EP3422815A1 - Induction cooking device and method for controlling same - Google Patents

Abstract

The invention relates to an induction cooking apparatus having a plurality of row lines, a plurality of column lines and a plurality of resonant circuit elements, wherein leakage currents are suppressed by a special interconnection of connected to a row line first poles of the resonant circuit elements at most a respective first pole with the respective second Row line end is connected directly.

Description

Field of application and state of the art

The invention relates to an induction cooking apparatus having a plurality of row lines, a plurality of column lines, a plurality of resonant circuit elements having a respective first pole and a respective second pole, a plurality of grid diodes and an inverter. Each resonant circuit element is connected with its first pole to exactly one of the row lines. Each resonant circuit element is connected to its second pole with exactly one of the column lines. Each column line has a respective end-side column switch. The invention likewise relates to a method for controlling such an induction cooking device.

Such induction cooking devices are known from the prior art and are used in particular for realizing a true surface cooking. Typically, the resonant circuit elements on induction heating coils, which can be used to heat pots standing on a hob. Exemplary embodiments are in EP 1 303 168 A1 such as EP 2 380 400 B shown.

The most widely used power electronic circuits for inductive heating of an induction hob are the resonant (series) resonant circuit and the quasi-resonant parallel resonant circuit. The latter has the advantage that a switching element and a capacitor are required less than with the series resonant circuit.

It is desirable to drive a large number of induction coils, in particular smaller induction coils, without relays with a few switching elements.

In known cooktops, each individual coil is driven in the case of quasi-resonant design by a semiconductor transistor or in the case of the embodiment as a series resonant circuit by two semiconductor transistors, usually IGBTs. This solution is very expensive for many induction coils (for example, 20 to 50) because of the large number of semiconductors. For n induction coils at least n semiconductors are required.

The driving of resistance heating elements in the multiplex method is known from the prior art. An interconnection of inductors or induction coils by rows and columns enables the saving of semiconductor switches and possibly of capacitors. Of the The design of a cooktop is also simplified, since it is not necessary for each induction coil to lead a line pair for high currents from an inverter, but the line is looped on.

An exemplary implementation of a prior art induction cooking apparatus is shown in FIG Fig. 1 shown. In this case, induction coils of the induction heating device are driven in series resonant circuits by means of half-bridge transistors. A respective resonant circuit has a respective inductor coil L and a respective capacitance or capacitor C. In the example shown, six series resonant circuits are shown, which are arranged in a matrix of rows and columns. The half-bridge consists of switches S _highside and S _lowside , which can be realized in particular by means of IGBT transistors or by means of MOSFETs. It is used to generate a high-frequency alternating voltage in the range of 20 kHz to 150 kHz, as is customary for the electrical excitation of an inductive heating by means of induction coils.

U is a rectified from the mains voltage, pulsating DC voltage source, possibly it may also be a pure DC voltage, which is generated by a PFC (Power Factor Correction) circuit. Cs is a DC link capacitor, which stabilizes the DC link voltage of the half bridges with resonant circuits. Each row (Sx1a-Sx4a) or column (Sy1-Sy4) has a switch (IGBT transistors or MOSFET transistors). The semiconductors for switching the rows and columns are in contrast to the inverter _switches (S _highside , S _lowside ) for generating the high frequency slowly switching and thus need not be executed high quality, alternatively, a low forward voltage Vce (sat) in IGBTs and / or a low on-resistance RDS (on) should be considered for MOSFETs.

For each transistor, a driver block is required for control, also for the inverter. For this come so-called "high-side" drivers such as pulse transformer (galvanic isolation possible) or charge pumps (without galvanic isolation) in question, this applies to all return and for the S _highside .

If now a switch (Sx1a or Sx2a) of a row and a column (Sy1 or Sy2) is closed, then the oscillating circuit L11C11 or L22C22 is excited (see Fig. 2 ). However, at the same time there is also an undesirable current flow over all further oscillating circuits of line 2 to the switch (Sy1 or Sy2). Although such leakage currents are smaller than the desired excitation current of the actual induction coil L11 or L22, they generate disturbing losses and electromagnetic fields at the inductances of all other resonant circuits of the matrix. An analytical calculation for the quantitative determination of these leakage currents is not trivial. For simulation, however, this current flow can be shown and quantified. In Fig. 2 the time course of the currents through the induction coils is shown when the induction coils L11 and L22, etc. are to be electrically excited at the time windows T11 and T22, respectively. In the time window T11 for the induction coil L11 of the desired current flow is shown thick, for the other induction coil L, the interference is shown thin. For the time window T22, the desired current flow is shown thick for the induction coil L22, and the disturbances for the other induction coils L are again shown as thin. This applies to the case where a pot is placed on the induction coils L11 and L22. Because of this, current flows are only effected in their time windows T11 and T22.

Task and solution

It is an object of the invention to provide an induction cooking apparatus and a method for controlling such an induction cooking, with which problems of the prior art can be avoided and which are optimized in particular with respect to disturbances or possible leakage currents.

This object is achieved by an induction cooking apparatus with the features of claim 1 and by a method for controlling such an induction cooking apparatus with the features of claim 14. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. In this case, some of the features are mentioned only for the induction cooking device or only for the method. However, they should be able to apply independently and independently of each other both for the induction cooking device and for the method. The wording of the claims is incorporated herein by express reference.

The invention relates to an induction cooking device. This has a plurality of row lines and a plurality of column lines. It has a plurality of resonant circuit elements with a respective first pole and a respective second pole. In addition, it has a plurality of grid diodes and an inverter. Each resonant circuit element is connected with its first pole to exactly one of the row lines. Each resonant circuit element is connected to its second pole with exactly one of the column lines. Each column line has a respective end-side column switch.

According to the invention, it is provided that each row line has a first line line end and a second line line end, between which the respective first poles of the connected resonant circuit elements are connected. The first and second row line ends are each connected to the inverter, wherein at least one of the row line ends, a respective line switch is arranged. Respective first poles of the resonant circuit elements are connected to a respective grid diode, which is connected to the respective second row line end with forward direction to the second Zeilenleitungsende, so that at most a respective first pole is connected directly to the second row line end of the connected to a row line first poles.

This embodiment avoids the disadvantage described above by a clever arrangement of the grid diodes. A direct series connection of a diode to the resonant circuit is not possible, otherwise a free swinging of the series resonant circuit is prevented. The embodiment described here, in particular the separation by grating diodes, however, the function of the resonant circuits is ensured. Unwanted currents through induction coils do not occur because they are prevented by the diodes. At any given time, a current flow takes place exclusively in the resonant circuit elements which are to be electrically excited at a particular time.

It should be understood that the term grating diodes is not a special type of diode, but that basically all known types of diodes can be used. Low-loss diodes or Schottky diodes are preferred. The designation of the grid diodes is chosen to make it clear that these are within a grid of row and column lines. According to one embodiment, the resonant circuit elements are a respective capacitor and a respective coil in series. This may in particular mean that each resonant circuit element represents a resonant circuit per se.

According to one embodiment, the resonant circuit elements are a respective coil, wherein a capacitor is further connected in each column line, which forms series resonant circuits with the respective connected coils. In this case, a resonant circuit typically can not already be formed by the respective resonant circuit elements per se, but rather arises only in conjunction with the respective capacitor. As a result, the number of capacitors required in total can be significantly reduced.

According to another embodiment, the resonant circuit elements are a respective coil, wherein further two capacitors are connected to each column line, which form series resonant circuits with the respective connected coils. The respective column line with the column switch is connected between the capacitors.

The column switches can in particular be bidirectionally conductive.

Preferably, the coils are induction coils. These can be used advantageously for heating cookware designed for this purpose and are then induction heating coils. The induction coils or other resonant circuit elements may preferably be identical to one another. This may in particular mean that all similar resonant circuit elements used in the induction cooking device are identical to each other.

The resonant circuit elements are preferably arranged in rows and columns, in particular in the form of a matrix. This leads to a clear design, which allows, for example, a uniform distribution of resonant circuit elements via a cooking surface to be heated.

According to one embodiment, a first line switch is arranged on each first line end of the line, and a second line switch is arranged on each second line line end. The first line switch and the second line switch of each row line are preferably configured to be switched simultaneously. As a result, an advantageous simultaneous switching of both row line ends is made possible, which ensures the operation of all resonant circuits even in the presence of the already mentioned grid diodes.

According to one embodiment, a line switch is arranged on each first row line end and on each second line line end a respective line diode is arranged in the forward direction away from the line switch. Even with such an embodiment, the operation of the resonant circuits is ensured even when using the grid diodes. The aforementioned line diode is in this case a component which is typically more favorable in comparison to row switches, which component also does not need to be controlled.

According to one embodiment, of the poles connected to a row line, only one pole, which is connected closest to the second row line end, is directly connected to the second row line end. Thereby, the already mentioned and desired suppression of leakage currents can be achieved in an advantageous manner.

Preferably, the switches are designed as self-locking N-channel MOSFETs. This has proven to be advantageous in practice. This may relate to all switches or even only a part of the switches, for example, line switches and / or column switches.

The column switches preferably have a respective freewheeling diode. Thus, any parasitic currents can be derived.

The line switches form an inverter according to an embodiment of the invention. As a result, additional switching elements for forming the inverter can be saved. The grid diodes are connected according to an embodiment between two first poles. Thus they can advantageously exert the desired effect to suppress unwanted leakage currents.

According to a further embodiment, each first pole is connected by means of a respective grid diode to the first row line end and connected by means of a respective further grid diode to the second row line end. Each grid diode is interconnected with the forward direction to the second end of the line line. Although this design is more complex, it has the advantage of even distribution of the voltages among the oscillating circuit elements.

Preferably, the induction cooking device further comprises a cup detection, which is designed to switch the line switches and column switches so that only resonant circuit elements are excited under a detected pot by the inverter. This allows optimal use and a saving of energy, since only the required resonant circuit elements are actually controlled.

The resonant circuit elements are preferably induction coils or induction heating coils or have such, which are arranged in rows and columns next to each other and behind each other. They are thus distributed in a corresponding configuration on a hob, wherein advantageously the columns means the arrangement one behind the other. The lines are the arrangement of induction coils side by side. Preferably, the induction coils are arranged in at least four rows and three columns, ie in a field with three induction coils in a row and four induction coils side by side. This has been proven for typical applications because sufficient variability in pot sizes and positions used is achieved without using excessive numbers of components.

These and other features will become apparent from the claims but also from the description and drawings, wherein the individual features each alone or more in the form of sub-combination in one embodiment of the invention and in other areas be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into individual sections as well as intermediate headings does not restrict the general validity of the statements made thereunder.

Brief description of the embodiments

Fig. 1:

eine Induktionskochvorrichtung gemäß dem Stand der Technik,

Fig. 2:

Spulenströme der Induktionskochvorrichtung gemäß dem Stand der Technik,

Fig. 3:

ein Ausführungsbeispiel der Erfindung,

Fig. 4:

Spulenströme zum ersten Ausführungsbeispiel der Erfindung,

Fig. 5:

eine Induktionskochvorrichtung gemäß dem Stand der Technik

Fig. 6 bis 15:

ein zweites bis elftes Ausführungsbeispiel der Erfindung,

Fig. 16:

ein Zeitdiagramm,

Fig. 17:

ein weiteres Zeitdiagramm,

Fig. 18:

eine mögliche Belegung eines Kochfelds,

Fig. 19:

ein zugehöriges Zeitdiagramm,

Fig. 20:

eine weitere mögliche Belegung eines Kochfelds,

Fig. 21:

ein zugehöriges Zeitdiagramm,

Fig. 22:

eine nochmals weitere mögliche Belegung eines Kochfelds,

Fig. 23:

ein zugehöriges Zeitdiagramm und

Fig. 24:

ein Ablaufdiagramm.

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings show:

Fig. 1:

an induction cooking apparatus according to the prior art,

Fig. 2:

Coil currents of the induction cooking apparatus according to the prior art,

3:

an embodiment of the invention,

4:

Coil currents to the first embodiment of the invention,

Fig. 5:

an induction cooking apparatus according to the prior art

6 to 15:

A second to eleventh embodiments of the invention,

Fig. 16:

a time diagram,

Fig. 17:

another time diagram,

Fig. 18:

a possible occupation of a hob,

Fig. 19:

an associated time diagram,

Fig. 20:

another possible occupation of a hob,

Fig. 21:

an associated time diagram,

Fig. 22:

another possible occupancy of a hob,

Fig. 23:

an associated timing diagram and

Fig. 24:

a flowchart.

Detailed description of the embodiments

The Fig. 1 shows an induction cooking apparatus according to the prior art, which has already been described in the introduction of this application. The Fig. 2 shows currents through the induction coils of the induction cooking of Fig. 1 , which have already been described.

Fig. 3 shows an induction cooking apparatus according to a first embodiment of the invention, which is in particular an induction hob. In this case, six resonant circuit elements are shown, which are each formed of an induction coil L and a respective capacitor C. In the present case, the induction coils L are induction heating coils. As shown, the resonant circuit elements are arranged in a matrix form, with the inductors L and the capacitors C being respectively indicated with two letters. The first letter indicates the line, with the second letter indicating the column.

In the induction cooking device of Fig. 3 furthermore, two line switches Sx1a, Sx1b of the first line and two further line switches Sx2a, 2x2b of the second line are arranged. Between these are respective row lines to which respective first poles of the resonant circuit elements are connected. Respective second poles facing the first poles, on the other hand, are connected to column switches Sy1, Sy2 and Sy3, each column switch Sy1, Sy2, Sy3 belonging to a respective column of the matrix. The column switches Sy1, Sy2, Sy3 are connected opposite to ground.

The respective line switches Sx1a, Sx1b, Sx2a, Sx2b are connected to an inverter whose output is designated RF supply. The inverter is formed by two inverter _switches S _highside , S _lowside . These are preceded by a capacitor Cs and a voltage source U.

In the rows between the row switches Sx1a, Sx1b, Sx2a, Sx2b respective grid diodes D11, D12, D21, D22 are connected. For each row, two of these grid diodes are interconnected. This leads to the fact that only the rightmost in the matrix lying resonant circuit elements are directly connected to the respective right line switches Sx1b, Sx2b. In this case, the forward direction points in each case to the second line switch Sx1b, Sx2b.

The grid diodes D11, D12, D21, D22 ensure that no unwanted currents occur through induction coils, as these are prevented by the grid diodes D11, D12, D21, D22. This is in Fig. 4 represented by the Fig. 2 similar. At all times, a current flow takes place exclusively in the induction coils, which at this time (T11 or T22 in Fig. 4 ) are to be electrically excited. Fig. 4 shows the respective coil currents through the induction coils L. A pot is on the coils L11 and L22.

In the Fig. 3 shown embodiment with a 2x3 matrix can also be extended, for example, to a 4x4 matrix. It shows Fig. 5 an embodiment according to the prior art, whereas Fig. 6 shows an embodiment according to the invention, ie with grid diodes D11, ..., D43.

Fig. 7 shows an embodiment in which the respective second, that is arranged on the right line return switches are replaced by diodes SDx1, SDx2, SDx3, SDx4. The advantage of such an embodiment is that a further switch per line is saved. The number N of semiconductor switches is significantly reduced to N = rows + columns instead of previously N = 2 × rows + columns. Instead of replacing the respective second line switches, a corresponding replacement of the first or left-hand line switches arranged by respective diodes would also be possible.

Fig. 8 shows an embodiment in which compared to in Fig. 7 illustrated embodiment, all semiconductor switches are realized by N-channel MOSFETs self-locking. It should be noted that the column switching elements in contrast to the line switches require a freewheeling diode. However, this does not mean that the line switches can not or should not have a freewheeling diode.

Fig. 9 shows an embodiment, which compared to in Fig. 8 embodiment shown instead of MOSFETs N-channel IGBTs used self-locking. This is advantageous because in the non-activated state of the gate (for example, failure in the power supply of the controller) no current can flow, even if voltage is applied to the semiconductor. In addition, N-channel semiconductors have a lower RDS (on) for MOSFETs and Vce (sat) for IGBTs, which is why they are more efficient than P-channel semiconductors.

Fig. 10 shows an embodiment of the invention, in which only one resonant circuit capacitor C1, C2, C3, C4 is provided per column. The resonant circuit elements are formed only by a respective induction coil L. Due to the line-wise and time-shifted control, the induction coils L in each column can share the resonant circuit capacitor C. In this case, the semiconductor switches Sy1-Sy4 are advantageously bidirectionally conductive so that the electrical current from the capacitor C can flow back to the induction coil L during one oscillation period. This is the case with MOSFETs or IGBTs with freewheeling diodes.

Fig. 11 shows an embodiment in which the respective column capacitor is designed as a double capacitor (C1a, b-C4a, b) to the highside and lowside, as is usually realized in a series resonant circuit with half-bridge drive for inductive heating. In this case, advantageously Cx / 2 = Cxa = Cxb.

Fig. 12 shows an embodiment in which the semiconductors for switching the lines are designed as fast inverter switches. Thus, by this measure, the main inverter (S (highside), S (lowside)) of the previous embodiments can be dispensed with. Each switch S1xa-S4xa or S1xb-S4xb can advantageously have a diode Dx1a-Dx4a or Dx1b-Dx4b connected in parallel to the current flow (analogous to the freewheeling diode of the IGBT) in order to generate a countervoltage generated by the inductance of the induction coil during the dead time in the switching process prevent.

Fig. 13 shows an embodiment, which compared to the embodiment of Fig. 12 is modified so that only a respective column capacitor C1, ..., C4 is used.

Fig. 14 shows an embodiment, which compared to the embodiment of Fig. 12 modified to the effect that the respective column capacitors are made in two parts.

With regard to the corresponding features with which the embodiments of the Fig. 13 and 14 from the embodiment of Fig. 12 Please refer to the descriptions above Fig. 10 and 11 directed.

Fig. 15 shows an embodiment which addresses the disadvantage that in previous embodiments with the number of columns, the number of diodes connected in series increases. This increases the loss with each additional column due to the Voltage drop at the diode lines. In addition, as the voltage is reduced, the transmittable power of the induction coils is also reduced. Since the current flow for the column 4 flows through a plurality of diodes, for example to column 2, the voltage and thus the transmittable power at the induction coils in column 4 is lower than at the induction coils in column 2.

To avoid this, the in Fig. 15 illustrated embodiment, each induction coil L, each with two diodes D directly connected to the respective line switch Sx1-4a. The disadvantage here is the approximate doubling of the number of diodes in comparison to the embodiments described above.

Fig. 16 shows a timing diagram for a driving variant of a cooktop with a 4x4 arrangement of induction coils L, in which each induction coil Lxy is excited in its associated time window Txy, where x is the row number and y is the column number of the respective induction coil L. The number of time windows corresponds to the number of induction coils. If an induction coil L is not switched on, the corresponding switch of the column remains switched off in the corresponding time window Txy. If, by way of example, the induction coil L22 is not to be excited, then the switch Sy2 blocks in the time window T22. This is represented in the time window T22 for Sy2 by a dotted line. The disadvantage here is that each induction coil requires a discrete time window and thus the instantaneous power must be N times the rated voltage, where N represents the number of induction coils L.

Fig. 17 shows a timing diagram for driving induction coils L, this control does not occur at fixed time windows. The control can also be done line by line or column by column, as is customary in the control of displays, for example, in time division multiplex. Fig. 17 shows an example of the time course of a line by line control of a hob with a 4x4 arrangement of induction coils. In a time window Txy for each line 1 to 4 in this case the corresponding line switch Sx1a-b becomes conductive. The corresponding switches of the column of electrically excited induction coils of this column are then also turned on. The line 1 are pulled through thin, the line 2 thinly dashed, the line 3 pulled through thick and line 4 thick dashed lines.

The power of the induction coil should be in the worst case at N columns (in the example N = 4) N times the rated power.

A corresponding algorithm can decide depending on the pot position, whether a row-wise or column-by-column control for the corresponding constellation of the induction coils L to be switched on is more favorable.

The control of induction coils can be carried out in pulse packets while adhering to a flicker standard.

In practice, it can be seen that the nominal power can be less than N times the rated power, since not all lines are or must be in operation or some lines have the same pattern, which leads to the simplification of the drive timing. This is explained by three examples, which in the Fig. 18 to 23 are shown.

Fig. 18 shows a 4x4 hob in matrix control with rows R1-4 and columns C1-4. A pot 1 is placed above the induction coils L21 and L22, and a pot 2 is placed above the induction coils L33 and L34. These are shown with 1 and 2. Thus, rows R1 and R4 are not needed.

The timing off Fig. 17 can thus be significantly simplified, namely to that which in Fig. 19 is shown. The rows R2 and R3 are excited twice per period of time. The maximum power of each induction coil L only has to correspond to twice the rated power. Again, the line 1 are pulled through thin, the line 2 thinly dashed, the line 3 pulled through thick and line 4 thick dashed lines.

In the execution of Fig. 20 are two cooking vessels 1 and 2 set up and cover each four induction coils L. Note that the driving pattern of the line R1 corresponds to that of line R2. Thus, the drive of the return line switch for R1 can be done simultaneously with that of the return line switch for R2. The same applies to R3 and R4.

This timing is in Fig. 21 shown. Again, due to the simplification of the timing, the required maximum power of each induction coil is twice the rated power. Again, the line 1 are pulled through thin, the line 2 thinly dashed, the line 3 pulled through thick and line 4 thick dashed lines.

If the control of two rows or columns is performed as described and this type of control with the execution of Fig. 14 combined, it may be advantageous to control different columns or rows with the same frequency and in phase to avoid interference between the individual inductors L. Not in-phase or not equal frequency control can lead both to unwanted induction currents in the induction coil L and resulting noise.

In the execution of Fig. 22 is only a pot 1 with the hob available, so that can be completely dispensed with a temporal multiplex of the control. Lines 1 and 4 are not covered and thus not activated. Activation of the columns for lines 2 and 3 is identical. Thus, can be dispensed with a time multiplex. The switches Sx2a / b and Sx3a / b can be permanently closed. The same applies to the switches Sy2 and Sy3. An appropriate timing is in Fig. 23 shown. Again, the line 1 are pulled through thin, the line 2 thinly dashed, the line 3 pulled through thick and line 4 thick dashed lines.

• Ermittlung der durch Töpfe auf der Induktionskochvorrichtung überdeckten Induktionsspulen,
• Zuordnung der Induktionsspulen zu den jeweiligen Töpfen,
• Zuordnung der Induktionsspulen zu den jeweiligen Zeilen,
• Ermittlung nicht angesteuerter Zeilen für das Timing, da diese Zeilen nicht betrieben werden sollen,
• Ermittlung der Zeilen mit gleicher Spaltenansteuerung, da diese Zeilen im gleichen Zeitfenster betrieben werden können,
• Ermittlung der Zeilen, die durch Multiplikation (Hinzufügen oder Weglassen) einer Induktionsspule zeitgleich mit anderen Zeilen angesteuert werden können, da auch diese Zeilen im gleichen Zeitfenster betrieben werden können,
• Ermittlung der Pulspakete für den entsprechenden Zustand und die entsprechende Kochstufe für jeden Topf.

For area cooktops with many small induction coils, it is possible to let lines in which only a single induction coil is covered by a pot, the pot being so large that several induction coils are covered, to completely switch off this line with this induction coil, in order to control the timing to simplify. This is on the premise that the induction coils are small enough and the power loss can be compensated by the remaining induction coils. Furthermore, this should occur inhomogeneity in the heating of the pot in the tolerable range. Likewise, an uncoated or insufficiently covered induction coil of a line can be energized in order to obtain the same drive patterns line by line and thus likewise to simplify the timing. Thus, a small increase of the stray field is to be expected, which is small for small coils. Finding a suitable drive timing is made possible by an algorithm according to a method according to the invention, which in Fig. 24 is shown. Such an algorithm or a method according to the invention generally comprises the following steps:

• Determination of the induction coils covered by pots on the induction cooking device,
• Assignment of the induction coils to the respective pots,
• Assignment of the induction coils to the respective lines,
• Determination of uncontrolled lines for the timing, since these lines should not be operated,
• Determination of the rows with the same column control, since these rows can be operated in the same time window,
• Determination of the lines that can be controlled by multiplication (addition or omission) of an induction coil at the same time as other lines, since these lines can also be operated in the same time window,
• Determination of the pulse packets for the corresponding state and the corresponding cooking level for each pot.

The entire calculation process can or is not only done line by line, but can or will be done column by column. The cheaper or less expensive variant is then executed. Cheaper means here mean that more columns remain off or can be operated together and thus the period of the control is shortened. So the choice depends on whether more rows or more columns remain off or can be operated together.

When looking at the power distribution, it is noticeable that cooking hobs are usually operated with two phases. As a result, for example, the rated total input power is 7.2 kW. With an output of 400 W per induction coil, this results in that a maximum of 7.2 kW / 400 = 18 induction coils can be operated simultaneously during a time window. This consideration also shows that only 18 induction coils have to be taken into account in the case of control in the time multiplex. This applies to this embodiment and at maximum power of all induction coils. At lower power correspondingly more induction coils can be operated.

Claims (15)

Induction cooking device, comprising a plurality of row wirings, a plurality of column lines, a plurality of resonant circuit elements (L, C) having a respective first pole and a respective second pole, - A plurality of grid diodes (D), and an inverter (S _highside , S _lowside ), - Wherein each resonant circuit element (L, C) is connected with its first pole to exactly one of the row lines, - Wherein each resonant circuit element (L, C) is connected with its second pole to exactly one of the column lines, each column line having a respective end-side column switch (Sy), characterized in that each row line has a first row line end and a second row line end, between which the respective first poles of the connected oscillatory circuit elements (L, C) are connected, - The first and second row line ends are each connected to the inverter (S _highside , S _lowside ), wherein at least one of the row line ends, a respective line switch (Sx) is arranged, respective first poles of the resonant circuit elements (L, C) are connected to a respective grid diode (D) which is connected to the respective second row line end in the forward direction to the second row line end, - So that of the connected to a row line first poles at most a respective first pole is directly connected to the second row line end. Induction cooking device according to claim 1, characterized in that the oscillating circuit elements (L, C) are a respective capacitor (C) and a respective induction coil (L) connected in series. Induction cooking device according to claim 1, characterized in that the resonant circuit elements (L, C) are a respective induction coil (L), wherein preferably in each column line, a capacitor (C) is connected, which with the respective connected induction coils (L) series resonant circuits forms, in particular, the column switches (Sy) are bidirectionally conductive. Induction cooking device according to claim 1,
characterized in that the resonant circuit elements (L, C) are a respective induction coil (L), - Wherein each capacitor line two capacitors (C) are connected, which form with the respective connected induction coil (L) series resonant circuits, - Wherein the respective column line is connected to the column switch (Sy) between the capacitors (C), in particular, the column switches (Sy) are bidirectionally conductive. Induction cooking device according to one of the preceding claims, characterized in that the resonant circuit elements (L, C) are arranged in rows and columns, in particular in the form of a matrix. Induction cooking device according to one of the preceding claims, characterized in that a first line switch (Sx1a, Sx2a) is arranged at each first line end and a second line switch (Sx1b, Sx2b) is arranged at every other line end, preferably the first line switch (Sx) and the second line switch (Sx) of each row line is configured to be switched simultaneously. Induction cooking device according to one of claims 1 to 5, characterized in that a line switch (Sx) is arranged at each first row line end and at each second row line end, a respective line diode (SDx) with the forward direction of the line switch (Sx) away. Induction cooking device according to one of the preceding claims, characterized in that of the connected to a row line poles only that pole, which is connected to the second end of the second line end, is directly connected to the second end of the row line. Induction cooking device according to one of the preceding claims, characterized in that the column switches (Sy) have a respective freewheeling diode and / or the line switches (Sx) form the inverter (S _highside , S _lowside ). Induction cooking device according to one of the preceding claims, characterized in that the grid diodes (D) are connected between two respective first poles. Induction cooking device according to one of claims 1 to 9, characterized in that each first pole is connected by means of a respective grid diode (D) to the first row line end and by means of a respective further grid diode (D) is connected to the second row line end, in particular each grid diode ( D) is connected with forward direction to the second end of the line line. An induction cooking apparatus according to any one of the preceding claims, characterized in that the induction cooking apparatus further comprises pot detection which is configured to switch the return switches (Sx) and the column switches (Sy) so that only resonant circuit elements (L, C) under a recognized pot (Pan) are excited by the inverter (S). Induction cooking device according to one of the preceding claims, characterized in that the resonant circuit elements (L, C) are induction heating coils, which are arranged in rows and columns next to each other and behind each other, preferably at least four rows and three columns. Method for controlling an induction cooking appliance according to one of the preceding claims, characterized by the steps: Determination of the induction coil covered by pots, Assignment of the induction coils to the respective pots, Assignment of the induction coils to respective rows or to respective columns, - determination of non-driven lines or non-driven columns for the timing, since these lines or columns are not operated, Determination of the rows with the same column control or the columns with the same row control, since these rows or columns can be operated in the same time window, Determination of the rows or columns which can be controlled by multiplication as addition or omission of an induction coil at the same time as other rows or columns, these rows or columns being able to be operated in the same time window, - Determination of pulse packets for the corresponding state and the corresponding cooking level for each pot on the induction cooking. A method according to claim 14, characterized in that the variant of the row drive or column drive is performed, in which more rows or columns can remain switched off or can be operated together, preferably thereby the period of the control is shortened.

Images