DOMESTIC APPLIANCE

Abstract

A household appliance device includes an inductor, a switching unit, at which an operating voltage is applied in an operating state, and a control unit configured to supply a supply voltage for the inductor by switching the switching unit. The control unit is configured to vary a frequency of the supply voltage within a period of the operating voltage in the operating state.

Claims

1-11. (canceled)

12. A household appliance device, comprising: an inductor; a switching unit, at which an operating voltage is applied in an operating state; and a control unit configured to supply a supply voltage for the inductor by switching the switching unit, said control unit configured to vary a frequency of the supply voltage within a period of the operating voltage in the operating state.

13. The household appliance device of claim 12, constructed in the form of a cooking appliance device.

14. The household appliance device of claim 12, wherein the control unit varies a duty factor of the supply voltage in the operating state.

15. The household appliance device of claim 12, wherein the control unit is configured to avoid an overload at an electrical component when the frequency is varied.

16. The household appliance device of claim 12, wherein the control unit is configured to reduce electromagnetic radiation when the frequency is varied.

17. The household appliance device of claim 12, further comprising a further inductor, said control unit being configured to supply a further supply voltage for the further inductor by switching the switching unit and to vary a further frequency of the further supply voltage within a period of the operating voltage in the operating state.

18. The household appliance device of claim 17, wherein the supply voltage and the further supply voltage complement one another at least partially.

19. The household appliance device of claim 12, wherein the switching unit includes an inverter unit configured to generate an inverter voltage from the operating voltage, and a variation switching unit configured to generate the supply voltage from the inverter voltage.

20. The household appliance device of claim 19, wherein the control unit is configured to vary the supply voltage in the operating state via the variation switching unit.

21. The household appliance device of claim 12, further comprising a heating matrix having a number NM of heating matrix elements, wherein the switching unit includes a number N of row switching elements and a number M of column switching elements, wherein, for any i from 1 to N and any j from 1 to M with a total number N+M of row switching elements and column switching elements greater than 2, the heating matrix element at position i,j comprises at least one of said inductor and is connected to both the i-th row switching element and the j-th column switching element.

22. A household appliance, in particular a cooking appliance, said household appliance comprising a household appliance device, said household appliance device comprising an inductor, a switching unit, at which an operating voltage is applied in an operating state, and a control unit configured to supply a supply voltage for the inductor by switching the switching unit, said control unit configured to vary a frequency of the supply voltage within a period of the operating voltage in the operating state.

23. The household appliance of claim 22, wherein the control unit varies a duty factor of the supply voltage in the operating state.

24. The household appliance of claim 22, wherein the control unit is configured to avoid an overload at an electrical component when the frequency is varied.

25. The household appliance of claim 22, wherein the control unit is configured to reduce electromagnetic radiation when the frequency is varied.

26. The household appliance of claim 22, wherein the household appliance device includes a further inductor, said control unit being configured to supply a further supply voltage for the further inductor by switching the switching unit and to vary a further frequency of the further supply voltage within a period of the operating voltage in the operating state.

27. The household appliance of claim 26, wherein the supply voltage and the further supply voltage complement one another at least partially.

28. The household appliance of claim 22, wherein the switching unit includes an inverter unit configured to generate an inverter voltage from the operating voltage, and a variation switching unit configured to generate the supply voltage from the inverter voltage.

29. The household appliance of claim 28, wherein the control unit is configured to vary the supply voltage in the operating state via the variation switching unit.

30. The household appliance of claim 22, wherein the household appliance device includes a heating matrix having a number NM of heating matrix elements, wherein the switching unit includes a number N of row switching elements and a number M of column switching elements, wherein, for any i from 1 to N and any j from 1 to M with a total number N+M of row switching elements and column switching elements greater than 2, the heating matrix element at position i,j comprises at least one of said inductor and is connected to both the i-th row switching element and the j-th column switching element.

31. A method for operating a household appliance device, in particular a cooking appliance device, said method comprising: applying an operating voltage in an operating state to a switching unit; switching the switching unit to provide a supply voltage for an inductor; and varying a frequency of the supply voltage within a period of the operating voltage in the operating state.

Description

[0028] Further advantages will emerge from the description of the drawing that follows. The drawing shows a number of exemplary embodiments of the invention. The drawing, description and claims container numerous features in combination. The person skilled in the art will also expediently consider the features individually and combine them in useful further combinations.

[0029] In the drawing:

[0030] FIG. 1 shows a schematic view from above of a household appliance with a household appliance device,

[0031] FIG. 2 shows a schematic circuit diagram of a part of the household appliance device with a heating matrix,

[0032] FIG. 3 shows a schematic view from above of a part of the household appliance device with an inductor matrix,

[0033] FIG. 4 shows a schematic flow chart of a method for operating a household appliance device with a cookware detection mode,

[0034] FIG. 5 shows different diagrams of typical current and/or voltage profiles during operation of the household appliance device,

[0035] FIG. 6 shows a circuit diagram of a further household appliance device,

[0036] FIG. 7 shows a circuit diagram of a further household appliance device,

[0037] FIG. 8 shows a circuit diagram of a further household appliance device,

[0038] FIG. 9 shows a circuit diagram of a further household appliance device,

[0039] FIG. 10 shows a circuit diagram of a further household appliance device,

[0040] FIG. 11 shows a circuit diagram of a further household appliance device,

[0041] FIG. 12 shows a further preferred method for controlling the household appliance device and in particular the further household appliance devices from FIGS. 6 to 11,

[0042] FIGS. 13a-b show different diagrams of typical current, voltage and power profiles during control of the household appliance device according to the method from FIG. 12,

[0043] FIG. 14 shows different diagrams of further power profiles during control of the household appliance device according to the method from FIG. 12,

[0044] FIG. 15 shows different diagrams of further power profiles during control of the household appliance device according to the method from FIG. 12,

[0045] FIGS. 16a-d show different diagrams of characteristic power lines of a first cookware item for control of the household appliance device according to the method from FIG. 12,

[0046] FIGS. 17a-d show different diagrams of characteristic power lines of a second cookware item for control of the household appliance device according to the method from FIG. 12,

[0047] FIGS. 18a-d show different diagrams of characteristic power lines of a third cookware item for control of the household appliance device according to the method from FIG. 12, and

[0048] FIG. 19 shows a circuit diagram of a further household appliance device provided to perform the method from FIG. 12.

[0049] FIG. 1 shows a schematic view from above of a household appliance 48a with a household appliance device. In the present instance the household appliance 48a is configured as a cooking appliance. The household appliance 48a is a cooktop, in particular a variable induction cooktop. Alternatively the household appliance 48a can be configured as any household appliance 48a, in particular a cooking appliance, that is different from a cooktop, and in particular appears advantageous to the person skilled in the art, for example a microwave or induction oven.

[0050] The household appliance device has a cooktop plate 50a. The household appliance device is provided to operate at least one cookware item, which is arranged in any position on the cooktop plate 50a. The cooktop plate 50a comprises preferred heating zone positions 52a, which characterize preferred positions for cookware items. In the present instance the cooktop plate 50a has six preferred heating zone positions 52a. Only one of the preferred heating zone positions 52a is shown with a reference character for greater clarity. The cooktop plate 50a can in particular have any number of preferred heating zone positions 52a or no preferred heating zone positions 52a.

[0051] FIG. 2 shows a schematic circuit diagram of a part of the household appliance device. The household appliance device comprises at least a number N of row switching elements 10a. The household appliance device also comprises at least a number M of column circuit elements 12a. The household appliance device comprises at least one heating matrix 14a. The heating matrix 14a has at least one heating matrix element 16a at position i,j for any i from 1 to N and any j from 1 to M. The heating matrix 14a has a number NM of heating matrix elements 16a. A total number N+M of row switching elements 10a and column switching elements 12a is greater than 2. The total number N+M of row switching elements 10a and column switching elements 12a is smaller than or equal to the number NM of heating matrix elements 16a. In the present instance the household appliance device has a number N=8 of row switching elements 10a. In the present instance the household appliance device has a number M=3 of column switching elements 12a. The household appliance device also has a number NM=24 of heating matrix elements 16a. It is however also conceivable for N and/or M to be any other natural number deemed particularly advantageous by a person skilled in the art. Alternatively or additionally a number N can be selected to be equal to a number M or such that the total number N+M is one greater than the number NM.

[0052] An, in particular schematic circuit-type, arrangement of the electrical components of the household appliance device is described by way of example below with reference to i-th and j-th components of the household appliance device as well as those at position i,j. The following descriptions here also apply to further, equivalent electrical components.

[0053] The i-th row switching element 10a is configured as a transistor. The i-th row switching element 10a has a first connection. The first connection is a source connection. The first connection of the i-th row switching element 10a is connected to the heating matrix element 16a at position i,j. The i-th row switching element 10a has a second connection. The second connection is a drain connection. The second connection of the i-th row switching element 10a is connected to a reference potential 30a common to the row switching elements 10a. The reference potential 30a common to the row switching elements 10a is an operating potential of an operating voltage, preferably a ground potential. The household appliance device in particular has a rectifier, which converts a line voltage to the operating voltage. The operating voltage here is the voltage present between the reference potential 30a common to the row switching elements 10a and a further reference potential 32a common to the column switching elements 12a. The i-th row switching element 10a has a control connection. The control connection is a gate connection. The control connection is connected to a control unit 38a of the household appliance device.

[0054] The j-th column switching element 12a is configured as a transistor. The j-th column switching element 12a has a first connection. The first connection is a source connection. The first connection of the j-th column switching element 12a is connected to the further reference potential 32a common to the column switching elements 12a. The further reference potential 32a common to the column switching elements 12a is the further operating potential. The j-th column switching element 12a has a second connection. The second connection is a drain connection. The second connection of the j-th column switching element 12a is connected to the heating matrix element 16a at position i,j. The j-th column switching element 12a has a control connection. The control connection is a gate connection. The control connection is connected to the control unit 38a of the household appliance device.

[0055] The i-th row switching element 10a and the j-th column switching element 12a are arranged in a half bridge topology. It is conceivable for the household appliance device to comprise i-th further row switching elements 10a and j-th further column switching elements 12a, so the i-th row switching elements 10a, the i-th further row switching elements 10a, the j-th column switching elements 12a and the j-th further column switching elements 12a can be arranged in a full bridge topology.

[0056] The i-th row switching element 10a and the j-th column switching element 12a serve as inverter switching elements. The i-th row switching element 10a and the j-th column switching element 12a together form at least one inverter unit 54a at position i,j of the household appliance device. The household appliance device in particular comprises a number NM of inverter units 54a. The control unit 38a is provided to activate the i-th row switching element 10a and the j-th column switching element 12a as inverter switching elements. The control unit 38a activates the i-th row switching element 10a and the j-th column switching element 12a in such a manner that a soft switching operation takes place between at least one first switching state and a second switching state of the i-th row switching element 10a and the j-th column switching element 12a.

[0057] The heating matrix element 16a at position i,j has at least one inductor 18a at position i,j. The inductor 18a at position i,j is connected to both the i-th row switching element 10a and the j-th column switching element 12a. The inductor 18a at position i,j has at least one connection 20a at position i,j. The connection 20a at position i,j is connected to both the i-th row switching element 10a, in particular the first connection of the i-th row switching element 10a, and the j-th column switching element 12a, in particular the second connection of the j-th column switching element 12a. A total NM of inductors 18a are arranged in a schematic circuit in the heating matrix 14a.

[0058] The heating matrix element 16a at position i,j has at least one diode 24a at position i,j. The inductor 18a at position i,j is connected at least to the i-th row switching element 10a by means of the diode 24a at position i,j. A first connection of the diode 24a at position i,j is connected to the connection 20a at position i,j of the inductor 18a at position i,j. A second connection of the diode 24a at position i,j is connected to a first connection of the i-th row switching element 10a. The diode 24a at position i,j allows a current flow in the direction of the i-th row switching element 10a. The diode 24a at position i,j blocks a current flow in the direction of the inductor 18a at position i,j.

[0059] The heating matrix element 16a at position i,j has at least one further diode 26a at position i,j. The inductor 18a at position i,j is connected at least two the j-th column switching element 12a by means of the further diode 26a at position i,j. A first connection of the further diode 26a at position i,j is connected to the connection 20a at position i,j of the inductor 18a at position i,j. A second connection of the further diode 26a at position i,j is connected to the second connection of the j-th column switching element 12a. The further diode 26a at position i,j allows a current flow in the direction of the inductor 18a at position i,j. The further diode 26a at position i,j blocks a current flow in the direction of the j-th column switching element 12a.

[0060] The heating matrix element 16a at position i,j has at least one capacitance 28a at position i,j. The capacitance 28a at position i,j is a capacitor. The inductor 18a at position i,j is connected at least to a reference potential 30a common to the heating matrix elements 16a by means of the capacitance 28a at position i,j. The reference potential 30a common to the heating matrix elements 16a is the operating potential. A first connection of the capacitance 28a at position i,j is connected to a further connection 42a at position i,j of the inductor 18a at position i,j. A second connection of the capacitance 28a at position i,j is connected to the common reference potential 30a.

[0061] FIG. 3 shows a view from above of a part of the household appliance device with an inductor matrix 22a. In the present instance inductors 18a at position i,j of identical i are shown with identical hatching in FIG. 3. Inductors 18a for which i=j in the heating matrix 14a are also marked with a dot. The inductors 18a at position i,j are arranged spatially in the inductor matrix 22a. The inductor matrix 22a is different from the heating matrix 14a in respect of proximity relationships of at least two of the inductors 18a at position i,j relative to one another. In the inductor matrix 22a inductors 18a at position i,j of identical i or j are adjacent to one another. In the inductor matrix 22a the inductors 18a at position i,j are arranged spatially in such a manner that at least one inductor 18a at position i,j, for which i=j in the heating matrix 14a, is adjacent to at least one inductor 18a at position i,j, for which ij in the heating matrix 14a. An inductor 18a at position i,j, for which i=j in the heating matrix 14a, is surrounded, preferably surrounded in a circular manner, by multiple, in particular at least three, preferably at least four and particularly preferably at least five inductors 18a at position i,j, for which ij in the heating matrix 14a.

[0062] FIG. 4 shows a method for controlling the household appliance device. In the present instance the method is described with reference to exemplary operation of the electrical components with the indices i=1 and i=2 and the electrical components with the indices j=1 and j=2. The method can be applied in the same way to any further i-th electrical components and j-th electrical components.

[0063] The method comprises an operating step 56a. In the operating step 56a the control unit 38a activates the 2.sup.nd row switching element 10a and the 1.sup.st column switching element 12a as inverter switching elements. The 2.sup.nd row switching element 10a and the 1.sup.st column switching element 12a transition alternately through a switching operation from a first switching state to a second switching state. The 2.sup.nd row switching element 10a and the 1.sup.st column switching element 12a connect the heating matrix element 16a at position 2,1, in particular the inductor 18a at position 2,1, alternately to the reference potential 30a common to the row switching elements 10a and the further reference potential 32a common to the column switching elements 12a. The 2.sup.nd row switching element 10a and the 1.sup.st column switching element 12a generate a supply voltage, with which the heating matrix element 16a at position 2,1, in particular the inductor 18a at position 2,1, is operated. A heating current flows through the heating matrix element 16a at position 2,1, in particular the inductor 18a at position 2,1.

[0064] The method comprises a cookware detection mode 40a. The cookware detection mode 40a runs at the same time as the operating step 56a. Alternatively the cookware detection mode 40a can take place independently of the operating step 56a. The cookware detection mode 40a comprises a charging step 58a. In the charging step 58a the control unit 38a activates the 1.sup.st column switching element 12a in such a manner that it transitions to a first switching state. The heating matrix element 16a at position 1,1, in particular the capacitance 28a at position 1,1, is charged by means of the 1.sup.st column switching element 12a to the further reference potential 32a common to the column switching elements 12a. The control unit 38a activates the 1.sup.st row switching element 10a in such a manner that it is in a second switching state and therefore does not establish a conducting connection to the reference potential 30a common to the row switching elements 10a. No current flows, with the result that the charged voltage is maintained. Similarly the heating matrix element 16a at position 2,2, in particular the capacitance 28a at position 2,2, is charged with the reference potential 30a common to the row switching elements 10a, which is made available by the 2.sup.nd row switching element 10a. In the charging step 58a the control unit 38a activates the 2.sup.nd row switching element 10a in such a manner that it transitions to a second switching state. The heating matrix element 16a at position 2,2, in particular the capacitance 28a at position 2,2, is charged to the reference potential 30a common to the row switching elements 10a. The control unit 38 activates the 2.sup.nd column switching element 12a in such a manner that it is in the second switching state and therefore no conducting connection is established to the further reference potential 32a common to the column switching elements 12a. No current flows, with the result that the charged voltage is maintained.

[0065] The cookware detection mode 40a comprises a discharging step 60a. The discharging step 60a is performed during the operating step 56a. The operating voltage, which is present between the 2.sup.nd row switching element 10a and the 1.sup.st column switching element 12a, varies over time. The discharging step 60a is performed when the operating voltage has an at least essentially vanishingly low value. The control unit 38a discharges the heating matrix element 16a at position 1,1. To this end the control unit 38a switches the 1.sup.st row switching element 10a to the first switching state. The 1.sup.st row switching element 10a connects the heating matrix element 16a at position 1,1, in particular the capacitance 28a at position 1,1, to the reference potential 30a common to the row switching elements 10a. The heating matrix element 16a at position 1,1, in particular the capacitance 28a at position 1,1, discharges. A characteristic line 46a of the discharging operation is acquired. A further characteristic line 47a of the discharging operation is acquired.

[0066] The cookware detection mode 40a comprises a determination step 62a. In the determination step 62a a comparative characteristic line is tailored to the characteristic line 46a acquired in the discharging step 60a and in particular to the further characteristic line 47a. A quality of the electromagnetic coupling is determined from parameters of the comparative characteristic line. A degree of cover between the inductor 18a at position 1,1 and a cookware item coupled to the inductor 18a at position 1,1 and/or a material of the cookware item is/are also determined from the quality of the electromagnetic coupling.

[0067] FIG. 5a shows a diagram of the method for controlling the household appliance device. A time is plotted on an x-axis 64a. A voltage is plotted on a y-axis 66a. A first voltage curve 68a shows a profile over time of the supply voltage present at the heating matrix element 16a at position 2,1. A second voltage curve 70a shows a profile over time of a voltage present at the heating matrix element 16a at position 1,1. A third voltage curve 72a shows a profile over time of a voltage present at the heating matrix element 16a at position 1,2. A fourth voltage curve 74a shows a profile over time of a voltage present at the heating matrix element 16a at position 2,2. A fifth voltage curve 76a shows a profile over time of the operating voltage. The curves 68a, 70a, 72a, 74a, 76a are shown again in FIG. 5b. FIG. 5b shows a region of the diagram in FIG. 5a about a time T, at which the operating voltage has an at least essentially vanishingly low value. In FIG. 5b the x-axis 64a has a finer scaling than in FIG. 5a.

[0068] FIG. 6a shows a diagram of the method for controlling the household appliance device. A time is plotted on an x-axis 64a. A current is plotted on a y-axis 66a. A first current curve 80a shows a profile over time of the heating current flowing through the heating matrix element 16a at position 2,1. A second current curve 82a shows a profile over time of a current flowing through the heating matrix element 16a at position 1,1. A third current curve 84a shows a current flowing through the heating matrix element 16a at position 1,2. A fourth current curve 86a shows a current flowing through the heating matrix element 16a at position 2,2. FIG. 6b shows a region of the diagram in FIG. 6a about a time T, at which the operating voltage has an at least essentially vanishingly low value. In FIG. 6b the x-axis 64a has a finer scaling than in FIG. 6a.

[0069] The second current curve 82a and the second voltage curve 70a show the charging step 58a of the heating matrix element 16a at position 1,1. In the charging step 58a the heating matrix element 16a at position 1,1 is charged with the further reference potential 32a common to the column switching elements 12a. In the discharging step 60a, as soon as the operating voltage, as in the fifth voltage curve 76a, has an at least essentially vanishing value, the heating matrix element 16a at position 1,1 is discharged. A current flows, corresponding to the second current curve 82a. The second voltage curve 70a is acquired. The second characteristic voltage line serves as a characteristic line 46a for determining the electrical characteristic variable. The second current curve 82a is acquired. The second current curve 82a serves as a further characteristic line 47a for determining the electrical characteristic variable.

[0070] FIGS. 7 to 11 and 19 show further exemplary embodiments of the invention. The description that follows and the drawings are essentially restricted to the differences between the exemplary embodiments, it being possible to refer, in respect of identically marked components, in particular components with identical reference characters, in principle also to the drawing and/or description of the other exemplary embodiments, in particular in FIGS. 1 to 6. To distinguish between the exemplary embodiments the letter a is used after the reference characters of the exemplary embodiments in FIGS. 1 to 6. The letter a is replaced by the letters b to f and g in the exemplary embodiments in FIGS. 7 to 11 and 19.

[0071] FIG. 7 shows a circuit diagram of a further exemplary embodiment of the invention. The further exemplary embodiment differs from the previous exemplary embodiment at least essentially in respect of a number N and a number M. In the present instance a number N of row switching elements 10b is equal to the number M of column switching elements 12b. The total number N+M of row switching elements 10b and column switching elements 12b is also smaller than or equal to the number NM of heating matrix elements 16b. In the present instance the number N=4 and the number M=4. In the present instance at least the i-th row switching element 10b, in particular all the row switching elements 10b, and/or at least the j-th column switching element 12b, in particular all the column switching elements 12b, is/are configured as switches, preferably relays. The household appliance device also has an additional inverter unit 54b. The inverter unit 54b has a first inverter element 88b. The inverter unit 54b also has a second inverter element 89b. The inverter elements 88b, 89b are configured as transistors. The inverter element 88b connects the row switching elements 10b to a reference potential 30b common to the row switching elements 10b. The further inverter element 89b connects the column switching elements 12b to a further reference potential 32b common to the column switching elements 12b.

[0072] FIG. 8 shows a circuit diagram of a further exemplary embodiment of the invention. The further exemplary embodiment differs from the previous exemplary embodiment at least essentially in respect of a number N and M. A total number N+M of row switching elements 10c and column switching elements 12c is one greater than a number NM of heating matrix elements 16c. In the present instance the number N=2 and the number M=1. A heating matrix 14c forms a schematic circuit vector, in particular a column vector. In a configuration, in which the total number N+M is one greater than the number N, diodes 24c at position i,1 can be dispensed with. A first connection of the i-th row switching element 10c is connected to a connection 20c at position i,j of an inductor 18c at position i,j.

[0073] FIG. 9 shows a further exemplary embodiment of the invention. The further exemplary embodiment differs from the previous exemplary embodiment at least essentially in respect of further electrical components of the household appliance device. The household appliance device has a number M of column diodes 36d. The j-th column diode 36d connects at least one j-th column switching element 12d to at least one reference potential 30d common to the column switching elements 12d. The reference potential 30d common to the column switching elements 12d is equal to a reference potential 30d common to the row switching elements 10d. A first connection of the j-th column switching element 12d is connected to a further reference potential 32d common to the column switching elements 12d. A second connection of the j-th column switching element 12d is connected to a first connection of a j-th column diode 36d. The j-th column diode 36d blocks a current in the direction of the reference potential 30d common to the column switching elements 12d. The j-th column diode 36d allows a current from the direction of the reference potential 30d common to the column switching elements 12d.

[0074] The household appliance device has a number N of row diodes 34d. The i-th row diode 34d connects at least one i-th row switching element 10d to at least one further reference potential 32d common to the row switching elements 10d. The further reference potential 32d common to the row switching elements 10d is a further operating voltage. The further reference potential 32d common to the row switching elements 10d is equal to the further reference potential 32d common to the column switching elements 12d. A first connection of the i-th row diode 34d is connected to a first connection of the i-th row switching element 10d. A second connection of the i-th row diode 34d is connected to the further reference potential 32d common to the row switching elements 10d. The i-th row diode 34d blocks a current from the direction of the further reference potential 32d common to the row switching elements 10d. The i-th row diode 34d allows a current from the direction of the further reference potential 32d common to the row switching elements 10d.

[0075] A heating matrix element 16d at position i,j has at least one further capacitance 29d at position i,j. The further capacitance 29d at position i,j is a capacitor. An inductor 18d at position i,j is connected at least to a further reference potential 32d common to the heating matrix elements 16d by means of the further capacitance 29d at position i,j. The further reference potential 32d common to the heating matrix elements 16d is a further operating voltage. A first connection of the further capacitance 29d at position i,j is connected to a further connection 42d at position i,j of the inductor 18d at position i,j. A second connection of the capacitance 28d at position i,j is connected to the further reference potential 32d common to the heating matrix elements 16d. Alternatively or additionally the capacitance 28d at position i,j can be configured as a capacitor network, which comprises multiple capacitors connected in series and/or in a parallel manner.

[0076] FIG. 10 shows a further exemplary embodiment of the invention. The further exemplary embodiment differs from the previous exemplary embodiment at least essentially in respect of a number N and a number M. The total number N+M of row switching elements 10e and column switching elements 12e is one greater than the number NM of heating matrix elements 16e. In the present instance the number N=2 and the number M=1. The heating matrix 14e forms a schematic circuit vector. In a configuration, in which the total number N+M is one greater than the number N, diodes 24e at position i,1 can be dispensed with. The household appliance device has a number N of backflow diodes 90e. The i-th backflow diode 90e is connected to the i-th row switching element 10e. The i-th backflow diode 90e is connected parallel to the i-th row switching element 10e. A first connection of the i-th backflow diode 90e is connected to a first connection of the i-th row switching element 10e. A second connection of the i-th backflow diode 90e is connected to a second connection of the i-th row switching element 10e. The i-th backflow diode 90e blocks a current flow in the direction of the reference potential 30e common to the row switching elements 10e. The i-th backflow diode 90e allows a current flow from the direction of the reference potential 30e common to the row switching elements 10e. Alternatively or additionally the household appliance device can have a number of further backflow diodes 90e. A j-th further backflow diode 90e could be connected parallel to a j-th column switching element 12e.

[0077] FIG. 11 shows a further exemplary embodiment of the invention. The further exemplary embodiment differs from the previous exemplary embodiment at least essentially in respect of a number of additional electrical components. The household appliance device has a number N of row capacitances 92f. The i-th row capacitance 92f is connected parallel to an i-th row switching element 10f. A first connection of the i-th row capacitance 92f is connected to a first connection of the i-th row switching element 10f. A second connection of the i-th row capacitance 92f is connected to a second connection of the i-th row switching element 10f. The present exemplary embodiment also differs by way of a circuit of row diodes 34f. In the present instance the i-th row diode 34f is connected to a connection 20f at position i,j of an inductor 18f at position i,j. A first connection of the i-th row diode 34f is connected to the connection 20f at position i,j. A second connection of the i-th row diode 34f is connected to a further reference potential 32f common to the row switching elements 10f. The i-th row diode 34f blocks a current from the direction of the further reference potential 32f common to the row switching elements 10f. The i-th row diode 34f allows the passage of a current from the direction of the further reference potential 32f common to the row switching elements 10f.

[0078] FIG. 12 shows a further preferred method for controlling the abovementioned household appliance device. The method improves the efficiency, in particular the cost efficiency and/or energy efficiency of the household appliance device. Variable operation of inductors 18a-g can advantageously be improved. Faster activation of the inductors 18a-g can also advantageously be achieved.

[0079] The method is described here with reference to a 1.sup.st row switching element 10, a 2.sup.nd row switching element 10, a 1.sup.st column switching element 12, an inductor 18 at position 1,1 and an inductor 18 at position 2,1. The following description can also be applied by the person skilled in the art to further i-th and j-th electrical components of the household appliance device and in particular of the further household appliance devices, as well as those at position i,j.

[0080] In a first method step 100 the control unit 38 activates the row switching elements 10 and the column switching element 12 to start a switching operation. The 1.sup.st row switching element 10, the 2.sup.nd row switching element 10 and the 1.sup.st column switching element 12 form a switching unit 53 of the household appliance device. At least one operating voltage is present at the switching unit 53 in at least one operating state. By switching the switching unit 53, the control unit 38 supplies at least one supply voltage for the inductor 18 at position 1,1. The control unit 38 at least partially converts the operating voltage to the supply voltage by pulse amplitude modulation. By switching the switching unit 53, the control unit 38 also supplies at least one further supply voltage for the inductor 18 at position 2,1. The control unit 38 at least partially converts the operating voltage to the further supply voltage by pulse amplitude modulation.

[0081] In a further method step 102 the control unit 38 varies a frequency of the supply voltage within at least one period of the operating voltage. The control unit 38 varies the frequency by pulse pause modulation of the operating voltage. The control unit 38 also varies at least one duty factor of the supply voltage. In the same way the control unit 38 varies a further frequency and in particular a duty factor of the further supply voltage at least within the period of the operating voltage. The control unit 38 varies the further frequency of the further supply voltage so that it complements the frequency of the supply voltage. The supply voltage and the further supply voltage are configured such that they at least partially complement one another. When the frequency is varied, the control unit 38 avoids an overload at at least one electrical component of the household appliance device. The control unit 38 reduces electromagnetic radiation when the frequency is varied. The control unit 38 takes into account a characteristic power line stored in a computation unit in the process.

[0082] FIG. 13a shows a diagram of control of the inductor 18 at position 1,1 and the inductor 18 at position 2,1. A time is plotted on an x-axis 104. A y-axis 106 is a value axis. The diagram comprises a line voltage curve 108. The line voltage curve 108 shows a profile over time of a line voltage. The line voltage curve 108 extends over two periods of the line voltage. The line voltage is an alternating voltage. The line voltage has a line frequency. The line frequency is 50 Hz. The diagram shows an operating voltage curve 110. The operating voltage curve 110 shows a profile over time of the operating voltage. The operating voltage curve 110 extends over four periods of the operating voltage. The line voltage is converted at least partially to the operating voltage by means of a rectifier of the household appliance device. The operating voltage has a frequency of 100 Hz. The diagram shows a power curve 112. The power curve 112 is a profile over time of a power output by the inductor 18 at position 1,1 to a cookware item. The diagram shows a further power curve 114. The further power curve 114 shows a profile over time of a power output by the inductor 18 at position 2,1 to a cookware item. The diagram shows a total power curve 116. The total power curve 116 is a profile over time of a total power output by the inductor 18 at position 1,1 and the inductor 18 at position 2,1 to a cookware item. The total power curve 116 is obtained by adding the power curve 112 and the further power curve 114.

[0083] FIG. 13b shows a further diagram. The further diagram is a temporally enlarged detail in region I of the maximum of the operating voltage curve 110. The further diagram shows a supply voltage curve 118. The supply voltage curve 118 shows a profile over time of the supply voltage present in particular at the inductor 18 at position 1,1. The frequency of the supply voltage is varied by the control unit 38 in region I of the maximum operating voltage. A duty factor of the supply voltage is also varied by the control unit 38. A pulse duration of the supply voltage remains constant. The further diagram shows a further supply voltage curve 120. The further supply voltage curve 120 shows a profile over time of the further supply voltage present in particular at the inductor 18 at position 2,1. A further frequency of the further supply voltage is varied by the control unit 38 in region I of the maximum operating voltage. A further duty factor of the further supply voltage is also varied by the control unit 38. A further pulse duration of the supply voltage remains constant. The supply voltage and the further supply voltage are configured such that they complement one another. The further diagram comprises a heating current curve 122. The heating current curve 122 shows a profile over time of a heating current flowing through the inductor 18 at position 1,1, in particular as a function of the supply voltage. The further diagram comprises a further heating current curve 124. The further heating current curve 124 shows a profile over time of a heating current flowing through the inductor 18 at position 2,1, in particular as a function of the further supply voltage. A power of the inductor 18 at position 1,1 output to a cookware item, as shown in particular in the power curve 112, is obtained, in particular at least essentially, by multiplying the supply voltage by the heating current. A power of the inductor 18 at position 2,1 output to a cookware item can be determined in the same way.

[0084] FIG. 14 shows a further variation of the frequency of the supply voltage and the further frequency of the further supply voltage based on the power curve 112, a further power curve 114 and a total power curve 116.

[0085] FIG. 15 shows a further variation of the frequency of the supply voltage and the frequency of the further supply voltage. A variation of an additional frequency of an additional supply voltage, which operates an additional inductor 18, is also shown based on a power curve 112, a further power curve 114, an additional power curve 113 and a total power curve 116.

[0086] FIGS. 16a-d show diagrams of typical characteristic power lines 130, 132, 134, 136 of a power, which is output to a cookware item by an inductor 18. The cookware item is made of an inductive material, in particular an alloy, in particular HAC. A time is plotted on an x-axis 126. A y-axis 128 is a value axis. A first characteristic power line 130 shows a profile over time of a power with a degree of cover of the inductor 18 of 30%. A second characteristic power line 132 shows a profile over time of a power with a degree of cover of the inductor 18 of 50%. A third characteristic power line 134 shows a profile over time of a power with a degree of cover of the inductor 18 of 75%. A fourth characteristic power line 136 shows a profile over time of a power with a degree of cover of the inductor 18 of 100%. FIGS. 16a-d differ in the maximum supply voltage present at the capacitance 28. In FIG. 16a a maximum supply voltage of at least 600 V is present. In FIG. 16b a maximum supply voltage of at least 900 V is present. In FIG. 16c a maximum supply voltage of at least 1200 V is present. In FIG. 16d a maximum supply voltage is unlimited.

[0087] FIGS. 17a-d show the same diagrams as FIGS. 16a-d for a cookware item made of a further material, in particular SIL.

[0088] FIGS. 18a-d show the same diagrams as FIGS. 17a-d for a cookware item made of a further material, in particular ZEN.

[0089] FIG. 19 shows a further exemplary embodiment of the household appliance device. In the present instance the household appliance device has a switching unit 53g with two switching elements 10g, 12g, which are arranged in a half bridge topology. The switching unit 53g at least partially forms at least one inverter unit 54g. The inverter unit 54g is provided to generate at least one inverter voltage from the operating voltage. The switching unit 53g also has a variation switching unit 55g. The variation switching unit 55g comprises an additional switching element 138g. The additional switching element 138g is connected to an inductor 18g in a first switching state. The additional switching element 138g is connected to a further inductor 18g of the household appliance device in a second switching state. In the present instance the control unit 38g is provided to convert the inverter voltage at least partially to a supply voltage and a further supply voltage by means of the variation switching unit 55g. The control unit 38g also varies the frequency of the supply voltage and the further supply voltage by means of the variation switching unit 55g.

REFERENCE CHARACTERS

[0090] 10 Row switching element [0091] 12 Column switching element [0092] 14 Heating matrix [0093] 16 Heating matrix element [0094] 18 Inductor [0095] 20 Connection [0096] 22 Inductor matrix [0097] 24 Diode [0098] 26 Further diode [0099] 28 Capacitance [0100] 29 Capacitance [0101] 30 Reference potential (ground) [0102] 32 Further reference potential [0103] 34 Row diode [0104] 36 Column diode [0105] 38 Control unit [0106] 40 Cookware detection mode [0107] 42 Further connection [0108] 44 Operating voltage [0109] 46 Characteristic line [0110] 47 Characteristic line [0111] 48 Household appliance [0112] 50 Cooktop plate [0113] 52 Heating zone position [0114] 53 Switching unit [0115] 54 Inverter unit [0116] 55 Variation switching unit [0117] 56 Operating step [0118] 58 Charging step [0119] 60 Discharging step [0120] 62 Determination step [0121] 64 X-axis [0122] 66 Y-axis [0123] 68 First voltage curve [0124] 70 Second voltage curve [0125] 72 Third voltage curve [0126] 74 Fourth voltage curve [0127] 76 Fifth voltage curve [0128] 80 First current curve [0129] 82 Second current curve [0130] 84 Third current curve [0131] 86 Fourth current curve [0132] 88 Inverter element [0133] 90 Backflow diode [0134] 92 Row capacitance [0135] 100 Method step [0136] 102 Method step [0137] 104 X-axis [0138] 106 Y-axis [0139] 108 Line voltage curve [0140] 110 Operating voltage curve [0141] 112 Power curve [0142] 113 Additional power curve [0143] 114 Further power curve [0144] 116 Total power curve [0145] 118 Supply voltage curve [0146] 120 Further supply voltage curve [0147] 122 Heating current curve [0148] 124 Further heating current curve [0149] 126 X-axis [0150] 128 Y-axis [0151] 130 First characteristic power line [0152] 132 Second characteristic power line [0153] 134 Third characteristic power line [0154] 136 Fourth characteristic power line [0155] 138 Additional switching element