EP2506666B1 - Cooking device - Google Patents

Description

The invention relates to a cooking device according to the preamble of claim 1.

The publication EP 1 951 003 A1 discloses an induction hob with at least two heating frequency units which are operated according to a specific method in order to at least largely avoid intermodulation noises. According to this method, both heating frequency units are operated with an identical and fixed first frequency in a first time interval. In a second time interval, one heating frequency unit is switched off, while the other heating frequency unit is operated with a fixed second frequency. The two frequencies and the relative lengths of the two time intervals are adjusted so that an average output power of each heating frequency unit corresponds to a heating power selected by an operator. At the same time flicker is minimized.

The publication WO 2006/117182 A1 discloses an induction hob. The induction coils of the induction hob are operated either with the same frequency or with a frequency difference of approximately 18 kHz.
The object of the invention is, in particular, to provide a generic cooking appliance device which enables an advantageously flexible setting of an average output power and simple scalability to a large number of heating frequency units. The object is achieved according to the invention by the features of patent claim 1 and method claim 9, while advantageous refinements and developments of the invention can be found in the subclaims.

The invention is based on a cooking device with at least one first and at least one second heating frequency unit and with at least one control unit which is provided for this purpose, the at least two heating frequency units to operate periodically together with a period and to divide the period into at least two time intervals.

It is proposed that the control unit be provided for selecting a control type from a catalog of control types for each of the at least two time intervals. The cooking appliance device is preferably designed as a hob device and particularly advantageously as an induction hob device. “Provided” is to be understood in particular to be specially programmed and / or designed and / or equipped. The fact that the control unit is intended to "subdivide the period into at least two time intervals" should in particular mean that the control unit defines at least one overlap-free time interval in at least one operating state within the period. A sum of the lengths of the at least two time intervals is preferably equal to the period. A “heating frequency unit” is to be understood in particular to mean an electrical unit which generates an oscillating electrical current, preferably with a frequency of at least 15 kHz, in particular at least 17 kHz and advantageously at least 20 kHz, for operating at least one heating unit. A “heating unit” is to be understood in particular as a unit which is intended to convert at least a large part of electrical energy into heat and thus in particular to heat a food to be cooked. In particular, the heating unit comprises a radiant heater, a resistance heater and / or preferably an induction heater, which is provided for converting electrical energy into heat indirectly via induced eddy currents. The heating frequency unit comprises in particular at least one inverter, which preferably comprises two switching units. A “switching unit” is to be understood in particular as a unit which is intended to interrupt a line path comprising at least part of the switching unit. The switching unit is preferably a bidirectional unipolar switch which, in particular, enables current to flow through the switch along the line path in both directions and which in particular shorts an electrical voltage in at least one polarity direction. Preferably the inverter comprises at least two bipolar transistors with an insulated gate electrode and, particularly advantageously, at least one damping capacitor. A “line path” is to be understood in particular as an electrically conductive conductor piece between two points. “Electrically conductive” is to be understood in particular to mean a specific electrical resistance of at most 10 ^-4 Ωm, in particular of at most 10 ^-5 Ωm, advantageously of at most 10 ^-6 Ωm and particularly advantageously of at most 10 ^-7 Ωm at 20 ° C.

A “control unit” is to be understood in particular to mean an electronic unit which is preferably at least partially integrated in a control and / or regulating unit of a cooking appliance, in particular an induction hob, and which preferably has a computing unit and in particular, in addition to the computing unit, a storage unit with one stored therein Control program includes. The control unit is preferably provided at least to control and / or regulate the heating frequency units with the aid of control signals and preferably electrical control signals. A “control signal” is to be understood in particular as a signal which triggers a switching process of a heating frequency unit, in particular also indirectly, in at least one operating state. An “electrical control signal” is to be understood in particular as a control signal with an electrical potential of at most 30 V, preferably of at most 20 V, particularly advantageously of at most 10 V and in particular of at least 5 V in relation to a reference potential. The control signal preferably has a periodicity, at least temporarily, in particular with a period of at most 1 ms, in particular of at most 0.1 ms and advantageously of at most 0.05 ms. The control signal is particularly advantageously at least essentially a square-wave signal, which in particular has two discrete values, preferably a switch-on value and a switch-off value. Each of the two values preferably corresponds to a switching position of the heating frequency units and, in particular, their inverters. Under a "frequency" of a heating frequency unit should in particular the frequency of the control signal controlling the heating frequency unit can be understood.

The fact that the control unit is intended to "select a control type from a catalog of control types" for each of the at least two time intervals is to be understood in particular to mean that the control unit is intended to be active and dependent on given framework conditions for the at least two time intervals Select combination of control types. The general conditions can be any general conditions that appear reasonable to a person skilled in the art, but preferably selected target powers for the at least two heating frequency units, curves of the power-frequency curves for a given system of cookware and heating unit, or a specification for minimization Flicker and / or a requirement to minimize a fluctuation in the output power of the heating frequency units. "Flicker" is to be understood in particular as a subjective impression of an instability of a visual perception, which is caused in particular by a light stimulus, the luminance and / or spectral distribution of which fluctuates over time. In particular, flicker can be caused by a voltage drop in a mains voltage.

A “type of control” is to be understood as a type of control of the at least two heating frequency units by the control unit in a time interval, two different types of control being delimited by the fact that the two types of control have a different number of operated heating frequency units and / or a different number of frequencies used and / or differ by at least one type of calculation and preferably a frequency-independent type of calculation, by means of which at least one frequency used for the control type results from another frequency used for the control type. A "used frequency" of a control type is to be understood in particular as a numerical value of a frequency used in the control type, with zero likewise is to be regarded as a numerical value. A “type of calculation” is to be understood in particular to mean a type of calculation using at least one mathematical operator, the type of calculation being defined exclusively by the at least one mathematical operator and in particular its arrangement with further mathematical operators. In particular, when distinguishing between two types of calculation, numerical values of constants should be irrelevant. The type of calculation is preferably a "simple type of calculation" which in particular has exactly one mathematical operator, such as in particular an addition operator. The type of calculation is preferably an addition of a frequency-independent constant, an exact numerical value of the constant being irrelevant. The fact that a heating frequency unit is “operated” is to be understood in particular to mean that the frequency of the heating frequency unit is different from zero in the relevant time interval. Each type of control preferably allows the at least two heating frequency units to be operated together, at least largely avoiding intermodulation noises. “Intermodulation noise” is to be understood in particular to mean noises whose frequency spectra have at least a non-zero component with a frequency of less than 18 kHz, in particular less than 17 kHz, preferably less than 16 kHz and particularly advantageously less than 15 kHz. The fact that one type of control allows the at least two heating frequency units to be operated jointly "while at least largely avoiding intermodulation noises" is to be understood in particular to mean that when the at least two heating frequency units are operated together according to the type of control, intermodulation noises are at a distance of 1 m from the cooking device device Sound pressure levels of at most 20 dB, in particular of at most 10 dB, preferably of at most 5 dB and particularly advantageously of at most 0 dB. The intermodulation noises are then preferably inaudible by an operator with average hearing.

A "catalog of control types" is to be understood in particular as a collection of different control types. As control types come all control types that appear to be useful to a specialist are considered. The catalog of control types preferably includes a control type in which all heating frequency units are operated with the same, non-zero frequency. The control types catalog preferably includes a control type in which all heating frequency units are switched off. The catalog of control types preferably includes control types in which at least one heating frequency unit is switched off and the other heating frequency units are operated at the same frequency. The catalog of control types preferably includes control types in which all heating frequency units are operated and a difference between frequencies of any two heating frequency units is zero or at least 15 kHz, in particular at least 16 kHz, preferably at least 17 kHz and particularly advantageously at least 18 kHz. The catalog of control types preferably includes control types in which at least one heating frequency unit is switched off and a difference between frequencies of any two operated heating frequency units is zero or at least 15 kHz, in particular at least 16 kHz, preferably at least 17 kHz and particularly advantageously at least 18 kHz. The fact that a heating frequency unit is “switched off” in a time interval should in particular be understood to mean that the heating frequency unit has at least essentially a negligibly low output power in the relevant time interval. An “output power that is at least essentially vanishing in the relevant time interval” is to be understood in particular to mean an output power that is at most 50 W, in particular at most 25 W, preferably at most 10 W and particularly advantageously 0 W and / or in the time interval exclusively during a period of time is given, which corresponds to at most 50%, in particular at most 25%, preferably at most 15% and particularly advantageously at most 10% of a length of the time interval. An “output power” of one of the at least two heating frequency units is to be understood in particular to mean a power which is supplied by the heating frequency unit in at least one heating operating state.

Such a configuration enables an advantageously flexible setting of an average output power to be achieved. Furthermore, simple scalability to a large number of heating frequency units can be made possible.

In a preferred embodiment of the invention, it is proposed that the control unit be provided to select those control types for the at least two time intervals that allow the at least two heating frequency units to be operated with as little fluctuations as possible in a total output power of the at least two heating frequency units and / or a respective output power of the at least one enable two heating frequency units. A “total output power” of the at least two heating frequency units is to be understood in particular as a sum of the output powers of the at least two heating frequency units. The fact that the control unit is intended to select those control types which enable the at least two heating frequency units to be operated “with as little fluctuations as possible in a respective output power” is to be understood in particular as meaning that it is provided to select those control types in which the greatest maximum fluctuation the output power of the at least two heating frequency units is minimal. The control unit is preferably provided to consider those control types for the at least two time intervals for which the total output power is at least largely constant and to select from these control types those which enable the at least two heating frequency units to be operated with the smallest possible fluctuations in a respective output power. The fact that an “total output power is at least largely constant” should be understood in particular to mean that the total output power in at least one operating state has a relative temporal fluctuation which is smaller than that caused by legal requirements and / or standards, in particular by the standard DIN EN 61000- 3-3 specified flicker limit. In this way, ease of use can advantageously be increased, since an at least largely uniform power output can be achieved and flicker can be minimized.

In a particularly preferred embodiment of the invention, it is proposed that the control unit be provided to determine, according to the selected control types, frequencies of control signals of the at least two heating frequency units for each of the at least two time intervals while keeping a total output power of the at least two heating frequency units constant over time. The fact that the control unit is intended to determine the frequencies of the control signals "while at least largely maintaining a constant total output power" means that the control unit specifies the frequencies of the heating frequency units in at least one operating state such that the total output power has a relative temporal Fluctuation that is smaller than a flicker limit determined by legal requirements and / or standards, in particular by the standard DIN EN 61000-3-3. This advantageously allows flicker to be minimized.

It is also proposed that the control unit be provided to adapt average output powers of the at least two heating frequency units to selected target powers. A “mean output power” is to be understood in particular as a time-averaged output power. A relative deviation of the average output power set by the control unit from the target power should be at most 10%, preferably at most 5% and particularly advantageously at most 1%. A high level of operating convenience can be achieved in this way. The mean output power of one of the at least two heating frequency units is preferably always less than or equal to the target power of the corresponding heating frequency unit. In this way, unsafe operating states can be avoided.

The control unit is advantageously provided for adapting the mean output powers of the at least two heating frequency units by adapting the at least two time intervals, in particular while keeping the previously determined frequencies constant. In this way, an advantageously high level of operating comfort can be achieved, since on the one hand minimizes flicker and on the other hand, an average output power adapted to the target power can be provided.

In a further embodiment of the invention, it is proposed that the control unit be provided to control and / or regulate the at least two heating frequency units each by means of a control signal and to adapt a duty cycle of at least one of the control signals in at least one operating state. A “duty cycle” is to be understood in particular as a ratio of a time period in which the control signal assumes the switch-on value within a period to the period of the control signal. In the case of a fixed frequency, one of the heating frequency units can preferably be changed by changing the duty cycle, an output power of the heating frequency unit. The fact that the control unit is intended to “adapt a duty cycle of at least one of the control signals” is to be understood in particular to mean that the control unit is intended to change the duty cycle of at least one of the control signals in order to thereby change an output power at a fixed level To reach the frequency of a heating frequency unit. This can advantageously further increase flexibility in setting the average output powers of the at least two heating frequency units.

It is further proposed that the control unit be provided to subdivide the period into a number of time intervals which corresponds to a number of heating frequency units to be operated simultaneously. The time intervals preferably follow one another directly, so that a sum of lengths of the time intervals corresponds to the period. As a result, the control method according to the invention for a cooking device with more than two heating frequency units and in particular for a cooking device for a matrix hob can be scaled. A “matrix cooktop” is to be understood in particular as a cooktop in which heating units are arranged in a regular grid under a cooktop plate, and an area of the cooktop plate that can be heated by means of the heating units is preferably at least 60%, in particular at least 70%, advantageously at least 80% and particularly advantageously at least 90% of a total surface of the hob plate. In particular, the matrix hob comprises at least 10, in particular at least 20, advantageously at least 30 and particularly advantageously at least 40 heating units.

The control unit is advantageously provided for determining power-frequency curves for different duty cycles of a control signal of the at least two heating frequency units. A “power-frequency curve” is to be understood in particular as a functional relationship which is specific to each combination of cookware and a heating unit and which is dependent on the duty cycle and which clearly assigns an output power to each frequency at a given duty cycle. The fact that the control unit is intended to “determine power-frequency curves for different duty cycles of a control signal of the at least two heating frequency units” should in particular be understood to mean that the control unit briefly operates one of the at least two heating frequency units with different frequencies in at least one operating state and reads the output power of the at least one heating frequency unit from a measuring unit for each of these frequencies. This enables an advantageously precise heating operation.

Furthermore, a method with a cooking device with at least a first and at least a second heating frequency unit, in particular according to one of the preceding claims, is proposed, in which the heating frequency units are operated periodically together with a period and the period is divided into at least two time intervals, each for a control type is selected from a catalog of control types in order to minimize intermodulation noises at least two time intervals. This enables an advantageously flexible setting of an average output power and simple scalability to a large number of heating frequency units.

Furthermore, a cooking device, in particular a hob, with a cooking device device according to the invention is proposed. The hob is preferably an induction hob. The hob can also be a matrix hob and particularly advantageously a matrix induction hob. A “matrix induction hob” is to be understood in particular as a matrix hob which has at least one heating unit comprising an induction heating element.

Further advantages result from the following description of the drawing. Two exemplary embodiments of the invention are shown in the drawing. The drawing, the description and the claims contain numerous features in combination.

Fig. 1

ein Induktionskochfeld mit einer erfindungsgemäßen Gargerätevorrichtung mit zwei Heizfrequenzeinheiten,

Fig. 2

ein beispielhaftes, nicht maßstabsgetreues Steuersignal einer der zwei Heizfrequenzeinheiten,

Fig. 3a

beispielhafte, nicht maßstabsgetreue Leistungs-Frequenz-Kurven für die zwei Heizfrequenzeinheiten gemäß einer ersten Kombination aus Steuerungsarten,

Fig. 3b

je eine beispielhafte, nicht maßstabsgetreue Leistungs-Zeit-Kurve für die zwei Heizfrequenzeinheiten gemäß der ersten Kombination der Steuerungsarten aus Fig. 3a,

Fig. 3c

beispielhafte, nicht maßstabsgetreue Leistungs-Frequenz-Kurven einer der zwei Heizfrequenzeinheiten bei unterschiedlichen Tastgraden eines Steuersignals,

Fig. 3d

beispielhafte, nicht maßstabsgetreue Gesamtleistungs-Zeit-Kurven gemäß der ersten Kombination der Steuerungsarten aus Fig. 3a,

Fig. 4a

beispielhafte, nicht maßstabsgetreue Leistungs-Frequenz-Kurven für die zwei Heizfrequenzeinheiten gemäß einer zweiten Kombination aus Steuerungsarten,

Fig. 4b

je eine beispielhafte, nicht maßstabsgetreue Leistungs-Zeit-Kurve für die zwei Heizfrequenzeinheiten gemäß der zweiten Kombination der Steuerungsarten aus Fig. 4a und

Fig. 5

beispielhafte, nicht maßstabsgetreue Leistungs-Zeit-Kurven für N gleichzeitig betriebene Heizfrequenzeinheiten einer weiteren erfindungsgemäßen Gargerätevorrichtung.

Show it:

Fig. 1

an induction hob with a cooking device device according to the invention with two heating frequency units,

Fig. 2

an exemplary, not to scale control signal of one of the two heating frequency units,

Fig. 3a

exemplary, non-to-scale power-frequency curves for the two heating frequency units according to a first combination of control types,

Fig. 3b

each an exemplary, not to scale, power-time curve for the two heating frequency units according to the first combination of control types Fig. 3a ,

Fig. 3c

exemplary, not to scale, power-frequency curves of one of the two heating frequency units with different duty cycles of a control signal,

Fig. 3d

exemplary, not to scale, total power-time curves according to the first combination of control types Fig. 3a ,

Fig. 4a

exemplary, non-to-scale power-frequency curves for the two heating frequency units according to a second combination of control types,

Fig. 4b

each an exemplary, not to scale, power-time curve for the two heating frequency units according to the second combination of control types Fig. 4a and

Fig. 5

exemplary, not to scale, power-time curves for N heating frequency units operated simultaneously in a further cooking device according to the invention.

Figure 1 shows a cooking device designed as an induction hob 16a. The induction hob 16a comprises a hob 18a, in particular made of a glass ceramic, on which two heating zones 20a, 22a are marked in a known manner. When the induction hob 16a is ready for operation, the hob 18a is arranged horizontally and is provided for setting up cooking utensils. Furthermore, touch-sensitive operating elements 26a and display elements 28a of an operating and display unit 30a of the induction hob 16a are marked on the hob 18a in a known manner. The induction hob 16a further comprises a cooking appliance device with a first and a second heating frequency unit 10a, 12a arranged below the hob plate 18a and with a control unit 14a arranged below the hob plate 18a. In Figure 1 Components which are arranged below the hob plate 18a are shown schematically and in broken lines, functional relationships being indicated by arrows. The control unit 14a is integrated in a control and regulating unit 32a of the induction hob 16a. An induction heating unit assigned to the heating zone 20a and arranged below it is supplied with energy by the first heating frequency unit 10a. An induction heating unit assigned to the heating zone 22a and arranged below it is supplied with energy by the second heating frequency unit 12a. An operator can use the control and display unit 30a to select a heating level for each of the heating zones 20a, 22a, which in each case results in a target power P _obj1 , P _obj2 for the two heating frequency units 10a, 12a. The control unit 14a is for this It is provided to _adapt a respective average output power P _ave1 , P _{ave2 of} the heating frequency units 10a, 12a to the target powers P _obj1 , P _obj2 while largely avoiding intermodulation noises, so that the selected heating levels of the heating zones 20a, 22a can be achieved. In addition, the control unit 14a is provided to minimize an overall output power difference F. The total output power difference F is a maximum difference between two total output powers P ₁ + P _{2 of} the two heating frequency units 10a, 12a at two different times t ₁ and t ₂ : $$\mathrm{F}=\left|{\mathrm{P}}_1\left({\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_1\right)+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_1\right)-{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{2nd}}\right)+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{2nd}}\right)\right|.$$

Here, P ₁ (t) denote the output power of the first heating frequency unit 10a at time t and P ₂ (t) the output power of the second heating frequency unit 12a at time t. The control unit 14a controls the first heating frequency unit 10a by means of a control signal V ₁ (t) and the second heating frequency unit 12a by means of a control signal V ₂ (t).

Figure 2 shows an example of a non-scale control signal V ₁ (t) of the first heating frequency unit 10a in a Cartesian coordinate system. A control voltage V ₁ is plotted on an ordinate axis 36 and a time t on an abscissa axis 38. The control signal V ₁ (t) is a square wave signal with a switch-on value Vo, a switch-off value of 0 volts and a frequency of f _1A during a first time interval T _{A of} a period T. The switch-on value Vo is held during a switch-on time t _0A . In the first time interval T _A , the period of the square wave _signal T _0A . The switch-off _value is held for a period of (T _0A - t _0A ). The frequency f _{1A of} the control signal V ₁ (t) is calculated from a reciprocal of the period T _0A . The frequency f _1A is usually between 20 kHz and 100 kHz. A duty cycle D _{1A of} the control signal V ₁ (t) in the first time interval T _{A is} calculated from a quotient of the switch-on time t _0A divided by the period T _0A . The control signal V ₁ (t) is also on during a second time interval T _{B of} a period T Square wave signal with switch-on value V ₀ and switch-off value of 0 volt. In the second time interval T _B , however, a frequency is f _1B . The switch-on _value Vo is held during a switch-on time t _0B . In the second time interval T _B , a period of the square wave _signal T _0B . The switch-off _value is held for a period of (T _0B - t _0B ). The frequency f _{1B of} the control signal V ₁ (t) is calculated from a reciprocal of the period T _0B . The frequency f _1B is usually between 20 kHz and 100 kHz. A duty cycle D _{1B of} the control signal V ₁ (t) in the second time interval T _{B is} calculated from a quotient of the switch-on time T _0B divided by the period T _0B . A time x separates the first time interval T _A and the second time interval T _B. After the period T has elapsed, the control signal V ₁ (t) is repeated. Following a course of V ₁ (t), a first of two switching units of the first heating frequency unit 10a is periodically switched in accordance with a periodic change in the switch-on value V ₀ and the switch-off value. A second switching unit of the first heating frequency unit 10a is periodically switched in an analog, but time-shifted manner, so that a high-frequency alternating current is produced to operate the induction heating unit assigned to the heating zone 20a.

For a joint operation of the two heating frequency units 10a, 12a, certain conditions have to be placed on the frequencies f _1X , f _{2X of} the control signals V ₁ (t), V ₂ (t) of the heating frequency units 10a, 12a, in order to make intermodulation noises that are perceived as disturbing by an operator to minimize. The index "X" here represents the letters "A" and "B", which characterize the time intervals T _A and T _B. In the case of two heating frequency units 10a, 12a to be operated simultaneously, the following largely intermodulation-free control types (f _1X , f _2X ) are conceivable for a time interval T _X : (1) Both heating frequency units 10a, 12a become in the time interval T _X with the same non-zero frequency f _1X , f _2X operated. (2) One of the two heating frequency units 10a, 12a is switched off in the time interval T _X. (3) Both heating frequency units 10a, 12a are switched off in the time interval T _X. (4) The two heating frequency units 10a, 12a are operated with a frequency difference k in the time interval T _X , the frequency difference k being at least 15 kHz. It is the job of the control unit 14a, from this catalog of control _types (f _1X , f _2X ) for each of the two time intervals T _A and T _B a suitable control type (f _1X , f _2X ) and the heating frequency units 10a, 12a according to this control type (f _1X , f _2X ) to operate together so that the average output power P _ave1 , P _ave2 of each heating frequency unit 10a, 12a corresponds to its target power P _obj1 , P _obj2 .

In the event that an operator selects a simultaneous operation of both heating frequency units 10a, 12a by means of the operating and display unit 30a, the control unit 14a first checks whether cookware suitable for inductive heating is placed on the heating zones 20a, 22a of the hob plate 18a. If this is the case, the control unit 14a determines in a next step for different duty cycles d _j power-frequency curves P ₁ (f, d _j ), P ₂ (f, d _j ) of a given combination of induction heating unit and cookware. To this end, changes the control unit 14a for a fixed duty cycle d _j stepwise a frequency f of a control signal V ₁ (t), V _{2 min1} (t) starting from a maximum frequency f _max f to a respective minimum frequency f _min2, operates the respective Heizfrequenzeinheit 10a, 12a briefly with the set frequency f and reads the output power P ₁ , P _{2 of} the relevant heating frequency unit 10a, 12a from a measuring unit of the cooking device. The control unit 14a makes this determination for duty cycles d _j = 50%, 40%, 30%, 20% and 10%. As an example, this results in the heating frequency unit 10a in Figure 3c shown power-frequency curves P ₁ (f, d _j ) for different duty cycles d _j .

und $$\left|{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{B}}\right)+{\mathrm{P}}_2\left({\mathrm{t}}_{\mathrm{B}}\right)-{\mathrm{P}}_{\mathrm{obj}1}-{\mathrm{P}}_{\mathrm{obj}2}\right|\le \mathrm{G},$$

wobei t_A bzw. t_B einen beliebigen Zeitpunkt innerhalb des Zeitintervalls T_A bzw. T_B kennzeichnet. Hierbei gelten zusätzliche Grenzwerte für die Frequenzen f_1A, f_2A, f_1B, f_2B. Zum einen existiert jeweils die kurvenspezifische Mindestfrequenz f_min1 und f_min2 und damit eine maximal erreichbare Ausgangsleistung P₁, P₂ für jede Heizfrequenzeinheit 10a, 12a. Des Weiteren existiert die gemeinsame durch elektronische Restriktionen gegebene Höchstfrequenz f_max und damit eine in einem kontinuierlichen Betrieb minimal erreichbare Ausgangsleistung P₁, P₂ für jede Heizfrequenzeinheit 10a, 12a. Der gültige Frequenzbereich ist also folgendermaßen eingeschränkt: $${\mathrm{f}}_{\min 1/2}\le {\mathrm{f}}_{1\mathrm{A}},{\mathrm{f}}_{2\mathrm{A}},{\mathrm{f}}_{1\mathrm{B}},{\mathrm{f}}_{\mathrm{2B}}\le {\mathrm{f}}_{\max }\mathrm{.}$$

Since two heating frequency units 10a, 12a are to be operated simultaneously, the period T must be divided into the two time intervals T _A and T _B , the lengths of which will be determined in a later step. First, the control unit 14a selects a catalog of types of control (f _{1X, 2X} f) for each of the two time intervals T _A, T _B, a control mode (f _{1X, 2X} f), so that with an appropriate choice of the frequencies f _{1 A,} f _2A , f _1B , f _2B and of duty cycles D _1A , D _2A , D _1B , D _{2B, the} smallest possible fluctuations in the total output power P ₁ + P _{2 of} the two heating frequency units 10a, 12a and a respective output power P ₁ , P _{2 of} the at least two heating frequency units 10 , 12 occur. The control unit 14a considered all types of control (f _1X , f _2X ) for which the total output power difference F during the transition from the first time interval T _A to the second time interval T _B with a corresponding choice of the frequencies f _1A , f _2A , f _1B , f _2B and of duty cycles D _1A , D _2A , D _1B , D _{2B is} smaller than a flicker limit value G defined by the standard DIN EN 61000-3-3: $$\left|{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{A}}\right)+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{A}}\right)-{\mathrm{P}}_{\mathrm{obj}1}-{\mathrm{P}}_{\mathrm{obj}\mathrm{2nd}}\right|\le \mathrm{G}$$

and $$\left|{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{B}}\right)+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{B}}\right)-{\mathrm{P}}_{\mathrm{obj}1}-{\mathrm{P}}_{\mathrm{obj}\mathrm{2nd}}\right|\le \mathrm{G},$$

where t _A and t _B a desired time within the time interval T _A and T _B indicates. Additional limit values apply for the frequencies f _1A , f _2A , f _1B , f _2B . On the one hand, there is the curve-specific minimum frequency f _min1 and f _min2 and thus a maximum achievable output power P ₁ , P ₂ for each heating frequency unit 10a, 12a. Furthermore, there is the common maximum frequency f _max given by electronic restrictions and thus an output power P ₁ , P ₂ that can be attained minimally in continuous operation for each heating frequency unit 10 a, 12 a. The valid frequency range is limited as follows: $${\mathrm{<figure-callout\; id="1"\; label="f\; min"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f\; </figure-callout>}}_{\min }\le {\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f</figure-callout>}}_{1\mathrm{A}},{\mathrm{f}}_{\mathrm{2nd}\mathrm{A}},{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f</figure-callout>}}_{1\mathrm{B}},{\mathrm{<figure-callout\; id="2B"\; label="f"\; filenames="imgf0002.png,imgf0004.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{2\; B}}\le {\mathrm{f}}_{\mathrm{Max}}\mathrm{.}$$

und $${\mathrm{P}}_{\mathrm{ave}2}={\mathrm{P}}_2\left({\mathrm{t}}_{\mathrm{A}}\right)\times \left({\mathrm{T}}_{\mathrm{A}}/\mathrm{T}\right)+{\mathrm{P}}_2\left({\mathrm{t}}_{\mathrm{B}}\right)\times \left({\mathrm{T}}_{\mathrm{B}}/\mathrm{T}\right)={\mathrm{P}}_{\mathrm{obj}2}.$$

From the observed control modes (f _1X, f _2X) selects the control unit 14a for the common operation of the Heizfrequenzeinheiten 10a, 12a finally that of control (f _{1X, 2X} f) for which a maximum variation of the output power P _1, P ₂ of each Heating frequency unit 10a, 12a is minimal. The control unit 14a then determines the lengths of the time intervals T _A and T _{B in} such a way that the average output power of each heating frequency unit 10a, 12a corresponds to the respective target power P _obj1 , P _obj2 : $${\mathrm{<figure-callout\; id="1"\; label="P\; ave"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P\; </figure-callout>}}_{\mathrm{ave}}={\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{A}}\right)\times \left({\mathrm{T}}_{\mathrm{A}}/\mathrm{T}\right)+{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{B}}\right)\times \left({\mathrm{T}}_{\mathrm{B}}/\mathrm{T}\right)={\mathrm{<figure-callout\; id="1"\; label="P\; obj"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P\; </figure-callout>}}_{\mathrm{obj}}$$

and $${\mathrm{P}}_{\mathrm{ave}\mathrm{2nd}}={\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{A}}\right)\times \left({\mathrm{T}}_{\mathrm{A}}/\mathrm{T}\right)+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{B}}\right)\times \left({\mathrm{T}}_{\mathrm{B}}/\mathrm{T}\right)={\mathrm{P}}_{\mathrm{obj}\mathrm{2nd}}.$$

The selection process carried out by the control unit 14a will be explained below using a case example. Assume that the control unit 14a has determined two combinations of control _types (f _1X , f _2X ) for predetermined target powers P _obj1 , P _obj2 , which when transitioning from the first time interval T _A to the second time interval T _B with a corresponding choice of the frequencies f _1A , f _2A , f _1B , f _2B and duty cycles D _1A , D _2A , D _1B , D _{2B have} a total output power difference F which is smaller than the flicker limit value G.

For this case shows Figure 3a In a Cartesian coordinate system, for example, two power-frequency curves P ₁ (f) and P ₂ (f), which are not to scale, for the first combination of control _types (f _1X , f _2X ). Output powers P ₁ and P _{2 of} the heating frequency units 10a, 12a are plotted on an ordinate axis 42. The frequency f is plotted on an abscissa axis 44. The target powers P _obj1 and P _{obj2 of} the heating frequency units 10a, 12a are set by an operator. The target powers P _obj1 , P _{obj2 are} assigned target frequencies f _obj1 , f _obj2 . Without restricting generality, it is assumed that the second heating frequency unit 12a has the highest target frequency f _obj2 . This is then operated continuously by the control unit 14a in both time intervals T _A and T _B at a fixed frequency f _2A = f _2B , which corresponds to the target frequency f _obj2 . The first heating frequency unit 10a is operated by the control unit 14a in the first time interval T _A with a frequency f _1A lower by 18 kHz. Since the output power P _{1 of} the first heating frequency unit 10a at the frequency f _1A exceeds the target power P _{obj1 of} the first heating frequency unit 10a, the first heating frequency unit 10a is switched off in the second time interval T _B. The types of control used here (f _1X , f _2X ) for the time intervals T _A , T _B are therefore as follows: In the first time interval T _A , the two heating frequency units 10a, 12a are operated with a frequency difference k of 18 kHz (4). In the second time interval T _B , one of the heating frequency units 10a is switched off (2).

Figure 3b shows, in a Cartesian coordinate system, two power-time curves P ₁ (t) and P ₂ (t), which are not to scale, for the first combination of control types Figure 3a . The output powers are on an ordinate axis 46 P ₁ and P _{2 of} the heating frequency units 10a, 12a are plotted. Time t is plotted on an abscissa axis 48. An in Figure 3b The illustrated course of the power-time curves P ₁ (t) and P ₂ (t) is run through periodically with the period T in a heating operating state of the heating frequency units 10a, 12a. The calculation of the lengths of the time intervals T _A and T _{B of} the period T by the control unit 14a is carried out as previously described. As with the Figure 3b to recognize, there is a jump in the total output power P ₁ + P ₂ during the transition from the first time interval T _A to the second time interval T _B. So that this type of control (f _1X , f _2X ) comes into question at all, the duty cycle D _{1A of} the control signal V ₁ (t) of the first heating frequency unit 10a was reduced from 50% to 20% in the first time interval T _A.

Figure 3c shows for this purpose in a Cartesian coordinate system, for example, not to scale power-frequency curves P ₁ (f, d _j ) for different duty cycles D _1A = d _j (j = 1, ..., n) of the control signal V ₁ (t) of the first Heating frequency unit 10a (see also Figure 2 ). The output power P _{1 of} the first heating frequency unit 10a is plotted on an ordinate axis 50. The frequency f is plotted on an abscissa axis 52. By adjusting the duty cycle D _1A , for example from 0.5 to smaller values, the control unit 14a can adjust the output power P _{1 of} the first heating frequency unit 10a. As a result, in particular a reduction in the output power P ₁ at a fixed frequency f _{1A of} the first heating frequency unit 10a can be achieved.

Figure 3d shows in two Cartesian coordinate systems, for example, two not to scale total power-time curves for the first combination of control types Figure 3a . The sum of the output powers P ₁ + P _{2 of} the heating frequency units 10a, 12a is plotted on an ordinate axis 54. The time t during three period durations T is plotted on an abscissa axis 56. The top of the two coordinate systems Figure 3d shows a case in which the duty cycle D _{1A of} the first heating frequency unit 10a has a value d ₁ . According to Figure 3c the frequency f _1A then results in an output power P _{1 of} the first heating frequency unit 10a of P ₁ (f _1A , d ₁ ). The lower of the two coordinate systems Figure 3d shows a case in which the duty cycle D _{1A of} the first heating frequency unit 10a has a value d _n which is smaller than d ₁ . According to Figure 3c The frequency f _1A then results in an output power P _{1 of} the first heating frequency unit 10a of P ₁ (f _1A , d _n ) which is smaller than the output power P ₁ (f _1A , d ₁ ). As with Figure 3d To recognize, the output power difference F can be reduced by choosing a smaller duty cycle D _1A . The control unit 14a uses this fact to minimize the total output power difference F below the flicker limit G.

Figure 4a shows in a Cartesian coordinate system, for example, two non-scale power-frequency curves P ₁ (f) and P ₂ (f) for the second combination of control types. The output powers P ₁ and P _{2 of} the heating frequency units 10a, 12a are plotted on an ordinate axis 58. The frequency f is plotted on an abscissa axis 60. The target powers P _obj1 and P _{obj2 of} the heating frequency units 10a, 12a are set by an operator. In the first time interval T _A , the first heating frequency unit 10a is operated with a frequency f _1A and the second heating frequency unit 12a with a frequency f _2A . In the second time interval T _B , the first heating frequency unit 10a is operated with a frequency f _1B and the second heating frequency unit 12a with a frequency f _2B . The frequencies f _1A and f _2A as well as f _1B and f _2B each form a set of frequencies (f _1A , f _2A ), (f _1B , f _2B ), the two frequencies of a set of frequencies (f _1A , f _2A ), (f _1B , f _2B ) by 18 kHz. The type of control used here (f _1X , f _2X ) is identical in both time intervals: the two heating frequency units 10a, 12a are operated in the time interval T _X with a frequency difference k of 18 kHz (4). Even if the same type of control is used in both time intervals T _A , T _B, the frequencies f _1A , f _2A , f _1B , f _2B used differ.

Figure 4b shows in a Cartesian coordinate system, for example, two non-scale power-time curves P ₁ (t) and P ₂ (t) for the second combination of control types Figure 4a . The output powers P ₁ and P _{2 of} the heating frequency units 10a, 12a are plotted on an ordinate axis 62. The time t is plotted on an abscissa axis 64. An in Figure 4b The illustrated course of the power-time curves P ₁ (t) and P ₂ (t) is run through periodically with the period T in a heating operating state of the heating frequency units 10a, 12a. The first heating frequency unit 10a is operated in the first time interval T _A with a greater output power P ₁ than in the second time interval T _B. In contrast, the second heating frequency unit 12a is operated in the first time interval T _A with a smaller output power P ₂ than in the second time interval T _B. The total output power P ₁ + P ₂ is constant over time and is identical to the sum of the target powers P _obj1 + P _obj2 .

Since the largest maximum fluctuation in the output powers of the heating frequency units 10a, 12a for the second combination of control types (f _1X , f _2X ) according to Figure 4b is smaller than for the first combination of control _types (f _1X , f _2X ) according to Figure 3b , the control unit 14a selects the second combination of control types (f _1X , f _2X ) for the joint operation of the two heating frequency units 10a, 12a.

In the Figure 5 Another embodiment of the invention is shown. The following descriptions are essentially limited to the differences between the exemplary embodiments, with the components, features and functions remaining the same as the description of the other exemplary embodiment, in particular the one Figures 1, 2 , 3a-d and 4a-b , can be referenced. To distinguish the exemplary embodiments, the letter a is in the reference numerals of the exemplary embodiment in the Figures 1, 2 , 3a-d and 4a-b by the letter b in the reference numerals of the embodiment of the Figure 5 replaced. With regard to components with the same designation, in particular with respect to components with the same reference numerals, it is also possible in principle to refer to the drawings and / or the description of the exemplary embodiment in FIG Figures 1, 2 , 3a-d and 4a-b to get expelled.

$$\begin{array}{l}{\mathrm{P}}_{\mathrm{ave}1}={\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{A}}\right)\times \left({\mathrm{T}}_{\mathrm{A}}/\mathrm{T}\right)+{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{B}}\right)\times \left({\mathrm{T}}_{\mathrm{B}}/\mathrm{T}\right)+\dots +{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{N}}\right)\times \left({\mathrm{T}}_{\mathrm{N}}/\mathrm{T}\right)={\mathrm{P}}_{\mathrm{obj}1},\\ {\mathrm{P}}_{\mathrm{ave}2}={\mathrm{P}}_2\left({\mathrm{t}}_{\mathrm{A}}\right)\times \left({\mathrm{T}}_{\mathrm{A}}/\mathrm{T}\right)+{\mathrm{P}}_2\left({\mathrm{t}}_{\mathrm{B}}\right)\times \left({\mathrm{T}}_{\mathrm{B}}/\mathrm{T}\right)+\dots +{\mathrm{P}}_2\left({\mathrm{t}}_{\mathrm{N}}\right)\times \left({\mathrm{T}}_{\mathrm{N}}/\mathrm{T}\right)={\mathrm{P}}_{\mathrm{obj}2},\\ \dots \\ {\mathrm{P}}_{\mathrm{aveN}}={\mathrm{P}}_{\mathrm{N}}\left({\mathrm{t}}_{\mathrm{A}}\right)\times \left({\mathrm{T}}_{\mathrm{A}}/\mathrm{T}\right)+{\mathrm{P}}_{\mathrm{N}}\left({\mathrm{t}}_{\mathrm{B}}\right)\times \left({\mathrm{T}}_{\mathrm{B}}/\mathrm{T}\right)+\dots +{\mathrm{P}}_{\mathrm{N}}\left({\mathrm{t}}_{\mathrm{N}}\right)\times \left({\mathrm{T}}_{\mathrm{N}}/\mathrm{T}\right)={\mathrm{P}}_{\mathrm{objN}}\mathrm{und}{\mathrm{f}}_{\min 1/2/\dots /\mathrm{N}}\le {\mathrm{f}}_{\mathrm{nX}}\le {\mathrm{f}}_{\max },\end{array}$$

wobei t_x einen beliebigen Zeitpunkt innerhalb des Zeitintervalls T_X, P_n die Ausgangsleistung der n-ten Heizfrequenzeinheit 10b, 12b und P_objn die Sollleistung der n-ten Heizfrequenzeinheit 10b, 12b bezeichnet. Eine Auswahl der Steuerungsarten (f_1X, f_2X, ..., f_NX) für die N Zeitintervalle T_x erfolgt analog zur Auswahl im vorhergehenden Ausführungsbeispiel.The method described above is easily transferable to a cooking appliance device with N heating frequency units 10b, 12b to be operated simultaneously, as in FIG Figure 5 shown by way of example in a representation of power-time curves P _n (t) with n = 1, 2,... N that is not to scale. In this case, a control unit 14b divides a period T into N time intervals T _X (X = A, B, ..., N) and operates the N heating frequency units 10b, 12b in each of the time intervals T _X with a control type (f _1X , f _2X , ..., f _NX ). As in the previous embodiment selects the control unit 14b for each time interval T _X a of control (f _1X, f _2X, ..., _NX f) from a catalog of types of control (f _1X, f _2X, ..., _NX F). This catalog includes at least the following types of control: (1) All heating frequency units 10b, 12b are operated at the same non-zero frequency in the time interval T _X. (2) Of the heating frequency units 10b, 12b, y heating frequency units 10b, 12b are switched off, where y = 1, 2, ..., N. (3) At least two heating frequency units 10b, 12b differ in their frequency f _nX (n = 1 , 2, ..., N) by a frequency difference k. Please note that the control _types (f _1X , f _2X , ..., f _NX ) marked with (2) are actually N control _types (f _1X , f _2X , ..., f _NX ), since the number of switched-off heating frequency units 10b, 12b represents a distinguishing feature of two different control types (f _1X , f _2X , ..., f _NX ). Furthermore, the control _types (f _1X , f _2X , ..., f _NX ) marked with (3) are also several control _types (f _1Xx , f _2X , ..., f _NX ). It is obvious to a person skilled in the art that by combining two of the control _types mentioned here (f _1X , f _2X , ..., f _NX ), in particular the control _types (f _1X , f _2X , ..) marked with (2) and (3). ., f _NX ), new control _types (f _1X , f _2X , ..., f _NX ) can be formed. It is particularly advantageous if, in each of the N time intervals T _X, another of the N heating frequency _{units is} operated with a frequency f _nX and the remaining (N − 1) heating frequency _{units are} operated in the same time interval T _X with a frequency (f _nX ± k), k = 18 kHz being particularly advantageous. The conditions mentioned in the previous exemplary embodiment are generalized as follows: $$\begin{array}{l}\left|{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{A}}\right)+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{A}}\right)+...+{\mathrm{P}}_{\mathrm{N}}\left({\mathrm{t}}_{\mathrm{A}}\right)-{\mathrm{P}}_{\mathrm{obj}1}-{\mathrm{P}}_{\mathrm{obj}\mathrm{2nd}}-...-{\mathrm{P}}_{\mathrm{objN}}\right|\le \mathrm{G},\\ \left|{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{B}}\right)+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{B}}\right)+...+{\mathrm{P}}_{\mathrm{N}}\left({\mathrm{t}}_{\mathrm{B}}\right)-{\mathrm{P}}_{\mathrm{obj}1}-{\mathrm{P}}_{\mathrm{obj}\mathrm{2nd}}-...-{\mathrm{P}}_{\mathrm{objN}}\right|\le \mathrm{G},\\ ...\\ \left|{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{N}}\right)+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{N}}\right)+...+{\mathrm{P}}_{\mathrm{N}}\left({\mathrm{t}}_{\mathrm{N}}\right)-{\mathrm{P}}_{\mathrm{obj}1}-{\mathrm{P}}_{\mathrm{obj}\mathrm{2nd}}-...-{\mathrm{P}}_{\mathrm{objN}}\right|\le \mathrm{G},\end{array}$$

$$\begin{array}{l}{\mathrm{<figure-callout\; id="1"\; label="P\; ave"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P\; </figure-callout>}}_{\mathrm{ave}}={\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{A}}\right)\times \left({\mathrm{T}}_{\mathrm{A}}/\mathrm{T}\right)+{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{B}}\right)\times \left({\mathrm{T}}_{\mathrm{B}}/\mathrm{T}\right)+...+{\mathrm{P}}_1\left({\mathrm{t}}_{\mathrm{N}}\right)\times \left({\mathrm{T}}_{\mathrm{N}}/\mathrm{T}\right)={\mathrm{<figure-callout\; id="1"\; label="P\; obj"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P\; </figure-callout>}}_{\mathrm{obj}},\\ {\mathrm{P}}_{\mathrm{ave}\mathrm{2nd}}={\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{A}}\right)\times \left({\mathrm{T}}_{\mathrm{A}}/\mathrm{T}\right)+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{B}}\right)\times \left({\mathrm{T}}_{\mathrm{B}}/\mathrm{T}\right)+...+{\mathrm{P}}_{\mathrm{2nd}}\left({\mathrm{t}}_{\mathrm{N}}\right)\times \left({\mathrm{T}}_{\mathrm{N}}/\mathrm{T}\right)={\mathrm{P}}_{\mathrm{obj}\mathrm{2nd}},\\ ...\\ {\mathrm{P}}_{\mathrm{aveN}}={\mathrm{P}}_{\mathrm{N}}\left({\mathrm{t}}_{\mathrm{A}}\right)\times \left({\mathrm{T}}_{\mathrm{A}}/\mathrm{T}\right)+{\mathrm{P}}_{\mathrm{N}}\left({\mathrm{t}}_{\mathrm{B}}\right)\times \left({\mathrm{T}}_{\mathrm{B}}/\mathrm{T}\right)+...+{\mathrm{P}}_{\mathrm{N}}\left({\mathrm{t}}_{\mathrm{N}}\right)\times \left({\mathrm{T}}_{\mathrm{N}}/\mathrm{T}\right)={\mathrm{P}}_{\mathrm{objN}}\mathrm{and}{\mathrm{<figure-callout\; id="1"\; label="f\; min"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f\; </figure-callout>}}_{\min }\le {\mathrm{f}}_{\mathrm{nX}}\le {\mathrm{f}}_{\mathrm{Max}},\end{array}$$

where t _x denotes an arbitrary point in time within the time interval T _X , P _n the output power of the nth heating frequency unit 10b, 12b and P _objn the target power of the nth heating frequency unit 10b, 12b. A selection of the control _types (f _1X , f _2X , ..., f _NX ) for the N time intervals T _x is carried out analogously to the selection in the previous exemplary embodiment.

Alternatively, a storage unit can be provided in both exemplary embodiments, in which characteristic power-frequency curves P _n (f, d _j ) for various typical combinations of cooking utensils and induction heating elements are stored. Storage is then preferably carried out by a manufacturer before delivery of a corresponding induction hob. This makes it possible to dispense with measuring the power-frequency curves P _n (f, d _j ) before starting heating operation. Reference numerals D _1B Duty cycle 10th Heating frequency unit D _1C Duty cycle 12th Heating frequency unit D _2A Duty cycle 14 Control unit D _2B Duty cycle 16 Induction hob F Total output power difference 18th Cooktop 20th Heating zone f frequency 22 Heating zone f _1A frequency 26 Control element f _1B frequency 28 Display element f _2A frequency 30th Control and display unit f _2B frequency 32 Control and regulation unit f _min1 Minimum frequency 36 Ordinate axis f _min2 Minimum frequency 38 Axis of abscissa f _max Maximum frequency 42 Ordinate axis f _nX frequency 44 Axis of abscissa f _obj1 Target frequency 46 Ordinate axis f _obj2 Target frequency 48 Axis of abscissa G Flicker limit 50 Ordinate axis k Frequency difference 52 Axis of abscissa P ₁ Output power 54 Ordinate axis P ₁ (f) Power frequency curve 56 Axis of abscissa P ₁ (f, d _j ) Power frequency curve 58 Ordinate axis P ₁ (t) Performance-time curve 60 Axis of abscissa P ₂ Output power 62 Ordinate axis P ₂ (f) Power frequency curve 64 Axis of abscissa P ₂ (f, d _j ) Power frequency curve d _j Duty cycle (j = 1, ..., n) Pn (f, d _j ) Power frequency curve D _1A Duty cycle P ₂ (t) Performance-time curve P _ave1 Average output power P _ave2 Average output power P _n Output power P _n (t) Performance-time curve P _obj1 Target power P _obj2 Target power P _objn Target power T Period duration T _0A Period duration T _0B Period duration T _A Time interval T _B Time interval T _x Time interval t time t _0A On time t _0B On time t ₁ time t ₂ time t _x time Vo Switch-on value V ₁ (t) Control signal V ₁ Control voltage V ₂ (t) Control signal x time y number

Claims (10)

1. Cooking appliance device having at least a first and at least a second heating frequency unit (10, 12) and having at least one control unit (14) that is provided so as to operate the at least two heating frequency units (10, 12) simultaneously periodically with one period duration (T) and to divide the period duration (T) into at least two time intervals (T_A, T_B), characterized in that the control unit (14) is provided so as to select a control mode (f_1x, f_2x) for each of the at least two time intervals (T_A, T_B) from a catalogue of control modes (f_1x, f_2x), wherein the control mode (f_1x, f_2x) is a mode of control of at least two heating frequency units by the control unit (14) in a time interval (T_A, T_B) and wherein two different control modes (f_1x, f_2x) are defined by virtue of the fact that the two control modes (f_1x, f_2x) involve operating a different number of heating frequency units (10, 12) and/or using a different number of frequencies (f_1A, f_2A, f_1B, f_2B) and/or said control modes differ by at least one calculating method by means of which at least one frequency (f_1A, f_2A, f_1B, f_2B) that is used in the control mode (f_1X, f_2X) is produced from another frequency (f_1A, f_2A, f_1B, f_2B) that is used in the control mode (f_1X, f_2X).
2. Cooking appliance device according to claim 1, characterised in that the control unit (14) is provided so as for the at least two time intervals (T_A, T_B) to select the particular control modes (f_1X, f_2X) that render it possible to operate the at least two heating frequency units (10, 12) with as few as possible fluctuations of a total output power of the at least two heating frequency units (10, 12) and/or of a respective output power (P₁, P₂) of the at least two heating frequency units (10, 12).
3. Cooking appliance device according to claim 1 or 2, characterised in that the control unit (14) is provided so as in accordance with the selected control modes (f_1X, f_2X), to determine for each of the at least two time intervals (T_A, T_B) frequencies (f_1A, f_2A, f_1B, f_2B) of control signals (V₁(t), V₂(t)) of the at least two heating frequency units (10, 12) while at least to a great extent temporarily maintaining constant a total output power (P) of the at least two heating frequency units (10,12).
4. Cooking appliance device according to one of the preceding claims, characterised in that the control unit (14) is provided so as to adapt average output powers (P_ave1, P_ave2) of the at least two heating frequency units (10, 12) to selected desired powers (P_obj1, P_obj2).
5. Cooking appliance device according to claim 4, characterised in that the control unit (14) is provided so as to adapt the average output powers (P_ave1, P_ave2) of the at least two heating frequency units (10, 12) by virtue of adapting the at least two time intervals (T_A, T_B).
6. Cooking appliance device according to one of the preceding claims, characterised in that the control unit (14) is provided so as to perform open-loop control and/or closed-loop control of the at least two heating frequency units (10, 12) respectively by means of a control signal (V₁(t), V₂(t)) and in at least one operating state to adapt a duty cycle (D_1A, D_2A, D_1B, D_2B) of at least one of the control signals (V₁(t), V₂(t)).
7. Cooking appliance device according to one of the preceding claims, characterised in that the control unit (14) is provided so as to divide the period duration (T) into a number of time intervals (T_A, T_B) that correspond to a number of heating frequency units (10, 12) that are to be operated simultaneously.
8. Cooking appliance device according to one of the preceding claims, characterised in that that the control unit (14) is provided so as to determine power-frequency graphs (P₁(f,d_j), P₂(f,d_j) for different duty cycles (dj) of a control signal (V₁(t), V₂(t)) of the at least two heating frequency units (10, 12).
9. Method for operating a cooking appliance device according to one of the preceding claims having at least a first and at least a second heating frequency unit (10, 12), wherein the heating frequency units (10, 12) are operated simultaneously periodically for a period duration (T) and the period duration (T) is divided into at least two time intervals (T_A, T_B), characterised in that a control mode (f_1X, f_2X) is selected for each of the at least two time intervals (T_A, T_B) from a catalogue of control modes (f_1X, f_2X) so as to minimize intermodulation noises, wherein a control mode (f_1X, f_2X) is a mode of control of at least two heating frequency units by the control unit (14) in a time interval (T_A, T_B) and wherein two different control modes (f_1x, f_2x) are defined by virtue of the fact that the two control modes (f_1x, f_2x) involve operating a different number of heating frequency units (10, 12) and/or use a different number of frequencies (f_1A, f_2A, f_1B, f_2B) and/or said control modes differ by at least one calculating method by means of which at least one frequency (f_1A, f_2A, f_1B, f_2B) that is used in the control mode (f_1X, f_2X) is produced from another frequency (f_1A, f_2A, f_1B, f_2B) that is used in the control mode (f_1X, f_2X).
10. Cooking appliance, in particular a hob, having a cooking appliance device according to one of claims 1 to 8.

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