EP1255421A2 - Induktionkochvorrichtung mit verbesserten Kennzeichenen - Google Patents

Induktionkochvorrichtung mit verbesserten Kennzeichenen Download PDF

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Publication number
EP1255421A2
EP1255421A2 EP02007362A EP02007362A EP1255421A2 EP 1255421 A2 EP1255421 A2 EP 1255421A2 EP 02007362 A EP02007362 A EP 02007362A EP 02007362 A EP02007362 A EP 02007362A EP 1255421 A2 EP1255421 A2 EP 1255421A2
Authority
EP
European Patent Office
Prior art keywords
resonance
real
control unit
inverter
current
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Withdrawn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
EP02007362A
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English (en)
French (fr)
Other versions
EP1255421A3 (de
Inventor
Roberto Raffaeta
Gianluca Nolli
Francesco Ieva
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.)
Cpe Consultants Plastics Engineering
Original Assignee
Cpe Consultants Plastics Engineering
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 Cpe Consultants Plastics Engineering filed Critical Cpe Consultants Plastics Engineering
Publication of EP1255421A2 publication Critical patent/EP1255421A2/de
Publication of EP1255421A3 publication Critical patent/EP1255421A3/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/06—Control, e.g. of temperature, of power
    • H05B6/062—Control, e.g. of temperature, of power for cooking plates or the like
    • 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
    • H05B6/04—Sources of current

Definitions

  • the present invention relates to an induction cooking apparatus with improved characteristics. More particularly, the invention relates to an induction cooking apparatus that also allows to use conventional pots or pans made of stainless steel or ordinary steel.
  • Induction heating which is one of the radio frequency heating methods, is based on the production of heat due to the parasitic eddy currents generated in conducting materials when they are immersed in a radiofrequency magnetic field. If the conducting material also has ferromagnetic characteristics, heating is also produced by losses due to hysteresis (a closed path whose area represents losses affecting a ferromagnetic material due to magnetic hysteresis, i.e., the fact that a material of this kind tends to demagnetize more slowly than it magnetizes) in addition to losses due to parasitic currents. Heating due to hysteresis increases as the frequency increases and as the area of the hysteresis cycle increases. Accordingly, induction heating is used for conducting materials.
  • the frequencies used for induction heating are in the kilohertz range and can be generated by using generators that use power devices such as transistors (IGBT), which are merely high-frequency DC-AC converters.
  • IGBT transistors
  • inductor used for coupling to the element to be heated (pan or container of any type and shape).
  • These generators are also required to have considerable shielding in order to avoid interference during services in the field of telecommunications.
  • shielding is provided mechanically and by means of filters on the power supply system.
  • DC power supply is provided by means of solid-state rectifiers (diode bridges).
  • Induction heating to cook food is currently recognized as a highly efficient and extremely safe process both for operators and for the environment.
  • induction heating apparatus does not allow to perform so-called sautéing, i.e., the operation that consists in moving the pan on the heating plate with an alternating movement, as might be performed on a gas-fired cooking range.
  • the aim of the present invention is to provide an apparatus for induction cooking that allows to use ordinary stainless steel or ordinary steel pots without losing power and therefore without forcing the user to use special pots.
  • an object of the present invention is to provide an apparatus for induction cooking that allows to work at all times in optimum resonance conditions, in order to optimize the overall efficiency of the process.
  • Another object of the present invention is to provide an apparatus for induction cooking that allows to perform so-called sautéing that is substantially similar to the sautéing allowed by a conventional gas-fired cooking apparatus.
  • Another object of the present invention is to provide an apparatus for induction cooking that allows to minimize leakages, with a consequent increase in the overall efficiency of the apparatus.
  • Another object of the present invention is to provide an apparatus for induction cooking that can be connected to similar apparatuses, by means of the dedicated local power supply grid, in order to distribute in an optimum manner the loads on the grid and therefore prevent the intervention of protection devices, which in professional environments can interrupt work processes.
  • Another object of the present invention is to provide an apparatus for induction cooking that is highly reliable, relatively easy to manufacture, and at competitive costs.
  • an induction cooking apparatus comprising an inductor element driven by an inverter, which is in turn controlled by a control circuit, resonance capacitors being connected in parallel to said inductor element, characterized in that it comprises a real-time control unit suitable to detect the resonance current of a resonance circuit constituted by the inductor element and by the resonance capacitors, and the phase current of the power supply line, in order to send, at each half-cycle of the fundamental wave, a driving signal for the control circuit in order to ensure a perfect resonance condition.
  • the induction cooking apparatus generally designated by the reference numeral 1, comprises a microcontroller 2, which is suitable to receive in input commands from a user interface 3, to detect an information item 4 related to the phase current of the power supply line and to drive accordingly a real-time control unit 5, which drives a circuit 6 for controlling the switching of an inverter 7 constituted by one or more pairs of IGBT transistors 8, each provided with a corresponding capacitor 9 in parallel.
  • a microcontroller 2 which is suitable to receive in input commands from a user interface 3, to detect an information item 4 related to the phase current of the power supply line and to drive accordingly a real-time control unit 5, which drives a circuit 6 for controlling the switching of an inverter 7 constituted by one or more pairs of IGBT transistors 8, each provided with a corresponding capacitor 9 in parallel.
  • An inductor element 10 is connected to the common node between the emitter terminal of the IGBT transistors and the capacitors 9, and a pair of resonance capacitors 11 arranged in parallel to the inductor element 10 form an LCR circuit together with the inductor element.
  • the control unit 5 detects the instantaneous value of the resonance current Ir and the value of the DC line voltage V CC of the circuit and sends to the control circuit 6 the appropriate control pulses in real time.
  • the LCR circuit formed by inductor elements 10 and by the pair of resonance capacitors 11 is kept always in a perfect condition of resonance by the real-time control unit 5, which is constituted by high-speed digital logic devices, which on the basis of the voltage of the DC bus V CC and of the instantaneous value of the resonance current Ir send to the control circuit 6 the appropriate control pulses in real-time.
  • a network filter 13 is interposed between the power supply network and the above described circuit and is designed to reduce the harmonic content of the phase current to values within the ranges currently specified in applicable statutory provisions.
  • a rectifier bridge 14 is cascade connected to the network filter 13 and is designed to convert the AC voltage of the bus voltage supply line into a direct current (V CC ).
  • An HS filter 15 is cascade-connected to the rectifier bridge 14 and drastically reduces the high-frequency components generated by the current of the inverter 7 at the resonance frequency and at the corresponding higher harmonics.
  • the microcontroller 2 receives from a phase current measurement transformer 16 information regarding the phase current of the power supply line (signal 4) and also receives temperature signals 17 and signals 18 from serial communications.
  • the particularity of the invention is that the switching frequency of the transistors 8 that compose the inverter 7 is updated in real time at each half cycle of the fundamental wave.
  • the circuit is kept in a constant resonance condition by the real-time control unit 5, thus achieving "zero voltage switching"-type switching, because the voltage and current fundamentals are perfectly in phase. Switching losses of the inverters 8 are very small by way of the adoption of a so-called soft switching strategy, which ensures at least one zero current switching ZCS.
  • the control must monitor continuously the resonance voltage and current and has a parametric identifier in order to detect the type of pot that is present so as to optimize transmitted power resources. Said identifier furthermore drastically reduces the power if the pot is removed, both for reasons of operator safety and to minimize consumption and any radio frequency harmonics introduced into the surrounding environment.
  • Self-tuning of the real-time control unit 5 ensure, at each half cycle of the fundamental wave, an appropriate driving signal for the control circuit 6 that must ensure the perfect resonance condition in order to utilize all the benefits of soft switching in resonant mode, because the switchings of the transistors must occur in the vicinity of the zero transition of the resonance current and because it is necessary to adopt a certain idle time in order to avoid cross conduction phenomena, the status change command to be given to the control circuit 6 must be given with a certain advance and this optimum advance time is a function of the maximum value of the resonance current Ir, of the resonance frequency, and of the capacitance of the capacitors 9 connected in parallel to the corresponding transistors.
  • the real-time control unit 5 deduces in real-time the equivalent inductor/pot resistance in order to detect in the shortest possible time the condition in which no pot is present.
  • This condition is very important, because it allows to reduce the high-frequency alternating magnetic field to very low values (minimum electromagnetic pollution) in order to purely detect the pot read insertion condition.
  • the microcontroller 2 monitors, by means of the transformer 16, the absorption of current in order to report to the control unit 5 the correct set point in order to obtain the intended transmitted power and perform other auxiliary functions.
  • the microcontroller by means of the communications line 18, receives the status of utilization of the maximum power of the three-phase line used: if the status of utilization is higher than a certain preset threshold, the microcontroller 2 decreases adequately the transmission of power until the status of full utilization returns within the threshold.
  • a general microcontroller can therefore monitor the current of the three lines of the three-phase power supply system and transmit it to the individual heating devices according to the present invention, so as to distribute uniformly all the useful power to all the devices and especially prevent an excessive load from tripping the line protections, consequently halting the cooking cycle, with the well-known consequences and inconveniences.
  • the induction cooking apparatus in order to optimize the overall efficiency of the process, and it can also use any type of pot available by way of its capacity to detect constantly and in real time the resonance current and therefore adapt the driving of the transistors that constitute the inverter.
  • the apparatus according to the present invention allows to perform so-called sautéing.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Inverter Devices (AREA)
  • General Induction Heating (AREA)
  • Induction Heating Cooking Devices (AREA)
  • Cookers (AREA)
EP02007362A 2001-05-03 2002-04-08 Induktionskochvorrichtung mit verbesserten Merkmalen Withdrawn EP1255421A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI010910 2001-05-03
IT2001MI000910A ITMI20010910A1 (it) 2001-05-03 2001-05-03 Apparecchiatura di cottura ad induzione avente caratteristiche migliorate

Publications (2)

Publication Number Publication Date
EP1255421A2 true EP1255421A2 (de) 2002-11-06
EP1255421A3 EP1255421A3 (de) 2003-09-24

Family

ID=11447582

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02007362A Withdrawn EP1255421A3 (de) 2001-05-03 2002-04-08 Induktionskochvorrichtung mit verbesserten Merkmalen

Country Status (2)

Country Link
EP (1) EP1255421A3 (de)
IT (1) ITMI20010910A1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2059091A2 (de) * 2007-11-12 2009-05-13 Samsung Electronics Co., Ltd. Vorrichtung und Verfahren zur Induktionserwärmung
WO2012125520A1 (en) * 2011-03-14 2012-09-20 Electrolux Home Products, Inc. Electric heating appliance with ac-line filter with low leakage current
EP2571331A1 (de) * 2011-09-15 2013-03-20 Electrolux Home Products Corporation N.V. Induktionsgenerator für Induktionsheizvorrichtungen und Verfahren zum Betrieb eines Induktionsgenerators für Induktionsheizelemente
WO2017019687A1 (en) * 2015-07-27 2017-02-02 Spectrum Brands, Inc. Cooking appliance with direct contact cooking grate
CN104641724B (zh) * 2012-06-01 2017-03-08 伊莱克斯家用产品股份有限公司 一种半桥式感应热发生器和一种用于半桥式感应热发生器的电容器组件

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109798547B (zh) * 2018-12-30 2021-08-03 佛山市顺德区美的洗涤电器制造有限公司 灶具的煲汤方法、装置、灶具及存储介质

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4897518A (en) * 1987-03-06 1990-01-30 Tocco, Inc. Method of monitoring induction heating cycle
US5450305A (en) * 1991-08-12 1995-09-12 Auckland Uniservices Limited Resonant power supplies
US5648008A (en) * 1994-11-23 1997-07-15 Maytag Corporation Inductive cooking range and cooktop
BR9701473A (pt) * 1996-04-22 1998-09-08 Illinois Tool Works Sistema e método para o aquecimento indutivo de uma peça de trabalho e sistema para a aquecimento indutivo segmentado contínuo de uma peça de trabalho

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2059091A3 (de) * 2007-11-12 2009-07-15 Samsung Electronics Co., Ltd. Vorrichtung und Verfahren zur Induktionserwärmung
EP2059091A2 (de) * 2007-11-12 2009-05-13 Samsung Electronics Co., Ltd. Vorrichtung und Verfahren zur Induktionserwärmung
CN103828483A (zh) * 2011-03-14 2014-05-28 伊莱克斯家用产品公司 具有交流线路滤波器的漏电流低的电热器
WO2012125520A1 (en) * 2011-03-14 2012-09-20 Electrolux Home Products, Inc. Electric heating appliance with ac-line filter with low leakage current
CN103828483B (zh) * 2011-03-14 2016-11-09 伊莱克斯家用产品公司 具有交流线路滤波器的漏电流低的电热器
US8921747B2 (en) 2011-03-14 2014-12-30 Electrolux Home Products, Inc. Electric heating appliance with AC-line filter with low leakage current
AU2012307521B2 (en) * 2011-09-15 2015-07-02 Electrolux Home Products Corporation N. V. An induction generator for induction heating devices and a method for the operation of an induction generator for induction heating elements
CN103797894A (zh) * 2011-09-15 2014-05-14 伊莱克斯家用产品股份有限公司 用于感应加热设备的感应发电机以及用于感应加热元件的感应发电机的操作方法
WO2013037791A1 (en) * 2011-09-15 2013-03-21 Electrolux Home Products Corporation N. V. An induction generator for induction heating devices and a method for the operation of an induction generator for induction heating elements
CN103797894B (zh) * 2011-09-15 2015-12-23 伊莱克斯家用产品股份有限公司 用于感应加热设备的感应发电机以及用于感应加热元件的感应发电机的操作方法
EP2571331A1 (de) * 2011-09-15 2013-03-20 Electrolux Home Products Corporation N.V. Induktionsgenerator für Induktionsheizvorrichtungen und Verfahren zum Betrieb eines Induktionsgenerators für Induktionsheizelemente
US9572202B2 (en) 2011-09-15 2017-02-14 Electrolux Home Products Corporation N.V. Induction generator for induction heating devices and a method for the operation of an induction generator for induction heating elements
CN104641724B (zh) * 2012-06-01 2017-03-08 伊莱克斯家用产品股份有限公司 一种半桥式感应热发生器和一种用于半桥式感应热发生器的电容器组件
US9781775B2 (en) 2012-06-01 2017-10-03 Electrolux Home Products Corporation Nv Half bridge induction heating generator and a capacitor assembly for a half bridge induction heating generator
WO2017019687A1 (en) * 2015-07-27 2017-02-02 Spectrum Brands, Inc. Cooking appliance with direct contact cooking grate
CN107920686A (zh) * 2015-07-27 2018-04-17 品谱公司 与烹饪炉箅直接接触的烹饪器具
EP3328249A4 (de) * 2015-07-27 2019-01-23 Spectrum Brands, Inc. Kochgerät mit direktkontaktkochrost

Also Published As

Publication number Publication date
EP1255421A3 (de) 2003-09-24
ITMI20010910A0 (it) 2001-05-03
ITMI20010910A1 (it) 2002-11-03

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