EP1361780B1 - Induction cooking module and control method of the module - Google Patents

Abstract

The cooking module has two inductors fed from inverters receiving rectified public supply. Each of the inductors has two independent windings (IND1,IND1') and (IND2,IND2') and the inverters have two arms (B1,B2) with electronic switching (T1,T1'T2,T2'). Electromagnetic switching (RL1,RL1'RL2,RL2') connects the inductor windings and capacitors (C1,C1'C2,C2') to the rectified supply either individually or in series.

Description

The present invention relates to an electric induction cooking module as defined in the preamble of the first claim.

The invention also relates to a method for controlling such a module.

State of the art - current solutions

Multi-fireplace induction cooking systems (2 or 4) in the consumer market use, for the most part, the architecture of Figure 1A.

The elementary module consists of two inductors I1, I2 and two generators G1, G2, each of these generators supplying an inductor and one. For a 4-burner hob, two modules are used. In single-phase networks with voltages greater than 200 V (Europe), the undeniably most suitable electronic generator for the application is the resonant inverter G of Figure 1B. The resonance is introduced by associating with the inductor, of naturally inductive nature, capacitors C1 and C2, typically of a few hundred nF, to achieve a nominal operating frequency of about twenty kHz, with the following technologies: Current inducers say "pancake". The power supplied to the inductor is adjusted by varying the control frequency of the inverter.

A major problem appears when one wants to realize the module comprising two inductors and two generators. The powers delivered by the two hearths must be able to be regulated independently. If different control frequencies are applied simultaneously to the two parts of this module, due to the electrical coupling of the two inverters by a single continuous supply line, phenomena of frequency beating which are extremely troublesome for the device are shown. user and must be eliminated.

• la première consiste à découpler électriquement les deux générateurs (onduleurs) à l'aide de filtres passifs (inductances et condensateurs),
• la seconde est une option de commande qui conduit à faire fonctionner en alternance les deux générateurs à des fréquences de quelques Hz (figure 2) en synchronisme avec la tension secteur redressée qui alimente classiquement les générateurs. Il existe donc deux fréquences dans le système, la fréquence de fonctionnement propre des onduleurs (>20kHz) et la fréquence à laquelle on autorise cycliquement ce fonctionnement.

Two association and control techniques are mainly implemented today:

• the first is to electrically decouple the two generators (inverters) using passive filters (inductors and capacitors),
• the second is a control option that leads to operate alternately the two generators at frequencies of a few Hz (Figure 2) in synchronism with the rectified mains voltage that typically powers the generators. So there are two frequencies in the system, the own operating frequency of the inverters (> 20kHz) and the frequency with which this operation is cyclically authorized.

Figure 2 shows in the top line the voltage applied to the generator G1 and in the bottom line the voltage applied to the generator G2.

Considering the typical example of a two-burner module connected to a 230V-16A standard receptacle, it is theoretically possible to have a total power of 3.7kW. Meanwhile, to benefit from high cooking performance, the trend is to allow the almost complete allocation of this power to a single household (3kW). The previous techniques then require the use of two inverters 3kW, an installed electronics with an overall power of 6kW, compared to the maximum power of 3.7kW manageable by the module. This technique is described in GB 2 348 750 (or FR 99 04 450) JAEGER REGULATION, constituting the state of the closest technique).

Presentation of the invention

The object of the present invention is to develop an induction electric cooking module of the corresponding type above, making it possible to better use the electronics and, above all, to be able to dispose of one or the other of the two foci in the case in question. of a module with two homes, the maximum power available.

• chaque inducteur est formé de deux bobinages indépendants,
• chaque générateur est formé de deux bras,
  • * formés chacun de deux interrupteurs électroniques montés en série entre les deux bornes d'alimentation du réseau et le point de jonction des deux interrupteurs électroniques est un point de branchement relié à un bobinage de chacun des deux inducteurs,
  • * à chaque bobinage est associé un condensateur de résonance placé en série formant un ensemble dont
    • l'une des deux bornes est connectée à l'un des bras et
    • l'autre borne est connectée à un moyen de commutation pour être reliée directement à l'une des bornes de l'alimentation (état direct) ou à la borne homologue de l'autre ensemble du même inducteur (état pont),
    • les moyens de commutation des deux inducteurs sont couplés pour ne pas prendre le même état en même temps.

For this purpose, the invention relates to an induction cooking module of the type defined above, characterized in that

• each inductor is formed of two independent windings,
• each generator is formed of two arms,
  • each formed of two electronic switches connected in series between the two supply terminals of the network and the junction point of the two electronic switches is a connection point connected to a winding of each of the two inductors,
  • * at each winding is associated a resonance capacitor placed in series forming a set of which
    • one of the two terminals is connected to one of the arms and
    • the other terminal is connected to a switching means to be connected directly to one of the terminals of the supply (direct state) or to the homologous terminal of the other set of the same inductor (bridge state),
    • the switching means of the two inductors are coupled to not take the same state at the same time.

The mounting of the cooking module according to the invention is perfectly symmetrical to a double title first at each level. home and between the two homes. This makes it possible on the one hand to produce totally identical and interchangeable circuits and, on the other hand, it reduces the power of the two electronic switches associated with each inverter arm. At the industrial level, this translates into considerable savings both in the cost of components and in manufacturing and storage. Even so, every household can operate at maximum power.

Next another interesting feature? the switching means of the two coils of the same inductor are controlled in the same way, the coils (and their resonance capacitors) of a focus being connected directly to one of the terminals of the power supply and the coils (and their resonance capacitors) of the other furnace being bridged between the two arms of the same generator.

According to another interesting feature the two arms of the same generator are controlled in phase or in phase opposition.

According to another advantageous characteristic, the switching means is provided with a passage resistance.

In this assembly, each electronic switch is provided with an antiparallel diode and a capacitor for switching assistance.

In the cooking module, the switching means are controlled in the same way, the two coils associated with their resonance capacitor of a focus being each connected directly to one of the two terminals of the power supply and the two associated coils to their resonance capacitor of the other focus being connected in series between the two arms (bridge state).

In a particularly advantageous manner, the two arms of the same generator are controlled at the same frequency in phase or in phase opposition.

According to another characteristic, the adjustment of the power of the hearth in the direct state is carried out by the adjustment of the switching frequency and the setting of the hearth in the bridge state is effected by the adjustment of the respective durations of the controls in phase or in opposition of phase.

For operation, the fully inactive state of one focus, the other operating, is achieved by placing it in the bridge state and continuously maintaining control in phase.

Finally, in general, the inductors of a home can be constituted by 2n coils.

drawings

• La figure 1A est un schéma d'un module de cuisson par induction à deux foyers selon l'art antérieur,
• la figure 1B est un schéma d'un générateur élémentaire associé à l'un des inducteurs des foyers de la figure 1,
• la figure 2 est un diagramme montrant l'alternance de la commande des deux générateurs du module de cuisson de la figure 1 selon l'art antérieur,
• la figure 3 montre le schéma d'un bras d'onduleur associé à un inducteur,
• la figure 4 montre l'état de branchement direct d'un bobinage et de son condensateur de résonance,
• la figure 5 montre l'état de branchement en pont de deux bobinages d'un même inducteur et de leur condensateur de résonance,
• la figure 6 représente la commande des bras en phase et en opposition de phase,
• la figure 7 est un schéma d'un module de cuisson à deux foyers selon un exemple de réalisation de l'invention,
• la figure 8 représente l'une des configurations du schéma de réalisation de la figure 7 dans laquelle l'inducteur I1 est dans l'état direct et l'inducteur I2 est dans l'état pont.

The present invention will be described hereinafter with the aid of an exemplary embodiment shown in the accompanying drawings as well as diagrams explaining the prior art.

• FIG. 1A is a diagram of a two-fired induction cooking module according to the prior art,
• FIG. 1B is a diagram of an elementary generator associated with one of the inductors of the foci of FIG. 1,
• FIG. 2 is a diagram showing the alternation of the control of the two generators of the cooking module of FIG. 1 according to the prior art,
• FIG. 3 shows the diagram of an inverter arm associated with an inductor,
• FIG. 4 shows the state of direct connection of a winding and its resonance capacitor,
• FIG. 5 shows the state of bridge connection of two coils of the same inductor and their resonance capacitor,
• FIG. 6 represents the control of the arms in phase and in phase opposition,
• FIG. 7 is a diagram of a cooking module with two burners according to an exemplary embodiment of the invention,
• FIG. 8 represents one of the configurations of the embodiment of FIG. 7 in which the inductor I1 is in the direct state and the inductor I2 is in the bridge state.

Description of the embodiments

According to Figure 3, the inductor (I1, I2) of the cooking module is divided into two independent windings of which one IND1 is shown. This winding IND1 is connected by a terminal to the electronic switches T1 and T2 of one of the two arms which receive the control signals S1 and S2. These electronic switches comprise in parallel a capacitor and a diode unreferenced. The other terminal of the winding is connected in series with the resonance capacitor C1. Downstream of the capacitor C1, the assembly comprises a switch RL1 which, in position P1, directly connects the assembly consisting of the coil IND1 and the resonance capacitor C1 to one of the terminals of the supply; in P2 position it connects the same set to the peer P2 output of the switch of the other winding associated with the same household. It is then a bridge mounting and the operation of this assembly depends on the difference of the voltages delivered by each of the two arms of the generator.

In general, using a writing with the index i, each inductor (Ii) is formed of two independent windings (INDi, INDi ') and each generator is formed of two arms (Bi, Bi + 1).

The arms Bi are each formed of two electronic switches (T1i, T2i) connected in series between the two supply terminals (L1, L2) of the network and the junction point (Ai) of the two electronic switches is a connected branch point. to a winding (IND1) and (IND2) (respectively IND1 'and IND2') of each of the two inductors (I1, I2).

• l'une des deux bornes est connectée à l'un des bras (Bi) et
• l'autre borne est connectée à un moyen de commutation (Rli) pour être reliée directement à l'une des bornes de l'alimentation (état direct) ou à la borne homologue de l'autre ensemble du même inducteur (état pont).

At each winding (INDi) is associated a resonance capacitor (Ci) placed in series forming a set of which

• one of the two terminals is connected to one of the arms (Bi) and
• the other terminal is connected to a switching means (Rli) to be connected directly to one of the terminals of the supply (direct state) or to the homologous terminal of the other set of the same inductor (bridge state).

Finally, the switching means (Rli) of the two inductors (I1, I2) are coupled so as not to assume the same state at the same time.

Figure 4 shows the first case of direct connection of the IND winding 1 which can then receive all the available power.

FIG. 5 shows the case of the bridge connection of two inverter arms B1 and B2, associated with the two windings IND1, IND1 'of the same inductor I1 and their resonance capacitor.

The timing diagram of FIG. 6 represents the control of the voltages VA, VB, either in phase or in phase opposition, which mainly concerns the operation of the inductor mounted in a bridge. For a phase control the terminals of the assembly consisting of the two windings and the two bridge-connected resonance capacitors receive the same voltages VA and VB so that the difference of these two voltages applied to the set is zero and that there is no current flowing through it. The windings IND1, IND1 'then provide no energy to the container

For an anti-phase control, the difference of the two voltages applied to the set is an alternating voltage to the frequency of the control signal S (typically 10kHz) and the windings IND1 and IND1 'can supply energy to the container

The combination of an inverter arm and a coil of a fireplace makes it possible to produce a cooking module with two perfectly symmetrical fireplaces, which is very interesting for the practical realization because the electronic switches of the arm can be sized for half of the maximum power of a home since the other half of the power is supplied by the other arm of the generator associated with the other winding of the same inductor.

The principle described above can be generalized to the division of the inductor of a focus into 2n independent coils.

• RL1, RL1' en position (P1), RL2, RL2' en position (P2) : chaque bobinage de l'inducteur 1 est alimenté indépendamment par chacun des bras à travers les condensateurs de résonance C1 et C1', tandis que les deux bobinages de l'inducteur 2, en série avec C2 et C2', sont alimentés simultanément par la structure en pont constituée des deux bras. La figure 8 fait apparaître plus précisément cette première configuration.
• RL2, RL2' en position (P1), RL1, RL1' en position (P2) : inversement, chaque bobinage de l'inducteur 2 est maintenant alimenté indépendamment par chacun des bras à travers les condensateurs de résonance C2 et C2', tandis que les deux bobinages de l'inducteur 1, en série avec C1 et C1' sont alimentés simultanément par la structure en pont constituée des deux bras.

FIG. 7 shows the circuit of a module according to the invention composed of two inductors each having two coils (IND1, IND1 ') and (IND2, IND2') and the inverter arms B1 and B2 installed on this assembly perfectly symmetrical allow to provide all the power to any of the inductors. According to FIG. 7, each inductor of a furnace is divided into two coils (IND1, IND1 ') and (IND2, IND2') and an inverter arm which is respectively associated with them. In this example the switches are electromechanical relays RL1, RL1 ', RL2, RL2'. In parallel with the resonance capacitors, there is a resistor R to enable correct initialization of the voltages across the capacitor during the state changes of the relays. The change of operating mode by the relays can be done only when the inverters are inactive, ie when the control signals S1, S1 ', S2, S2' of the electronic switches are blocked. The two possible operating positions are given below:

• RL1, RL1 'in position (P1), RL2, RL2' in position (P2): each coil of inductor 1 is supplied independently by each arm through resonance capacitors C1 and C1 ', while the two coils of the inductor 2, in series with C2 and C2 ', are fed simultaneously by the bridge structure consisting of the two arms. Figure 8 shows more precisely this first configuration.
• RL2, RL2 'in position (P1), RL1, RL1' in position (P2): conversely, each coil of inductor 2 is now supplied independently by each arm through resonance capacitors C2 and C2 ', while the two coils of the inductor 1, in series with C1 and C1 'are fed simultaneously by the bridge structure consisting of the two arms.

From these configurations of the power stage, the command then makes it possible to obtain the various desired modes of operation. For this, we first define the notion of master and slave. The master inductor-generator set is the one on which the user requests the highest power. It is placed in the configuration where the two parts are powered independently (inductor 1 in Figure 7).

The control of the two arms then operates as follows: the frequency of the control signals Si is the same (synchronous control) for the two arms and it is adjusted according to the desired power on the master inductor. By cons, the two arms can be controlled either in phase or in phase opposition (Figure 6), at the scale of the switching frequency (≥20kHz).

At a given frequency, the power supplied to the master inductor is independent of the phase mode or in phase opposition mode, each coil being supplied independently by an arm (voltages VA and VB).

In the case of the slave inductor, its two windings in series with the resonance capacitors are powered by the bridge consisting of the two arms, therefore by the voltage VA - VB. In phase opposition, this voltage will be a slot of amplitude equal to the DC supply voltage of the arms and frequency equal to the frequency imposed by the master. In phase, the voltage VA - VB will be zero. It is then enough to alternate, over some periods of the alternative network, the mode in phase and the mode in opposition of phase to regulate the power on the inductor slave. At the limit, if we want to completely stop it, we keep the mode permanently in phase.

In summary, the power on the master inductor is regulated by the switching frequency of the inverter arms, the power on the slave inductor by the choice of the number of network periods on which the mode in opposition of phase is allowed.

• l'électronique (constituée des deux bras) est globalement dimensionnée pour la puissance totale susceptible d'être fournie aux deux inducteurs simultanément, soit 3,7kW,
• il existe une seule fréquence de commande du système, ce qui élimine tout risque de battement de fréquence.

This technique has two main advantages:

• the electronics (consisting of the two arms) is globally sized for the total power that can be supplied to the two inductors simultaneously, ie 3.7kW,
• there is only one frequency of control of the system, which eliminates any risk of frequency beating.

Claims (8)

1. Electric induction modular hob comprising two inductors supplied by a generator (inverter) receiving the rectified voltage of the electric network and formed of two arms each formed of two electronic interrupters mounted in series between two supply terminals of the network, and a resonance capacitor associated with each winding and placed in series, characterised in that

   - each inductor is formed of two independent windings (IND1, IND1') and (IND2, IND2'),

   - each generator is formed of two arms (B1, B2),

   * the connection point (Ai) of the two electronic interrupters is a branching point connected to a winding (IND1) and (IND2) (respectively IND1' and IND2') of each of the two inductors,

   * the resonance capacitor (Ci) associated with each winding (IND1) is placed in series forming an assembly wherein

   • one of the two terminals is connected to one of the arms (Bi) and

   • the other terminal is connected to a switching means (Rli) in order to be directly connected to one of the supply terminals (direct state) or to the counterpart terminal of the other assembly of the same inductor (bridge state),

   • the switching means (Rli) of the two inductors are coupled so as not to be in the same state at the same time.
2. Electric modular hob as claimed in Claim 1, characterised in that
   the switching means (Rli) is provided with a transition resistor.
3. Electric modular hob as claimed in Claim 1, characterised in that
   each electronic interrupter (T1i, T2i) is provided with an anti-parallel diode and a capacitor for facilitating switching.
4. Electric modular hob as claimed in Claim 1, characterised in that
   the switching means (RL1, RL1' respectively RL2, RL2') are controlled in the same manner, the two windings associated with their resonance capacitor of one hot plate each being directly connected to one of the two supply terminals and the two windings associated with their resonance capacitor of the other hot plate being mounted in series between the two arms (bridge state).
5. Electric modular hob as claimed in Claim 1, characterised in that
   the two arms (Bi) of a single generator are controlled at the same frequency in phase or in antiphase.
6. Electric modular hob as claimed in Claim 1, characterised in that
   the power of the hot plate in the direct state is controlled by controlling the cut-off frequency and the hot plate in the bridge state is controlled by controlling the respective lenghs of phase control or antiphase control.
7. Electric modular hob as claimed in Claim 1, characterised in that
   one hot plate is made totally inactive, whilst the other hot plate is operational, by putting it in the bridge state and permanently maintaining the phase control.
8. Electric modular hob as claimed in Claim 1, characterised in that
   the inductors of the hot plate are formed by 2n windings.

Images