ES2362607B1 - MULTIPLEXATION OF INDUCTION HEATING LOADS. - Google Patents

Abstract

Multiplexing of induction heating charges. # A method is provided for multiplexing at least two induction heating loads through an electronic connection device used for each load, where the at least two induction heating loads are inactive during a predetermined time interval by disconnecting the respective electronic connection devices, said predetermined time interval being arranged in a suppression interval with respect to said multiplexing. In addition, a corresponding circuit and a domestic heating device comprising such a circuit are proposed.

Description

Multiplexing of induction heating loads.

The invention relates to a method for multiplexing induction heating loads, a suitable circuit, and a domestic heating device comprising such a circuit.

Domestic induction heating loads can be temporarily multiplexed using two-way unipolar switches, or using two-way bipolar switches. For example, any type of transistor with an intrinsic diode or with an external antiparallel diode can be used. In addition, electronic or electromechanical devices can be used for connection purposes. For example, a triac (triode for alternating current) can be used, in which the triacs are used at low switching frequencies (up to 1 kHz), for example, for motor control or for light reduction purposes.

Figure 1 shows an exemplary group of composite switches, for example, IGBT (bipolar isolated gate transistor), which provide switching frequencies of up to tens of kHz. An arrangement 101 shows a conventional approach comprising two IGBT and two diodes, an implementation 102 represents two reverse blocking IGBT, and an example 103 shows four diodes and a single IGBT implementation.

In addition, the connection can be carried out through electromagnetic relays, which can be incorporated into single-pole unipolar (SPST, or Single Pole Single Throw) or unipolar double-throw (SPDT, or Single Pole Double Throw) configurations. The SPDT configuration allows two multiplexes to be directly multiplexed as shown, for example, in EP 0 971 562.

Figure 2 shows an implementation of SPST and SPDT configurations that use triacs and relays. A column 201 shows schematic symbols, a column 202 shows a relay implementation, and a column 203 shows a triac implementation of SPST and SPDT configurations.

It should be noted that any multiplexing functionality or any routing matrix of increased complexity can be implemented using SPST devices. Figure 3 shows a symbol 301 of a multiplexer (one input and N outputs) and a corresponding implementation 302 using triacs.

Temporal multiplexing requires that loads and inverters be arranged using a routing matrix that is set for low frequency values (below 1 kHz) for a bipolar device such as that triac to function properly. The bipolar device, however, when connecting at low frequencies, needs to allow high frequency currents (in the order of tens of kHz) to be passed through said device. In addition, a voltage across the triac can vary rapidly (in the order of tens of kHz) during the triac blocking state; In this case, the triac needs to block the oscillating voltages without any significant leakage.

Figure 4A shows a low frequency application of a triac 401, which is arranged in series with an inductive load comprising an inductor 402 and a resistor 403. The inductive load is connected to an AC voltage of switching frequency of 50/60 Hz through said triac 401, where the triac 401 performs a phase control. The frequency of the current flowing through the triac and the switching frequency of the device are the same.

Figure 4B shows a circuit behavior of Figure 4A in case of a mainly resistive load (R >> ωL). Operation of the triac 401 is delayed based on a delay Δθ introduced in the form of a door control wave with respect to the zero crossing of the current. A disconnection of the triac 401 takes place at the next zero crossing of the current after the gate signal vG of the triac has been deactivated. The triac remains disconnected until said gate signal vG is activated again.

Figure 4C shows a circuit behavior of Figure 4A in case of a mainly inductive load (R << ωL). Here, a gap between the voltage across the inductor vL and the current iL takes place, and a transient oscillation of the significant voltage dvL / dt may be apparent at the moment when the current is removed from the circuit. Such a transient oscillation of the voltage dvL / dt can lead to a deficient activation of the triac 401. To avoid this problem, an RC damping circuit is arranged in parallel with the triac to reduce any such transient voltage oscillations. In addition, manufacturers introduced triacs without a shock absorber that face high dv / dt values.

The problem to be solved is to overcome the above-mentioned disadvantages and, in particular, to provide an effective approach to control connection devices, in particular triacs, when they are used for temporary multiplexing of domestic induction heating loads.

This problem is solved in accordance with the characteristics of the independent claims. Other embodiments result from the dependent claims.

In order to overcome this problem, a method is provided for multiplexing at least two induction heating charges through an electronic connection device used for each load,

-

where the at least two induction heating loads are inactive for a predetermined time interval by disconnecting the respective electronic connection devices,

-

said predetermined time interval being arranged in a suppression interval with respect to said multiplexing.

Therefore, the suppression interval is provided between induction heating loads that are active (for example, alternately). For example, if an induction heating load is deactivated, and another induction heating load is activated using said multiplexing, said suppression interval does not determine a duration for any of the induction heating loads that are activated. The electronic connection devices can be deactivated during the entire period of this suppression interval

or during a part of it.

This advantageously avoids or reduces any transient oscillation that may lead to erroneous activation of the electronic connection device, and effectively reduces or eliminates the current of the induction heating load.

Said multiplexing can provide alternating activation of one or more induction heating charges. In particular, if at least one induction heating load is active, at least one other induction heating load may be inactive (for example, all remaining induction heating loads may be inactive). In this respect, "inactive" means that there is no activation through the electronic connection device arranged for this respective induction heating load. Therefore, "active" means that the connection device activates its associated induction heating load.

As indicated, an electronic connection device can be provided for each induction heating load. Thus, this electronic connection device can activate / deactivate its induction heating load and thus allow multiplexing between several induction heating loads. Multiplexing can be controlled by a central control unit that activates and / or deactivates the electronic connection devices accordingly.

It is also an option that more than one induction heating load is associated with an electronic connection device.

In one embodiment, a converter that drives the at least two induction heating charges is disconnected at least partially during the predetermined time interval.

Said converter can control the induction heating load and the electronic connection device, where the electronic connection device and the induction heating load are connected in series. The converter can control several such induction heating loads with its associated electronic connection devices. Said induction heating load and the electronic connection device can be understood as a unit, where several such units are connected in parallel with one another, and are operated by said converter. The converter may comprise at least one electronic switch that is controlled by a central control function.

Advantageously, said converter is disconnected during said predetermined time interval, in particular, during said suppression interval.

In another embodiment, said converter is disconnected for the duration of the suppression interval.

Therefore, said converter is disconnected in the event that no load is being connected to it. This effectively allows any current stored in a capacitor at the input of said converter to be discharged. Such a capacitor may, in particular, be a film capacitor arranged behind a rectifier before said converter. Therefore, a supply direction of the at least one induction heating load can be perceived from a power source (for example, an AC voltage supply) through a filter and a rectifier through said capacitor to the converter, and continuing to the induction heating load that is driven by said converter. As described above, each induction heating load comprises an electronic connection device (connected in series with said induction heating load), which is used to multiplex several such induction heating loads.

In another embodiment, said converter is a half-bridge resonant inverter or a full-bridge resonant inverter, where induction heating loads are, in particular, connected to the output of said converter.

Advantageously, the resonant inverter allows efficient operation of said various induction heating loads. When a particular induction heating load is active (multiplexed), the converter can supply various modulation parameters depending on the actual connected load, and the target requirement or value set, for example, by a user of a domestic heating device. Therefore, the parameters may be different for each active multiplexing cycle, that is, for each period of time that is associated with a particular induction heating load.

In a following embodiment, the at least one induction heating load is connected to a central socket between switches of said converter.

It is also an embodiment that said electronic connection device comprises at least one of the following components:

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a triac;

-

a triac without shock absorber;

-

a transistor;

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a MOSFET (semiconductor metal-oxide field effect transistor);

-

an IGBT (isolated bipolar gate transistor).

Such connection devices are used in particular to temporarily multiplex several induction heating charges, in which each such induction heating load is activated and deactivated through its electronic connection device. It should be noted that the electronic connection device can activate the respective induction heating load, and the output signal provided by the converter can be used to control modulation parameters depending on the actual induction heating load. It should be noted, in particular, that, through said multiplexing, only one induction heating load can be activated during a given time interval, while the other induction heating loads are deactivated by said electronic connection devices. Also, several induction heating charges can be activated during said given time interval.

In relation to another embodiment, the predetermined time interval is sized such that a capacitor that is arranged at the input of the inverter can be substantially discharged during said predetermined time interval.

Therefore, any transient oscillation that may come from the charge of this capacitor can be reduced and / or eliminated. In particular, any charge accumulating effect that may result in a significant transient oscillation is effectively avoided by means of said predetermined time interval by disconnecting the electronic connection devices (and the converter).

The problem described above is further resolved by means of a circuit that comprises

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at least two induction heating charges that are controlled by an electronic connection device, wherein said at least two induction heating charges are being multiplexed;

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a control unit for operating said electronic connection devices in such a way that the at least two heating loads are inactive for a predetermined time interval, the respective electronic connection devices being disconnected, where said predetermined time interval is arranged in a range of suppression with respect to said multiplexing.

According to one embodiment, a converter is provided to drive the at least two induction heating loads, where the converter is disconnected at least partially during the predetermined time interval, in particular, during the duration of the suppression interval.

According to another embodiment, the converter is a full-bridge resonant inverter or a half-bridge resonant inverter.

The problem set out above is further solved by means of a domestic heating device comprising the circuit as described herein.

In the following figures, embodiments of the invention are shown and schematically illustrated:

Fig. 5 shows an exemplary triac exciter circuit, where a generator produces a square wave that is supplied to an optical coupler to control said triac;

Fig. 6 shows another example of a triac driver circuit, where a generator is connected to a primary side of a transformer, whose secondary side is connected to the door of said triac;

Fig. 7 shows a circuit diagram using triacs as load multiplexing devices, where a series resonant inverter powered by semipuence voltage provides multiple outputs that are multiplexed by said triacs;

Fig. 8 shows an equivalent circuit scheme for the inverter topology illustrated in Figure 7, where a pulsing DC voltage is supplied to a modulator, which is also fed by a generator signal to provide a modulated output signal to drive various branches of induction heating loads;

Fig. 9 shows timing charts representing waveforms of currents and voltages represented in Figure 8;

Fig. 10 shows timing graphs illustrating current and voltage waveforms illustrated in Figure 8, associated with triac behavior in a conductive state;

Fig. 11 shows timing graphs based on the circuits illustrated in Figure 7 and Figure 8, where a disconnection period T0ff between the multiplexing segments is provided to avoid a transient oscillation of the current.

Figure 5 shows an exemplary triac driver circuit with a triac 501 (comprising terminals T1, T2, and a gate G), where a generator 506 produces a square wave that is supplied to an optical coupler 505 comprising a photodiode 504 and an optotriac 503. The generator 506 is connected to the photodiode 504 of the optical coupler 505, and the optotriac 503 is connected to the door of the triac 501 and, through a resistor 502, to the terminal T2 of the triac 501.

The triac 501 is driven by said generator 506 through the optical coupler 505. A main current i2 is used to introduce the gate current iG required to drive the triac 501, where said gate current iG is limited by the resistor 502. When the triac 501 is connected, the current i2 'through the triac 501 ascends to i2, where the current iG amounts to 0 due to the lower impedance presented in this path.

The signal from generator 506 can be a two-level waveform that indicates the duration of the driving state. At the moment i2 ’= 0, if the voltage vG at the door of the triac 501 is in an elevated state, the current i2 can again flow to the door of the triac 501.

It should be noted that optotriac 503 is connected between the door and terminal T2 of triac 501. This optotriac 503 can be perceived as an activating circuit in this example.

Figure 6 shows another example of a triac driver circuit with a triac 601 (comprising terminals T1, T2, and a gate G). A generator 604 is connected to a primary side 603 of a transformer, whose secondary side 602 is connected through the Gyla terminal T1 of said triac 601.

The transformer is used as an activating circuit. A short pulse provided by generator 604 is used to introduce a required current into gate G of triac 601. Preferably, small transformers (small available dv / dt) can be used to transport short pulses to the secondary side; the activation pulse can be repeated continuously during a triac 601 connection interval, in particular, essentially at the zero crossing of the current i2 ’.

Figure 7 shows a circuit scheme that uses triacs as load multiplexing devices, where a series resonant inverter powered by semipuence voltage provides multiple outputs that are multiplexed by said triacs.

A power supply 701 provides an AC voltage that is supplied to a fi lter 702 and a rectifier 703 resulting in a pulsing DC voltage that is filtered by a capacitor 704. The filtered DC voltage is connected to a semi-source comprising two switches 706 and 707 , where each switch 706, 707 has a buffer capacitor connected in parallel (Csnb1, Csnb2). A triac 708 is connected in series with a load 711, a triac 709 is connected in series with a load 712, and a triac 710 is connected in series with a load 713. Each such load comprises a serial connection of an inductor and a resistor (for example, inductive heating element). The serial connections comprising triac 708, load 711, triac 709, load 712, and triac 710, load 713 are connected in parallel with each other, and are connected through a central socket between said switches 706, 707, and a central socket between two capacitors 714 and 715, which are connected in series and connected to the pulsating DC voltage. Capacitors 714 and 715 can be resonant capacitors, for example, that amount to Cres / 2 each.

Switches 706, 707 are operated by a control and driver unit 705 by means of signals Q1 (for switch 706) and Q2 (for switch 707).

The inverter topology of Figure 7 comprises said series resonant inverter powered by semipuence voltage that delivers power to N domestic loads of induction heating 711 to 713. Each load 711 to 713 is activated at particular (different) intervals by its triac 708 to 710 respectively.

The example in Figure 7 shows a common resonant capacitor 714, 715 for all loads 711 to 713, although particular resonant capacitors can be arranged for each load 711 to 713.

A similar scheme can be applied for a complete bridge topology using an individual series resonant capacitor, which ascends to Cres, instead of two separate capacitors 714 and 715.

When one of the loads 711 to 713 is connected to the inverter, an equivalent circuit according to Figure 8 can be represented.

Figure 8 shows a pulsing DC voltage 801 that is supplied to a modulator 803. Also, a signal from a generator 802 is supplied to said modulator 804. The output signal of modulator 804 is supplied to a branch A comprising a connection in series of a triac 804, a load 806 and a resonant capacitor 808. A ground is connected to the DC voltage 801, the generator 802, the modulator 803 and the remaining plug of the capacitor

808

Likewise, a branch B is indicated comprising a serial connection of a triac 805 and a load 807 which is connected through the resonant capacitor 808 to ground.

Each load 806, 807 comprises a series connection of an inductor and a resistor (inductive heating element).

The generator 802 can supply a square wave signal to modulator 803. Modulator 803 can provide a signal modulated by amplitude.

The modulator 803 modulates, in particular, the pulsing DC voltage signal at a frequency that can be twice (greater than) the main frequency. As a carrier frequency, a square wave [unipolar or bipolar can be used depending on the topology of the circuit, ie semipuente (unipolar) or full bridge (bipolar) topology]]. This carrier frequency corresponds to the input signal of the inverter according to Figure 7.

The amplitude modulated signal is connected to an 806 (or 807) series resonant load, which comprises the induction heating load, and to the common resonant capacitor.

The behavior of triac 708 to 710 or 804, 805 can be illustrated as follows:

Triac in locked state:

If the triac 804 is in a CONNECTED state, the parallel triac 805 is in a DISCONNECTED state, thereby blocking a load voltage vL in the case of a commonly shared resonant capacitor 808 (or blocking an output voltage vO in the case of a individual resonant capacitor, not shown in Figure 8).

Figure 9 shows exemplary voltage waveforms across the triac for the blocking state, based on the circuit in Figure 8.

In order to maintain the blocking state of the triac 805, a maximum dv / dt value should not be exceeded through terminals T2 and T1 of the triac 805. Otherwise, the triac 805 may be connected in error due to a wrong activation. A voltage vL through load 807 and an output voltage vO of modulator 803 can produce contours with spikes based on the connection speed of the inverter and based on the shock absorber capacitors CSNB1, CSNB2. Therefore, the inverter can be adapted to avoid reaching or exceeding such a maximum dv / dt value.

Preferably, the inverter can operate in a ZVS mode (zero voltage switching, or zero voltage switching), that is, the buffer capacitors CSNB1, CSNB2 can be sized sufficiently large. Also, a cut-off switch current value may be limited under expected operating conditions.

In addition, a high dv / dt value can be produced in case the triac 805 is in the OFF state, and all loads are disconnected from the inverter. Therefore, the CSNB1, CSNB2 buffer capacitors are being continuously charged and unloaded. The effective load of the inverter results in a high impedance resistive load. As a result, all triac block the output voltage vO, which is a square waveform with peaks with a high dv / dt value. Preferably, this situation can be avoided by avoiding any mode of operation such that in it the inverter does not experience any real load. Therefore, in the event that no load is connected to the inverter, the modulation of the inverter can be disconnected.

Also, in case of discontinuous operation of the inverter, capacitor 704 cannot be completely discharged at the beginning of a subsequent active time interval. Therefore, during several cycles of the inverter being repeatedly active, transient oscillations of the voltage at the output of the inverter can be generated. The higher the capacitor voltage 704 is set, the greater the risk with respect to potential transient oscillations (dv / dt values). Such generation of transient oscillations (dv / dt) can be reduced at least partially (in particular, avoided) by discharging (at least partially) the capacitor 704 before a subsequent cycle, or in case the remaining voltage of the capacitor 704 is sufficiently little.

Triac in driving state:

Figure 10 shows waveforms that illustrate triac behavior during a CONNECTED state, that is, in the case that a load is being connected. After each cycle (with an adjustable delay), the load is connected to the inverter.

Figure 10 illustrates a load current iL, which is also the current that flows through triac 804. It should be noted that a high frequency current generated by the inverter is visible in triac 804. For di / dt values elevated, the triac 804 may react differently compared to low frequency applications.

To DISCONNECT the triac 804, the envelope of the current iL needs to approach zero to ensure iL = 0 and diL / dt = 0. Thus, for high current frequencies, disconnecting the triac 804 depends more on the low frequency envelope of the current than on the value of the instantaneous current.

To ensure an effective disconnection of the triac 804, the current envelope needs to reach almost zero, as shown in the bottom of Figure 10. Since the current iL depends on the vbus voltage through the capacitor 704 (see Figure 4), vbus needs to reach zero as well. This requirement can be met if capacitor 704 is (essentially) completely discharged at the end of each cycle without any (considerable) amount of voltage remaining in this capacitor 704.

The value of capacitor 704 affects the high frequency currents and any decoupling effect between the rectifier 703 and the inverter. Therefore, the capacitor value cannot be arbitrarily reduced. The approach provided here suggests in particular to ensure that the triac 804 is OFF to disconnect the modulator, and to ensure iL = 0, as well as diL / dt = 0.

Control scheme:

To effectively control the triac in a multiplexing application, the following control scheme can be applied. This avoids any incorrect triac activation based on high transient dv / dt oscillations. In particular, the approach suggests effectively reducing transient di / dt oscillations.

Figure 11 shows timing charts based on the circuits illustrated in Figure 7 and Figure 8. Signal Q1 shows control of switch 706, signal Q2 shows control of switch 707, signal 1101 shows the control signal for triac 708 , signal 1102 shows the control signal for triac 709, signal 1103 shows the control signal for triac 710, vbus is the voltage across capacitor 704, iL1 is the charging current for load 711, iL2 is the load current for load 712, and iLN is the load current for load 713.

The signals Q1 and Q2 represent the control waveform applied to inverter switches 706, 707. These may be based on an arbitrary modulation scheme. The signals 1101 to 1103 represent activation signals for each of the triac multiplexers 708 to 710. The vbus voltage corresponds to the voltage waveform rectified at a frequency that can rise, in particular, to 100/120 Hz. iL1 aiLN signals represent the waveforms of the load current.

Each load 711 to 713 is connected to the inverter an arbitrary number of half cycles periodically. The inverter is controlled by different modulation parameters (TS, N, TON, N, tm, N), depending on the respective load connected to it.

To avoid any defective activation of any triac, it may be advantageous to DISCONNECT the triac and ensure that the modulation signal of the inverter Qi is disconnected during a TOFF time interval around the vbus voltage that passes through 0 volts. This allows to obtain iL = 0ydiL / dt = 0 in return.

The TOFF interval can be sized extensively enough to allow the triac to disconnect.

Other advantages:

The solution proposed here uses triacs in high frequency applications such as domestic induction heating devices. Otherwise, the use of such triacs as multiplexer elements would not be feasible.

The approach using triacs allows a sufficiently high switching frequency, as required by the application (about 1 kHz).

Another advantage is that, due to the arrangement of triacs, no acoustic noise is produced during connection.

Claims (12)

1. Method for multiplexing at least two induction heating charges through an electronic connection device used for each load;

-

where the at least two induction heating loads are inactive for a predetermined time interval by disconnecting the respective electronic connection devices,

-

said predetermined time interval being arranged in a suppression interval with respect to said multiplexing.

2.

Method according to claim 1, wherein a converter that drives the at least two induction heating charges is disconnected at least partially during the predetermined time interval.

3.

Method according to claim 2, wherein said converter is disconnected for the duration of the suppression interval.

Four.

Method according to any one of claims 2 or 3, wherein said converter is a semi-bridge resonant inverter or a full-bridge resonant inverter, wherein the induction heating loads are, in particular, connected to the output of said converter.

5.

Method according to claim 4, wherein the at least one induction heating load is connected to a central socket between switches of said converter.

6.

Method according to any of the preceding claims, wherein said electronic connection device comprises at least one of the following components:

-

a triac (triode for alternating current);

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a triac without shock absorber;

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a transistor;

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a MOSFET (semiconductor metal-oxide field effect transistor);

-

an IGBT (isolated bipolar gate transistor).

7. Method according to any of the preceding claims, wherein the predetermined time interval is sized such that a capacitor that is disposed at the input of the inverter can be substantially discharged during said predetermined time interval. 8. Circuit comprising

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at least two induction heating charges that are controlled by an electronic connection device, wherein said at least two induction heating charges are being multiplexed;

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a control unit for actuating said electronic connection devices in such a way that the at least two heating loads are inactive for a predetermined time interval, the respective electronic connection devices being disconnected, where said predetermined time interval is arranged in a range of suppression with respect to said multiplexing.

9.

Circuit according to claim 8, comprising a converter for driving the at least two induction heating loads, wherein the converter is disconnected at least partially during the predetermined time interval, in particular, for the duration of the suppression interval.

10.

Circuit according to any of claims 8 or 9, wherein said converter is a full-bridge resonant inverter or a semi-bridge resonant inverter.

eleven.

Domestic heating device comprising the circuit according to any one of claims 8 to 10.

SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 200930631 SPAIN Date of submission of the application: 27.08.2009 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: H05B6 / 06 (2006.01) RELEVANT DOCUMENTS

Category

Documents cited Claims Affected

X

EN 2265758 A1 (BSH ELECTRICAL APPLIANCES SPAIN) 16.02.2007, the whole document. 1-11

X

ES 2028923 T3 (THOMSON ELECTROMENAGER S.A.) 16.07.1992, column 1, lines 21-37; column 2, line 50 - column 3, line 14; figures. 1-6,8-11

X

AU 537649 B2 (WHITE WESTINGHOUSE CORP) 05.07.1984, description; page 10, lines 21-29; figures. 1-11

TO

EN 2273400 T3 (BRANDT IND) 01.05.2007, the whole document. 1-11

TO

US 6370046 B1 (NEBRIGIC DRAGAN DANILO et al.) 04.09.2002, summary; column 17, lines 41-50; column 33, lines 1-3; figures. 1-11

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 27.06.2011

Examiner M. López Sabater Page 1/4

REPORT OF THE STATE OF THE TECHNIQUE Application number: 200930631 Minimum documentation searched (classification system followed by classification symbols) H05B Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC State of the Art Report Page 2/4  WRITTEN OPINION Application number: 200930631 Date of Completion of Written Opinion: 06.27.2011 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 1-11 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 1-11 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986).  Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/4  WRITTEN OPINION Application number: 200930631 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

ES 2265758 A1 (BSH ELECTRICAL APPLIANCES SPAIN) 02/16/2007

2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement Claim 1: It can be considered that the state of the art document closest to this first claim is document D01, in which a method for multiplexing at least two induction heating loads is disclosed through an electronic connection device used for each load and where the at least two induction heating loads are inactive for a predetermined time interval, the respective electronic connection devices being disconnected, said predetermined time interval being arranged in a suppression interval with respect to said multiplexing. (Read column 3 of D01, of lines 11 to 15, as well as its ninth claim) Therefore, this first claim is not new in the sense established by article 6 of Patent Law 11/86. Claims 2 to 7: These dependent claims also see their novelty annulled by document D01 as can be seen from reading their description, as well as their figures. Claim 8: Document D01 discloses all the circuit elements to be protected in this independent claim. Therefore, D01 also cancels the novelty of this claim. Claim 9: These dependent claims of claim 8 are anticipated in document D01 of the prior art, so they lack novelty. State of the Art Report Page 4/4