EP2911472B2 - Cooking appliance, in particular cooking hob device, with a plurality of inverters - Google Patents

Description

The invention is based on a cooking appliance device according to the preamble of claim 1.

Induction cooktops are known from the prior art which have two inverters and a control unit which is intended to operate the two inverters together periodically with one period and to operate them continuously at least within the period. In order to avoid flicker and/or intermodulation hum, which can occur when two inverters are operated simultaneously, the control unit is provided for dividing the period duration into two time intervals.

Furthermore, from the EP 1 951 003 A1 an induction hob is known which has two inverters which are operated together periodically with a period. In this case, a control unit can be provided for dividing the period duration into three time intervals, with none of the inverters being operated in one of the three time intervals. This operating mode is used in particular for low output powers.

Out of EP 2 506 665 A2 a cooking appliance device with a first and a second heating frequency unit and with a control unit is known. The control unit is intended to set a respective mean output power of the two heating frequency units while minimizing a flicker characteristic and to switch the two heating frequency units in a first time interval with a first set of frequencies and in a second time interval with a second set of frequencies that is different from the first set operate.

Out of EP 2 506 666 A1 discloses a cooking appliance device with a first and a second heating frequency unit and a control unit, which is intended to operate the two heating frequency units together periodically with a period and to divide the period into at least two time intervals.

Out of U.S. 2010/0237065 A1 a heating device with a first and a second induction coil and a power supply unit is known, which supplies the first induction coil with a first power and the second induction coil with a second power depending on a control signal.

Out of EP 2 506 663 A1 a cooking appliance device with a first and a second heating frequency unit and with a control unit is known, which is intended to operate the first heating frequency unit continuously and in a first time interval at a fixed first frequency, to operate the second heating frequency unit in the first time interval and in at least one second time interval to minimize at least one flicker parameter.

The object of the invention consists in particular in providing a generic device with improved properties with regard to a power supply. The object is achieved according to the invention by the features of patent claim 1, while advantageous configurations and developments of the invention can be found in the dependent claims.

The invention is based on a cooking appliance device, in particular a hob device, with a plurality of inverters, in particular at least two, preferably at least four and particularly preferably at least six inverters, which are each intended to operate at least one inductor, and with a control unit which is intended to operate at least some of the inverters together, at least in one operating state, and continuously at least within a first time window.

The control unit is provided for dividing the first time window into a first number of time intervals which is greater by at least one, preferably by exactly one, than a second number of inverters to be operated simultaneously. “A number of inverters to be operated simultaneously” should be understood to mean at least two inverters. Thus, a number of time intervals corresponds to at least three time intervals. A “cooking appliance device” is to be understood in particular as at least a part, in particular a subassembly, of a cooking appliance, in particular a hob and preferably an induction hob. In particular, the cooking appliance device can also include the entire cooking appliance, in particular the entire hob and preferably the entire induction hob. The inverters are intended to provide a high-frequency heating current for the inductors. For this purpose, the inverters are operated in at least one operating state with a frequency of at least 1 kHz, advantageously at least 10 kHz, preferably at least 20 kHz and particularly preferably at most 100 kHz. The high-frequency heating current flows in at least one operating state through at least one of the inductors and is intended in particular for heating, in particular cookware, in particular by eddy current and/or magnetic reversal effects. Furthermore, a “time window” is to be understood in particular as a period of between 5 ms and 2.5 s, preferably between 8 ms and 2.3 s and particularly preferably between 9 ms and 2.1 s. In particular, a minimum duration of the time window is specified by at least one flicker standard. Below this minimum period of time, the at least one flicker standard is violated. Furthermore, a maximum duration of the time window is defined by a thermal inertia of the cooking utensil. The control unit is preferably provided to subdivide an operating time of the cooking appliance device into at least one, preferably at least two, advantageously several time windows, preferably with the same time duration, which in particular follow one another directly. Furthermore, “at least some of the inverters” should be understood to mean at least two inverters. The phrase that the control unit is intended to "operate continuously" at least some of the inverters at least within a time window is to be understood to mean that the at least two inverters have a finite output power, at least within the time window, which is different from zero . In this context, an “output power” of an inverter should be understood to mean, in particular, a power which is made available at at least one output of the inverter in at least one operating state. In particular, the output power is fed to at least one inductor. The output power preferably corresponds at least essentially to a power consumption of the inverter. In this context, a “power consumption” of an inverter is to be understood in particular as power that is provided in particular by a power grid and is consumed by the inverter at least in one operating state. The fact that the output power “at least essentially” corresponds to the power consumption of the inverter should be understood in this context to mean that the two power values deviate from one another by a maximum of 5%, preferably a maximum of 3% and particularly preferably a maximum of 1%. In this context, a “time interval” should be understood to mean in particular a time period between 0.1 ms and 1.5 s, preferably between 1 ms and 1 s and particularly preferably between 0.1 s and 0.5 s. In particular, in this case the inverters are operated at least essentially with a constant output power, at least for the duration of one of the time intervals, which in particular has a relative fluctuation of at most 5%, preferably at most 3% and particularly preferably at most 1%.

A configuration according to the invention makes it possible to provide a generic device with improved properties with regard to a power supply. Furthermore, a maximum output power can advantageously be increased and/or in particular an efficiency of the cooking appliance device can be increased. Furthermore, operational reliability can advantageously be increased. Furthermore, the cooking appliance device can advantageously be adapted to different requirements. Furthermore, in particular a particularly uniform power output can be achieved and advantageously a selected setpoint power can be provided as exactly as possible.

The control unit is preferably provided for the purpose of switching at least two of the operated inverters, preferably all operated inverters, in at least one of the time intervals, preferably in all time intervals, in particular in all time intervals of a time window, with at least one moving by at least 15 kHz, preferably at least 16 kHz and particularly preferred to operate at least 17 kHz different frequency or the same frequency. In this way, in particular, a possible intermodulation hum can be reduced and/or avoided.

It is also proposed that the control unit is provided to operate the inverters operated in the first time window in such a way that for each of the operated inverters an output power averaged over the first time window corresponds at least essentially to a setpoint power assigned by the control unit. The expression “to be operated in this way” is to be understood in this context in particular as meaning that the control unit is intended to select an operating parameter in such a way that an output power averaged over the first time window corresponds at least essentially to a setpoint power assigned by the control unit. An "operating parameter" should be understood as meaning the duration of the time intervals and/or the frequency and/or a duty cycle and/or the output power of the inverters. A "duty cycle" is to be understood in particular as a ratio of a time duration in which a periodic control signal of the inverter assumes a switch-on value within a period duration to the period duration of the control signal. Preferably, with a fixed switching frequency of one of the inverters, the output power of the inverters can be changed by changing the duty cycle. Furthermore, an “average output power” is to be understood in particular as an output power averaged over time, which corresponds in particular to an arithmetic mean of the output powers of the individual time intervals of the time window, in particular an individual time window. In this context, the phrase that the averaged output power “at least essentially” corresponds to a setpoint power assigned by the control unit is to be understood in particular to mean that the two power values deviate from one another by a maximum of 5%, preferably a maximum of 3% and particularly preferably a maximum of 1%. In this context, a "setpoint power" is to be understood in particular as a power which is to be effectively provided by at least one of the inverters. In particular, the setpoint power assigned by the control unit can correspond to a power selected by a user. As a result, a number of inverters can advantageously be operated together and, in particular, possible intermodulation hum can be avoided.

According to the invention , it is proposed that the control unit is intended to subdivide the first time window into the first number of time intervals in such a way that consecutive, preferably all, time intervals within the first time window differ in at least one operating parameter, namely in a frequency and/or a Tastarad and / or an output power differ. In this context, “successive time intervals” should be understood to mean, in particular, at least two time intervals, in particular at least two time intervals of a time window, which in particular directly adjoin one another in terms of time. The fact that two time intervals “immediately adjoin one another in terms of time” is to be understood in particular to mean that the two time intervals lie directly one after the other, at least in terms of time, and in particular have at least one common point in time. As a result, a setpoint power can be achieved in a particularly advantageous manner and, in particular, an advantageously uniform power output can be achieved, as a result of which flicker can be reduced in particular.

If the total power consumption of the inverters is at least substantially constant, in particular in a time interval, at least in one operating state, at least over two consecutive time intervals, preferably at least within the first time window, a requested target power can advantageously be provided and the efficiency of the cooking appliance device can be increased. Furthermore, a flicker can be avoided at least to a large extent. A total power consumption of the inverters, at least in one operating state, is advantageously at least essentially constant over all successive time intervals, preferably at least within a time window. In this context, a “total power consumption of the inverters” is to be understood in particular as a sum of the power consumptions of all operated inverters, in particular in a time interval. The phrase "at least essentially" constant is to be understood in particular as meaning that a relative deviation in the total power consumption of the inverters in at least two consecutive time intervals is a maximum of 2%, preferably a maximum of 1.5% and particularly preferably a maximum of 1%.

In an advantageous embodiment of the invention, it is proposed that a total power consumption of the inverters, in particular in a time interval, at least in one operating state, is at least significantly different over at least two consecutive time intervals, preferably at least within the first time window. A total power consumption of the inverters, at least in one operating state, is advantageously at least significantly different over all time intervals, preferably at least within the first time window. The phrase "at least significantly" different is to be understood in particular as meaning that a relative deviation in the total power consumption of the inverters in at least two consecutive time intervals is at least 2%, preferably at least 3% and particularly preferably at least 4% and in particular at most 40%, preferably at most 20% and particularly preferably a maximum of 10%. In this way, in particular, a maximum achievable power and/or a maximum achievable desired power can be increased.

Furthermore, it is proposed that an output power of at least one first inverter increases at least significantly in consecutive, in particular all, time intervals of the first time window and an output power of at least one second inverter in consecutive, in particular all, time intervals of the first time window at least significantly decreases. In this context, the fact that an output power of an inverter "at least significantly increases and/or decreases" is to be understood in particular as meaning that a relative deviation in the power consumption of an inverter in successive time intervals is at least 2%, advantageously at least 10%, preferably at least 20% and in particular preferably at least 40%. A flicker in particular can be reduced as a result. Furthermore, operational reliability of the cooking appliance device can advantageously be increased, since in particular power fluctuations, in particular when changing between two intervals, can be minimized.

According to the invention , it is proposed that the control unit is intended to continuously operate at least some of the inverters together at least in one operating state and at least within a second time window, which differs from the first time window, and the control unit is intended to switch the second time window to to subdivide a third number of time intervals which is greater by at least one, preferably exactly one, than a fourth number of inverters to be operated simultaneously. In particular, the second time window is arranged before and/or after the first time window, at least in terms of time. The second time window is preferably directly adjacent to the first time window. According to the invention, the first time window and the second time window differ at least in one operating parameter. Furthermore, the third number of time intervals can differ from the first number of time intervals and/or the fourth number of inverters to be operated can differ from the second number of inverters to be operated. The fact that two time windows "immediately adjoin one another" is to be understood in this context in particular as meaning that the two time windows lie directly one after the other, at least in terms of time, and in particular have at least one common point in time. In this way, in particular, the efficiency of the cooking appliance device can be increased. Furthermore, the cooking appliance device can advantageously be adapted to different operating conditions.

It is also proposed that the second time window is directly adjacent to the first time window and that both time windows have the same number of time intervals with identical operating parameters, with the time intervals of the second time window being arranged in the reverse order compared to the time intervals of the first time window. In this context, a "reverse order" is to be understood in particular as meaning that the control unit is intended to arrange the time intervals of the first time window in the second time window in such a way that the time intervals in the second time window are mirrored in comparison to an end point of the first time window have order. In this context, an “end point of the first time window” is to be understood in particular as a point in time of the first time window which in particular directly adjoins a further time window, preferably the second time window. Alternatively, the time intervals of the second Timeslots can also be arranged in any order. As a result, flicker can be further reduced and operational reliability, in particular when lifting a cooking utensil, can be further increased.

Further advantages result from the following description of the drawing. In the drawing an embodiment of the invention is shown. The drawing, the description and the claims contain numerous features in combination.

Fig. 1

ein Induktionskochfeld mit einer erfindungsgemäßen Gargerätevorrichtung mit zwei Wechselrichtern,

Fig. 2

schematische, nicht maßstabsgetreue Leistungs-Frequenz-Kurven für die zwei Wechselrichter,

Fig. 3

beispielhafte, nicht maßstabsgetreue Leistungs-Zeit-Kurven für die zwei Wechselrichter für ein erstes Zeitfenster,

Fig. 4

beispielhafte, nicht maßstabsgetreue Leistungs-Zeit-Kurven für die zwei Wechselrichter für das erste Zeitfenster und ein zweites Zeitfenster,

Fig. 5

beispielhafte, nicht maßstabsgetreue Frequenz-Zeit-Kurven für die zwei Wechselrichter und

Fig. 6

eine schematische Darstellung eines maximal erreichbaren Leistungsbereichs der erfindungsgemäßen Gargerätevorrichtung.

Show it:

1

an induction hob with a cooking appliance device according to the invention with two inverters,

2

Schematic, not to scale, power-frequency curves for the two inverters,

3

exemplary power-time curves, not true to scale, for the two inverters for a first time window,

4

exemplary power-time curves, not true to scale, for the two inverters for the first time window and a second time window,

figure 5

exemplary, not to scale, frequency-time curves for the two inverters and

6

a schematic representation of a maximum achievable power range of the cooking appliance device according to the invention.

figure 1 shows an exemplary cooking appliance designed as an induction hob with a cooking appliance device according to the invention in a schematic plan view. The cooking appliance device has a hob plate with two heating zones 14 . The cooking appliance device also has an operating unit 16 . The operating unit 16 is used for the input and/or selection of a power level by a user. Furthermore, the cooking appliance device has two inverters 10 in the present case. The inverters 10 are arranged below the hob plate of the cooking appliance. In addition, the cooking appliance device has two inductors (not shown). The two inductors are arranged below the hob plate. Each inductor is associated with one of the two heating zones 14 . Furthermore, each inductor is associated with one of the two inverters 10 . Furthermore, the hob device has a control unit 12 . The control unit 12 has at least one computing unit and at least one memory unit. A control program is stored in the storage unit and can be retrieved during operation of the cooking appliance device. The control unit 12 is intended to operate the two inverters 10 . Furthermore, the control unit 12 together with the inductors forms a detection unit for detecting a cooking utensil. For this purpose, the control unit 12 can use the inductors as inductive sensors for detecting the cooking utensil. Furthermore, each of the two inverters 10 is intended to supply one of the inductors with a high-frequency heating current, as a result of which cooking utensils placed on the cooktop plate in particular can be heated inductively. However, a cooking appliance device according to the invention is not limited to two inverters and/or two inductors, but can have any number of inverters and/or inductors. In particular, a cooking appliance device according to the invention can also be provided for a matrix hob. Furthermore, a cooking appliance device can also have an additional switching unit, which is provided to interrupt a conduction path between inverters and inductors and/or to assign multiple inverters to an inductor.

In the present case, an operator can select a power level for each of the two heating zones 14 using the operating unit 16 . The control unit 12 can set a target power P _obj1 , P _obj2 for the two inverters 10 on the basis of the selected value. In the present case, the power level selected by the operator corresponds directly to the target power P _obj1 , P _obj2 of the two inverters 10. If cooking utensil is now to be heated, the control unit 12 and/or the detection unit first checks whether cooking utensil suitable for inductive heating is on the Heating zones 14 of the hob plate is placed. If this is the case, then in a next step the control unit 12 and/or the detection unit determines a power-frequency curve of a given combination of inductor and cooking utensil in a known manner for different duty cycles. In this case, for a fixed duty cycle, the control unit 12 changes a frequency of a control signal of the inverters 10 step by step, starting from a maximum frequency f _max to a respective minimum frequency f _min1 , f _min2 . As an example, for the two inverters 10, the results in figure 2 power-frequency curves shown. The frequency of the inverters 10 is entered on an abscissa axis 22 and the output power of the inverters 10 is entered on an ordinate axis 24 . In the present case, the first of the two inverters 10 has a maximum output power of 2300 W. The second inverter 10 has a maximum output power of 2350 W.

figure 3 shows exemplary power-time curves, not true to scale, for the two inverters 10. A time is plotted on an abscissa axis 26 and the output power of the inverters 10 is plotted on an ordinate axis 28. In an operating state in which only one of the two inverters 10 is being operated, the control unit 12 can be provided to continuously provide an output power. In an operating state in which the inverters 10 can be operated continuously at the same time with a frequency difference of greater than or equal to 17 kHz, the control unit 12 is intended to operate the inverters 10 continuously. In an operating state in which the inverters 10 are to be operated simultaneously and cannot be operated continuously, the control unit 12 is intended to operate the inverters 10 together and continuously at least within a first time window T _a and to split the first time window T _a into one Number M of time intervals t _a , t _b , t _c to be divided, with a number N of inverters 10 to be operated simultaneously. In this case, the control unit 12 is provided to determine suitable frequencies f _1a , f _1b , f _1c , f _2a , f _2b , f _2c and/or durations of the time intervals t _a , t _b depending on the target powers P _obj1 , P _obj2 of the inverters 10 , to determine t _c . For this purpose, the control unit 12 is intended to solve the following matrix equation: $$\mathrm{A}\cdot \mathrm{x}=\mathrm{b}$$

A matrix A is composed of the output powers P _1a , P _1b , P _1c , P _2a , P _2b , P _2c of each inverter 10 (rows i) in the various time intervals t _a , t _b , t _c (columns j). . This results in a value P _ij for each element of the matrix A. A number of rows corresponds to the number N of operated inverters 10.

Furthermore, a number of columns corresponds to the number M of time intervals t _a , t _b , t _c . In general, the matrix A thus corresponds to an N x M matrix. Furthermore, an M x 1 vector x is composed of a normalized time duration r _j of the time intervals t _a , t _b , t _c , with a time duration of one of the time intervals _{ta , t b ,} t _c being defined in particular by a duration of the time window T _a , T _b is normalized. Furthermore, an N x 1 vector b is composed of the setpoint power P _obj1 , P _obj2 of the inverter 10 . In general, the matrix equation or the system of equations can be solved if the number M is at least as large as the number N.

Furthermore, the time intervals t _a , t _b , t _c and/or the normalized time durations r _j have the following relationship: $${\displaystyle \sum {\mathrm{right}}_{\mathrm{j}}={\displaystyle \sum {\mathrm{t}}_{\mathrm{j}}/{\mathrm{T}}_{\mathrm{a}\mathrm{,\; b}}=1}}$$

This reduces a number of unknown variables in the matrix equation to be solved by 1. If the control unit 12 is intended to divide the first time window T _a into a number M of time intervals, which is equal to a number N of inverters to be operated simultaneously, the matrix equation has no solution because it is an overdetermined system of equations (N > M).

For this reason, in this case the control unit 12 is provided to keep a total power consumption P _Ta , P _Tb , P _Tc of the inverters 10 constant over successive time intervals t _a , t _b , t _c . In this case: $${\displaystyle \sum {\mathrm{P}}_{\mathrm{ij}}={\displaystyle \sum {\mathrm{P}}_{\mathrm{obji}}}\mathrm{for}\mathrm{Everyone}\mathrm{j}}$$

This also reduces the number of equations to be solved by one. A specific system of equations is thus present and the matrix equation can be solved (N = M). This corresponds to a state in which no flicker occurs.

The cooking appliance device according to the invention now proposes that the control unit 12 is intended to divide the first time window T _a into a first number M of time intervals t _a , t _b , t _c which is at least one greater than a second number N an inverters 10 to be operated at the same time. This results in a specific system of equations even if only equation (2) is satisfied. Thus, a total power consumption P _Ta , P _Tb , P _Tc of the inverter 10, at least in one operating state _, can be different over at least two consecutive time intervals ta, _tb , _tc , whereby in particular a maximum output power of the cooking appliance device can be increased.

Furthermore, at least in one operating state, a total power consumption P _Ta , P _Tb , P _Tc of the inverters 10 can be constant over at least two consecutive time intervals ta, _tb , _tc , as _a result of which equation (3) is satisfied in particular. In this case, an underdetermined system of equations results when solving the matrix equation, which results in an infinite number of solutions for a division of the time intervals t _a , t _b , t _c . In this case, the control unit 12 is provided to select the time intervals t _a , t _b , t _c in such a way that the most efficient possible operation of the cooking appliance device is made possible.

Such a control program and/or maximum and/or minimum durations of the time intervals t _a , t _b , t _c and/or the time windows T _a , T _b are stored in the memory unit of the control unit 12c.

In the present case, two inverters 10 are to be operated simultaneously, so that the control unit 12 is provided for dividing the first time window T _a into three time intervals t _a , t _b , t _c . The first time window T _a has a fixed duration of 1 s. In the present case, the three time intervals t _a , t _b , t _c have different durations. A first time interval t _a has a duration of 460 ms. A second time interval t _b has a duration of 490 ms. A third time interval t _c has a duration of 50 ms. Furthermore, the control unit 12 is provided to subdivide the first time window T _a into the three time intervals ta , t _b , t _c in _{such a} way that successive time intervals _{ta , t b ,} t _c within the first time window T _a are at least one Distinguish operating parameters. In the present case, the three time intervals ta _, tb, _tc differ in a duration of the time intervals ta _{, tb} , _{tc ,} a frequency _{f1a, f1b, f1c , f2a , f2b} , _f2c two inverters 10 and in an output power P _1a , P _1b , P _1c , P _2a , P _2b , P _2c of the two inverters 10.

The first inverter 10 has _a constant output power P _1a and/or a constant frequency f _1a over the entire duration of the first time interval ta. Furthermore, the first inverter 10 has an output power P _1a over the entire duration of the first time interval t _a which corresponds to the maximum output power of the first inverter 10 . In the present case, the first inverter 10 thus has an output power P _1a of 2300 W over the entire duration of the first time interval t _a . Furthermore, the first inverter 10 has _a frequency f _1a over the entire duration of the first time interval ta, which corresponds to the minimum frequency f _min1 of the first inverter 10 (cf. figure 2 ). The first inverter 10 has _a frequency f _1a of 41.7 kHz over the entire duration of the first time interval ta. Furthermore, the first inverter 10 has a constant output power P _1b and/or a constant frequency f _1b over the entire duration of the second time interval _tb . In this case, the first inverter 10 has a smaller output power P _1b in the second time interval t _b than in the first time interval t _a . In the present case, the first inverter 10 has an output power P _1b of 1630 W over the entire duration of the second time interval t _b . Furthermore, the first inverter 10 has a frequency f _1b of 46.3 kHz over the entire duration of the second time interval t _b .

In this case, the first inverter 10 has a higher frequency f _1b in the second time interval t _b than in the first time interval t _a . Furthermore, the first inverter 10 has a constant output power P _1c and/or a constant frequency f _1c over the entire duration of the third time interval t _c . In this case, the first inverter 10 has a lower output power P _1c in the third time interval t _c than in the second time interval t _b . In the present case, the first inverter 10 has an output power P _1c of 850 W over the entire duration of the third time interval t _c . The first inverter 10 has a higher frequency f _1c in the third time interval t _c than in the second time interval t _b . Furthermore, the first inverter 10 has a frequency f _1c of 58.8 kHz over the entire duration of the third time interval t _c .

Furthermore, the control unit 12 is provided to operate the first inverter 10 operated in the first time window T _a in such a way that for the first inverter 10 an output power P _ave1 averaged over the first time window T _a corresponds to the setpoint power P _obj1 assigned by the control unit 12 . In the present case, the setpoint power P _obj1 requested by the control unit 12 and/or an operator is 1900 W. The output power P _ave1 of the first inverter 10 averaged over the first time window T _a is also 1900 W.

The second inverter 10 has _a constant output power P _2a and/or a constant frequency f _2a over the entire duration of the first time interval ta. In the present case, the second inverter 10 has an output power P _2a of 710 W over the entire duration of the first time interval t _a . Furthermore, the second inverter 10 has _a frequency f _2a of 58.7 kHz over the entire duration of the first time interval ta. Furthermore, the second inverter 10 has a constant output power P _2b and/or a constant frequency f _2b over the entire duration of the second time interval t _b . In this case, the second inverter 10 has a greater output power P _2b in the second time interval t _b than in the first time interval t _a . In the present case, the second inverter 10 has an output power P _2b of 1600 W over the entire duration of the second time interval t _b . In this case, the second inverter 10 has a lower frequency f _2b in the second time interval t _b than in the first time interval t _a . Furthermore, the second inverter 10 has a frequency f _2b of 46.3 kHz over the entire duration of the second time interval t _b . Furthermore, the second inverter 10 has a constant output power P _2c and/or a constant frequency f _2c over the entire duration of the third time interval t _c . Furthermore, the second inverter 10 has an output power P _2c over the entire duration of the third time interval t _c which corresponds to the maximum output power of the first inverter 10 . In this case, the second inverter 10 has a greater output power P _2c in the third time interval t _c than in the second time interval t _b . In the present case, the first inverter 10 thus has an output power P _2c of 2350 W over the entire duration of the third time interval t _c . Furthermore, the second inverter 10 has a frequency f _2c over the entire duration of the third time interval t _c which corresponds to the minimum frequency f _min2 of the second inverter 10 (cf. figure 2 ). The second inverter 10 thus has a lower frequency f _2c in the third time interval t _c than in the second time interval t _b . The second inverter 10 has a frequency f _2c of 41.8 kHz over the entire duration of the third time interval t _c .

The control unit 12 is provided to operate the second inverter 10 operated in the first time window T _a in such a way that for the second inverter 10 an output power P _ave2 averaged over the first time window T _a corresponds to the setpoint power P _obj2 assigned by the control unit 12 . In the present case, the setpoint power P _obj2 requested by the control unit 12 and/or an operator is 1200 W. The output power P _ave2 of the second inverter 10 averaged over the first time window T _a is also 1200 W.

Furthermore, the control unit 12 is provided to the two inverters 10 at least in one of To operate time intervals t _a , t _b , t _c with a frequency that differs by at least 15 kHz or the same frequency. In this case, the first inverter 10 has _a higher output power P _1a and/or a lower frequency f _1a than the second inverter 10 over the entire duration of the first time interval ta. The first inverter 10 has a higher output power P _1b than the second inverter 10 over the entire duration of the second time interval t _b . In this case, however, the first inverter 10 has the same frequency f _1b as the second inverter 10 over the entire duration of the second time interval t _b . The two inverters 10 are thus operated at the same frequency over the entire duration of the second time interval t _b . In addition, the first inverter 10 has a lower output power P _1c and/or a higher frequency f _1c than the second inverter 10 over the entire duration of the third time interval t _c . Thus, the two inverters 10 are operated over the entire duration of the first time interval t _a and over the entire duration of the third time interval t _c at a frequency that differs by 17 kHz. Furthermore, the output power P _1a , P _1b , P _1c of the first inverter 10 increases in successive time intervals t _a , t _b , t _c of the first time window T _a and the output power P _2a , P _2b , P _2c of the second inverter 10 falls in successive ones Time intervals t _a , t _b , t _c of the first time window T _a .

In the present case, the total power consumption P _Ta , P _Tb , P _Tc in one of the time intervals _{ta, t b , t c results from} a summation of the output power P _1a , P _1b , P _1c of the first inverter 10 in one of the time intervals t _a , t _b , t _c and the output power P _2a , P _2b , P _2c of the second inverter 10 in the same time interval t _a , t _b , t _c . In the present case, the total power consumption P _Ta , P _Tb , P _Tc of the two inverters 10 is different, at least in one operating state, at least over two consecutive time intervals t _a , t _b , t _c and differs in particular by at least 200 W, which in particular maximum output power can be increased. Alternatively, however, a total power consumption of the inverters, at least in one operating state, can also be constant over at least two consecutive time intervals.

figure 4 12 shows exemplary power-time curves for the two inverters 10 for the first time window T _a and a second time window T _b , during figure 5 shows exemplary frequency-time curves for the two inverters 10 for the first time window T _a and the second time window T _b . In figure 4 a time is plotted on an abscissa axis 30 and the output power of the inverters 10 is plotted on an ordinate axis 32 . In figure 5 a time is plotted on an abscissa axis 34 and the frequency of the inverter 10 is plotted on an ordinate axis 36 . In the present case, the second time window T _b is directly adjacent to the first time window T _a . The control unit 12 is provided to operate the two inverters 10 together at least in one operating state and continuously at least within the second time window Tb and to divide the second time window _Tb into a third number of time intervals _{ta , tb} , _tc , which is greater by at least one than a fourth number of inverters 10 to be operated simultaneously within the time window T _b . In the present case, the second time window T _b has a fixed time duration, which is identical to the time duration of the first time window T _a . The second time window _Tb thus has a fixed time duration of 1 s. Alternatively, in this case, however, a duration of a second time window can also differ from a duration of a first time window. Provision can also be made to vary a number of time windows with a mains frequency and/or a multiple of the mains frequency, in particular twice the mains frequency.

Furthermore, the two inverters 10 are also operated simultaneously in the second time window Tb, so that the control unit 12 is intended to divide the second time window _Tb into three time intervals _{ta, tb , tc ,} which in particular are at the three time intervals _ta , t _b , t _c into which the first time window T _a is divided are identical. Thus, the two time windows T _a , T _b have the same number of time intervals _{ta , t b ,} t _c with identical operating parameters, in particular frequencies and output _{powers, with the time intervals ta , t b ,} t _c of the second time window T _b however, are arranged in a reverse order compared to the time intervals t _a , t _b , t _c of the first time window T _a . An output power P ave3 of the first inverter 10 averaged over the second time window T _b corresponds to the output power P _ave1 of the first inverter 10 averaged over the first time window T _{a .} Furthermore, an output power P _ave4 of the second inverter 10 averaged over the second time window T _b corresponds the output power P _ave2 of the second inverter 10 averaged over the first time window T _a . Thus for both inverters 10 an output power P _ave3 , P _ave4 averaged over the second time window T _b corresponds to a setpoint power P _obj1 , P _obj2 assigned by the control unit 12 .

figure 6 shows schematically a maximum achievable power range of the two inverters 10. The output power of the first inverter 10 is plotted on an abscissa axis 38 and the output power of the second inverter 10 is plotted on an ordinate axis 40. The cooking device according to the invention has a larger maximum power range than a maximum power range of a cooking device from the prior art. The area 18 shows a performance range which cannot be reached by a cooking appliance device of the prior art, in particular since the cooking appliance device is operated in a state in which no flicker occurs. A maximum power range of about 94% of an entire power range can be achieved. The area 20 shows a power range which cannot be reached by a cooking appliance device according to the invention. In the present case, the maximum power range is only limited by a maximum mains voltage that can be supplied and/or a maximum current and/or by a flicker limit value of a flicker standard. Overall, in the present case, a maximum power range of about 98% of an entire power range can be achieved. The maximum achievable power range is thus increased compared to the maximum achievable power range of the prior art, since operation in a range between a state without flicker and the flicker limit value is possible.

Reference sign

10

inverter

12

control unit

14

heating zone

16

operating unit

18

power range

20

power range

22

abscissa axis

24

ordinate axis

26

abscissa axis

28

ordinate axis

30

abscissa axis

32

ordinate axis

34

abscissa axis

36

ordinate axis

38

abscissa axis

40

ordinate axis

A

matrix

b

vector

fmax

maximum frequency

fmin1

minimum frequency

fmin2

minimum frequency

f1a

frequency

f1b

frequency

f1c

frequency

f2a

frequency

f2b

frequency

f2c

frequency

M

number of time intervals

N

number of inverters

Pave1

Average output power

Pave2

Average output power

Pave3

Average output power

Pave4

Average output power

Pobj1

target performance

Pobj2

target performance

PTa

total power consumption

PTb

total power consumption

PTc

total power consumption

P1a

output power

P1b

output power

P1c

output power

P2a

output power

P2b

output power

P2c

output power

Pij

matrix value

rj

Normalized duration

ta

Time window

TB

Time window

ta

time interval

tb

time interval

Claims (8)

1. Cooking appliance device, in particular hob device, with a plurality of inverters (10) which are provided to operate in each case at least one inductor, and with a control unit (12), which is provided to operate at least one part of the inverter (10) in at least one operating state collectively and at least within a first time frame (T_a) continuously, wherein the control unit (12) is provided to divide the first time frame (T_a) into a first number (M) of time intervals (t_a, t_b, t_c), which is greater by at least one than a second number (N) of inverters (10) to be operated at the same time, wherein the control unit (12) is provided to divide the first time frame (T_a) into the first number (M) of time intervals (t_a, t_b, t_c) such that consecutive time intervals (t_a, t_b, t_c) within the first time frame (T_a) differ at least in one operating parameter, namely in a frequency and/or a pulse duty factor and/or an output power,
   characterised in that
   the control unit (12) is provided to operate the at least one part of the inverter (10) at least in one operating state collectively and at least within a second time frame (T_b), which differs from the first time frame (T_a), continuously, wherein the first time frame (T_a) and the second time frame (T_b) differ at least in one operating parameter, and the control unit (12) is provided to divide the second time frame (T_b) into a third number of time intervals (t_a, t_b, t_c), which is greater by at least one than a fourth number of inverters (10) to be operated at the same time, wherein the control unit (12) is provided to divide the second time frame (T_b) into the third number of time intervals (t_a, t_b, t_c) such that consecutive time intervals (t_a, t_b, t_c) within the second time frame (T_b) differ at least in one operating parameter, namely in a frequency and/or a pulse duty factor and/or an output power.
2. Cooking appliance device according to claim 1, characterised in that the control unit (12) is provided to operate at least two of the operated inverters (10) in at least one of the time intervals (t_a, t_b, t_c) with at least one frequency which differs by at least 15 kHz or the same frequency.
3. Cooking appliance device according to claim 1 or 2,
   characterised in that
   the control unit (12) is provided to operate the inverters (10) operated in the first time frame (T_a) such that for each of the operated inverters (10) a power output (P_ave1, P_ave2) which is averaged over the first time frame (T_a) corresponds at least essentially to a desired output (P_obj1, P_obj2) assigned by the control unit (12).
4. Cooking appliance device according to one of the preceding claims,
   characterised in that
   an entire power drain (P_Ta, P_Tb, P_Tc) of the inverters (10) is at least essentially constant at least in one operating state at least during two consecutive time intervals (t_a, t_b, t_c).
5. Cooking appliance device according to one of the preceding claims,
   characterised in that
   an entire power drain (P_Ta, P_Tb, P_Tc) of the inverters (10) is at least essentially different at least in one operating state at least during two consecutive time intervals (t_a, t_b, t_c).
6. Cooking appliance device according to one of the preceding claims,
   characterised in that
   a power output (P_1a, P_1b, P_1c) of at least a first inverter (10) in consecutive time intervals (t_a, t_b, t_c) of the first time frame (T_a) increases at least essentially and a power output (P_2a, P_2b, P_2c) of at least a second inverter (10) drops at least essentially in consecutive time intervals (t_a, t_b, t_c) of the first time frame (T_a).
7. Cooking appliance device according to one of the preceding claims,
   characterised in that
   the second time frame (T_b) directly borders the first time frame (T_a) and both time frames (T_a, T_b) have an identical number of time intervals (t_a, t_b, t_c) with identical operating parameters, wherein the time intervals (t_a, t_b, t_c) of the second time frame (T_b) are arranged in a reverse sequence compared with the time intervals (t_a, t_b, t_c) of the first time frame (T_a).
8. Cooking appliance, in particular induction hob, having a cooking appliance device according to one of the preceding claims.

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