EP0269414A2 - Circuits pour le chauffage à induction des appareils de cuisson - Google Patents

Circuits pour le chauffage à induction des appareils de cuisson Download PDF

Info

Publication number
EP0269414A2
EP0269414A2 EP87310358A EP87310358A EP0269414A2 EP 0269414 A2 EP0269414 A2 EP 0269414A2 EP 87310358 A EP87310358 A EP 87310358A EP 87310358 A EP87310358 A EP 87310358A EP 0269414 A2 EP0269414 A2 EP 0269414A2
Authority
EP
European Patent Office
Prior art keywords
induction heating
circuit
coil
switching device
thyristor
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.)
Withdrawn
Application number
EP87310358A
Other languages
German (de)
English (en)
Other versions
EP0269414A3 (fr
Inventor
Peter William Lee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Creda Ltd
Original Assignee
Creda Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Creda Ltd filed Critical Creda Ltd
Publication of EP0269414A2 publication Critical patent/EP0269414A2/fr
Publication of EP0269414A3 publication Critical patent/EP0269414A3/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • 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

Definitions

  • This invention relates to induction heating circuits for cooking appliances.
  • Such circuits comprise a rectifier for converting A.C. mains supply to direct current which is then converted by an inverter to an alternating current supply at a suitable frequency usually in the range of from 20-34 kHz. That supply energises a coil which induces currents in a suitable utensil placed over the coil thereby heating the utensil and its contents.
  • the inverter comprises a semi-conductor switching device for example a thyristor or a high voltage bipolar device and it is found that when operating from mains supply commonly available in the U.K. and in Europe, high peak voltages are developed during resonant periods of the operating cycle of the circuit and this is undesirable. It is also found that the current rise during the initial phase of the powering cycle of the coil can be excessive.
  • an induction heating circuit for a cooking appliance comprises an inverter for powering an induction heating coil at values determined by the periods of conduction of a switching device and with a further inductance is included in series connection with the heating coil of such value as to effect a reduction in peak voltage developed during resonance in the heating circuit.
  • the present invention also provides an induction heating circuit for a cooking appliance comprising an inverter for powering an induction heating coil at values determined by the periods of conduction of a switching device, in which a further inductance is included in series connection between the heating coil and the switching device and in which a uni-directional current path including the further inductance is provided for turn-on current through the switching device.
  • the switching device may be a gate turn-on thyristor.
  • input terminals 1, 2 are supplied with a D.C. voltage obtained, for example, from the full-wave rectification of an A.C. voltage.
  • the current may be supplied from amny suitable source, for example that described in the co-pending Patent Application No. 86.28098 (Case 218) which also gives further details of the overall system.
  • inductor L2 In series connection across the terminals 1, 2 is an inductor L2, which forms a pan coil over which a cooking utensil is placed when it is to be heated by currents induced therein by the coil, a second inductor L1 and a switch S1.
  • capacitor CR In parallel connection across switch S1 is capacitor CR which is the resonance capacitor for the pan coil L2.
  • Switch S1 is a schematic representation of the device which would actually be used in practice and which may be a semi-conductor switching device for example a thyristor which may be a gate turn off thyristor, or a high voltage bipolar device.
  • a diode D1 is connected as shown and is the so-called "free wheeling" diode.
  • the inductance of the pan coil L2 is resonated by capacitor CR whilst capacitor CS is the line filter and resonant reversed commutator capacitor.
  • the induction heating system operates in the manner described in the Application referred to above. Briefly, the inverter is switched on and the current through the pan coil L2 increases until a set and sensed level is detected at which point the inverter is switched off. The inverter now resonates at a frequency determined by the inductance of pan coil L2 and other circuit constants. When the voltage in the resonant circuit reaches a minimum value, the inverter is turned on again. That cycle repeats as long as the system is in use.
  • the inductance of the pan coil L2 is defined by the circuit operating voltage V, current, frequency of resonance and power throughput. However, once those operating conditions have been established, it may be found that the resultant inductance and coil geometry of the pan coil may not be the optimum for the application.
  • the capacitances of the filter capacitor CS and of the capacitor CR must be so selected to allow the voltage VCS across capacitor CS to reduce during current flow in the pan coil during periods of closure of the switch S1 and to allow absorption of the current during the resonant periods of operation of the circuit. That implies that the value of the pan coil inductances must be reduced. There must be some increase in the capacitance of capacitor CR to maintain the optimum resonant frequency.
  • Fig. 2 is a circuit diagram of an improved form of snubber.
  • the reference used in Fig. 2 are the same as those used in Fig. 1 where components are the same.
  • the switch S1 is shown as a gate turn-on thyristor but it could also be some other form of high voltage bipolar semi-conductor device.
  • a further inductor L3 is in series connection between the pan coil L2 and thyristor VT1 across the capacitor CS.
  • inductor L3 Across inductor L3 are series connected diodes D2 and D3, the resonant capacitor CR being connected to the junction between the diodes.
  • Diode D2 provides a conducting path for circulating currents during periods of resonance when thyristor VT1 is turned-off as is described in the Patent Application referred to above. In addition, D2 blocks turn on current through thyristor VT1.
  • Diode D3 is poled to provide a further route for current flow during resonant periods in a direction opposite to that permitted by diode D2.
  • diode D3 provides a route for turn-on current for thyristor VT1 but this route includes inductor L3 which limits the rate of increase of current and peak current at turn-on.
  • Inductor L3 does not, however, reduce thyristor dissipation and thus it is necessary to extend the range over which variation of power input to the pan coil L1 is effected by control of mark-space ratio as is described in the Patent Application referred to above.
  • the cooking appliance may be a hob unit in which case one or more of the pan heating units may be of the form described above.
  • Other pan heating units may be gas burners and/or electric heating units.
  • the invention may also be embodied in a cooker which may be free-standing.
  • One or more of the top or pan heating units may be of the form described above.
  • Other top heating units may be gas burners and/or electric heating units.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Inverter Devices (AREA)
  • General Induction Heating (AREA)
EP87310358A 1986-11-25 1987-11-24 Circuits pour le chauffage à induction des appareils de cuisson Withdrawn EP0269414A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8628099A GB2197995B (en) 1986-11-25 1986-11-25 Improvements in or relating to induction heating circuits for cooking appliances
GB8628099 1986-11-25

Publications (2)

Publication Number Publication Date
EP0269414A2 true EP0269414A2 (fr) 1988-06-01
EP0269414A3 EP0269414A3 (fr) 1989-01-11

Family

ID=10607864

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87310358A Withdrawn EP0269414A3 (fr) 1986-11-25 1987-11-24 Circuits pour le chauffage à induction des appareils de cuisson

Country Status (2)

Country Link
EP (1) EP0269414A3 (fr)
GB (1) GB2197995B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2712763A1 (fr) * 1993-11-15 1995-05-24 Moulinex Sa Générateur de courant ondulé à self saturable.
DE19841759C2 (de) * 1997-09-11 2003-12-24 Toshiba Kawasaki Kk Elektromagnetisches Kochgerät

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3832621A (en) * 1971-12-27 1974-08-27 Gen Electric Reliable static power converter with control logic
JPS52147729A (en) * 1976-06-04 1977-12-08 Matsushita Electric Ind Co Ltd Frequency converter
JPS58834B2 (ja) * 1978-01-25 1983-01-08 松下電器産業株式会社 誘導加熱調理器の保護装置
FR2495876B1 (fr) * 1980-12-05 1985-06-07 Scholtes Ets Eugen Dispositif electronique de chauffage a induction
US4701588A (en) * 1984-02-09 1987-10-20 Sanyo Electric Co., Ltd. Oscillation control circuit of an induction heating apparatus
JPS6134884A (ja) * 1984-07-26 1986-02-19 株式会社東芝 誘導加熱調理器
FR2575354B1 (fr) * 1984-12-20 1988-09-09 Poumey Michel Installation utilisable pour la realisation de plaques de cuisson a chauffage par induction comportant plusieurs foyers reglables separement et un seul generateur
US4578552A (en) * 1985-08-01 1986-03-25 Inductotherm Corporation Levitation heating using single variable frequency power supply
GB2183950A (en) * 1985-11-16 1987-06-10 British United Shoe Machinery A device suitable for use in removing a shoe heel from the bottom of a shoe

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2712763A1 (fr) * 1993-11-15 1995-05-24 Moulinex Sa Générateur de courant ondulé à self saturable.
WO1995014364A1 (fr) * 1993-11-15 1995-05-26 Moulinex S.A. Generateur de courant ondule a self saturable
CN1067836C (zh) * 1993-11-15 2001-06-27 幕林克斯公司 带饱和扼流圈的交变电流发生器
DE19841759C2 (de) * 1997-09-11 2003-12-24 Toshiba Kawasaki Kk Elektromagnetisches Kochgerät

Also Published As

Publication number Publication date
EP0269414A3 (fr) 1989-01-11
GB8628099D0 (en) 1986-12-31
GB2197995A (en) 1988-06-02
GB2197995B (en) 1991-06-19

Similar Documents

Publication Publication Date Title
US4112287A (en) Central oscillator for induction range using triac burner controls
US4473732A (en) Power circuit for induction cooking
KR102762405B1 (ko) 간섭 소음 제거 기능 및 출력 제어 기능이 개선된 유도 가열 장치
US4962292A (en) High-frequency heating apparatus having digital controlled inverter
KR20060054159A (ko) 유도 가열 조리기
JP3831298B2 (ja) 電磁誘導加熱装置
KR20190083263A (ko) 간섭 소음 제거 및 출력 제어 기능이 개선된 유도 가열 장치
EP0269414A2 (fr) Circuits pour le chauffage à induction des appareils de cuisson
KR100318806B1 (ko) 포화자기유도코일을갖는리플전류제너레이터
EP1255421A2 (fr) Dispositif de cuisson à induction possédant des caractéristiques améliorées
CN210670622U (zh) 低功率加热电路及烹饪器具
KR930011812B1 (ko) 인버터 전자레인지의 제어회로
KR100692634B1 (ko) 유도가열 조리기 구동회로 및 그 구동방법
JP7107746B2 (ja) 電磁誘導加熱調理器
EP0269413A2 (fr) Circuits pour le chauffage à induction des appareils de cuisson
EP3836753B1 (fr) Procédé et système pour commander un convertisseur qr dans un appareil de cuisson à induction
EP0269417A1 (fr) Circuits de chauffage par induction pour la cuisson
JP2000286051A (ja) 調理機器
Dede et al. A 12 kW/250 kHz series resonant converter for induction heating
JP6832810B2 (ja) 電力変換装置
JP3011482B2 (ja) 電子レンジ用電源装置
KR100186471B1 (ko) 유도가열조리기의 인버터손실 저감장치
EP0269415A2 (fr) Circuits pour le chauffage à induction des appareils de cuisson
JP4427848B2 (ja) 誘導加熱調理器
EP0269416A1 (fr) Circuits de chauffage par induction pour la cuisson

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): BE DE ES FR GB IT NL

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

RHK1 Main classification (correction)

Ipc: H05B 6/12

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): BE DE ES FR GB IT NL

17P Request for examination filed

Effective date: 19890116

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: CREDA LIMITED

17Q First examination report despatched

Effective date: 19900615

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19920428

RIN1 Information on inventor provided before grant (corrected)

Inventor name: LEE, PETER WILLIAM