CN107147298B - A kind of microwave oven magnetic power supply device with pull-up active clamp branch - Google Patents

A kind of microwave oven magnetic power supply device with pull-up active clamp branch Download PDF

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Publication number
CN107147298B
CN107147298B CN201710405864.5A CN201710405864A CN107147298B CN 107147298 B CN107147298 B CN 107147298B CN 201710405864 A CN201710405864 A CN 201710405864A CN 107147298 B CN107147298 B CN 107147298B
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voltage
power supply
main switch
frequency
circuit
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CN107147298A (en
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王春芳
李震
魏芝浩
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Qingdao University
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Qingdao University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/38—Means for preventing simultaneous conduction of switches
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
    • H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
    • H02M5/10—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using transformers
    • H02M5/12—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using transformers for conversion of voltage or current amplitude only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/06—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • H02M7/10—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode arranged for operation in series, e.g. for multiplication of voltage
    • H02M7/103—Containing passive elements (capacitively coupled) which are ordered in cascade on one source
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0038—Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Control Of High-Frequency Heating Circuits (AREA)
  • Inverter Devices (AREA)

Abstract

The invention belongs to electroporation fields, it is related to an a kind of microwave oven magnetic power supply device with pull-up active clamp branch, in frequency-conversion microwave oven magnetron power source one pull-up active clamp branch of increase in LC resonance single tube bipolarity inverter topology, it include an auxiliary switch in the branch, main switch is identical with the switching frequency of auxiliary switch, Sofe Switch control can be achieved, and improve reliability without the problem of leading directly between two pipes；And in the case where keeping original circuit advantage, switching tube is set to reduce pressure original 2/3, it can be using MOS transistor as switching tube, switching frequency is up to 100kHz or more, simultaneously because auxiliary switch turn-on time is short, low in energy consumption, technical solution is provided to reduce the volume and weight of power supply, reducing power supply cost.

Description

A kind of microwave oven magnetic power supply device with pull-up active clamp branch
Technical field:
The invention belongs to electroporation fields, are related to a kind of microwave oven magnetic power supply device with active clamp circuit, Especially a kind of microwave oven magnetic power supply device with pull-up active clamp branch.
Background technique:
Currently, household variable-frequency microwave oven magnetron power source circuit generally uses LLC resonance oscillation semi-bridge inverter topology or LC Resonance single tube bipolarity inverter topology, that there is circuit structures is relative complex for the former, and the cost is relatively high for power supply, on bridge arm Lower switch tube capacity easily causes the problems such as leading directly to and burning out；Although the latter's circuit structure is simple, it is at low cost, high-efficient, can be achieved zero Voltage is opened the advantages that with zero voltage turn-off control, but there is also some disadvantages, when micro-wave oven input voltage is 220Vac/ When 50Hz alternating current, switching tube bears pressure resistance up to 1200V or more to micro-wave oven in the process of running, causes switching tube that can only select The higher isolated-gate field effect transistor (IGFET) (IGBT) of pressure resistance, and for the output power of Serial regulation magnetron, need IGBT mono- The switching frequency of pipe does Frequency-variable Modulation between 20kHz to 40kHz, and after the switching frequency of IGBT is greater than 25kHz, damage Consumption can increase with the increase of switching frequency, to constrain further increasing for switching frequency, cannot make power supply device Volume and cost further decrease, and are unfavorable for the popularization and application of this novel microwave oven magnetron power supply.Therefore, one is designed The novel microwave oven magnetic power supply device with pull-up active clamp branch of kind has application and development value very much.
Summary of the invention:
The purpose of the present invention is to overcome the shortcomings of the existing technology, in frequency-conversion microwave oven magnetron power source LC resonance single tube Increase a pull-up active clamp branch in bipolarity inverter topology, include an auxiliary switch in the branch, master opens It is identical with the switching frequency of auxiliary switch to close pipe, Sofe Switch control can be achieved, and without the problem of leading directly between two pipes, raising can By property；And in the case where keeping original circuit advantage, switching tube is made to reduce pressure original 2/3, metal can be used Oxide transistor (MOSFET) be used as switching tube, switching frequency up to 100kHz or more, while because auxiliary switch conducting when Between it is short, low in energy consumption, for reduce power supply volume and weight, reduce power supply cost provide technical solution.
To achieve the goals above, the microwave oven magnetic power supply device of the present invention with pull-up active clamp branch Main structure include rectifier bridge, L1C1Filter circuit, sample circuit, pull-up active clamp branch, resonant capacitance, main switch, First diode, high frequency transformer, high frequency voltage doubling rectifier circuit, discharge resistance, magnetron and control circuit, first diode are The anti-paralleled diode of main switch, single phase industrial frequence alternating current successively pass through rectifier bridge, L1C1Direct current is converted into after filter circuit Electricity, main switch, first diode and pull-up active clamp branch are by DC inverter at high-frequency alternating current, this high-frequency alternating current The primary side winding both ends of high frequency transformer are applied to, after transformer boosts, the vice-side winding both ends of high frequency transformer generate high Frequency High Level AC Voltage, this high-frequency and high-voltage alternating current are powered after high frequency voltage doubling rectifier circuit for magnetron；High frequency transformer pair side Filament Winding generate alternating current direct be connected in magnetron heater power supply；Rectifier bridge rectifies single phase industrial frequence alternating current, L1C1 Filter circuit is made of filter inductance and filter capacitor electrical connection, is filtered for power frequency；Sample circuit is by the first sampling resistor, Two sampling resistors and current transformer electrical connection composition, sample circuit is together with the input voltage and input current detection circuit of control circuit For detecting input voltage and input current；Active clamp branch routing clamp capacitor, auxiliary switch and the second diode are pulled up according to electricity It learns principle to be electrically connected to form, the second diode is the anti-paralleled diode of auxiliary switch, auxiliary switch source electrode and main switch Pipe drain electrode is connected, and clamp capacitor one end is connected with auxiliary switch drain electrode, and the other end is connected with the anode of filter capacitor；Work as power supply Device accesses 220VacAlternating current and control circuit powers on, after main switch shutdown, main switch drain-source both end voltage is gradually risen Height, when this voltage rises to the sum of filter capacitor and clamp capacitor voltage, the voltage at main switch drain-source both ends is clamped at Filter capacitor and clamp capacitor both ends reduce main switch pressure resistance；Resonant capacitance is in parallel with the primary side winding of high frequency transformer, Main switch is opened, is turned off under variation, and resonance occurs for the inductance of resonant capacitance and primary side winding, realizes high-frequency inversion；High frequency Transformer by primary side winding, vice-side winding, Filament Winding and with air gap magnetic core electrical connection form, the former and deputy side of high frequency transformer The coefficient of coup is 0.5-0.95, and vice-side winding accesses high frequency voltage doubling rectifier circuit, and the filament of Filament Winding and magnetron is connected to Magnetron provides Alternating Current Power Supply, realizes electrical isolation while high frequency transformer is by primary side high-frequency ac electric boost；High frequency voltage-multiplying Rectification circuit is by the first kenotron, the second kenotron, the first filter capacitor and the second filter capacitor electricity Connection composition, high frequency voltage doubling rectifier circuit will be after vice-side winding institute's output voltage progress voltage multiplying rectifier filtering of high frequency transformer Magnetron power supply；Discharge resistance provides discharge loop for the first filter capacitor and the second filter capacitor；Magnetron is micro- for generating Wave；Control circuit is by input voltage and input current detection circuit, first voltage detection circuit, second voltage detection circuit, micro-wave oven function Energy menu or artificial setting signal, single-chip microcontroller, driving circuit, accessory power supply are electrically connected to form, input voltage and input current detection circuit For detecting input voltage, electric current, single-chip microcontroller is according to detection data making frequency adjustment, to change output voltage, realizes permanent Power control；First voltage detection circuit detects the voltage at clamp capacitor both ends, when the voltage for detecting clamp capacitor both ends increases The control signal of auxiliary switch is become high level by added-time, single-chip microcontroller, and auxiliary switch realizes that no-voltage is open-minded, when clamper electricity When holding the voltage increase at both ends, primary side winding is clamp capacitor charging by the second diode, and the second diode current flow, auxiliary is opened The voltage for closing pipe drain-source both ends is zero；The voltage at second voltage detection circuit detection main switch drain-source both ends；Micro-wave oven function Menu or artificial setting signal provide the combination of microwave firepower and its respective action time for single-chip microcontroller；Driving circuit is in single-chip microcontroller control The on-off of system lower driving main switch and auxiliary switch；Accessory power supply is single-chip microcontroller and drive circuitry.
The present invention realize with pull-up active clamp branch microwave oven magnetic power supply device control process include with Lower step:
(1) circuit powers on, first SCM program initialization, and receives and passed by micro-wave oven function menu or artificial setting signal The correspondence microwave firepower combination come and its respective action time；Then judge whether to press job key, if not pressing job key Then enter standby mode and the moment detects whether to press job key, PWM (pulse width modulation) is entered if pressing job key just Beginningization；After PWM initialization, single-chip microcontroller is combined according to microwave firepower and its respective action time sets corresponding to each microwave firepower Switching frequency and pwm signal, and first output microwave firepower combination in the corresponding switching frequency of first microwave firepower and PWM Signal, power supply device is started to work at this time；
(2) when power supply device works, output power is adjusted by power limitation control, first according to output microwave firepower Set corresponding power；Then voltage, the current signal that will test by input voltage and input current detection circuit are sent to monolithic Machine, single-chip microcontroller obtain input power by calculating the product of input voltage, electric current；Finally by compare input power and setting function Rate adjusts the switching frequency of power supply device, if input power is greater than setting power, single-chip microcontroller by increase switching frequency come Reduce output power, if input power is less than setting power, single-chip microcontroller increases output power by reducing switching frequency, real The power limitation control of existing power supply device；Meanwhile power supply device is during the work time, makes main switch by the control and regulation of single-chip microcontroller Pipe and auxiliary switch realize that Sofe Switch controls, and first voltage detection circuit detects that the voltage at clamp capacitor both ends increases When, the control signal of auxiliary switch is become high level by single-chip microcontroller, and auxiliary switch realizes that no-voltage is open-minded；It is opened in current master Before closing the arrival of pipe driving signal rising edge, second voltage detection circuit detects the voltage value at main switch drain-source both ends, if main The voltage at switching tube drain-source both ends is not 0, that is, is not carried out that no-voltage is open-minded, then single-chip microcontroller reduces the duty ratio of main switch, If the voltage at main switch drain-source both ends is 0, i.e. realization no-voltage is open-minded, then the duty ratio of main switch is constant；
(3) single-chip microcontroller moment in the power supply device course of work judges whether corresponding firepower action time terminates, if not tying Shu Ze continues to current switch frequency and pwm signal；The last one microwave firepower is judged whether it is if terminating, if not Then microwave firepower+1 exports the corresponding switching frequency of next microwave firepower and pwm signal, and repeats the above steps；If PWM locking signal is then exported, block PWM output, then power supply device stops working；In program operation, the moment is detected whether End key is pressed, the normal operation of reprogramming does not stop power supply and fill if being directly entered PWM locking signal if not Work is set, the control of microwave oven magnetic power supply device is completed.
Compared with prior art, the present invention bidirectional excitation may be implemented in the high frequency transformer of power supply device, so that power supply fills Biggish power can be exported by setting；Main switch and auxiliary switch switching frequency having the same, there is no straight-through problems, all It is able to achieve Sofe Switch, and a bit of time is only connected in each switch periods in auxiliary switch, conduction loss greatly reduces；Transformation The asymmetrical voltage that the cascade high frequency voltage doubling rectifier circuit in device pair side exports transformer secondary winding is utilized effectively, and makes The whole efficiency of power supply device further increases；The resonant capacitance of transformer primary side parallel connection and the inductance of transformer primary winding into Row resonance makes voltage gain with higher between power supply device input/output, in the case where transformer turn ratio is certain, energy Output voltage amplitude is improved by pulse frequency modulated moment, frequency-conversion microwave oven magnetron is made to fast implement starting；It pulls up active What the clamping action of clamper branch made main switch reduces pressure 1/3, enables main switch and auxiliary switch using MOSFET As switch, switching frequency further decreases the volume and weight of power supply device up to 100kHz or more, reduces power supply device Cost；Its circuit structure is simple, at low cost, and high reliablity is high-efficient, can pass through pulse width modulation+pulse frequency tune It makes the control method combined and precisely changes output voltage and power in a wide range of and small range, application prospect is extensive.
Detailed description of the invention:
Fig. 1 is the main circuit structure of the microwave oven magnetic power supply device of the present invention with pull-up active clamp branch Schematic illustration.
Fig. 2 is the work that the present invention realizes the microwave oven magnetic power supply device control with pull-up active clamp branch Skill flow diagram.
Fig. 3 is the work wave of the microwave oven magnetic power supply device of the present invention with pull-up active clamp branch Scheme, wherein Ugs1For main switch Q1Driving voltage, Ugs2For auxiliary switch Q2Driving voltage, Uds1For main switch Q1Leakage The voltage at source both ends, Uds2For auxiliary switch Q2The voltage at drain-source both ends, UC3For resonant capacitance C3The voltage at both ends, IL2For original Side winding L2Electric current, UC2For clamp capacitor C2The voltage at both ends.
Specific embodiment:
Technical solution of the present invention is described in more detail in the following with reference to the drawings and specific embodiments.
Embodiment:
The main structure of microwave oven magnetic power supply device with pull-up active clamp branch described in the present embodiment includes Rectifier bridge 1, L1C1Filter circuit 2, sample circuit 3, pull-up active clamp branch 4, resonant capacitance C3, main switch Q1, the one or two Pole pipe VD1, high frequency transformer 5, high frequency voltage doubling rectifier circuit 6, discharge resistance R3, magnetron 7 and control circuit 8, first diode VD1For main switch Q1Anti-paralleled diode, single phase industrial frequence alternating current successively passes through rectifier bridge 1, L1C1Turn after filter circuit 2 Change direct current, main switch Q into1, first diode VD1With pull-up active clamp branch 4 by DC inverter at high-frequency ac Electricity, this high-frequency alternating current are applied to 5 primary side winding L of high frequency transformer2Both ends, after transformer boosts, the secondary side of high frequency transformer 5 Winding L3Both ends generate high-frequency and high-voltage alternating current, this high-frequency and high-voltage alternating current supplies after high frequency voltage doubling rectifier circuit 6 for magnetron 7 Electricity；The Filament Winding L on the secondary side of high frequency transformer 54The alternating current direct of generation is connected in magnetron heater power supply；Rectifier bridge 1 will be single-phase Industrial-frequency alternating current is rectified, L1C1Filter circuit 2 is by filter inductance L1With filter capacitor C1Electrical connection composition, is filtered for power frequency Wave；Sample circuit 3 is by the first sampling resistor R1, the second sampling resistor R2And Current Transmit1Electrical connection composition, sample circuit 3 Input voltage and input current detection circuit 81 with control circuit 8 is together for detecting input voltage and input current；Pull up active clamp branch 4 By clamp capacitor C2, auxiliary switch Q2With the second diode VD2It is electrically connected to form according to electrical principles, the second diode VD2For Auxiliary switch Q2Anti-paralleled diode, auxiliary switch Q2Source electrode and main switch Q1Drain electrode is connected, clamp capacitor C2One end With auxiliary switch Q2Drain electrode is connected, the other end and filter capacitor C1Anode be connected；When power supply device accesses 220VacAlternating current And control circuit powers on, main switch Q1After shutdown, main switch Q1Drain-source both end voltage gradually rises, when this voltage rises To filter capacitor C1With clamp capacitor C2When the sum of voltage, main switch Q1The voltage at drain-source both ends is clamped at filter capacitor C1 With clamp capacitor C2Both ends reduce main switch Q1Pressure resistance；Resonant capacitance C3With the primary side winding L of high frequency transformer 52Parallel connection, Main switch Q1Open, turn off variation under, resonant capacitance C3With primary side winding L2Inductance occur resonance, realize high-frequency inversion； High frequency transformer 5 is by primary side winding L2, vice-side winding L3, Filament Winding L4With band air gap magnetic core T electrical connection composition, high frequency transformation The former and deputy side coefficient of coup of device 5 is 0.5-0.95, vice-side winding L3Access high frequency voltage doubling rectifier circuit 6, Filament Winding L4With magnetic The filament of keyholed back plate 7 is connected to magnetron 7 and provides Alternating Current Power Supply, and high frequency transformer 5 will be real while primary side high-frequency ac electric boost Existing electrical isolation；High frequency voltage doubling rectifier circuit 6 is by the first kenotron VD3, the second kenotron VD4, first Filter capacitor C4With the second filter capacitor C5Electrical connection composition, high frequency voltage doubling rectifier circuit 6 is by the vice-side winding of high frequency transformer 5 L3Institute's output voltage is powered after carrying out voltage multiplying rectifier filtering for magnetron 7；Discharge resistance R3For the first filter capacitor C4With the second filter Wave capacitor C5Discharge loop is provided；Magnetron 7 is for generating microwave；Control circuit 8 is by input voltage and input current detection circuit 81, One voltage detecting circuit 82, second voltage detection circuit 83, micro-wave oven function menu or artificial setting signal 84, single-chip microcontroller 85, Driving circuit 86, accessory power supply 87 are electrically connected to form, and input voltage and input current detection circuit 81 is used to detect input voltage, electric current, Single-chip microcontroller 85 is according to detection data making frequency adjustment, to change output voltage, realizes power limitation control；First voltage detection Circuit 82 detects clamp capacitor C2The voltage at both ends, when detecting clamp capacitor C2When the voltage at both ends increases, single-chip microcontroller 85 will be auxiliary Help switching tube Q2Control signal become high level, auxiliary switch Q2Realize that no-voltage is open-minded, as clamp capacitor C2The electricity at both ends When pressure increases, primary side winding L2Pass through the second diode VD2For clamp capacitor C2Charging, the second diode VD2Conducting, auxiliary are opened Close pipe Q2The voltage at drain-source both ends is zero；Second voltage detection circuit 83 detects main switch Q1The voltage at drain-source both ends；Micro-wave oven Function menu or artificial setting signal 84 are that single-chip microcontroller 85 provides the combination of microwave firepower and its respective action time；Driving circuit 86 Main switch Q is driven under the control of single-chip microcontroller 851With auxiliary switch Q2On-off；Accessory power supply 87 is single-chip microcontroller 85 and driving Circuit 86 is powered.
The present embodiment realizes that the process of the microwave oven magnetic power supply device control with pull-up active clamp branch includes Following steps:
(1) circuit powers on, first SCM program initialization, and receives by micro-wave oven function menu or artificial setting signal 84 The correspondence microwave firepower combination transmitted and its respective action time；Then judge whether to press job key, if not pressing work Key then enters standby mode and the moment detects whether to press job key, and PWM (pulse width modulation) is entered if pressing job key Initialization；After PWM initialization, single-chip microcontroller 85 is combined according to microwave firepower and its respective action time sets each microwave firepower institute Corresponding switching frequency and pwm signal, and the corresponding switching frequency of first microwave firepower first in the combination of output microwave firepower And pwm signal, power supply device is started to work at this time；
(2) when power supply device works, output power is adjusted by power limitation control, first according to output microwave firepower Set corresponding power；Then list is sent to by voltage, current signal that input voltage and input current detection circuit 81 will test Piece machine 85, single-chip microcontroller 85 obtain input power by calculating the product of input voltage, electric current；Finally by compare input power with Power is set to adjust the switching frequency of power supply device, if input power is greater than setting power, single-chip microcontroller 85 is opened by increasing Frequency is closed to reduce output power, if input power is less than setting power, single-chip microcontroller 85 increases by reducing switching frequency Output power realizes the power limitation control of power supply device；Meanwhile power supply device is during the work time, passes through the control of single-chip microcontroller 85 System, which is adjusted, makes main switch Q1With auxiliary switch Q2Realize Sofe Switch control, first voltage detection circuit 82 detects clamper Capacitor C2When the voltage at both ends increases, single-chip microcontroller 85 is by auxiliary switch Q2Control signal become high level, auxiliary switch Q2 Realize that no-voltage is open-minded；In current main switch Q1Before driving signal rising edge arrives, second voltage detection circuit 83 is detected Main switch Q1The voltage value at drain-source both ends, if main switch Q1The voltage at drain-source both ends is not 0, that is, is not carried out no-voltage and opens Logical, then single-chip microcontroller 85 reduces main switch Q1Duty ratio, if main switch Q1The voltage at drain-source both ends is 0, i.e. realization no-voltage It is open-minded, then main switch Q1Duty ratio it is constant；
(3) moment in the power supply device course of work of single-chip microcontroller 85 judges whether corresponding firepower action time terminates, if not having End then continues to current switch frequency and pwm signal；The last one microwave firepower is judged whether it is if terminating, if not Then then microwave firepower+1 exports the corresponding switching frequency of next microwave firepower and pwm signal, and repeats the above steps；If It is to export PWM locking signal, block PWM output, then power supply device stops working；In program operation, moment detection is No to press end key, the not normal operation of reprogramming if not stops power supply if being directly entered PWM locking signal Device work, completes the control of microwave oven magnetic power supply device.
The working waveform figure packet of microwave oven magnetic power supply device with pull-up active clamp branch described in the present embodiment It includes with the next stage:
t0-t1Period: in t0Moment, main switch Q1Driving voltage Ugs1Become high level, at this time primary side winding L2Electricity Stream is negative, main switch Q1It is not turned on, primary side winding L2Pass through first diode VD1With filter capacitor C1Afterflow, main switch Q1 Pressure resistance be 0, arrive t1Moment, primary side winding L2Electric current become 0, main switch Q1Main switch Q is realized in conducting1No-voltage is opened It is logical；
t1-t2Period: input voltage is primary side winding L2Charging, primary side winding L2Electric current gradually increase, arrive t2It is moment, main Switching tube Q1Driving voltage Ugs1Become low level, main switch Q1Shutdown；
t2-t3Period: resonant capacitance C3For primary side winding L2Charging, primary side winding L2Electric current continue growing, arrive t3Moment, Resonant capacitance C3Voltage be reduced to 0, primary side winding L2Electric current increase to maximum；
t3-t4Period: primary side winding L2It is reversed resonant capacitance C3Charging, resonant capacitance C3Voltage reversal increase, resonance Capacitor C3Voltage be less than clamp capacitor C2Voltage, the second diode VD2Reversed cut-off, arrives t4Moment, resonant capacitance C3Electricity Pressure is greater than clamp capacitor C2Voltage, the second diode VD2Conducting；
t4-t5Period: primary side winding L2It is simultaneously clamp capacitor C2With resonant capacitance C3Charging, clamp capacitor C2Voltage by It is cumulative big, arrive t5Moment, auxiliary switch Q2Driving voltage Ugs2Become high level, but primary side winding L2Electric current be still positive, Auxiliary switch Q2It is not turned on；
t5-t6Period: primary side winding L2Continue as clamp capacitor C2With resonant capacitance C3Charging, the second diode VD2Conducting, Auxiliary switch Q2The voltage at both ends is 0, arrives t6Moment, primary side winding L2Electric current fall to 0, clamp capacitor C2Voltage increase It is added to maximum, while resonant capacitance C3Voltage reversal increase to maximum, resonant capacitance C3Start as primary side winding L2Reversely fill Electricity, at this time resonant capacitance C3Voltage is less than clamp capacitor C2Voltage, auxiliary switch Q2Auxiliary switch Q is realized in conducting2Zero Voltage is open-minded；
t6-t7Period: clamp capacitor C2For primary side winding L2T is arrived in reverse charging7Moment, auxiliary switch Q2Driving electricity Press Ugs2Become low level, auxiliary switch Q2Shutdown, clamp capacitor C2Stop being primary side winding L2Charging；
t7-t8Period: resonant capacitance C3Voltage reduce, primary side winding L2Electric current reduce, arrive t8Moment, resonant capacitance C3 Voltage become 0；
t8-t9Period: primary side winding L2For resonant capacitance C3Reverse charging, resonant capacitance C3Voltage gradually increase, arrive t9 Moment, resonant capacitance C3Voltage increase to and filter capacitor C1Voltage it is equal；
t9-t10Period: primary side winding L2Pass through first diode VD1With filter capacitor C1T is arrived in afterflow10Moment, main switch Pipe Q1Driving voltage Ugs1Become high level, at this time primary side winding L2Electric current be negative, main switch Q1It is not turned on.

Claims (2)

1. a kind of microwave oven magnetic power supply device with pull-up active clamp branch, it is characterised in that: in frequency-conversion microwave oven Magnetron power source one pull-up active clamp branch of increase, specific structure packet in LC resonance single tube bipolarity inverter topology Include rectifier bridge, L1C1Filter circuit, sample circuit, pull-up active clamp branch, resonant capacitance, main switch, first diode, High frequency transformer, high frequency voltage doubling rectifier circuit, discharge resistance, magnetron and control circuit, first diode are main switch Anti-paralleled diode, single phase industrial frequence alternating current successively pass through rectifier bridge, L1C1It is converted into direct current after filter circuit, main switch, First diode and pull-up active clamp branch by DC inverter at high-frequency alternating current, this high-frequency alternating current be applied to high frequency change The primary side winding both ends of depressor, after transformer boosts, the vice-side winding both ends of high frequency transformer generate high-frequency and high-voltage alternating current, This high-frequency and high-voltage alternating current is powered after high frequency voltage doubling rectifier circuit for magnetron；The Filament Winding on high frequency transformer pair side generates Alternating current direct be connected in magnetron heater power supply；Rectifier bridge rectifies single phase industrial frequence alternating current, L1C1Filter circuit is by filtering Inductance and filter capacitor electrical connection composition, filter for power frequency；Sample circuit is by the first sampling resistor, the second sampling resistor and electricity Current transformer electrical connection composition, sample circuit are used to detect together with the input voltage and input current detection circuit of control circuit input electricity Current voltage；It pulls up active clamp branch routing clamp capacitor, auxiliary switch and the second diode and is electrically connected structure according to electrical principles At the second diode is the anti-paralleled diode of auxiliary switch, and auxiliary switch source electrode is connected with main switch drain electrode, clamper Capacitor one end is connected with auxiliary switch drain electrode, and the other end is connected with the anode of filter capacitor；When power supply device accesses 220VacIt hands over Galvanic electricity and control circuit powers on, after main switch shutdown, main switch drain-source both end voltage is gradually risen, when this voltage rises When to the sum of filter capacitor and clamp capacitor voltage, the voltage at main switch drain-source both ends is clamped at filter capacitor and clamper electricity Hold both ends, reduces main switch pressure resistance；Resonant capacitance is in parallel with the primary side winding of high frequency transformer, the opening of main switch, Under shutdown variation, resonance occurs for the inductance of resonant capacitance and primary side winding, realizes high-frequency inversion；High frequency transformer by primary side around Group, vice-side winding, Filament Winding and being electrically connected with air gap magnetic core form, and the former and deputy side coefficient of coup of high frequency transformer is 0.5- 0.95, vice-side winding accesses high frequency voltage doubling rectifier circuit, and Filament Winding is connected to magnetron offer with the filament of magnetron and exchanges Power supply, realizes electrical isolation while high frequency transformer is by primary side high-frequency ac electric boost；High frequency voltage doubling rectifier circuit is by first Kenotron, the second kenotron, the first filter capacitor and the second filter capacitor electrical connection composition, high frequency times Voltage rectifier is that magnetron is powered after vice-side winding institute's output voltage of high frequency transformer is carried out voltage multiplying rectifier filtering；Electric discharge Resistance provides discharge loop for the first filter capacitor and the second filter capacitor；Magnetron is for generating microwave；Control circuit is by defeated Enter voltage and current detection circuit, first voltage detection circuit, second voltage detection circuit, micro-wave oven function menu or artificial setting Signal, single-chip microcontroller, driving circuit, accessory power supply are electrically connected to form, input voltage and input current detection circuit for detect input voltage, Electric current, single-chip microcontroller is according to detection data making frequency adjustment, to change output voltage, realizes power limitation control；First voltage Detection circuit detects the voltage at clamp capacitor both ends, and when detecting the voltage increase at clamp capacitor both ends, single-chip microcontroller will be assisted The control signal of switching tube becomes high level, and auxiliary switch realizes that no-voltage is open-minded, when the voltage at clamp capacitor both ends increases When, primary side winding is clamp capacitor charging, the second diode current flow, the electricity at auxiliary switch drain-source both ends by the second diode Pressure is zero；The voltage at second voltage detection circuit detection main switch drain-source both ends；Micro-wave oven function menu or artificial setting letter Number for single-chip microcontroller provide microwave firepower combination and its respective action time；Driving circuit drives main switch under single-chip microcontroller control With the on-off of auxiliary switch；Accessory power supply is single-chip microcontroller and drive circuitry.
2. the microwave oven magnetic power supply device according to claim 1 with pull-up active clamp branch, it is characterised in that: Realize microwave oven magnetic power supply device control process the following steps are included:
(1) circuit powers on, the initialization of first SCM program, and receives and transmitted by micro-wave oven function menu or artificial setting signal Corresponding microwave firepower combination and its respective action time；Then judge whether to press job key, if not pressing job key into Enter standby mode and the moment detects whether to press job key, PWM initialization is entered if pressing job key；It is single after PWM initialization Piece machine is combined according to microwave firepower and its respective action time sets switching frequency corresponding to each microwave firepower and PWM letter Number, and the corresponding switching frequency of first microwave firepower and pwm signal, at this time power supply device first in the combination of output microwave firepower It starts to work；
(2) when power supply device works, output power is adjusted by power limitation control, first according to output microwave firepower setting Corresponding power；Then voltage, the current signal that will test by input voltage and input current detection circuit are sent to single-chip microcontroller, single Piece machine obtains input power by calculating the product of input voltage, electric current；Finally by compare input power and setting power The switching frequency of power supply device is adjusted, if input power is greater than setting power, single-chip microcontroller reduces by increasing switching frequency Output power, if input power is less than setting power, single-chip microcontroller increases output power by reducing switching frequency, realizes electricity The power limitation control of source device；Meanwhile power supply device is during the work time, by the control and regulation of single-chip microcontroller make main switch and Auxiliary switch realizes that Sofe Switch controls, single when first voltage detection circuit detects the voltage increase at clamp capacitor both ends The control signal of auxiliary switch is become high level by piece machine, and auxiliary switch realizes that no-voltage is open-minded；In current main switch Before driving signal rising edge arrives, second voltage detection circuit detects the voltage value at main switch drain-source both ends, if main switch The voltage at pipe drain-source both ends is not 0, that is, is not carried out that no-voltage is open-minded, then single-chip microcontroller reduces the duty ratio of main switch, if main The voltage at switching tube drain-source both ends is 0, i.e. realization no-voltage is open-minded, then the duty ratio of main switch is constant；
(3) single-chip microcontroller moment in the power supply device course of work judges whether corresponding firepower action time terminates, if not terminating Continue to current switch frequency and pwm signal；The last one microwave firepower is judged whether it is if terminating, if not microwave Then firepower+1 exports the corresponding switching frequency of next microwave firepower and pwm signal, and repeats the above steps；If then defeated PWM locking signal out, block PWM output, then power supply device stops working；In program operation, the moment detects whether to press End key, the not normal operation of reprogramming if not stop power supply device work if being directly entered PWM locking signal Make, completes the control of microwave oven magnetic power supply device.
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