EP0113704A1 - Induktionsheizvorrichtung für mehrere, als Schwingkreise ausgebildete, Belastungen, die vom gleichen Wechselrichter mit Stromeinprägung gespeist werden - Google Patents

Induktionsheizvorrichtung für mehrere, als Schwingkreise ausgebildete, Belastungen, die vom gleichen Wechselrichter mit Stromeinprägung gespeist werden Download PDF

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Publication number
EP0113704A1
EP0113704A1 EP19840400004 EP84400004A EP0113704A1 EP 0113704 A1 EP0113704 A1 EP 0113704A1 EP 19840400004 EP19840400004 EP 19840400004 EP 84400004 A EP84400004 A EP 84400004A EP 0113704 A1 EP0113704 A1 EP 0113704A1
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EP
European Patent Office
Prior art keywords
switch
inverter
inductor
induction heating
loads
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Withdrawn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
EP19840400004
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English (en)
French (fr)
Inventor
Jean-Marie Thouvenin
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.)
Societe dApplications de la Physique Moderne et de lElectronique SAPHYMO Stel
Original Assignee
Societe dApplications de la Physique Moderne et de lElectronique SAPHYMO Stel
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Publication of EP0113704A1 publication Critical patent/EP0113704A1/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Withdrawn legal-status Critical Current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
    • 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 invention relates to heating or induction heating devices for metal products in permanent travel, comprising several oscillating loads, the respective inductors of which are arranged in the path of these products and which are supplied by a single inverter of the current source type.
  • It relates, more particularly, to devices for regulating the power delivered by such an inverter to the oscillating loads which it supplies, each consisting of parallel resonant circuits, in particular as a function of an operating parameter, such as the outlet temperature or product running speed.
  • Such metallic products can be wires, cables, bars, billets or pieces, for example.
  • Such an induction fireside machine may be intended for heat treatment operations, such as surface hardening or annealing, or for preheating for machining, such as forging, extrusion, rolling or forming, for example, of the aforementioned products made of ferrous (steel) or non-ferrous metals or alloys. It is sometimes necessary to have several inductors on the product trajectory, each of them being according to the state of the art supplied by its respective inverter.
  • inverter with current source a DC-AC converter comprising thyristors or rectifiers controlled with unidirectional conduction, preferably connected in bridge (or half-bridge) whose input diagonal is joined to poles of the direct current source via at least one so-called smoothing inductor.
  • the output diagonal of the inverter is, preferably, assembled here at the terminals of at least one parallel resonant circuit, hence also the name of parallel inverter.
  • Inverters of this general type are described, for example, in the publications FR-A-1.311.479, 1.482.472, 1.502.490, 1.602.456, 2.001.919 or 2.228.318, and generally require the use of various starting circuits and / or methods known per se, making it possible to achieve their normal operation at the desired power.
  • a first coil of the inductor, adjacent to the jack, is normally intended to ensure the rise in temperature of the ferritic steel parts. which cross it, from room temperature to the Curie point (magnetic zone), the following coils (non-magnetic zone) used to heat them up to the forging temperature.
  • This first coil is here bypassed by a switch which enables it to be switched off without interrupting the supply of current to the other coils of the inductor.
  • the fireside Downstream of the field field exit, the fireside includes on the one hand, a detector of the presence of an available heated room, which makes it possible to indicate the arrival and removal of a heated room and on the other hand, a pyrometric scope which measures the temperature of the room leaving the oven.
  • a microprocessor respectively coupled to the detector, to the telescope, to the generator, to the actuator control device and switch, can command the closing of the latter to short-circuit the first coil.
  • the microprocessor is considered capable of allowing the modification of the rate of supply of parts to the furnace as a function of that of their removal, indicated by the detector, the maintenance of a constant outlet temperature using the indications provided by the telescope and by acting on the generator, and control of the preheating consecutive to each restart after stopping, because it is possible for it to store in memory the power supplied by the generator before and during stopping, the duration of the latter and perform calculations of the input energy necessary to obtain the forging temperature at the outlet.
  • the switch for short-circuiting the first coil is intended there only to close during a stop and to remain open throughout the normal operating time of the fireside chair. Consequently, this switch is liable to be subjected to significant stresses. Furthermore, the short circuit of one or more coils of a series arrangement of these, has the effect of changing the overall inductance of the inductor and, consequently, the resonance frequency of the oscillating circuit, it is a notable part. This requires the use of a generator controlled by the load which determines the frequency and when the latter is close to its upper limit value (determined, for example, by the recovery time of the thyristors), the operation of the generator at a higher frequency may become uneasy (power reduction), if not impossible. The heating energy supplied by the inductor all whole or by the coils remaining in circuit after closing the inductor is determined only by that supplied by the generator.
  • an induction heating device in which an inverter with voltage source and thyristors connected in half-bridge supplies several loads constituted by series resonant circuits, connected in parallel by the respective intermediary of bidirectional electronic switches, each composed of two thyristors connected head to tail (in antiparallel) or a triac, for example.
  • the power supplied to each load is adjustable by the duty cycle of its connection to the output terminals of the inverter, the bidirectional switches being respectively controlled using rectangular signals of variable duration. It is however necessary to periodically stop the inverter to allow simultaneous blocking of all electronic switches respectively in series with the resonant loads, their respective engagement can be controlled at different times, offset in time to allow obtaining different duty cycles.
  • one of the embodiments of the device recommends the use of the rectangular signal of maximum duration controlling one of the switches to determine the period of operation of the inverter, via a logic "OR" gate receiving all the rectangular signals for controlling the switches.
  • the induction heating device with several parallel resonant loads, supplied by a single inverter with current source, object of the invention, makes it possible to vary independently the power supplied by it to each of the heating inductors.
  • the subject of the invention is an apparatus for induction heating of moving metal products, in which several oscillating charges each comprising a heating inductor connected in parallel with a capacitor, are supplied by a single inverter of the current source type.
  • these loads connected in series between the output terminals of the inverter are respectively connected, in addition, possibly with the exception of one of them, in parallel with electronic switches with bidirectional conduction, which can be periodically controlled to be alternately open and closed, so that the average heating power of the inductors of each load is determined substantially independently, by the duty cycle of its alternating current supply by the inverter with source of current in continuous operation.
  • FIG. 1 is a block diagram of a heating or firing device of the state of the art, comprising an inverter 1 supplied by a rectifier 2 from the three-phase AC network.
  • the voltage of the three-phase alternating network brought to the input of rectifier 2 by cables R, S, T, is generally rectified there at full alternation using diodes or rectifiers controlled of the thyristor type, so as to provide a fluctuating DC voltage on its output.
  • One of the well-known methods for adjusting the average output voltage of rectifier 2 is, for example, by varying the phase delay of the thyristor ignition with respect to the zero crossings of each alternation of the voltage -alternative in each phase (called “AC PHASE CONTROL” in Anglo-American literature and described, for example, on pages 231 to 282 of the 5th edition of the American work entitled “SCR MANUAL”, edited and published by GENERAL ELECTRIC COMPANY in 1977, or on pages 88 to 102 of PEARMAN's American work entitled “POWER ELECTRONICS", published in 1980 by RESTON PUBLISHING COMPANY).
  • AC PHASE CONTROL phase delay of the thyristor ignition with respect to the zero crossings of each alternation of the voltage -alternative in each phase
  • the phase control rectifier can advantageously be! constitutes by a thyristor assembly in "double bridge".
  • the two bridges of such an assembly can then be controlled with a phase offset of 30 electrical degrees, one with respect to the other, so as to reduce the stresses imposed on the supply network. It can also include several bridges associated with each of the phases, which are then respectively controlled with appropriate phase shifts.
  • This average supply voltage of the inverter 1 subsequently determines the alternating power delivered by the latter to the load.
  • Control of phase shift or phase delay is performed by means of a circuit 3, either as a function of a control quantity displayed at its input 30, or as a function of an electric quantity T obtained using a sensor of the thermoelectric transducer type 4 measuring the temperature of the parts 5 which leave the field of the heating inductor 6, for example, by detecting the intensity of the infrared radiation which they emit, or also as a function of the speed of travel of the parts 5 in the field of the inductor 6 which can be given in the form of an analog or digital signal V by the device for transferring or conveying the parts to be heated 7 supplying the device.
  • the oscillating load 8 comprises a capacitor 9 connected in parallel with the latter.
  • the inductor 6 is shown here in series with a resistor 60 which symbolizes the power transferred by induction into the parts 5 and the specific ohmic losses of the parallel oscillating circuit 6-9 occurring in the damping of the latter and contributing to the determination of its effective overvoltage coefficient Q.
  • the output poles (+, -) of the rectifier 2 are respectively connected to the input terminals 11, 12 of the inverter 1 which comprises four thyristors 13, 14, 15 and 16 connected in bridge.
  • the junction of the anodes of the thyristors 13 and 14 is connected to the positive input terminal 11 by means of a smoothing inductor 17 of high value, which has the effect of rendering the inverter 1 of the current source type.
  • the cathodes of the thyristors 15 and 16 are connected together to the negative input terminal 12, either directly or by means of another smoothing inductor (not shown).
  • the junction of the thyristor cathode 14 with the thyristor anode 16 is connected to the output terminal 18 of the inverter 1 and that of the thyristor cathode 13 with the anode of the thyristor 15, to the output terminal 19 inverter 1.
  • the terminals 18 and 19 are respectively connected to those 80 and 81 of the oscillating load 8 which thus joins the diagonal of the alternating output of the thyristor bridge 13, 14, 15, 16.
  • the thyristors 14 and 15 are first simultaneously started, when the current stored in the smoothing inductor 16 and the voltage across the tuning capacitor 9 are sufficient to ensure inverter 1 normal operation (after the conventional start-up process).
  • the oscillating load 8 then begins a half-period of oscillation during which the voltage across the capacitor 9 passes through a maximum and then falls back to zero. A few tens of microseconds before the zero crossing of this voltage, the thyristors 13 and 16 are started and the thyristors 14 and 15 are blocked, thus allowing the oscillation of the oscillating load circuit to continue.
  • the alternating ignition of the two pairs of thyristors 14-15 and 13-16 is respectively controlled by two trigger circuits 145 and 136 of two triggers each.
  • This alternating and periodic triggering must be controlled by the oscillating load 8 according to its resonant frequency clean.
  • a control circuit 100 of the inverter 1 is connected to the output terminals 18, 19, so as to allow the detection of zero crossings of the voltage across the capacitor 9.
  • the inductor 6 can be composed of several inductors connected in series or in parallel. The distribution between them of the power supplied by the inverter which will then depend on the values of the effective inductance and the respective overvoltage coefficients thereof (which in turn depend on the coupling and the magnetic properties of the parts located in the fields various inductors), is not independently adjustable.
  • FIG. 2 is the block diagram of an induction heating apparatus in which two oscillating loads 8 and 83 are connected in series between the output terminals 18, 19 of an inverter of the current source type 1 of FIG. 1 and where the power supplied to the second load 83 can be regulated according to the invention, independently of that supplied to the first 8.
  • FIGS. 3A, 3B, and 3D are diagrams of the waveforms of the currents at various points of the circuit of FIG. 2, while FIG. 3C shows the waveform of the voltage across the terminals of the second load 83.
  • the first load 8 similar to that of FIG. 1, is supplied continuously during the operation of the inverter 1.
  • the power which it receives from it is regulated by means of the control device.
  • phase 32 of the priming of the thyristors of the rectifier 2 preferably, as a function of the running speed of the product to be heated.
  • a second load 83 it may prove necessary to control this power by means of the alternating voltage present between the terminals of its tuning capacitor 9 using a voltage measurement 130 providing a corresponding analog or digital signal, which can be compared with a setpoint variable chosen in particular as a function of the running speed V (or of the temperature T of the product outlet).
  • This comparison makes it possible to generate an error signal by means of which, when applied to the input 33 of the device for controlling the ignition phase 32, the average value of the DC output voltage of the output can be varied rectifier 2, applied to the inputs 11, 12 of the inverter 1, in order to cancel the error signal.
  • the comparison is carried out in a central computing and control unit 140 which here has other functions which are explained below.
  • the second oscillating load 83 which includes a heating inductor 61 with its series resistor 62, connected in parallel with one. capacitor 90, is shunted here by a bidirectional controlled switch 110 comprising thyristors 111, 112 connected head to tail, which has the effect, when open, of connecting the two oscillating loads 8 and 83 in series between the output terminals 18, 19 of the inverter 1 and, when closed, short-circuit the second load 83 so that the second terminal 81 of the first load 8 is substantially directly joined to that 19 of the inverter 1.
  • the two oscillating loads 8 and 83 preferably have substantially the same resonant frequency, so that the alternating voltage wave between the output terminals 18, 19 of the inverter 1, which is used for its autopilot, is substantially sinusoidal . It is however possible to admit a certain difference between the respective resonant frequencies of these loads 8 and 83, but it must be limited to a few tens of percent, for example, of that of load 8, so that the content of harmonics of the resulting voltage wave between terminals 18 and 19 is sufficiently reduced, so that between the beginning and the end of each oscillation period, it comprises only one passage through intermediate zero.
  • the current i supplied by the inverter 1 is represented by FIG. 3A. It has a rectangular or trapezoidal shape.
  • the outputs of this circuit 114 supply rectangular signals applied between trigger and cathode of each thyristor 111 and 112, in order to control them so that they are made alternately conductive and blocked at the same time.
  • the trigger currents i G which they cause are represented by the diagram in FIG. 3B.
  • such a control circuit 114 comprises a generator of periodic pulses of variable duration as a function of an electrical control quantity which depends in particular on the running speed of the product to be heated.
  • a generator can comprise in cascade a clock synchronized with one of the zero crossings of the voltage U 90 between the terminals 84 and 85, represented by the diagram of FIG. 3C (see at instant t 2 ) and a modulator conventional pulse width, triggered by this clock and controlled, as regards the duration of the pulses, using a voltage, for example, which corresponds to the desired average power.
  • the frequency of recurrence of the clock pulses is preferably generally lower than the frequency of the network, in order to reduce the interference due to switching, but the duration of a period T F (see FIGS.
  • alternating switch 110 comprising an opening interval T 0 and a consecutive closing interval T S , must be significantly less than the residence time of a section of the product to be heated in the field of the inductor 61.
  • the operating frequency (1 / T F ) can be chosen less than or equal to 15 Hz.
  • the operating frequency may be chosen equal to or greater than 70 Hz.
  • the residence time of the product in the induction furnace will be obtained by the ratio of the length of the inductor 61 at the running speed V of the product.
  • the opening of the switch 110 by the respective blocking of the thyristors 111 and 112 occurs automatically during the first zero crossing of the output current of the inverter i shown in FIG. 3A, at the instant t ,, which is immediately consecutive to the instant t of the cancellation of the trigger current 0 iG111 / 112 (see FIG. 3B), obtained by the application of a negative or zero trigger-cathode voltage, this is ie at the end of each positive rectangular signal.
  • the power supplied to the second oscillating load 83 is therefore controlled by the duty cycle of its supply, that is to say the ratio T o / T F of the duration of the opening period T o of the switch 110 to that of the operating period T F.
  • the average power supplied to the second load 83 is therefore the product of the maximum power that it receives during the permanent opening of the switch 110 with this duty cycle.
  • the power required to heat a metal product while traveling in the field of an inductor depends on many parameters, such as the transverse dimension (section) relative to that of the inductor, which determines the coupling, the resistivity of the metal or of the alloy, its magnetic properties (permeability) and their variation with temperature (Curie point) and desired production rates, i.e. - say scrolling speed.
  • the power necessary to reach, from ambient temperature, a desired outlet temperature is a function varying almost linearly with the running speed. It is therefore necessary to vary the opening duty cycle of the switch 110 as a function of this speed.
  • the other parameters must be taken into account when calculating the proportionality coefficient.
  • central computing and control unit 140 which is advantageously equipped with a microprocessor and interchangeable read-only memories which are previously programmed as a function of the product to be heated and which, in response to address words corresponding to the running speed V which is sent in the form of an analog voltage to the input 141, provides data corresponding to the average power necessary to reach the desired temperature.
  • a microprocessor and interchangeable read-only memories which are previously programmed as a function of the product to be heated and which, in response to address words corresponding to the running speed V which is sent in the form of an analog voltage to the input 141, provides data corresponding to the average power necessary to reach the desired temperature.
  • the peak (or rms) voltage between the terminals 84 and 85 of the capacitor 90 is measured during the opening periods T of the switch by means of another voltage measuring device 120 which supplies the input 143 of the central computing and control unit 140 an analog or digital quantity making it possible to calculate the peak power and, from this (stored during the periods of closure of the switch 110), the duty cycle ToIT F necessary to obtain the desired outlet temperature as a function of the running speed V.
  • the outlet 145 of the central computing and control unit 140 will then supply a command signal proportional to the calculated duty cycle, at control input 117 of circuit 114 so as to control the duration of the signals rectangular supplied by the thyristor trigger control outputs 111, 112. This gives independent control of the average power supplied by inverter 1 at the second load 83. If the power of inverter 1 varies for the same speed scrolling, the central computer unit 140 will vary the duty cycle in the opposite direction.
  • the power supplied by the inverter 1 to the first load 8 which is continuously supplied can be regulated by varying the average supply voltage of the inverter 1 by varying the phase d priming of the thyristors of the three-phase rectifier 2 as a function of the running speed V.
  • This is also carried out here by means of the central computing and control unit 140, the input 142 of which is connected to the output of the voltmeter 130 and whose output 144 for controlling the overall power of the inverter 1 is connected to the input 33 of the control device 32 of the ignition phase of the rectifier 2.
  • the second oscillating load 83 further comprises an additional inductance 63, called a protection inductor, connected in series with the tuning capacitor 90 between its terminals 84 and 86.
  • the value of this inductance 63 is preferably chosen to be less than one tenth of that of the heating inductor 61, so as to have little influence on the other parameters of this load 83. It makes it possible to protect the thyristors 111, 112 against rates d 'excessive increase in their anode currents (di / dt), when they start, as well as against the excessive rate of rise of their anode-cathode voltage, when they are blocked.
  • this protective inductor 63 forms with the capacitor 90 a parallel resonant circuit whose resonant frequency is significantly higher than that of the load 83.
  • this comprises in series with thyristors 111, 112 mounted head to tail, a resistor damping 113, preferably of low value, in order to limit the power dissipated in pure loss.
  • the damping of the oscillating circuit 90-63-113 being then given by the formula 0.5 R 113 C 90 / L 63 , it will be chosen to be between 0.25 and 0.60.
  • the current i 110 in the switch 110 has been represented by the diagram in FIG. 3D.
  • FIG. 4 represents the block diagram of an embodiment of the heater with several oscillating loads connected in series between the output terminals of a current source inverter, each of which is shunted by a switch controlled to be alternately open and closed, independently.
  • the two oscillating loads 82 and 83 are respectively connected in parallel with two switches 118 and 110 (analogous to that 110 in FIG. 2), each controlled from a central computing and control unit 150 in a similar manner to that described above, for example, for varying the duty cycle of switching on each load 82, 83 as a function of the running speed V of the product to be heated.
  • the two loads 82, 83 shunted by their respective switches 118, 110 being connected in series between the output terminals 18, 19 of the inverter combined with the rectifier 10, it is essential that one of the two loads is connected to the 'Inverter 10, when the other is short-circuited by its associated switch.
  • the central computing and control unit 150 of FIG. 4 must be arranged in such a way that it inhibits the simultaneous closing of the two switches 110, 118, which is achievable by means of logic gates (exclusive OR) , for example.
  • logic gates exclusive OR
  • the regulation of the power delivered to the other load in steady state must be carried out using a control signal from the priming phase of the controlled rectifiers, delivered by the output 154 of this central unit.
  • each of the n or n - 1 loads will be shunted by a power switch at bidirectional conduction, to allow independent adjustment of the power according to the invention.
  • FIGS. 5A and 5B are diagrams of the power to be supplied as a function of the speed V to two oscillating loads connected in series and arranged on the trajectory of billets or of steel plots, in an induction forging firing machine, represented on the Figure 2.
  • the movement of the parts 5 passing through the aligned axes 50 of two solenoidal inductors 61, 6 arranged side by side, is carried out from right to left.
  • the inductor 61 performs the preheating (up to the Curie point) and the heating of the product to the forging temperature and the inductor 6 equips the section for maintaining and homogenizing the temperature of the billets or slips scrolling in his field.
  • the power P 83 or Pc of the preheating and heating section (the inductor 61) varies substantially linearly with the running speed V up to the maximum speed V max '
  • the regulation of the power P83 as a function of the speed V is done here by the variation of the switching duty cycle by the switch 110, that is to say by the control of the duty cycle of the load 83.
  • the power supplying the load 8 ( Figure 2) can be regulated by varying the ignition phase at the rectifier 2 ( Figure 2) as a function of the speed V as in the case of a load single ( Figure 1).
  • the inverter 1 (10) can deliver to the two loads 83, 8 (82) the maximum power (zero phase shift) and the single switch 110 or the two switches 110 and 118 will remain open permanently.
  • the maximum power P Mmax of the holding section (8, 82) will be of the order of a quarter of the maximum power P Cmax of the heating section (83).
  • FIGS. 6A and 6B respectively show diagrams of the variations of the power applied as a function of the running speed at two sections (loads) of a heater of a metal wire (or of a cable) in view of its annealing, for example, arranged according to the block diagram of FIG. 4.
  • FIG. 6A illustrates the theoretical evolution of the power applied to the load 82 (of FIG. 4) which is used only for starting the induction annealing device for catching up the lengths of cable or wire which have not been heated by the heating section constituted by the load 83 (of FIG. 4). It is generally called the "dead end" make-up section and it is located downstream of the heating section, the power of which varies according to the diagram in FIG. 6B.
  • the maximum power that is supplied to the rat- tra p section a g e (P Rmax) is generally less than or equal to one sixth of the maximum power delivered to the heating section (P Cmax).
  • the oscillating load 83 of the heating section receives a linearly increasing power with speed V, the growth of which is determined by that of the duty cycle of switch 110, while the load 82 of the take-up section which remains permanently supplied receives a linearly decreasing power with speed.
  • the power supplied to the catch-up load 82 which decreases linearly is regulated by the phase shift of the priming of the rectifier (2, FIG. 2), up to a speed V (greater than V o ).
  • the heating power was regulated by the duty cycle of the supply of the load 83, using the switch 110 shunting the inductor of heating and the make-up power was regulated by the decrease in the average supply voltage of the inverter 10, that is to say the increase in the phase delay of the ignition of the thyristor-rectifiers, without any closing of the switch 118 bypassing the make-up load 80, the duration of the opening of the switch 110 has increased sufficiently (to compensate for the decrease in the supply voltage of the inverter 10) so that from speed V 1 , the sum of the respective opening times of the two switches 110, 118 is greater than or at least equal to their common operating period (T F , FIGS. 3A to 3D).
  • the duration of the opening of the switch 110 increases linearly with the increase in the speed V, while that of the switch 118 decreases.
  • the opening time T o110 of the switch 110 becomes equal to the operating period T F , while that T o118 of the switch 118 becomes zero.
  • the heating load 83 is therefore continuously supplied, while the make-up load 82 remains short-circuited.
  • the heating power P C supplied to the oscillating load 83 is regulated with a steeper slope, only by the gradual decrease from the tripping delay of the thyristors of the three-phase rectifier to a zero phase shift which corresponds to an average maximum supply voltage of the inverter and, consequently, to a maximum heating power P Cmax , represented in FIG. 6B.
  • the main advantage of the invention is to allow the heating to be easily adapted to the desired production rates, as well as to products of different materials and dimensions.
  • the invention is not limited to the embodiments and operations described and illustrated, given by way of illustrative example, but applies to other induction heating devices with inverter of the current source type which must supply several oscillating loads, each of which must provide independently variable heating power.

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  • Electromagnetism (AREA)
  • General Induction Heating (AREA)
EP19840400004 1983-01-07 1984-01-03 Induktionsheizvorrichtung für mehrere, als Schwingkreise ausgebildete, Belastungen, die vom gleichen Wechselrichter mit Stromeinprägung gespeist werden Withdrawn EP0113704A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8300173A FR2539265A1 (fr) 1983-01-07 1983-01-07 Appareil de chauffage par induction a plusieurs charges oscillantes alimentees par un meme onduleur a source de courant
FR8300173 1983-01-07

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EP0113704A1 true EP0113704A1 (de) 1984-07-18

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ES (1) ES8407640A1 (de)
FR (1) FR2539265A1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2671929A1 (fr) * 1991-01-18 1992-07-24 Thomson Tubes Electroniques Generateur de chauffage par haute frequence.
EP1763285A1 (de) * 2005-09-13 2007-03-14 HWG Inductoheat GmbH Induktionshärtungsanlage
WO2018091248A1 (en) * 2016-11-18 2018-05-24 Compagnie Generale Des Etablissements Michelin Heating a continuously moving wire

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2179697A1 (de) * 1972-04-10 1973-11-23 Matsushita Electric Ind Co Ltd
FR2206644A1 (de) * 1972-11-15 1974-06-07 Matsushita Electric Ind Co Ltd
FR2284245A1 (fr) * 1974-09-06 1976-04-02 Partridge Donald Appareil de chauffage par induction
FR2494953A1 (fr) * 1980-11-21 1982-05-28 Celes Procede de regulation d'une installation de chauffage a induction, notamment pour produits metalliques

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2179697A1 (de) * 1972-04-10 1973-11-23 Matsushita Electric Ind Co Ltd
FR2206644A1 (de) * 1972-11-15 1974-06-07 Matsushita Electric Ind Co Ltd
FR2284245A1 (fr) * 1974-09-06 1976-04-02 Partridge Donald Appareil de chauffage par induction
FR2494953A1 (fr) * 1980-11-21 1982-05-28 Celes Procede de regulation d'une installation de chauffage a induction, notamment pour produits metalliques

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2671929A1 (fr) * 1991-01-18 1992-07-24 Thomson Tubes Electroniques Generateur de chauffage par haute frequence.
US5286941A (en) * 1991-01-18 1994-02-15 Thompson Tubes Electroniques High frequency heating generator having an improved matching network between a tetrode amplifier and a resonant circuit
EP1763285A1 (de) * 2005-09-13 2007-03-14 HWG Inductoheat GmbH Induktionshärtungsanlage
WO2018091248A1 (en) * 2016-11-18 2018-05-24 Compagnie Generale Des Etablissements Michelin Heating a continuously moving wire
FR3058914A1 (fr) * 2016-11-18 2018-05-25 Compagnie Generale Des Etablissements Michelin Chauffage d'un fil en mouvement continu

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FR2539265B1 (de) 1985-03-15
ES528673A0 (es) 1984-09-16
FR2539265A1 (fr) 1984-07-13
ES8407640A1 (es) 1984-09-16

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