CN1163697C - Microwave oven - Google Patents
Microwave oven Download PDFInfo
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- CN1163697C CN1163697C CNB001081691A CN00108169A CN1163697C CN 1163697 C CN1163697 C CN 1163697C CN B001081691 A CNB001081691 A CN B001081691A CN 00108169 A CN00108169 A CN 00108169A CN 1163697 C CN1163697 C CN 1163697C
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
- F24C7/00—Stoves or ranges heated by electric energy
- F24C7/06—Arrangement or mounting of electric heating elements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F2038/003—High frequency transformer for microwave oven
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- 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
- Y02B40/00—Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of High-Frequency Heating Circuits (AREA)
- Insulating Of Coils (AREA)
Abstract
The subject of this invention is to provide a microwave oven. Because the primary side of a booster transformer 5 is connected with an inverter power supply of half bridge type, no DC component flows in the primary winding of the booster transformer 5, and its saturate voltage may remain small. The transformer 5 has a core gap 40 consisting of core segments 28 and 29, and because the core gap 40 is positioned on the side with the secondary winding 22, the secondary winding 22 has a reduced self-coupling coefficient, and the self-resonance frequency on the side with secondary winding 22 is shifted to the high frequency side. This enlarges the resistance of the side with secondary winding 22 and lessens the Q value of self-resonance on the side with the transformer secondary winding 22, so that generation of ringing due to self-resonance can be prevented.
Description
Technical field
The present invention relates to be equipped with the micro-wave oven of inverter power supply.
Background technology
In the past, in micro-wave oven, used the single hose voltage resonance type inverter power supply that is called " accurate E level " as the driven by magnetron inverter power supply.
But, though this single hose voltage resonance type inverter power supply has advantages of simple structure and simple, owing to have DC component to flow into step-up transformer, therefore in order to improve the saturation voltage of step-up transformer, must be difficult to make the further miniaturization of step-up transformer with large-scale transformer.
Therefore, consider to adopt the semi-bridge type inverter power supply that to realize the step-up transformer miniaturization.That is, the semi-bridge type inverter power supply is to connect 2 switch elements and 2 resonant capacitors with the half-bridge form, because therefore output DC component not can use small-sized transformer as step-up transformer.
But, in the occasion that adopts the semi-bridge type inverter power supply, when magnetron starts (negative electrode also is in does not have abundant heated state) and since with the secondary coil of step-up transformer in spuious (parasitism) electric capacity of producing produce self-vibration, can be called the unwanted vibration of damped oscillation.Therefore, under the situation that this damped oscillation takes place, because of the primary side at step-up transformer takes place above the high pressure more than the step-up ratio, so must use the high transformer of dielectric voltage withstand as step-up transformer.
On the other hand, if the high voltage that the damped oscillation that takes place owing to the secondary coil at step-up transformer with the control circuit inhibition produces, the negative electrode heating when then magnetron starts will reduce relatively with electric current, can produce the problem that the magnetron starting time increases.
Summary of the invention
The present invention is in view of foregoing problems, and its purpose is, a kind of micro-wave oven is provided, and described micro-wave oven can use the little transformer of dielectric voltage withstand as step-up transformer in the structure with the semi-bridge type inverter power supply, and can prevent that the magnetron starting time from increasing.
Micro-wave oven of the present invention comprises:
Have with the half-bridge form and connect 2 switch elements and 2 resonant capacitors and the inverter power supply of the switch element that constitutes,
Receive from the high frequency electric of this inverter power supply and the step-up transformer that boosts and export in primary side at primary coil,
The high-voltage rectifying unit that the oudin's current that is boosted by this step-up transformer is carried out rectification,
Under applying by the state of the high-voltage dc voltage of this high-voltage rectifying unit rectification with the magnetron of microwave irradiation in the kitchen range chamber,
Described step-up transformer is by the coil rack of parallel connection coiling primary coil and secondary coil, insert in the hole with the magnetic core that is inserted into this coil rack and the 1st to cut apart magnetic core and the 2nd and cut apart magnetic core and constitute, the 1st cuts apart magnetic core and the 2nd and cuts apart the middle position that magnetic core gap between the magnetic core is positioned at secondary coil under this insertion state.
Adopt this structure, then the primary coil at step-up transformer receives the high frequency electric of being exported by inverter power supply, and boosts, again from secondary coil output oudin's current.At this moment, in step-up transformer, cut apart magnetic core and the 2nd and cut apart the magnetic core gap of magnetic core and be positioned at the second coil side that is wound on the coil rack because of the 1st, so the self coupling coefficient of secondary coil reduces, the natural frequency of vibration of secondary coil moves to high frequency side.Its result, the resistance of dimension level coil sides increases, and the self-vibration Q value of the second coil side of step-up transformer reduces, so can suppress the damped oscillation that takes place owing to self-vibration.
Therefore, can use the low miniature transformer of dielectric voltage withstand, simultaneously,, not use electric current, also can not increase the starting time of magnetron so can not reduce the negative electrode heating because of step-up ratio can not reduce as step-up transformer.And, adopt this structure, then,, can prevent the generation of damped oscillation effectively so can reduce the self-vibration Q value of the second coil side of step-up transformer widely because of the resistance maximum of the second coil side of step-up transformer.
In addition, by the parasitic capacitance of the second coil side of step-up transformer and resonant frequency that inductance is determined be inverter power supply switching frequency more than 10 times for good.
Adopt this structure, then because be offset the switching frequency of inverter power supply significantly by the parasitic capacitance of the second coil side of step-up transformer and the natural frequency of vibration that inductance is determined, utilize the acting in conjunction effect of the resistance increase of the second coil side that causes with the magnetic core gap again, just can reduce self-vibration Q value widely.
In addition, the full-wave voltage doubler be made up of 2 high-voltage capacitors and 2 high-voltage diodes of high-voltage rectifying unit is good.
Adopt this structure, then because of the secondary circuit of step-up transformer for the action of positive and negative half-wave symmetry, so consistent with symmetry action as the semi-bridge type inverter power supply of primary-side circuitry, can make whole actions be the symmetry action.Therefore, 2 switch elements and 2 resonant capacitors of using at the semi-bridge type inverter power supply, and 2 high-voltage capacitors that use in the high-voltage rectifying unit and high-voltage diode can use components identical respectively, and can easily carry out component management.
In addition, with the end contiguous in two ends of the secondary coil of step-up transformer, be connected on the common tie point of the high-voltage capacitor that is connected in series that constitutes full-wave voltage doubler to good with primary coil.
Adopt this structure, then because of being connected with microwave oven frame by high frequency with the secondary coil of primary coil static coupling, so the voltage resonance energy with the natural frequency of vibration of secondary coil is difficult to leak into primary side, can prevent that the conversion efficiency of step-up transformer from reducing.
In addition, a plurality of independent coil units that are connected in series, the secondary coil that forms step-up transformer is good.
Adopt this structure, then the voltage between layers of dimension level coil integral body reduces, and equivalence electric capacity reduces, so increase for the resistance of high frequency, the self-vibration Q value of second coil side reduces, and can suppress the generation of damped oscillation.
In addition, be good by the stranded primary coil that the twisted wire of the heart yearn below 0.1 millimeter forms step-up transformer more than 8.
Adopt this structure, then can improve the magnetron secondary resistance value in when starting, and can be suppressed at about 1.2 times of low frequency with the secondary resistance value of the operating frequency (for example 50KHz) of inverter power supply
That is to say, owing in the secondary coil of step-up transformer, flow through high frequency electric, so the influence of Kelvin effect and closing effect is remarkable, but, can avoid the influence of Kelvin effect and closing effect by means of reducing core line diameter and increasing the heart yearn number.
In this case, though it is favourable at the resistance under the natural frequency of vibration to increasing secondary coil to reduce core line diameter as far as possible, but then, and because of reducing the resistance value of operating frequency, must be in certain scope so reduce core line diameter.
The desirable twisted wire of Gou Chenging is like this, can guarantee the resistive component under the operating frequency and the ratio of the resistance value under the natural frequency of vibration of secondary coil, and the loss under the operating frequency is enough little simultaneously.
In addition, between the terminal of the primary coil of step-up transformer, connect the series circuit that resistance and capacitor are formed.Perhaps, between the common junction and a power line of described switch element, connect the series circuit that resistance and capacitor are formed.
Adopt this structure, then because of in the primary coil of step-up transformer, the voltage change ratio that can suppress the part that voltage change ratio is big in the voltage waveform (part that the absolute value of dV/dt is big) is so can suppress higher harmonic components with respect to the operating frequency that is applied to the voltage waveform on the primary coil.Therefore,, and the damped oscillatory component of secondary coil voltage waveform can be suppressed,, the starting of magnetron can be carried out apace so unwanted high voltage can not take place because of the oscillation amplitude for the natural frequency of vibration of secondary coil reduces.
Description of drawings
Fig. 1 represents the step-up transformer cutaway view of one embodiment of the invention.
Fig. 2 represents the micro-wave oven stereogram of an open mode.
Fig. 3 is a circuit diagram of roughly representing the piece electrical structure.
Fig. 4 represents the stereogram of step-up transformer.
Fig. 5 represents the exploded perspective view of step-up transformer.
Fig. 6 represents the stereogram of twisted wire structure.
Fig. 7 represents the primary side voltage oscillogram of step-up transformer.
Fig. 8 represents the secondary-side voltage oscillogram corresponding with the primary side voltage of step-up transformer.
Fig. 9 represent Q value different conditions with the corresponding oscillogram of Fig. 8.
The specific embodiment
Below, describe implementing embodiments of the invention with reference to accompanying drawing.
Embodiment
Fig. 2 represents the micro-wave oven stereogram.In Fig. 2, casing 1 is the box structure of front openings, and kitchen range chamber 2 is arranged on the inside of casing 1, simultaneously Machine Room 3 is arranged on a side of casing 1.
Printed circuit board (PCB) 4 is configured in the bottom of Machine Room 3, step-up transformer 5 is contained on this printed circuit board (PCB) 4.
In addition, stationary plane will advance from the microwave irradiation of magnetron 7 on the kitchen range chamber 2 by this waveguide pipe 6 waveguide pipe 6 in kitchen range chamber 2 in Machine Room 3.
Fig. 3 roughly represents the circuit structure of micro-wave oven.In Fig. 3, on printed circuit board (PCB) 4,, rectification unit 8, inverter control unit 9, switch element 10 and high-voltage rectifying unit 11 are housed also, and constitute inverter power supply by inverter control unit 9 and switch element 10 except step-up transformer 5.
The series circuit of 2 switch elements 14 that are connected in series between the power line 12,13 and the series circuit of 2 resonant capacitors 15 that are connected in series are connected in parallel, be output with the common tie point of switch element 14 and the common tie point of resonant capacitor 15 respectively simultaneously, form the semi-bridge type circuit like this, to constitute switch element 10.This occasion, the fly-wheel diode 16 with diagram polarity is connected between the collector and emitter of switch element 14.In addition, the series circuit that will be made up of capacitor 17 and resistance 18 is connected between the common tie point and power line 13 of switch element 14.
The primary coil 19 of step-up transformer 5 is connected with the output of switch element 10 respectively.
High-voltage rectifying unit 11 is made of the full-wave voltage doubler that the series circuit of the series circuit of 2 high-voltage capacitors 20 that are connected in series and 2 high-voltage diodes 21 that are connected in series is connected in parallel, the common tie point of high-voltage capacitor 20 is connected an end of the secondary coil 22 of step-up transformer 5, the common tie point of high-voltage diode 21 is connected the other end of secondary coil 22.In addition, the positive power line 23 of 11 output high-voltage direct currents is connected with the anode 7a of magnetron 7 from the high-voltage rectifying unit, and negative power line 24 is connected with the negative electrode 7b of magnetron 7.
On the other hand, the negative electrode heating is connected with the negative electrode 7b of magnetron 7 with secondary coil 25.
Here, owing to produce parasitic capacitance (dotting among Fig. 3) in secondary coil 22 sides of step-up transformer 5, therefore by this parasitic capacitance and inductance, the resonant frequency of secondary coil 22 sides of decision step-up transformer 5.In the present embodiment, by adjusting the inductance of secondary coil 22, the switching frequency that will be set in inverter unit 10 by the resonant frequency of parasitic capacitance and inductance decision is more than 10 times of 50KHz.
Below, the structure of aforementioned step-up transformer 5 is described.
Fig. 4 represents the stereogram of step-up transformer 5.Fig. 5 represents the exploded perspective view of step-up transformer.In Fig. 4 and Fig. 5, cut apart magnetic core 28 (only Fig. 5 diagram), the 2nd by coiling primary coil 19 and secondary coil 22 and negative electrode heating with coil rack 26, the magnetic core supporting member the 27, the 1st of secondary coil 25 (in Fig. 4 and Fig. 5, omitting) and cut apart magnetic core 29 and magnetic core hoop 30 formation step-up transformers 5.
In addition, secondary coil is isolated into 3 independent coil unit 32a (only Fig. 1 diagram) with coil rack part 32 by 2 little division boards 37, uses a Wire-wound secondary coil 22 simultaneously, makes to walk around each independent coil unit 32a continuously.Be that secondary coil 22 is divided into 3 independent coil unit 22a, and be connected in series after cutting apart independent coil unit 22a and form.One end of this secondary coil 22 with is connected from the outstanding terminal (not shown) that is provided with in the bottom surface of the big division board 36 of coil rack 26, and the other end is connected with the terminal (not shown) of giving prominence to setting from the bottom surface of bearing support 34.
Fig. 6 represents to constitute the structure of the twisted wire 38 of primary coil 19.In Fig. 6,38a is stranded with 8 heart yearns below the 0.1mm (periphery insulation), forms twisted wire 38.
On the other hand, in Fig. 4 and Fig. 5,, form cable keeper 39 in the side of the bearing support 34 of coil rack 26, the end of 2 negative electrode heating with secondary coil 25 (omitting in Fig. 4 and Fig. 5) remained on respectively on this cable keeper 39, and draw from illustrated below.This occasion, 2 negative electrodes that remain on the keeper 39 heat the end of using secondary coil 25, are welded on the printed circuit board (PCB) 4, just as connecting as one, and under this connection status, the negative electrode heating centers on the magnetic core bearing support 35 that is formed on the coil rack 26 with secondary coil 25.In addition, connector (not shown) is connected the end of negative electrode heating with secondary coil 25, and is connected with the negative electrode 7b of magnetron 7.
Magnetic core supporting member 27 by means of the peristome that the 27a of this two legs portion is embedded the magnetic core bearing support 35 of coil rack 26 formation, just constitutes one with coil rack 26 for having " コ " font of the 27a of two legs portion.
On the other hand, the 1st cuts apart magnetic core 28 and the 2nd and cuts apart magnetic core 29 and be respectively " コ " font.These stem stem 28a, 29a of cutting apart magnetic core 28,29 are formed cylindrical, and the stem stem 28a of cutting apart magnetic core 28 on one side is longer than the stem stem 29a of cutting apart magnetic core 29 of another side.These stem stem 28a, 29a of cutting apart magnetic core 28,29 are inserted among the magnetic core patchhole 26a of coil rack 26, under this insertion state, stop (not shown) that stop (not shown) and form in magnetic core supporting member 27 respectively cutting apart stem stem 28a, the 29a of magnetic core 28,29 and form in magnetic core patchhole 26a connects, simultaneously by magnetic core bearing support 35 that forms in coil rack 26 and magnetic core supporting member 27 location.
Here, Fig. 1 represents the cutaway view of step-up transformer 5.In Fig. 1, be inserted into the 1st in the coil rack 26 and cut apart magnetic core 28 and the 2nd and cut apart magnetic core 29, dock with not shown the stopping that the magnetic core patchhole 26a and the magnetic core supporting member 27 of coil rack 26 form, and form magnetic core gap 40 in this mated condition.This occasion, magnetic core gap 40 are positioned at the corresponding position of substantial middle of secondary coil 22.
The step-up transformer 5 of structure as previously mentioned utilizes screw to be screwed into the screw binding thread 41 (only Fig. 4 and Fig. 5 diagram) that the bearing support 33,34 at coil rack 26 forms from the back side of printed circuit board (PCB) 4, is installed on the printed circuit board (PCB) 4.This occasion is cut apart the 1st, the 2nd and to be formed the ditch 28a of portion, 29b on the lateral surface of magnetic core 28,29, by means of this magnetic core hoop 30 is embedded among this groove 28a, the 29b, respectively cuts apart magnetic core 28,29 and coil rack 26 and is integral.In addition, magnetic core hoop 30 is welded on the printed circuit board (PCB) 4, under this welded condition, be installed on the printed circuit board (PCB) 4 with step-up transformer, and it is inclined respectively to cut apart magnetic core 28,29.
On the other hand, the primary coil 19 of step-up transformer 5, the circuit figure of secondary coil 22 by forming on printed circuit board (PCB) 4 are connected with the electronic component of regulation.
That is,, primary coil 19 is connected with the common tie point of the switch element 14 of switch element 10 and the common tie point of resonant capacitor 15 by on printed circuit board (PCB) 4, welding.
In addition, by on printed circuit board (PCB) 4, welding, make to be connected with secondary coil 22 and to be connected with the common tie point of the high-voltage capacitor 20 of high-voltage rectifying unit 11 and the common tie point of high-voltage diode 21 by circuitous pattern by the terminal that draw the bottom surface of coil rack 26.
By on printed circuit board (PCB) 4, welding, the negative electrode heating is connected by the common tie point of circuitous pattern with high-voltage capacitor 20 and high-voltage diode 21 with secondary coil 25.
Below, the effect of aforementioned structure is described.
Under the state of connecting mains supply, if the operation firing switch, inverter control unit 9 is just to switch element 10 output switching signals, and then switch element 10 usefulness 50KHz carry out switching manipulation to the DC voltage from rectification unit 8.At this moment, be under conducting (ON) state, in the primary coil 19 of step-up transformer 5, flow through electric current, flow through the electric current that produces along with 15 discharges of the 1st resonant capacitor simultaneously by the 2nd resonant capacitor 15 at the 1st switch element 14.In addition, be under conducting (ON) state at the 2nd switch element 14, rightabout ground flows through the electric current by the 2nd resonant capacitor 15 in the primary coil 19 of step-up transformer 5, and rightabout ground flows through the electric current that produces along with 15 discharges of the 1st resonant capacitor simultaneously.
Like this,, in the primary coil 19 of step-up transformer 5, flow through the high frequency electric of 50KHz, so from secondary coil 19 outputs and the corresponding oudin's current of step-up ratio corresponding to the switch motion of switch element 14.In addition, with secondary coil 25 high frequency electric is exported to the negative electrode 7b of magnetron 7 from negative electrode heating, so target 7b heats.
At this moment, the series circuit of forming because of capacitor 17 and resistance 18 is connected, between the common tie point and power line 13 of switch element 14, so in the primary coil 19 of step-up transformer 5, can suppress the voltage change ratio (with reference to Fig. 7) of the part that voltage change ratio is big in the voltage waveform (part that the dV/dt absolute value is big).
On the other hand, the full-wave voltage doubler that constitutes high-voltage rectifying unit 11 is finished the action of the half-wave voltage doubler of combination, utilize the charging of high-voltage capacitor 20, improved the oudin's current that produces according to step-up ratio from the secondary coil 22 of step-up transformer 5, thus the output high-voltage dc voltage.
Like this, if be applied on the magnetron 7 from high-voltage rectifying unit 11 with high-voltage dc voltage, starting magnetron 7 under such state, then magnetron 7 vibration, from magnetron 7 with microwave irradiation in kitchen range chamber 2.
But, shown in the dotted line of Fig. 3, because in the secondary coil 22 of step-up transformer 5, produce parasitic capacitance, so owing to produce self-vibration with parasitic capacitance, the voltage that the secondary coil 22 of step-up transformer 5 produces can be called the unwanted resonance of damped oscillation.
The secondary-side voltage of the primary side voltage of step-up transformer 5 when Fig. 8 represents the magnetron starting.In addition, primary side voltage is different with the voltage level of secondary-side voltage.This occasion, ideally the secondary-side voltage of step-up transformer 5 only is the voltage (representing with solid line among Fig. 8 (b)) of the step-up ratio multiple of primary side voltage, but when damped oscillation takes place, because of damped oscillation (dotting among Fig. 8 (b)), secondary coil voltage take place than should the high voltage of voltage, and the size of this voltage is determined by predetermined parameter.That is, by the Q value of primary side voltage and step-up ratio and self-vibration, the generation voltage of decision damped oscillation.Wherein, the conditional decision because of primary side voltage and step-up ratio during by the regular event of switch motion so only the Q value of self-vibration is an independent parameter, by means of the Q value of control self-vibration, can suppress the generation voltage of damped oscillation.
Specifically, shown in Fig. 9 (b), when the Q value of the self-vibration of secondary coil 22 sides of step-up transformer 5 was big, damped oscillation was big, and shown in Fig. 9 (c), and when the Q of self-vibration value hour, damped oscillation is little.Therefore, the Q value that reduces self-vibration can reduce damped oscillation effectively.
Therefore, in the present embodiment, as described later, the Q value by means of the primary side self-vibration that reduces step-up transformer 5 can suppress the generation of damped oscillation.
Promptly, if be conceived to step-up transformer 5, then as shown in Figure 1, be positioned at secondary coil 22 sides because of being inserted into the magnetic core gap 39 that the 1st, the 2nd in the coil rack 26 cut apart between the magnetic core 28,29, so compare with the situation that makes magnetic core gap 39 be positioned at primary coil 19 sides, can reduce the self coupling coefficient of secondary coil 22, the natural frequency of vibration of secondary coil 22 is moved to high frequency side.Therefore, the resistance of dimension level coil 22 increases, so the Q value of the self-vibration of the secondary coil 22 of step-up transformer 5 reduces, can suppress the damped oscillation that produces owing to self-vibration effectively.
In experiment, the situation that is positioned at secondary coil 22 sides in magnetic core gap 39 with step-up transformer 5 be positioned under the situation of primary coil 19 sides, the magnetic core gap of adjusting separately makes the leakage inductance (primary inductances during secondary coil 22 open circuits) of primary coil become identical value, under such condition, confirm, can make secondary leakage inductance value be reduced to 10mH from 12mH.
That is to say, because of by means of reducing secondary leakage inductance, correspondingly can improve the resonant frequency of secondary coil 22 sides of step-up transformer 5, so can relatively reduce the Q value of self-vibration.
Like this, adopt present embodiment, then cut apart the magnetic core gap 39 of magnetic core 29 and be positioned at secondary coil 22 sides because of cut apart magnetic core 28 and the 2nd by means of the 1st among the magnetic core patchhole 26a that makes the coil rack 26 that is inserted into step-up transformer 5, secondary leakage inductance is reduced, so the natural frequency of vibration of secondary coil 22 sides of step-up transformer 5 increases, and can relatively reduce the Q value of self-vibration.Therefore, in the secondary coil 22 of step-up transformer 5 damped oscillation takes place in the time of being suppressed at the magnetron starting, and can be with small-sized transformer as step-up transformer 5.
This occasion, just can be suppressed at the damped oscillation that primary side takes place because of adjusting primary side voltage, the negative electrode heating that reduces magnetron 7 so do not adopt the step-up ratio that reduces step-up transformer 5 just can realize with electric current, also can not produce the elongated problem of starting time of magnetron 7.
In addition, be positioned on the position of substantial middle of secondary coil 22 of step-up transformer 5,, can suppress the generation of damped oscillation so the resistance of the secondary coil 22 of step-up transformer 5 can be maximum because of making the 1st, the 2nd magnetic core gap 39 of cutting apart magnetic core 28,29.
In addition, inductance because of secondary coil 22 sides of adjusting step-up transformer 5, make, by the parasitic capacitance of secondary coil 22 sides of step-up transformer 5 and the resonant frequency that inductance is determined is more than 10 times of switching frequency of switch element 10, so the resonant frequency of secondary coil 22 sides of step-up transformer 5 departs from the switching frequency of switch element 10 widely, utilization makes the Q value of self-vibration reduce with the position adjustment in the magnetic core gap 39 of aforementioned step-up transformer 5 acting in conjunction effect, can reduce the Q value of self-vibration widely, further suppress the generation of damped oscillation.
In addition, because of using full-wave voltage doubler, so the high-voltage rectifying unit 11 of the primary side of step-up transformer 5 moves for positive and negative half-wave symmetry as high-voltage rectifying unit 11, consistent with the symmetry action of the switch element 10 of primary-side circuitry, can make whole actions be the symmetry action.Therefore, 2 switch elements 14 that use in the switch element 10 of semi-bridge type and 2 resonant capacitors 15 and 2 high-voltage capacitors 20 that use in high-voltage rectifying unit 11 and high-voltage diode 21 can be used components identical respectively, can easily carry out parts management.
In addition, be positioned at the end of primary coil 19 sides in the end because of the secondary coil 22 of step-up transformer 5, be connected on the common tie point of high-voltage capacitor 20 series circuits of the full-wave voltage doubler that constitutes high-voltage rectifying unit 11, so the secondary coil 22 with primary coil 19 couplings is connected by high frequency with microwave oven frame.Therefore, the voltage resonance energy that produces with the natural frequency of vibration of secondary coil 22 is difficult to leak into primary side, can prevent that the conversion efficiency of step-up transformer 5 from reducing.
In addition, form because of the secondary coil 22 with step-up transformer 5 is divided into a plurality of independent coil unit 22a and is connected in series, so the voltage between layers of secondary coil 22 integral body reduces, equivalence electric capacity reduces, so the resistance for high frequency increases, and can reduce the Q value of the self-vibration of secondary coil 22 sides.
In addition, because of the primary coil of step-up transformer 5 is twisted wires of the heart yearn below stranded 8 above 0.1mm, so can guarantee the resistive component under operating frequency and the ratio of the resistance value under the natural frequency of vibration of secondary coil, make in the loss of operating frequency fully little.
In addition, because of between the common tie point and power line 13 of switch element 14, the series circuit that connection is made up of capacitor 17 and resistance 18, so can suppress higher harmonic components for the operating frequency that is applied to the voltage waveform on the primary coil 19, reduce amplitude of oscillation, and can suppress the damped oscillatory component of the voltage waveform of secondary coil 22 for the natural frequency of vibration of secondary coil 22.Therefore, unnecessary high voltage can not take place, the starting of energy acceleration magnetron 7.
The invention is not restricted to aforesaid embodiment, can be following distortion or expansion.
Also can be with half-wave voltage doubler as high-voltage rectifying unit 11.
Also the series circuit of being made up of capacitor 17 and resistance 18 can be connected between the primary coil 19 of step-up transformer 5.
As previously mentioned as seen, adopt micro-wave oven of the present invention, then because of the 1st cutting apart the magnetic core gap that magnetic core and the 2nd cuts apart between the magnetic core and be positioned at second coil side by means of what make that the magnetic core that is inserted into step-up transformer inserts in the hole, the self coupling coefficient of secondary coil is reduced, the natural frequency of vibration of secondary coil moves to high frequency side, so in micro-wave oven with the semi-bridge type inverter power supply, can use the low transformer of dielectric voltage withstand as step-up transformer, and can prevent the increase of magnetron starting time, have desirable effect.
Claims (8)
1. micro-wave oven comprises:
Have with the half-bridge form and connect 2 switch elements and 2 resonant capacitors and the inverter power supply of the switch element that constitutes,
Receive from the high frequency electric of this inverter power supply and the step-up transformer that boosts and export in primary side at primary coil,
The high-voltage rectifying unit that the oudin's current that is boosted by this step-up transformer is carried out rectification,
Under applying by the state of the high-voltage dc voltage of this high-voltage rectifying unit rectification with the magnetron of microwave irradiation in the kitchen range chamber,
It is characterized in that,
Described step-up transformer is by the coil rack of parallel connection coiling primary coil and secondary coil, the 1st cut apart magnetic core and the 2nd and cut apart magnetic core and constitute with the magnetic core that is inserted into this coil rack inserts in the hole, the 1st cuts apart magnetic core and the 2nd and cuts apart the middle position that magnetic core gap between the magnetic core is positioned at secondary coil under this insertion state.
2. micro-wave oven as claimed in claim 1 is characterized in that,
By the parasitic capacitance of the second coil side of step-up transformer and the resonant frequency that inductance is determined is more than 10 times of switching frequency of inverter power supply.
3. micro-wave oven as claimed in claim 1 is characterized in that,
The high-voltage rectifying unit is by 2 high-voltage capacitors and 2 full-wave voltage doublers that high-voltage diode is formed.
4. micro-wave oven as claimed in claim 3 is characterized in that,
An end with contiguous with primary coil in two ends of the secondary coil of step-up transformer is connected on the common tie point of the high-voltage capacitor that is connected in series that constitutes full-wave voltage doubler.
5. micro-wave oven as claimed in claim 1 is characterized in that,
A plurality of independent coil units that are connected in series form the secondary coil of step-up transformer.
6. micro-wave oven as claimed in claim 1 is characterized in that,
By the stranded twisted wire of the heart yearn below 0.1 millimeter more than 8, form the primary coil of step-up transformer.
7. micro-wave oven as claimed in claim 1 is characterized in that,
Between the terminal of the primary coil of step-up transformer, connect the series circuit that resistance and capacitor are formed.
8. micro-wave oven as claimed in claim 1 is characterized in that,
Between the common junction and a power line of described switch element, connect the series circuit that resistance and capacitor are formed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18501299A JP3735490B2 (en) | 1999-06-30 | 1999-06-30 | microwave |
| JP185012/1999 | 1999-06-30 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1279377A CN1279377A (en) | 2001-01-10 |
| CN1163697C true CN1163697C (en) | 2004-08-25 |
Family
ID=16163236
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB001081691A Expired - Lifetime CN1163697C (en) | 1999-06-30 | 2000-04-27 | Microwave oven |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP3735490B2 (en) |
| KR (1) | KR100375849B1 (en) |
| CN (1) | CN1163697C (en) |
| TW (1) | TW438952B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004111528A (en) | 2002-09-17 | 2004-04-08 | Matsushita Electric Ind Co Ltd | Step-up transformer for magnetron drive |
| JP6018763B2 (en) * | 2012-02-21 | 2016-11-02 | Ｎｅｃトーキン株式会社 | Reactor |
| JP6675260B2 (en) * | 2016-04-27 | 2020-04-01 | 東京エレクトロン株式会社 | Transformer, plasma processing apparatus, and plasma processing method |
| CN106533184A (en) * | 2016-12-29 | 2017-03-22 | 广东美的厨房电器制造有限公司 | Frequency converter and microwave oven |
| CN109065336A (en) * | 2018-09-20 | 2018-12-21 | 广东尚研电子科技有限公司 | A kind of potential device and its manufacturing method of microwave variable-frequency power sources |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2608348B1 (en) * | 1986-12-10 | 1993-11-12 | Electricite De France | ELECTRICAL INDUCTION COOKING APPARATUS WITH REDUCED HARMONIC EMISSION |
| KR890010948A (en) * | 1987-12-07 | 1989-08-11 | 서주인 | High frequency transformer by Leeds wire |
| JP2674107B2 (en) * | 1988-06-28 | 1997-11-12 | 松下電器産業株式会社 | High voltage transformer |
| JPH02306577A (en) * | 1989-05-19 | 1990-12-19 | Matsushita Electric Ind Co Ltd | High frequency heating device |
| JP2691626B2 (en) * | 1990-01-16 | 1997-12-17 | 株式会社ユタカ電機製作所 | Switching power supply for high frequency heating equipment |
| JPH0513247A (en) * | 1991-07-03 | 1993-01-22 | Matsushita Electric Ind Co Ltd | High frequency heater |
| JPH065187U (en) * | 1992-06-23 | 1994-01-21 | 株式会社日立ホームテック | High frequency heating device |
| JPH0662571A (en) * | 1992-08-03 | 1994-03-04 | Yamaha Corp | Switching power circuit |
| KR950002532A (en) * | 1993-06-15 | 1995-01-04 | 배순훈 | Level variable output circuit of microwave oven |
| JPH08124760A (en) * | 1994-10-26 | 1996-05-17 | Matsushita Electric Works Ltd | Electromagnetic device |
| JPH09163734A (en) * | 1995-12-07 | 1997-06-20 | Matsushita Electric Ind Co Ltd | Power supply circuit |
| KR19980065544A (en) * | 1997-01-11 | 1998-10-15 | 김광호 | Microwave high voltage transformer |
| JPH10261532A (en) * | 1997-03-18 | 1998-09-29 | Matsushita Electric Ind Co Ltd | High-voltage transformer for compact inverter power supply |
| JPH10261524A (en) * | 1997-03-18 | 1998-09-29 | Matsushita Electric Ind Co Ltd | High voltage transformer |
| JPH11168015A (en) * | 1997-12-03 | 1999-06-22 | Toshiba Tec Corp | Transformer |
-
1999
- 1999-06-30 JP JP18501299A patent/JP3735490B2/en not_active Expired - Lifetime
-
2000
- 2000-03-16 TW TW089104854A patent/TW438952B/en not_active IP Right Cessation
- 2000-04-27 CN CNB001081691A patent/CN1163697C/en not_active Expired - Lifetime
- 2000-05-03 KR KR10-2000-0023690A patent/KR100375849B1/en active IP Right Grant
Also Published As
| Publication number | Publication date |
|---|---|
| CN1279377A (en) | 2001-01-10 |
| TW438952B (en) | 2001-06-07 |
| KR100375849B1 (en) | 2003-03-15 |
| JP2001015259A (en) | 2001-01-19 |
| JP3735490B2 (en) | 2006-01-18 |
| KR20010007038A (en) | 2001-01-26 |
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