one embodiment of present invention, first filter circuit includes：First resistor, the of the first resistor
One end as first filter circuit input；Second resistance, is connected between the second end of the first resistor and ground；
First clamps, are connected in parallel with the second resistance；Second clamps, be connected to the first resistor the second end and
Between dc source；Electrochemical capacitor, is connected in parallel with the second resistance；Current limiting device, the first end of the current limiting device connects
Be connected to the second end of the first resistor, the second end of the current limiting device as first filter circuit output end；Electricity
Hold element, be connected between the second end of the current limiting device and ground.
Microwave oven circuit according to an embodiment of the invention, magnetron current signal is inputted after the first filter circuit, by the
One resistance and second resistance carry out partial pressure, and carry out clamper by the first clamps and the second clamps, are not higher than it
Dc source (VCC), be also not less than GND (), will while processing can be filtered by electrochemical capacitor and capacity cell
The current signal of high frequency is changed into the direct current signal of low frequency.By the second end and ground that capacity cell is connected to current limiting device
Between, that is, it is connected close to the position of the output end of the first filter circuit, it is possible to achieve the filter effect more having.
According to one embodiment of present invention, first clamps include the first diode, first diode
Negative electrode be connected to the second end of the first resistor, the plus earth of first diode.
According to one embodiment of present invention, second clamps include the second diode, second diode
Anode be connected to the second end of the first resistor, the negative electrode of first diode connects the dc source.
According to one embodiment of present invention, the current limiting device includes resistive element.
A kind of embodiment according to a second aspect of the present invention, it is also proposed that micro-wave oven, including：It is any in such as above-mentioned embodiment
Microwave oven circuit described in.
The additional aspect and advantage of the present invention will be set forth in part in the description, and will partly become from the following description
Obtain substantially, or recognized by the practice of the present invention.
Brief description of the drawings
The above-mentioned and/or additional aspect and advantage of the present invention will become from description of the accompanying drawings below to embodiment is combined
Substantially and be readily appreciated that, wherein：
Fig. 1 shows the structural representation of the control system of the frequency-conversion microwave oven in correlation technique；
Fig. 2 shows the electrical block diagram of the inverter in the microwave oven circuit in correlation technique；
Fig. 3 shows the control timing diagram of inverter in the microwave oven circuit in correlation technique；
Fig. 4 shows the control of inverter voltage waveform, microwave relay of city's electric signal when opening in correlation technique
Signal waveform and the voltage waveform view at rectifier bridge stack two ends；
Fig. 5 shows the structural representation of microwave oven circuit according to an embodiment of the invention；
Fig. 6 shows the structural representation of inverter circuit according to an embodiment of the invention；
Fig. 7 shows the structural representation of the filter circuit in electric-controlled plate according to an embodiment of the invention；
Fig. 8 shows the schematic block diagram of the control device of microwave oven circuit according to an embodiment of the invention；
Fig. 9 shows the time diagram of each signal according to an embodiment of the invention.
Embodiment
It is below in conjunction with the accompanying drawings and specific real in order to be more clearly understood that the above objects, features and advantages of the present invention
Mode is applied the present invention is further described in detail.It should be noted that in the case where not conflicting, the implementation of the application
Feature in example and embodiment can be mutually combined.
Many details are elaborated in the following description to facilitate a thorough understanding of the present invention, still, the present invention may be used also
Implemented with being different from other modes described here using other, therefore, protection scope of the present invention is not by described below
Specific embodiment limitation.
As shown in figure 5, microwave oven circuit according to an embodiment of the invention, including：Electric-controlled plate 1 and high-frequency heating circuit 2；
Wherein, electric-controlled plate 1 includes：
Relay drive circuit 11, for being transmitted electric power signal to the high-frequency heating circuit 2；Power driving circuit 12,
For conveying power signal to the high-frequency heating circuit 2；First filter circuit 13, is connected to the high-frequency heating circuit 2
Signal feedback end (not shown), for being filtered place to the magnetron current signal that the high-frequency heating circuit 2 feeds back
Reason；Analog to digital conversion circuit 14, is connected to first filter circuit 13, for the signal exported to first filter circuit 13
Carry out analog-to-digital conversion process；Controller 15, is connected to analog-digital conversion circuit as described 14, the relay drive circuit 11 and described
Power driving circuit 12, for the electric power signal for controlling the relay drive circuit 11 to convey, and according to the analog-to-digital conversion
The signal that circuit 14 is exported controls the power signal that the power driving circuit 12 is conveyed.
By being filtered processing to the magnetron current signal that high-frequency heating circuit 2 feeds back, and by analog-to-digital conversion electricity
Road 14 carries out analog-to-digital conversion process, to control power driving circuit 12 defeated according to the signal after analog-to-digital conversion process by controller 15
The power signal sent, enabling the problem of avoiding inverter circuit 22 emergent power is overshooted in start-up course, while can be with
Interference signal of the reduction inverter circuit 22 when opening, such as reduces the IGBT when opening of inverter circuit 22 G poles as far as possible
Voltage and the backward voltage at rectifier bridge stack two ends, it is to avoid the overtension at rectifier bridge stack two ends and damage rectifier bridge stack, keep away simultaneously
The G pole tensions for exempting from IGBT are excessive and damage.
Specifically, the control process of the controller 15 in electric-controlled plate 1 is as follows：
When receiving the instruction for starting micro-wave oven, if detecting civil power signal zero-crossing, in control microwave oven circuit
Fan circuit and rotating disk circuit turn-on, when controlling fan circuit and after rotating disk circuit turn-on certain time length, when detecting civil power
When signal reaches zero crossing, (i.e. control relay drive circuit 11 is defeated to inverter circuit 22 for electricity on control inverter circuit 22
Power transmission force signal).It is low to the incoming frequency of inverter circuit 22 after one section of time delay on inverter circuit 22 after electricity
In the power signal (controlling power driving circuit 12 to convey power signal to inverter circuit 22) of target frequency；Work as magnetron
When electric current in 21 reaches predetermined current value, if detecting the city's electric signal powered to microwave oven circuit reaches zero crossing, to
The incoming frequency of inverter circuit 22 is equal to the power signal of target frequency.
In above-mentioned control process, because fan and rotating disk are inductive loads, therefore electromagnetism spoke can be produced when opening
Penetrate and voltage disturbance, and then influence whether IGBT G pole tensions, therefore by when receiving the instruction for starting micro-wave oven,
And when detecting city electric signal and reaching zero crossing, control fan circuit and rotating disk circuit turn-on, and after certain time length,
And when detecting city's electric signal arrival zero crossing, then control electricity on inverter circuit 22 (to determine to need to start inverter circuit
22) interference of fan circuit and rotating disk circuit in conducting to IGBT G pole tensions, can effectively be reduced, it is to avoid IGBT G poles
Damaged because voltage is excessive, improve IGBT service life.
And by when detecting city's electric signal arrival zero crossing, it is electric on control inverter circuit 22 so that in inverter
When electric on circuit 22, the backward voltage at rectifier bridge stack two ends can be effectively reduced, the reliability of microwave oven circuit is improved, extended
The service life of rectifier bridge stack.
After the electricity on inverter circuit 22, and not directly to the input power signal of inverter circuit 22, but in warp
Inputted again after spending one section of time delay, enabling reserve the power-up initializing time to the electronic device in inverter circuit 22,
Ensure the stability that inverter circuit 22 works.
It is less than the power signal of target frequency to the incoming frequency of inverter circuit 22 by elder generation, and is detecting magnetron 21
In electric current when reaching predetermined current value (predetermined current value illustrates that magnetron 21 is started working), inputted to inverter circuit 22
Frequency is the power signal of target frequency so that inverter circuit 22 can be with less energetic start up, and starts in magnetron 21
During work, then with the total power power signal of target frequency (input) operation, it is to avoid inverter circuit 22 is in start-up course
The problem of middle emergent power is overshooted.
Microwave oven circuit according to the abovementioned embodiments of the present invention, can also have following technical characteristic：
According to one embodiment of present invention, the high-frequency heating circuit 2 includes：Magnetron 21, for producing microwave；It is inverse
Become device circuit 22, be connected to the magnetron 21, for receiving electric power signal and the institute that the relay drive circuit 11 is conveyed
The power signal of the conveying of power driving circuit 12 is stated, and the magnetron is driven according to the electric power signal and the power signal
Produce microwave；Sampling feedback circuit (not shown in Fig. 5), for being sampled to the electric current in the magnetron 21, and will be adopted
The current signal of magnetron 21 that sample is obtained feeds back to the electric-controlled plate 1.
As shown in fig. 6, inverter circuit 22 according to an embodiment of the invention includes：
Rectification circuit 221, is connected to AC power, and the alternating current for being inputted to the AC power is carried out at rectification
Reason；Second filter circuit 222, is connected to the rectification circuit 221, and the signal for being exported to the rectification circuit 221 is carried out
Filtering process；Resonance circuit, including resonant capacitance 223 and high-frequency step-up transformer 224, the resonant capacitance 223 and IGBT
The two ends of second filter circuit 222, the primary coil of the high-frequency step-up transformer 224 and institute are connected in parallel on after 225 series connection
Resonant capacitance 223 is stated to be connected in parallel；Voltage-multiplying circuit 226, is connected to the secondary coil of the high-frequency step-up transformer 224, is used for
Produce the voltage of the driving magnetron 21.
Sampling feedback circuit in high-frequency heating circuit 2 includes current detection circuit, wherein, current detection circuit is by 4
Resistance R1~R4 and piezo-resistance VR1 are composed in parallel, and R5 is current-limiting resistance, and R60 is fictitious load, 227 connect magnetron 21 casing
Anode, the negative electrode of magnetron 21 meets OUT1 and OUT2, OUT1 and OUT2 connect 224 levels of high-frequency step-up transformer it is another around
Group, effect is the filament voltage for driving magnetron 21.When magnetron 21 works, electric current with passing through anode, i.e. casing 227, stream
To negative electrode formation loop, therefore just there is voltage at R1~R4 two ends, and the current signal IB in magnetron is detected by detecting voltage.
According to one embodiment of present invention, the rectification circuit 221 includes rectifier circuit.
According to one embodiment of present invention, second filter circuit 222 include LC filter circuits, i.e., by inductance L1 with
The LC filter circuits of electric capacity C1 compositions.
As shown in fig. 7, according to one embodiment of present invention, first filter circuit 13 includes：First resistor 131,
The first end of the first resistor 131 as first filter circuit 13 input；Second resistance 132, is connected to described
Between second end of first resistor 131 and ground；First clamps 133, are connected in parallel with the second resistance 132；Second pincers
Position device 134, is connected between the second end of the first resistor 131 and dc source；Electrochemical capacitor 135, with described second
Resistance 132 is connected in parallel；Current limiting device 136, the first end of the current limiting device 136 is connected to the of the first resistor 131
Two ends, the second end of the current limiting device 136 as first filter circuit output end；Capacity cell 137, is connected to institute
State between the second end of current limiting device 136 and ground.
Specifically, magnetron current signal is inputted after the first filter circuit 13, by first resistor 131 and second resistance
132 carry out partial pressure, and carry out clamper by the first clamps 133 and the second clamps 134, make its not higher than dc source
(VCC), be also not less than GND (), while processing can be filtered by electrochemical capacitor 135 and capacity cell 137, by height
The current signal of frequency is changed into the direct current signal of low frequency.By capacity cell 137 is connected to current limiting device 136 the second end and
Between ground, that is, it is connected close to the position of the output end of the first filter circuit 13, it is possible to achieve the filter effect more having.
According to one embodiment of present invention, first clamps 133 include the first diode, the one or two pole
The negative electrode of pipe is connected to the second end of the first resistor 131, the plus earth of first diode.
According to one embodiment of present invention, second clamps 134 include the second diode, the two or two pole
The anode of pipe is connected to the second end of the first resistor 131, and the negative electrode of first diode connects the dc source.
According to one embodiment of present invention, the current limiting device 136 includes resistive element.
Fig. 8 shows the schematic block diagram of the control device of microwave oven circuit according to an embodiment of the invention.
As shown in figure 8, the control device 800 of microwave oven circuit according to an embodiment of the invention, including：Zero-crossing examination
Unit 802, the first control unit 804, the second control unit 806 and current detecting unit 808.
Wherein, zero-crossing examination unit 802, for when needing to start the inverter circuit, detecting to the microwave
The zero crossing for city's electric signal that stove circuit is powered；First control unit 804, for being detected in the zero-crossing examination unit 802
When reaching zero crossing to city's electric signal, electricity on the inverter circuit is controlled；Second control unit 806, for described
When the upper electric duration of inverter circuit reaches the first scheduled duration, to the inverter circuit incoming frequency less than target frequency
First power signal, and be used for when the electric current that current detecting unit 808 is detected in the magnetron reaches predetermined current value,
It is equal to the second power signal of the target frequency to the inverter circuit incoming frequency.The current detecting unit 808, is used
Electric current in the detection magnetron.
By when needing to start inverter circuit, detecting the zero crossing of city's electric signal, and arrived detecting city's electric signal
During up to zero crossing, electricity on control inverter so that when electric on inverter circuit, can effectively reduce the anti-of rectifier bridge stack two ends
To voltage, the reliability of microwave oven circuit is improved, the service life of rectifier bridge stack is extended.
After the electricity on inverter circuit, and not directly to inverter circuit input power signal, but in delay the
Inputted again after one scheduled duration, enabling reserve the power-up initializing time to the electronic device in inverter circuit, it is ensured that inverse
Become the stability of device circuit work.
By when the upper electric duration of inverter circuit reaches the first scheduled duration, being less than to inverter circuit incoming frequency
First power signal of target frequency, and electric current in magnetron is detected reaches that predetermined current value (say by the predetermined current value
Bright magnetron is started working) when, to the power signal that inverter circuit incoming frequency is target frequency so that inverter circuit energy
With less energetic start up, and when magnetron is started working, then with total power (power signal for inputting target frequency) fortune
OK, it is to avoid inverter circuit is the problem of in start-up course emergent power is overshooted.
The control device 800 of microwave oven circuit according to the abovementioned embodiments of the present invention, can also have following technology special
Levy：
According to one embodiment of present invention, the microwave oven circuit also includes fan circuit and rotating disk circuit, the control
Device 800 processed also includes：3rd control unit 810, for when receiving the instruction for starting micro-wave oven, if the current detecting
Unit 808 detects city's electric signal and reaches zero crossing, then controls the fan circuit and the rotating disk circuit turn-on；It is determined that
Unit 812, for controlling the fan circuit and the pre- timing of the rotating disk circuit turn-on second in the 3rd control unit 810
After length, it is determined that needing to start the inverter circuit.
Because fan and rotating disk are inductive loads, therefore electromagnetic radiation and voltage disturbance can be produced when opening, entered
And IGBT G pole tensions are influenced whether, therefore by when receiving the instruction for starting micro-wave oven, and detecting city's electric signal
When reaching zero crossing, then fan circuit and rotating disk circuit turn-on are controlled, and after the second scheduled duration is postponed, then control inverter
Electricity (determine need start inverter circuit) on circuit, can effectively reduce fan circuit and rotating disk circuit in conducting pair
The interference of IGBT G pole tensions, it is to avoid IGBT G poles are damaged because voltage is excessive, improve IGBT service life.
According to one embodiment of present invention, second control unit 806 is additionally operable to, and the microwave is closed receiving
During the instruction of stove, stop to the inverter circuit input power signal；First control unit 804 is additionally operable to, when described
Second control unit 806 stops reaching after the 3rd scheduled duration to the duration of the inverter circuit input power signal, if institute
State zero-crossing examination unit 802 and detect city's electric signal arrival zero crossing, then control the inverter circuit to power off.
Because when stopping to inverter circuit input power signal, inverter circuit will be by one section of power reduction to 0
Process and corresponding electric discharge link, therefore by when receiving the instruction for closing micro-wave oven, stopping defeated to inverter circuit
Enter power signal, and postpone after the 3rd scheduled duration, and when detecting civil power signal zero-crossing, then control inverter circuit to break
Electricity, enabling after the power reduction of guarantee inverter circuit to 0, and powered off again when city's electric signal is in zero crossing, it is to avoid
When stopping input power signal, directly control inverter circuit powers off and abnormal problem occurs.
According to one embodiment of present invention, the 3rd control unit 810 is additionally operable to：In first control unit
The 804 control inverter circuits are powered off after the 4th scheduled duration, if detecting city's electric signal reaches zero crossing, are controlled
The fan circuit and the rotating disk down circuitry.
By when controlling inverter circuit to power off four scheduled durations, and when detecting city electric signal and reaching zero crossing,
Fan circuit and rotating disk down circuitry are controlled again, can reduce the G of inductive load (i.e. fan and rotating disk) when closed to IGBT
The interference of pole tension.
According to one embodiment of present invention, first scheduled duration is more than or equal to 300 milliseconds；Described second makes a reservation for
Duration is more than or equal to 200 milliseconds；3rd scheduled duration is more than or equal to 200 milliseconds；4th scheduled duration is more than
Or equal to 600 milliseconds.
According to one embodiment of present invention, the frequency of first power signal is to maintain the inverter circuit continuous
The low-limit frequency of work, or
The frequency of first power signal is less than or equal to the low-limit frequency for maintaining the inverter circuit continuously to work
Half.
According to one embodiment of present invention, the predetermined current value is less than or equal to the inverter circuit in input institute
State 1/6th of current value when target frequency is operated in the magnetron.
In any of the above-described embodiment, electricity and power-off can be carried out by microwave relay on control inverter circuit
Control.
The whole control scheme of the present invention is illustrated below in conjunction with Fig. 9.
Fig. 9 shows the time diagram of each signal according to an embodiment of the invention.
Because the control program in correlation technique is：Microwave relay is being opened in micro-wave oven (i.e. to inverter power supply)
When, fan and rotating disk relay are also simultaneously turned on.It can be produced because fan and rotating disk are all inductive loads, therefore when conducting
Raw electromagnetic radiation and voltage disturbance, simultaneously because the complicated electrical cable of micro-wave oven, it is impossible to focus on specific circuit,
And it is difficult measurement to be also in terms of radiation, therefore for the electric voltage exception (i.e. abnormal to raise) of the G poles of reducing IGBT, in the reality
The interference of fan and rotating disk will at utmost be reduced by applying in example, detailed process is as follows：
As shown in figure 9, when receiving the instruction for starting micro-wave oven, the zero crossing of electric signal in city is opened fan and turned
Disk relay, makes after fan and rotating disk conducting, delay a period of time, such as more than 200ms, then in civil power signal zero-crossing,
Microwave relay is opened to inverter power supply, to reduce fan and rotating disk relay with microwave relay while opening and generation pair
The interference signal of IGBT G pole tensions.And microwave relay is opened in civil power signal zero-crossing, microwave relay can be also avoided
The problem of device unlatching moment produces high back voltage to rectifier bridge stack and damages rectifier bridge stack.Wherein, microwave relay opening process
It is to process electric on inverter.
Secondly, when microwave relay is turned on, i.e., when providing electric power signal to inverter, it should not be provided at once to inverter
Power signal, and a period of time that to be delayed, such as more than 300ms, with first to the reserved enough upper electricity of the device in inverter circuit
The time of beginningization, it is ensured that inverter will not tamper work.The stage is referred to as initial phase.
Again, after initial phase, then into warm-up phase, 300Hz pre-heat frequency is provided to inverter.Work as inversion
Device is received after pre-heat frequency, and inverter will be with less energetic start up, to reduce the power mistake being likely to occur in start-up course
The situation of punching.Wherein, pre-heat frequency can select the low-limit frequency for maintaining inverter continuously to work, or selection to be less than or equal to dimension
Hold the arbitrary value of the half for the low-limit frequency that inverter continuously works.
In warm-up phase, the current signal of magnetron is detected, and obtains AD values with analog-to-digital conversion process after filtering, if AD
When value is more than predetermined value, then all one's effort operation phase is transferred to.
The usual predetermined value is smaller, relevant with the value of the device shown in Fig. 7, in a preferred embodiment of the present invention
In, if first resistor 131 is 10K, second resistance 132 is 1M, and electrochemical capacitor 135 is 2.2uF, and now the predetermined value may be selected to be
0.3V, 0.3V represent the mark of magnetron start-up operation；But, the predetermined value can not be too big, such as more than 0.5V, because in low temperature
When, it is smaller when the electric current that magnetron works initial stage is than normal temperature, it can cause to rest on warm-up phase always.
In one embodiment of the invention, the predetermined value for being compared with AD values can select to be less than or equal to
Electric-controlled plate to inverter input target frequency power signal when magnetron in current signal 1/6th arbitrary value.
Finally, when entering all one's effort operation phase, electric-controlled plate inputs the power signal of target frequency to inverter.
For example, electric-controlled plate wants inverter to export 1500W power, 300Hz pre-heat frequency is exported in warm-up phase, works as AD
When value is more than 0.3V, then 1500Hz frequency is exported, the problem of emergent power is overshooted in start-up course can be so reduced.
When inverter is run with all strength, if desired inverter is stopped, then first to stop defeated to inverter
Enter power signal, and after delay a period of time, such as more than 200ms turns off microwave relay；Because when electric-controlled plate stop to
During inverter input power signal, inverter will the process through power reduction after a while to 0, and the ring that discharges accordingly
Section, if turning off microwave relay quickly, the process that it can be caused to turn off is imperfect, and then anomaly occurs.While, it is necessary to
It is to be noted that should also be closed when closing microwave relay in civil power signal zero-crossing.
In addition, after microwave relay shut-off and after a period of time, and in civil power signal zero-crossing, then turn off fan
With rotating disk relay, fan and rotating disk relay are such as turned off again by more than 600ms, when can equally reduce inductive load closing
Influence to IGBT G pole tensions.
Those skilled in the art should be noted：Concrete numerical value shown in Fig. 9 is only a specific embodiment, and
It is not specifically limited.
In one embodiment of the invention, because the micro-wave oven for selling to Japan has compulsory authentication requesting input current not
15A is can exceed that, therefore in order to meet corresponding requirement, by the control mode of the inverter in the micro-wave oven for selling to Japan and other
Conventional control mode is distinguished, and takes the mode of different pre-heat frequencies, specifically, in conventional control mode
When pre-heat frequency is 300Hz, it is 100Hz to sell to the pre-heat frequency in the control mode of the inverter in the micro-wave oven of Japan.
The technical scheme of the above embodiment of the present invention starts the electric current in magnetron as electric-controlled plate the key of inverter
Signal, to inverter carry out be switched on and off be compared rational design；Simultaneously by inverter startup and turn off process
Startup sequential of other loads done respective specified, reduce IGBT G poles interference voltage；In addition, using in line voltage mistake
The conveying of inverter power is carried out during zero point, the high back voltage at rectifier bridge stack two ends is reduced, adds reliability, improve whole
The service life of current circuit.
Technical scheme is described in detail above in association with accompanying drawing, the present invention proposes a kind of new microwave oven circuit
Control program, the voltage at rectifier bridge stack two ends can be reduced, it is to avoid the voltage mistake at rectifier bridge stack two ends when inverter is opened
It is high and damage rectifier bridge stack, while IGBT G poles can be avoided to be damaged because voltage is excessive.
The preferred embodiments of the present invention are the foregoing is only, are not intended to limit the invention, for the skill of this area
For art personnel, the present invention can have various modifications and variations.Within the spirit and principles of the invention, that is made any repaiies
Change, equivalent substitution, improvement etc., should be included in the scope of the protection.
Claims (9)
1. a kind of microwave oven circuit, it is characterised in that including：
Electric-controlled plate and high-frequency heating circuit；Wherein, the electric-controlled plate includes：
Relay drive circuit, for being transmitted electric power signal to the high-frequency heating circuit；
Power driving circuit, for conveying power signal to the high-frequency heating circuit；
First filter circuit, is connected to the signal feedback end of the high-frequency heating circuit, for anti-to the high-frequency heating circuit
The magnetron current signal of feedback is filtered processing；
Analog to digital conversion circuit, is connected to first filter circuit, and the signal for being exported to first filter circuit is carried out
Analog-to-digital conversion process；
Controller, is connected to analog-digital conversion circuit as described, the relay drive circuit and the power driving circuit, for controlling
The electric power signal of the relay drive circuit conveying is made, and the signal exported according to analog-digital conversion circuit as described controls the work(
The power signal of rate drive circuit conveying；
First filter circuit includes：
First resistor, the first end of the first resistor as first filter circuit input；
Second resistance, is connected between the second end of the first resistor and ground；
First clamps, are connected in parallel with the second resistance；
Second clamps, are connected between the second end of the first resistor and dc source；
Electrochemical capacitor, is connected in parallel with the second resistance；
Current limiting device, the first end of the current limiting device is connected to the second end of the first resistor, the of the current limiting device
Two ends as first filter circuit output end；
Capacity cell, is connected between the second end of the current limiting device and ground.
2. microwave oven circuit according to claim 1, it is characterised in that the high-frequency heating circuit includes：
Magnetron, for producing microwave；
Inverter circuit, is connected to the magnetron, electric power signal and institute for receiving the relay drive circuit conveying
The power signal of power driving circuit conveying is stated, and drives the magnetron to produce according to the electric power signal and the power signal
Raw microwave；
Sampling feedback circuit, for being sampled to the electric current in the magnetron, and the magnetron current that sampling is obtained is believed
Number feed back to the electric-controlled plate.
3. microwave oven circuit according to claim 2, it is characterised in that the inverter circuit includes：
Rectification circuit, is connected to AC power, and the alternating current for being inputted to the AC power carries out rectification processing；
Second filter circuit, is connected to the rectification circuit, for being filtered processing to the signal that the rectification circuit is exported；
Resonance circuit, including resonant capacitance and high-frequency step-up transformer, the resonant capacitance are connected in parallel on described after being connected with IGBT
The two ends of second filter circuit, the primary coil of the high-frequency step-up transformer is connected in parallel with the resonant capacitance；
Voltage-multiplying circuit, is connected to the secondary coil of the high-frequency step-up transformer, the voltage for producing the driving magnetron.
4. microwave oven circuit according to claim 3, it is characterised in that the rectification circuit includes rectifier circuit.
5. microwave oven circuit according to claim 3, it is characterised in that second filter circuit includes LC filtered electricals
Road.
6. microwave oven circuit according to any one of claim 1 to 5, it is characterised in that the first clamps bag
The first diode is included, the negative electrode of first diode is connected to the second end of the first resistor, first diode
Plus earth.
7. microwave oven circuit according to any one of claim 1 to 5, it is characterised in that the second clamps bag
The second diode is included, the anode of second diode is connected to the second end of the first resistor, second diode
Negative electrode connects the dc source.
8. microwave oven circuit according to any one of claim 1 to 5, it is characterised in that the current limiting device includes electricity
Resistance element.
9. a kind of micro-wave oven, it is characterised in that including：Microwave oven circuit as any one of claim 1 to 8.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201511030511.9A CN105485731B (en) | 2015-12-29 | 2015-12-29 | Microwave oven circuit and micro-wave oven |
| EP16880461.5A EP3397024B1 (en) | 2015-12-29 | 2016-06-24 | Microwave oven circuit and microwave oven |
| KR1020187020320A KR102117432B1 (en) | 2015-12-29 | 2016-06-24 | Microwave circuit, control method and control device for microwave circuit and microwave |
| EP19215533.1A EP3641498B1 (en) | 2015-12-29 | 2016-06-24 | Microwave oven circuit, control method and control device of microwave oven circuit and microwave oven |
| JP2018533746A JP6720314B2 (en) | 2015-12-29 | 2016-06-24 | Microwave oven circuit, control method of microwave oven circuit, control device and microwave oven |
| PCT/CN2016/087159 WO2017113656A1 (en) | 2015-12-29 | 2016-06-24 | Microwave oven circuit, method and device for controlling microwave oven circuit and microwave oven |
| US16/021,167 US20180332674A1 (en) | 2015-12-29 | 2018-06-28 | Microwave oven circuit, control method and control device of microwave oven circuit and microwave oven |
| JP2020001347A JP6839308B2 (en) | 2015-12-29 | 2020-01-08 | Microwave oven circuit, control method of microwave oven circuit, control device and microwave oven |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201511030511.9A CN105485731B (en) | 2015-12-29 | 2015-12-29 | Microwave oven circuit and micro-wave oven |
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| CN105485731A CN105485731A (en) | 2016-04-13 |
| CN105485731B true CN105485731B (en) | 2017-10-31 |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017113656A1 (en) * | 2015-12-29 | 2017-07-06 | 广东美的厨房电器制造有限公司 | Microwave oven circuit, method and device for controlling microwave oven circuit and microwave oven |
| CN110169200B (en) * | 2017-01-10 | 2021-10-19 | 松下电器产业株式会社 | Electromagnetic field distribution adjusting device and microwave heating device |
| CN111586910A (en) * | 2019-02-18 | 2020-08-25 | 上海点为智能科技有限责任公司 | Mixed frequency heating system |
| CN111010757B (en) * | 2019-12-20 | 2022-03-18 | 深圳市鑫汇科股份有限公司 | Electromagnetic heating method and electromagnetic heating device |
| CN111613609B (en) * | 2020-05-06 | 2022-08-23 | 广东威特真空电子制造有限公司 | High-voltage diode, high-voltage rectifying circuit and variable-frequency magnetron driving power supply |
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| US4593167A (en) * | 1982-08-02 | 1986-06-03 | Nilssen Ole K | Electronic microwave oven power supply |
| JP3131530B2 (en) * | 1993-10-21 | 2001-02-05 | 株式会社東芝 | microwave |
| CN205351423U (en) * | 2015-12-29 | 2016-06-29 | 广东美的厨房电器制造有限公司 | Microwave oven circuit and microwave oven |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR940005470B1 (en) * | 1992-05-13 | 1994-06-18 | 주식회사 금성사 | Over output protection apparatus of inveter microwave oven |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4593167A (en) * | 1982-08-02 | 1986-06-03 | Nilssen Ole K | Electronic microwave oven power supply |
| JP3131530B2 (en) * | 1993-10-21 | 2001-02-05 | 株式会社東芝 | microwave |
| CN205351423U (en) * | 2015-12-29 | 2016-06-29 | 广东美的厨房电器制造有限公司 | Microwave oven circuit and microwave oven |
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