CN1138455C - Variable frequency induction heater - Google Patents
Variable frequency induction heater Download PDFInfo
- Publication number
- CN1138455C CN1138455C CNB991226291A CN99122629A CN1138455C CN 1138455 C CN1138455 C CN 1138455C CN B991226291 A CNB991226291 A CN B991226291A CN 99122629 A CN99122629 A CN 99122629A CN 1138455 C CN1138455 C CN 1138455C
- Authority
- CN
- China
- Prior art keywords
- circuit
- output
- inverter
- control
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Abstract
The present invention relates to a variable frequency operation induction heating device. A power supply is composed of a rectification circuit, a filter circuit, an inverter circuit and a load which are connected in series. The present invention is characterized in that the inverter circuit is an inversion bridge circuit formed from V1, V2, V3, V4 and four IGBT; output of the bridge circuit is added on a parallel resonance circuit formed from an induction load L and a compensation capacitor C via a medium frequency transformer; the core of an inverter control circuit is a 98C51 single-chip computer; the inverter control circuit uses a medium frequency voltage signal as an input signal and makes comparison and tracking with an outputted trigger pulse phase; an outputted trigger pulse controls alternative turn-on of V1/V4 and V2/V3. The present invention realizes the requirements of variable frequency operation and melting of different frequency points in a smelting process, etc. The present invention can meet requirements of modern metal heat-treatment in maximum crest.
Description
The present invention relates to the melting technique of metal material, a kind of variable frequency induction heater is provided especially.
Induction heating equipment is widely used in operations such as the melting of metal material and goods, diathermanous, heat treatment and welding, and it is fast to have firing rate, and oxide layer is thin, iron loss is few, furnace temperature advantage such as control easily.What traditional induction heating equipment adopted is thyristor intermediate frequency power supply, thyristor is a commutation cutoff type device, after the pipe conducting, can only rely on outside converter circuit to make the electric current that flows through pipe drop to zero, or make the voltage reversal at pipe two ends and turn-off, thereby when thyristor is used for induction heating equipment, except that need are provided with start-up circuit and forced commutation circuit, also because the turn-off time of thyristor is long, and switching loss is big, switching frequency hangs down problems such as reaching the easy failure of starting.Its corresponding inverter control circuit generally adopts separating component or common integrated circuit to form, can only in fixing frequency range, carry out the tracking of load resonant frequency, and complex circuit, failure rate height, maintenance difficult.Intrinsic limitation (reverse blocking shutoff type device just because of conventional art, starting difficulty, be difficult for being applied in the frequent starting occasion), thereby equipment can not satisfy the requirement of modern metal heat treatmet technology, as improving the material degree that homogenizes, then in fusion process, require the firing equipment variable frequency, i.e. high frequency melting, low frequency stirs; The research material novel process for smelting requires equipment can be operated in different frequency range etc., and these require traditional heating equipment to be difficult to satisfy.
The object of the present invention is to provide a kind of variable frequency induction heater, it can overcome above technological deficiency, realize the variable frequency in the fusion process, and requirement such as different frequent points melting, can satisfy the requirement of modern metal heat treatmet technology to greatest extent.
The invention provides a kind of variable frequency induction heater, form by power supply and body of heater two large divisions, power unit is wherein connect in proper order by rectification circuit, filter circuit, inverter circuit, load and forms, load is joined by inverter control circuit and inverter circuit, join by rectifier control circuit and rectification circuit simultaneously, it is characterized in that:
Described inverter circuit is by V
1, V
2, V
3, V
4Four inversion bridge circuits that IGBT forms, V
1/ V
4And V
2/ V
3Control alternate conduction respectively by inverter control circuit, bridge circuit output is added on the antiresonant circuit of inductive load L and building-out capacitor C composition by intermediate frequency transformer B;
The core of described inverter control circuit is the 89C51 single-chip microcomputer, and its voltage of intermediate frequency signal with detected inverter circuit output is an input signal, compares tracking with the trigger impulse phase place of exporting, and the trigger impulse of its output is by IGBT drive circuit control V
1/ V
4And V
2/ V
3Alternate conduction.
In addition, the present invention also adopts integrated dephasing thyristor module ZLMK to constitute rectified three-phase circuit; Rectifier control circuit is made up of control and protection two parts; Threephase current transformer IM
1, IM
2, IM
3Output by with P
6The signal of current limit value relatively amplifies, through diode D
17Again with power given potentiometer P
7Output is at U
30DCarry out the synthetic formation of signal control circuit part among the TL084, its output connects the control end of rectification module ZLMK to regulate the rectification module output voltage; The output of voltage of intermediate frequency instrument transformer and power given potentiometer P
7Output by XOR gate A
1Control triode T
3Base stage constitute protective circuit part, T
3Collector electrode and the control end of rectification module link.
The B of intermediate frequency transformer described in the present invention is many tapped transformers.Described capacitor C can be switched by the contact of intermediate frequency contactor and change its capacity.Described V
1, V
2, V
3, V
4Two ends parallel resistance R respectively
sC
sConstitute the RC resistance capaciting absorpting circuit.
Specifically, the correlation of each part of the present invention is seen accompanying drawing 1, Fig. 2.
Three-phase alternating current becomes Rectified alternating current through integrated dephasing thyristor module ZLMK, becomes the smooth direct current electricity after smoothing reactor Ld filtering, as the constant-current source of inverter; The inverter bridge of being made up of IGBT (V1, V2, V3, V4) is converted into the intermediate frequency alternate electric energy with direct current energy, and send into by many taps intermediate frequency transformer B in the shunt load of LC (L is that inductor coil, C are compensation condenser) composition, this mode can make same smelting equipment adapt to the requirement of different loads impedance as long as change the tap of transformer, mates to reach optimum load.Control system comprises rectifier control circuit (see figure 3) and inverter control circuit (see figure 5); Rectifier control circuit is realized the power adjustments of power supply, dam pressure and over-current over-voltage protection function.Inversion control is finished frequency-tracking, pulse-triggered and isolation drive function, because being used for the load of melting has nothing in common with each other, load parameter changes greatly in the fusion process, thereby inverter control circuit tackles load resonant frequency and follow the tracks of, and makes to load on to be in the quasi-resonance state in the fusion process all the time.
The present invention adopts brand-new technology of frequency tracking, all can finish automatically from it any load and swash the overall process that starts to the self-excitation operation, and load is in the quasi-resonance state all the time.Its principle is to be current mode (constant-current source) inverter according to shunt chopper, the grid trigger impulse of IGBT must with the electric current of intermediate frequency same-phase of inverter output, thereby by detecting the voltage of intermediate frequency signal, adopt regularly principle, voltage of intermediate frequency is lagged behind the electric current of intermediate frequency set time all the time, system is operated near resonance condition (capacitive partially), can realize frequency-tracking.Promptly at first send suitable fixed frequency pulse drive signal after the start by MCU, system is started by separate excitation, set up the voltage of intermediate frequency signal, increase along with power, after intermediate frequency voltage reaches set point, MCU just can detect the voltage of intermediate frequency signal, and compare with the phase place of trigger impulse, when lag time oversize (surpass setting-up time scope) the inclined to one side capacitive of illustrative system too big, should reduce the frequency of trigger impulse, and too short when lag time, illustrative system is perception partially, thereby should increase the frequency of trigger impulse, MCU is by constantly detecting, judge and correction, just can follow the tracks of the variation of load resonant frequency all the time.
The present invention has following characteristics:
1. adopt integrated dephasing thyristor module to constitute rectified three-phase circuit.
2. adopt self-turn-off device IGBT (igbt) to form the inversion bridge circuit.
3. be that core constitutes inverter control circuit with MCU, finish automatically from it and swash the overall process that starts to the self-excitation operation.
4. the correspondent frequency following function can automatically be operated in different frequency ranges, can automatically follow the tracks of the variation of load resonant frequency again at different frequency range.
5. be that core constitutes inverter and inductive load working state monitoring and protection system with the NOR gate circuit.
6. adopt many taps intermediate frequency transformer output intermediate frequency power, can the regulating load impedance, adapts to different inductive loads, mate Maximum Power Output to reach optimum load.
7. adopt automatic switchover compensation condenser mode to change resonance frequency, realize the variable frequency in the fusion process.
8. adopt the mode of parallel resonance to form the load resonant tank circuit.
9. the overall process of smelting operation is finished in MCU control able to programme automatically, is applicable to automatic continuous production.
In a word, the present invention is owing to adopt above technological means, novel induction melting equipment can pass through compensation capacitors, the tap that changes isolating transformer is adapted to different inductive loads, reach the purpose of a tractor serves several purposes, be that metal can melting under different induction frequencies,, can find best smelting process condition by contrast test; And, can use different frequencies to carry out induction melting by compensation capacitors to same load, reach the high frequency melting, the purpose that low frequency stirs, promptly by the high frequency melting, can Fast Heating, to alleviate oxidation, to reduce scaling loss, stir by low frequency, improve the degree that homogenizes of material.Under any circumstance, inverter control circuit can both be followed the tracks of the variation of load resonant frequency, makes to load on to be in the quasi-resonance state in the heating process all the time.
Below by embodiment in detail the present invention is described in detail.
Accompanying drawing 1 is main circuit block diagram of the present invention.
Accompanying drawing 2 is inversion schematic diagram of the present invention.
Accompanying drawing 3 is rectifier control circuit of the present invention.
Accompanying drawing 4 is rectification control principle figure of the present invention.
Accompanying drawing 5 is inverter control circuit of the present invention.
Accompanying drawing 6 is inverter control circuit of the present invention.
Accompanying drawing 7 is inverter control circuit of the present invention.
Accompanying drawing 8 is IGBT drive circuit of the present invention.
Accompanying drawing 9 is inverter control circuit of the present invention.
Accompanying drawing 10 shows for working state signal of the present invention.
Embodiment
Select the 75A of SIEMENS company for use, 1700V IGBT module constitutes inverter, and isolated drive circuit selects for use the M57962L of MITSUBISHI company to succeed in developing 5KG induction melting equipment.
Output dc voltage is 500V during fusing, and direct current is 54A, and power output is 27KW, and the resonance frequency of load is 5681HZ during the high frequency fusing, and fusing time is 9min; The resonance frequency of load was 2143Hz when low frequency stirred, and owing to electrodynamic squeezing action, melt sharply seethed up and down in the crucible when low frequency stirred, and tangible hump appears in melt liquid level.
Fig. 1 is the main circuit block diagram
The three-phase main-frequency AC energy becomes Rectified alternating current after the rectification circuit rectification, become level and smooth direct current after filter circuit filtering, sends into inverter; By inverter control circuit control, inverter becomes the midfrequent AC electric energy with dc inverter, is added in the load, realizes the purpose of induction heating.
Fig. 2 is the inversion schematic diagram
The ABC three-phase electricity is after rectification module ZLMK rectification, through filter inductance L
dBecome constant DC stream source after the filtering.Four IGBT (V
1, V
2, V
3, V
4) form four brachium pontis of inversion, control V respectively by inverter control circuit
1/ V
4And V
2/ V
3Alternate conduction just becomes direct current into medium frequency alternating current, and is added to by intermediate frequency transformer B on the antiresonant circuit of inductance L (inductive load), capacitor C composition.The capacity of building-out capacitor C can switch by the contact of intermediate frequency contactor, to realize variable frequency.V
1, V
2, V
3, V
4Two ends parallel resistor R
s, capacitor C
sBe used to constitute the RC resistance capaciting absorpting circuit, the surge voltage that causes owing to the stray inductance on the circuit when turn-offing to absorb IGBT.SCR and R form discharge loop, start when abnormal conditions (stopping as inversion) take place, so that the electric energy that stores among the filter inductance Ld that releases prevents that inversion device IGBT from damaging because of overvoltage.
Fig. 3 is the rectifier control circuit block diagram
Regulate the power given potentiometer and can regulate the output dc voltage of rectification module, thereby regulate the power output of inverter.When the current transformer output signal is lower than current limit value, diode D
17End, constitute open-loop control system, power output is linear to be increased.When the current transformer output signal is higher than current limit value, diode D
17Conducting constitutes closed-loop control system, the increase of restriction output current.
XOR gate A among the figure
1Function be to prevent inversion device failure or output inductor short circuit and the protective circuit that is provided with.When set value of the power surpasses given threshold voltage (comparator A exports high level), and the voltage of intermediate frequency instrument transformer does not surpass when starting voltage of intermediate frequency set point (comparator B output low level) as yet, the output high level is after holding circuit after NOR gate circuit is judged, turn-off the rectification module control signal by triode, making its output voltage is zero; Diode D is set
7, be the erroneous judgement that causes for the fluctuation that prevents because of voltage of intermediate frequency instrument transformer output signal, diode D when comparator B output low level
7Conducting is forced the output of comparator A to draw to be low level (its input signal is inoperative), and when comparator B output high level, diode D
7End, at this moment, comparator A has only the output high level, and promptly voltage of intermediate frequency should surpass set point, could normally start (XOR gate output low level, triode T
3By), and when comparator A is output as low level (abnormal conditions such as inversion device failure or the short circuit of output inductor), XOR gate output high level, triode T
3Conducting, thus turn-off control signal.
Fig. 4 is rectification control principle figure
The threephase current transformer output signal is through diode D
10-D
15Rectification, capacitor C
22, resistance R
45Become level and smooth direct current signal after the filtering.By P
3Sampling is again through R
51, R
52, R
53, C
24, C
25The RC filter circuit that constitutes is delivered to the TL084A-3 pin, and TL084A is connected into voltage follower and plays buffer action, and its 1 pin output connects TL084B end of oppisite phase 6 pin, and its in-phase end 5 pin connect electric current and limit potentiometer P
6, after the TL084B comparison operation, by 7 pin output signals and through diode D
17Deliver to 12 pin of TL084D.And power adjustments potentiometer P7 voltage signal is after the TL084C isolation drive, by 8 pin output voltage signals through R
59, R
60Deliver to 12 pin of TL084D after the dividing potential drop simultaneously, after add operation, pass through R
63The output control signal is added to rectification module 2 pin control ends, regulates rectifier output voltage.
Diode D
18, potentiometer P
5Be used to limit control signal voltage magnitude or rectification module output voltage.
Comparator LM339D is used to monitor over-current signal, and its output 2 pin meet U
292 pin of-NE555, U
29-NE555 is connected into trigger to constitute signal holding circuit, and its 3 pin output is through diode D
16Be added to triode T
3Base stage.
Voltage of intermediate frequency instrument transformer output signal is through B
5Rectification, capacitor C
14, resistance R
35, R
36The direct current signal of exporting after the filtering is delivered to comparator LM339A-7 pin, compares after 1 pin outputs level signals to XOR gate CD4030A-1 pin, is passed through diode D simultaneously with 6 pin setting voltages
7Enter 2 pin; Power given potentiometer signal is delivered to comparator LM339B-11 pin, with the given voltage ratio of 10 pin after 13 pin outputs level signals to XOR gate CD4030A-2 pin, after logic determines, by 3 pin outputs level signals to the CD4030B-6 pin, 5 pin connect fixedly high level, make CD4030B constitute inverter, and the level signal of 4 pin output is delivered to 2 pin of NE555, NE555 is connected into trigger and constitutes signal holding circuit, and inhibit signal is exported by 3 pin.During abnormal conditions, 3 pin output high level passes through R
64, T
3Turn off the rectification control signal.
Fig. 5 is the inverter control circuit block diagram
Control system is that the control core is finished frequency-tracking, produced functions such as inverter control signal, building-out capacitor automatic switchover, fault-signal processing, input signal processing, output signal demonstration with the single-chip microcomputer.
Fig. 6 is an inverter control circuit
U among Fig. 6
21-LM339 is a voltage comparator, its end of oppisite phase 6 pin ground connection.The detected sine voltage signal of voltage transformer is through R
21Be added to in-phase input end 7 pin of comparator, antiparallel two diode D
2, D
3Be used to limit the input voltage amplitude.After relatively, export square wave voltage signal, through U by 1 pin
23Optocoupler 6N137 photoelectricity is isolated 14 pin of the electric sheet machine 89C51 of conversion back input, is used for the synchronizing signal of frequency-tracking and drive signal.
U
23Optocoupler TLP521-4, U
24A-C voltage comparator LM339 and auxiliary circuit thereof are used for the three-phase electricity open-phase protection.
U among Fig. 7
6Be eeprom chip X25045, U
7Be WATCHDOG chip DS1302.The P0.0-P0.3 port output IGBT control signal of single-chip microcomputer 89C51 is respectively through 6N137 optocoupler U
9-U
12Be added to four IGBT brachium pontis (V of inverter after the isolation drive
1, V
2, V
3, V
4) on.U
13Optocoupler TLP521-2 is used to detect the IGBT over-current signal, and its signal is added to U
812 pin.
M57962 is the IGBT integrated drive electronics among Fig. 8, and its 13 and 14 pin is a signal input part, and 5 pin are signal output part, pass through resistance R
4Be added to the G utmost point of IGBT, 1 pin is by fast recovery diode D
1Receive the C utmost point of IGBT, 8 pin are the over-current signal output.
The P2.0-P2.2 port of single-chip microcomputer 89C51 output shows signal among Fig. 9 is through U
16D-FAfter driver 74LS07 drives, through U
17-19Export after the optocoupler 6N137 isolation drive; The P2.4 port is through U
16ADriver 74LS07 drives, U
20After the optocoupler TLP521-2 isolation drive, be used to drive intermediate frequency contactor, carry out capacitor and switch.U
14, U
15Optocoupler is used for input and isolates.
MAX7219 is eight LED display drivers of serial ports among Figure 10, and its 1 pin is the serial data input, and 13 pin are input end of clock, resistance R
1Be used to control the drive current of LED.Its D
0-D
8Pin connects the position control end of LED charactron, and its SA-SG connects the section control end of LED charactron.The D of display part
0-D
7Be LED charactron, wherein D
0-D
3Be time showing, D
4-D
7For frequency shows; D
8-D
13Be the LED malfunction indicator lamp.
Claims (4)
1. variable frequency induction heater, form by power supply and body of heater two large divisions, power unit is wherein connect in proper order by rectification circuit, filter circuit, inverter circuit, load and forms, load is joined by inverter control circuit and inverter circuit, join by rectifier control circuit and rectification circuit simultaneously, it is characterized in that:
Described inverter circuit is by V
1, V
2, V
3, V
4Four inversion bridge circuits that IGBT forms, V
1/ V
4And V
2/ V
3Control alternate conduction respectively by inverter control circuit, bridge circuit output is added on the antiresonant circuit of inductive load L and building-out capacitor C composition by intermediate frequency transformer B;
The core of described inverter control circuit is the 89C51 single-chip microcomputer, and its voltage of intermediate frequency signal with detected inverter circuit output is an input signal, compares tracking with the trigger impulse phase place of exporting, and the trigger impulse of its output is by IGBT drive circuit control V
1/ V
4And V
2/ V
3Alternate conduction;
Described V
1, V
2, V
3, V
4Two ends parallel resistance R respectively
sC
sConstitute the RC resistance capaciting absorpting circuit.
2. according to the described variable frequency induction firing equipment of claim 1, it is characterized in that: adopt integrated dephasing thyristor module ZLMK to constitute rectified three-phase circuit; Rectifier control circuit is made up of control and protection two parts; Threephase current transformer IM
1, IM
2, IM
3Output by with P
6The signal of current limit value relatively amplifies, through diode D
17Again with power given potentiometer P
7Output is at U
30DCarry out the synthetic formation of signal control circuit part among the TL084, its output connects the control end of rectification module ZLMK to regulate the rectification module output voltage; The output of voltage of intermediate frequency instrument transformer and power given potentiometer P
7Output by XOR gate A
1Control triode T
3Base stage constitute protective circuit part, T
3Collector electrode and the control end of rectification module link.
3. according to claim 1 or 2 described variable frequency induction firing equipments, it is characterized in that: described intermediate frequency transformer B is many tapped transformers.
4. according to claim 1 or 2 described variable frequency induction firing equipments, it is characterized in that: described capacitor C is by its capacity of contact switching change of intermediate frequency contactor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB991226291A CN1138455C (en) | 1999-12-14 | 1999-12-14 | Variable frequency induction heater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB991226291A CN1138455C (en) | 1999-12-14 | 1999-12-14 | Variable frequency induction heater |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1300176A CN1300176A (en) | 2001-06-20 |
| CN1138455C true CN1138455C (en) | 2004-02-11 |
Family
ID=5282616
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB991226291A Expired - Fee Related CN1138455C (en) | 1999-12-14 | 1999-12-14 | Variable frequency induction heater |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1138455C (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101232750B (en) * | 2002-01-25 | 2011-09-07 | 松下电器产业株式会社 | Induction heater |
| CN100433943C (en) * | 2002-07-12 | 2008-11-12 | 乐金电子(天津)电器有限公司 | Inverter circuit of inverter microwave oven |
| CN101877920B (en) * | 2010-07-01 | 2012-08-15 | 深圳和而泰智能控制股份有限公司 | Soft start method and device of half-bridge resonance induction cooker IGBT (Insulated Gate Bipolar Translator) |
| EP2518889A1 (en) * | 2011-04-29 | 2012-10-31 | AEG Power Solutions B.V. | Resonant circuit inverter with controllable operating point |
| CN102393538B (en) * | 2011-08-08 | 2013-08-07 | 西安思坦仪器股份有限公司 | Anti-interference circuit system for heating furnace of induction log tool |
| CN102403923A (en) * | 2011-09-01 | 2012-04-04 | 阳春丽 | PWM (pulse width modulation) phase-shifting control method |
| CN102685954A (en) * | 2012-05-20 | 2012-09-19 | 黄文武 | Domestic induction cooker |
| CN103441664B (en) * | 2013-08-28 | 2016-09-14 | 淮北市平祥感应炉有限公司 | Parallel resonance intermediate frequency power supply starter |
| CN103862222A (en) * | 2014-03-18 | 2014-06-18 | 国家电网公司 | Portable high frequency heating puller |
| CN104227324A (en) * | 2014-09-02 | 2014-12-24 | 国家电网公司 | High-frequency heating screw detacher |
| CN104602376B (en) * | 2014-12-29 | 2016-05-11 | 重庆恒锐机电有限公司 | High-power eddy-current heating parallel operation power-supply device |
| CN105934013A (en) * | 2016-07-04 | 2016-09-07 | 青岛天地鸿华新能源科技有限公司 | Variable-frequency heating system for electric heating plate |
| CN107166981A (en) * | 2017-06-20 | 2017-09-15 | 山东滨州渤海活塞股份有限公司 | A kind of longitudinal electromagnetic mixing apparatus of electromagnetic induction holding furnace |
| CN111016103A (en) * | 2019-12-31 | 2020-04-17 | 苏州安驰控制系统有限公司 | Injection molding machine control device |
| CN116247959A (en) * | 2023-05-08 | 2023-06-09 | 北京化工大学 | Driving circuit capable of generating positive and negative alternate pulse voltage |
-
1999
- 1999-12-14 CN CNB991226291A patent/CN1138455C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1300176A (en) | 2001-06-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1138455C (en) | Variable frequency induction heater | |
| CN109889073B (en) | Drive control circuit and household electrical appliance | |
| JP2007058676A5 (en) | ||
| CN103138381A (en) | Alternating current and direct current power supply conversion device capable of improving standby electric power efficiency | |
| CN103546055A (en) | Control method for multilevel power conversion circuit | |
| CN1259643A (en) | Device for improving power factor for air conditioner | |
| CN102806407A (en) | Inverter welding machine | |
| CN110022055B (en) | Operation control method, device, circuit, household appliance and computer storage medium | |
| CN1801588A (en) | Variable-frequency air-condition power supply power factor correcting device | |
| CN2399898Y (en) | Frequency variable operation induction heating equipment | |
| CN103280955B (en) | The DC side harmonics of double reverse-stars type thyristor rectifier system suppresses System and method for | |
| CN103178704A (en) | Peak current controlled power factor compensation circuit | |
| CN101170283A (en) | A voltage self-adapted commutation circuit | |
| CN100401625C (en) | Active passive mixed single phase power factor correcting circuit | |
| CN205356183U (en) | Electric current source type three -phase inverter topological structure | |
| CN2489367Y (en) | AC switch compensating voltage stabilizer | |
| CN103051206A (en) | Control circuit and device of power source of fresh keeping machine and control method thereof | |
| CN206908512U (en) | PFC circuit and transducer air conditioning | |
| CN2755859Y (en) | Power factor compensator of frequency-variable air conditioner | |
| CN103546043A (en) | IGBT current transformer and static var generator formed by same | |
| CN210745034U (en) | IGBT half-bridge inverter power supply adopting frequency tracking technology | |
| CN110011529B (en) | Operation control method, device, circuit, household appliance and computer storage medium | |
| CN109889031B (en) | Operation control method, device, circuit, household appliance and computer storage medium | |
| CN1104750A (en) | Induction heating cooker | |
| CN107404779A (en) | Electromagnetic Heating cooking system and its heating control apparatus |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| AR01 | Abandonment of patent right to avoid double patenting |
According to article 9 of the patent law and article 13 of the detailed rules for the implementation of the patent law: 99122629.1 of the invention patents in this issue as a notice of authorization, and at the same time corresponding to the 99250636 utility model patent to be given up, and in the 20 volume of the 06 issue of the new type of communique on the patent right to abandon the announcement. |
|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |