EP2550841B1 - Hob device - Google Patents

Description

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

From the DE 197 08 335 A1 a hob device is known which comprises a resonant circuit, a control unit and a switching element having first and second switching means. By the states of the switching element, a period of oscillation of the resonant circuit is divided into first time intervals, in which voltage is applied to the resonant circuit, and in second time intervals, in which no voltage is applied. The control unit causes the switching element in at least one operating operation to periodically establish a certain electrical contact and interrupt.

From the publication DE 10 2005 021 888 A1 is a Kochmuldenvorrichtung known in which a coil is operated at an operating process alternately with different frequencies.

The US patent specification US 5,004,881 A1 discloses a method and circuit for controlling the energy level in an electric induction cooker by establishing a combination of duty cycle control and pulse width modulation control in response to the power level by the user. At a low power level, the turning on and off of the power transistor is controlled by the duty cycle control method. At high power level, the on and off of the power transistor is controlled by the pulse width modulation control method.

From the US patent application US 2003/0205572 A1 For example, a method and apparatus is known, comprising an induction heat source with a controller, a resonant converter, and an induction coil. The controller generates a variable duty cycle variable frequency control voltage in response to a set power. The variable duty cycle of the control voltage decreases as the variable frequency of the control voltage increases. Depending on the control voltage, the resonant converter generates an output between a first node and a second node. The induction coil is coupled between the first and second nodes and modifies the amount of heat generated by them in dependence on the output power.

The US patent application US 2007/0258274 A1 discloses a MF power generator having a DC voltage source connected to an inverter. The inverter comprises at least one switching element connected to a power supply potential of the first polarity and an output network. Each switching element has a decoupling circuit for decoupling the switching element from a voltage of the output network. This allows switching of the switching element with little loss.

The object of the invention is in particular to provide a generic device with improved properties in terms of an effective design. The object is achieved by the features of claim 1, while advantageous embodiments and modifications of the invention can be taken from the dependent claims.

The invention is based on an induction cooking cavity device having at least one switching element and at least one control unit, which causes the switching element in at least one operating operation to periodically produce and interrupt a specific electrical contact in time.

gegeben, wobei t₁ eine Anfangfangszeit des anderen Zeitabschnitts ist und t₂ ein Ende des anderen Zeitabschnitts ist, T = t ₂ - t ₁ ist und "f" die Schaltfunktion ist. Die Integral-Unterschiedskenngröße ist für denjenigen Fall, dass der zeitlich früher verstreichende der beiden Zeitabschnitte des Paars zeitlich kürzer dauert als der zeitlich später verstreichende der beiden Zeitabschnitte des Paars, durch $\frac{1}{T}{\displaystyle {\int }_{t_1}^{t_2}}\left|f\left(t\right)-f\left(t-T\right)\right|\mathit{dt}$

gegeben, wobei t₁ eine Anfangfangszeit des zeitlich kürzer dauernden Zeitabschnitts ist und t₂ ein Ende des zeitlich kürzer dauernden Zeitabschnitts ist und T = t ₂ - t ₁ ist. Mit einer erfindungsgemäßen Ausgestaltung kann eine effektive Bauweise erreicht werden. Insbesondere kann eine geringe Geräuschbelastung bei Betriebsvorgängen der Kochmuldenvorrichtung erreicht werden. Insbesondere kann für jeweils eine bestimmte Periodendauer ein großes Intervall von möglichen Ausgangsleistungen erreicht werden. Im Besonderen kann ein flexibles Schalten des Schaltelements erreicht werden. Insbesondere kann erreicht werden, dass zwei Schaltelemente, welche verschiedenen Schaltkreisen angehören, mit identischer Periodendauer betrieben werden können und die Schaltkreise voneinander verschiedene Ausgangsleistungen erbringen.It is proposed that the control unit cause the switching element in the operating process, in a primitive period of substantially temporally periodic Make and break the particular electrical contact at least twice the particular electrical contact. A "control unit" is to be understood as meaning in particular an electronic unit which controls an operation in at least one operating procedure, wherein the electronic unit preferably has at least one memory unit and / or one arithmetic unit and / or one operating program which is stored in the memory unit. An "electrical contact" is to be understood in particular as an electrically conductive connection, which may be formed in particular by metal components. A "time-periodic" establishment and interruption of an electrical contact in an operating process is to be understood in particular as establishing and interrupting an electrical contact, which causes a switching function to be periodic for a total time during which the operating process takes place distinguishes the function from a periodic pulse function with a primitive period consisting of a first time period in which the pulse function is periodic and a second time period in which the pulse function is zero. A "switching function" is to be understood in particular as a function which is defined by having the function value 1 for all points of time in which the contact is made, and the function value for all points in time at which the contact is interrupted Has zero. An "operating process" is to be understood as meaning in particular a part of a heating process of a cookware, wherein the part preferably lasts at least 0.01 seconds, preferably at least one second and particularly preferably at least ten seconds. A "substantially time-periodic" establishment and interruption of an electrical contact is to be understood in particular as establishing and interrupting an electrical contact which takes place in a time interval consisting of at least two and in particular more than two time periods, wherein for all pairs of Time periods of the time periods for which a first time period of the pair immediately precedes a second time period of the pair, the two time periods of the pair with respect to their length by at most twenty percent, preferably at most five percent, preferably at most one percent, and particularly preferably at most 0.01 percent differ from each other and an integral difference characteristic of the two time periods of the pair is at most 0.3, preferably at most 0.1, preferably at most 0.01 and particularly preferably zero, wherein the time interval is subdividable in time en which meet the above-mentioned conditions for the time periods and which are shorter in time and the switching functions of the pulse function and of all periodic functions whose primitive period is formed of two time periods in which the function is periodic but has different period lengths, and the time periods each one have a time extension which is greater than zero seconds. A "primitive period" of the essentially time-periodic production and interruption of the electrical contact should be understood to mean in particular one of the time segments, wherein in the case in which the switching function is periodic, the period is a primitive period of the switching function. The integral difference parameter is in this case for the case in which the earlier time passing of the two time periods of the pair takes longer than or equal to the time of the other of the two time periods of the pair, by $\frac{1}{T}{\displaystyle {\int }_{t_1}^{t_2}}\left|f\left(t\right)-f\left(t-T\right)\right|\mathit{dt}$

where t _{1 is} an initial time of the other period and t _{2 is} an end of the other period, T = t ₂ -t ₁ and "f" is the switching function. The integral difference characteristic is for the case that the temporally earlier passing of the two time periods of the pair takes time shorter than the temporally later passing of the two time periods of the pair, by $\frac{1}{T}{\displaystyle {\int }_{t_1}^{t_2}}\left|f\left(t\right)-f\left(t-T\right)\right|\mathit{dt}$

where t _{1 is} an initial start time of the temporally shorter time period and t _{2 is} an end of the temporally shorter time period and T = t ₂ -t ₁ . With an embodiment according to the invention, an effective construction can be achieved. In particular, a low noise level during operation of the hob unit can be achieved. In particular, a large interval of possible output powers can be achieved for a particular period duration. In particular, a flexible switching of the switching element can be achieved. In particular, it can be achieved that two switching elements, which belong to different circuits, can be operated with identical period duration and the circuits provide mutually different output powers.

It is further proposed that at least two total turn-on times, during which the contact is made continuously during the period, differ. A "total switch-on time" is to be understood as meaning, in particular, a total duration of a time span during which the contact is kept uninterrupted during the period is established, wherein the period of time begins with establishing the contact and the time period ends with a break in the contact and wherein the period has at least two total turn-on. As a result, a flexible switching can be achieved. In particular, different output powers can be achieved.

Preferably, in the operation, the control unit causes the switching element to make contact in at least two different time intervals. By "making the contact at least two different time intervals" is meant in particular that the contact is made at a first time, then interrupted, thereafter made at a second time, the contact is interrupted after the second time, and the Contact is subsequently restored to a third time, wherein a time difference between the second time and the first time and a time difference between the third time and the second time are different. This allows a particularly flexible switching can be achieved. In particular, different output powers can be achieved.

In addition, it is proposed that the control unit causes the switching element in at least one operating mode to produce the contact substantially periodically and exactly once during a period of time. In this way, a versatile switching behavior can be achieved.

Advantageously, the control unit is provided to cause the switching element to interrupt the contact while the switching element is de-energized. By the fact that the switching element is "de-energized" is to be understood in particular that a current flowing between two main contacts of the switching element current has the current zero ampere. A "main contact" of a switching element is to be understood in particular as a contact of the switching element, which is provided for conducting a current to a consumer unit, which is formed separately from the switching element. In particular, in an insulated gate bipolar transistor, only the emitter and the collector are main contacts. As a result, a gentle switching and in particular a low energy loss can be achieved.

Preferably, the cooker device comprises at least one control device which is arranged to cause the switching element to make or break the contact at least once while a heating element is de-energized and to cause another switching element to make another contact at least once while the heating element carries current. As a result, a gentle and comfortable operation can be achieved. In particular, it can be achieved that, during operation of the switching element, a low energy loss occurs and a large interval of heating powers, with which the heating element can be operated, is available. In particular, quiet operation of the cooktop apparatus can be achieved.

In addition, it is proposed that the cooktop device has at least one control device which is provided for a period-related time interval between one transmission period of the switching element and one transmission period of a further switching element, which exists within the primitive period, and a further period-related time interval, which exists between the passage time period of the switching element and a further passage time period of the further switching element and elapses within the same primitive period, to change the variation of a heating power of a heating element. A "period-related" time interval is to be understood as meaning, in particular, a duration of the time interval in seconds divided by a duration of the primitive period duration in seconds. An "on-time period" of a switching element should be understood to mean, in particular, a time span during which a first and a second main contact of the switching element are electrically conductively connected. This allows a high degree of flexibility and in particular a flexible change in the heating power can be achieved. In particular, it can be achieved that when the period duration remains constant, a large interval of heating powers of the heating element with which the heating element can be operated is available. In particular, it can be achieved that two switching elements, which are provided for influencing different heating elements, are operated with the same switching period lengths but with greatly different heating powers of the heating elements.

Further, it is proposed that the control unit be provided for a total number of times the contact is made during the primitive period change. In this way, a heating power can be flexibly changed, in particular with a temporally constant primitive period.

Preferably, the Kochmuldenvorrichtung has a control device, which switches the switching element and another switching element in such a way that the primitive period consists of at least three time intervals in which the switching element makes the contact exactly once and the other switching element exactly one more contact Times and each of the time intervals ends at a time at which the other switching element interrupts the further contact. In this way, a flexible adjustability of a heating power can be achieved.

Advantageously, for each time interval of a majority of the time intervals, a switching behavior of the two switching elements in the respective time interval differs from a switching behavior of the two switching elements in a majority of the time intervals. A "majority" of the time intervals should be understood in particular to be a number of time intervals which corresponds to at least fifty percent and preferably at least seventy percent of a total number of time intervals. By the fact that a "switching behavior of two switching elements in a time interval differs from a switching behavior of the two switching elements in a different time interval" should be understood in particular that the two time intervals are different lengths or, if the time intervals are the same length, that at least one of Switching elements in which one time interval switches at a first time and this switching element is inactive at a second time in the other time interval, wherein the second time in the other time interval is arranged the same as the first time in the one time interval. As a result, a high switching flexibility can be achieved. In particular, a heating power can be set flexibly, in particular with a time-constant primitive period duration.

Preferably, the control device is provided to change a period-related time duration of at least one of the time intervals. A "period-related time period" should be understood to mean in particular a time duration of the relevant time interval divided by the primitive period duration. As a result, a flexible power supply of the heating element can be achieved.

Advantageously, the switching element is a bipolar transistor with insulated gate electrode. As a result, efficient usability can be achieved.

The cooktop device has at least one circuit which has the switching element and at least one further switching element. Thereby, an effective heating and in particular an effective electrical excitation of a coil can be achieved.

In a preferred embodiment of the invention, the circuit has at least a third switching element. This allows a high degree of flexibility can be achieved.

The cooktop device has at least one first induction heating circuit, which has the switching element. This allows a user-friendly heating can be achieved.

Furthermore, it is proposed that the cooktop device has at least one second induction heating circuit and at least one further control unit, which causes at least one switching element of the second induction heating circuit to produce and interrupt an electrical contact substantially periodically with the period duration during the operating process. This allows a low-noise and effective cooking can be achieved. In particular, noises can be avoided which occur when making and breaking the contacts of the first and second induction heating circuits with frequencies that differ and whose difference is smaller than 17 kHZ.

Further, a cooking hob is proposed with a Kochmuldenvorrichtung, whereby an effective construction can be achieved.

Furthermore, a Kochmuldensteuerungsverfahren, in particular for at least partially controlling a Kochmuldenvorrichtung, proposed in which substantially time periodically an electrical contact is established and interrupted and in a primitive period of substantially time periodic production and interruption of the particular electrical contact at least twice certain electrical contact is made. As a result, an effective construction can be achieved.

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Fig. 1

Eine Draufsicht auf eine Induktionskochmulde mit einer erfindungsgemäßen Induktionskochmuldenvorrichtung,

Fig. 2

ein Schaltbild eines Induktionsheizschaltkreises der Induktionskochmuldenvorrichtung,

Fig. 3

eine schematische Darstellung von Periodendauern zweier Spannungen, welche von zwei Steuereinheiten der Induktionskochmuldenvorrichtung angelegt werden, einer Spannung zwischen zwei bestimmten Punkten des Induktionsheizschaltkreises und eines Stroms durch eine Spule des Induktionsheizschaltkreises,

Fig. 3a

ein alternativer zeitlicher Verlauf der Spannungen, welche von den zwei Steuereinheiten der Induktionskochmuldenvorrichtung angelegt werden,

Fig. 4

ein weiterer alternativer zeitlicher Verlauf der Spannungen, welche von den zwei Steuereinheiten der Induktionskochmuldenvorrichtung angelegt werden, wobei jede der Spannungen in der Periodendauer ein Maximum aufweist,

Fig. 5

ein weiterer Induktionsheizschaltkreis der Induktionskochmuldenvorrichtung,

Fig. 6

Leistungskurven für einen Betriebsvorgang, einen bestimmten Betriebsmodus und einen weiteren Betriebsmodus und

Fig. 7

einen alternativen Induktionsheizschaltkreis.

Show it:

Fig. 1

A top view of an induction hob with an induction hob according to the invention,

Fig. 2

a circuit diagram of an induction heating circuit of the induction hob,

Fig. 3

a schematic representation of periods of two voltages which are applied by two control units of the induction cooker device, a voltage between two specific points of the Induktionsheizschalteses and a current through a coil of the Induktionsheizschaltkreises,

Fig. 3a

an alternative time profile of the voltages applied by the two control units of the induction hob device,

Fig. 4

a further alternative time profile of the voltages which are applied by the two control units of the induction cooker device, wherein each of the voltages has a maximum in the period duration,

Fig. 5

another induction heating circuit of the induction hob device,

Fig. 6

Performance curves for one operating procedure, a specific operating mode and another operating mode, and

Fig. 7

an alternative induction heating circuit.

FIG. 1 shows a plan view of an induction hob with an induction hob according to the invention, which coils 38 and a cookware carrier surface 40 has. The coils 38 are heating elements 38 'and are intended to generate eddy currents in cooking utensils (not shown) during cooking operations, which heat the cookware, thereby heating food in the cookware. The induction cooker device has an induction heating circuit 26 '( FIG. 2 ) formed circuit 26 having one of the coils 38. Furthermore, the induction cooker device has further induction heating circuits, which are identical to the induction heating circuit 26 'and also have one of the coils 38. The induction heating circuit 26 'comprises two switching elements 10, 28 each formed as an insulated gate bipolar transistor. Further, the induction heating circuit 26' includes two control units 12, 13 provided for controlling the switching elements 10, 28.

The control unit 12 causes the switching element 10 in an operation to periodically make an electrical contact, namely an electrical contact between a collector 44 and an emitter 46 of the formed as a bipolar transistor with insulated gate switching element 10, and interrupt. For this purpose, the control unit 12 applies a voltage 42 (FIG. FIG. 3 ) between a gate 48 of the switching element 10 and the emitter 46, which is a periodic function with respect to time. In the operation, the control unit 12 causes the switching element 10 to make contact twice during a primitive period 14 of time-periodic making and breaking of the electrical contact. The period 14 is identical to a period of the voltage 42, which is a periodic function. The period 14 is composed of four directly successive time intervals. Two of the time intervals are total turn-on times 16, 18 during which the voltage 42 causes the contact to be made uninterrupted. Two of the time intervals are total off times 50, 52 during which the voltage 42 causes the contact to be broken. The two total switch-on times 16, 18 have different lengths. Further, the control unit 12 causes the switching element 10 in the operation to make the contact at two different time intervals 20, 22. The time interval 20 is the time interval between establishing the contact that occurs at the beginning of the total turn-on time 16 and establishing the contact that occurs at the beginning of the total turn-on time 18. The time interval 22 is the time interval between the establishment of the contact, which takes place at the beginning of the total turn-on time 18, and the making of the contact, which adjoins the total turn-off time 52 in terms of time. The total switch-off time 52 follows directly on the total turn-on time 18, the total turn-off time 50 follows directly on the total turn-on time 16.

Parallel to a temporarily existing conductive connection between the collector 44 and the emitter 46, a diode 54 is connected. The switching element 28 is also an insulated gate bipolar transistor. Further, the emitter 46 is conductively connected to a collector 56 of the switching element 28. The control unit 13 applies in the operation a voltage 58 between a gate 64 of the switching element 28 and an emitter 60 of the switching element 28 ( Figures 2 and 3 ). Parallel to a temporary conductive connection between the collector 56 and the emitter 60, a diode 62 is connected. The voltage 58 is designed such that it causes a conductive contact between the collector 56 and the emitter 60 whenever the contact between the emitter 46 and the collector 44 is interrupted. In addition, the voltage 58 is formed so that the contact between the collector 56 and the emitter 60 is interrupted whenever the conductive contact between the emitter 46 and the collector 44 is present.

The collector 44 is conductively connected to a positive pole of a voltage source 66. Furthermore, the emitter 46 is conductively connected to a minus pole of the voltage source 66. The voltage source 66 supplies DC during operation. In principle, it is conceivable that the voltage source 66 outputs a rectified alternating current. A resistor 68 incorporating a resistor of a cookware to be heated, one of the coils 38 having an inductance of twenty-five microhenries, and a cooktop condenser 70 are connected in series and connected in parallel with the diode 62 in total. The capacitor 70 has a capacitance of 1440 nanofarads.

In FIG. 3 Furthermore, a time course of a current 80, which flows through the coil 38 of the circuit 26 during the operation, is shown. Furthermore, a time profile of a voltage 86, which is applied between two points 82, 84 in the course of operation, is shown. A straight line 88 forms a zero line for the current 80 and the voltage 86.

In principle, it is also conceivable that the period duration 14 is composed of individual time intervals T ₁ , T ₂ ,..., T _n , where n can be any natural number, which is greater than one ( FIG. 3a ). In particular, n = 3. Here, the voltage 42 at certain contact times D ₁₁ , D ₁₂ , ..., D _1n , which are time intervals and which parts of the time intervals T ₁ , T ₂ , ..., T _n , the contact between the collector 44 and the emitter 46 ago. Further, the voltage 58 at certain contact times D ₂₁ , D ₂₂ , ..., D _2n , which are time intervals and which parts of the time intervals T ₁ , T ₂ , ..., T _n , the contact between the collector 56 and the emitter 60 ago. The contact between the collector 44 and the emitter 46 is made exactly once in each of the time intervals T ₁ , T ₂ ,..., T _n . Further, the contact between the collector 56 and the emitter 60 is made exactly once in each of the time intervals T ₁ , T ₂ ,..., T _n . Between the individual contact times D ₁₁ , D ₁₂ ,..., D _1n and D ₂₁ , D ₂₂ ,..., D _2n can non-disappearing blocking times d ₁₁ , d ₁₂ , ..., d _1n and d ₂₁ , d ₂₂ , ..., d _2n , in which neither the contact between the collector 56 and the emitter 60 nor the contact between the collector 44 and the emitter 46 is. The control units 12, 13, which together form a control device 11, the values of the time intervals T ₁ , T ₂ , ..., T _n , the contact times D ₁₁ , D ₁₂ , ..., D _1n and the contact times D ₂₁ , D ₂₂ , ..., D _2n and the blocking times d ₁₁ , d ₁₂ , ..., d _1n and the blocking times d ₂₁ , d ₂₂ , ..., d _2n vary. However, the condition applies that at least one of the time intervals T ₁ , T ₂ ,..., T _{n is constructed} differently and / or has a different length than at least one other of the time intervals T ₁ , T ₂ ,..., T _n . In particular, it is conceivable that the blocking times d ₁₁ , d ₁₂ ,..., D _1n and the blocking times d ₂₁ , d ₂₂ ,..., D _{2n are} equal to zero and / or the contact times D ₁₁ , D ₁₂ , .. ., D _1n and the contact times D ₂₁ , D ₂₂ , ..., D _2n each form a half of the time interval of which they are part, or the contact times D ₁₁ , D ₁₂ , ..., D _1n and the contact times D ₂₁ , D ₂₂ , ..., D _2n each differ from one half of the time interval of which they are part.

Hereinafter, a plurality of time interval switching modes, with which the control device 11 can switch the switching elements 10 and 28, described on the basis of the time interval T ₂ , ie that each described in a description of the respective time interval Schaltart switching a switching element 10, 28 within the time interval T ₂ occurs.

In a first time interval switching mode, the control device 11 switches a first of the switching elements 10, 28 to passage, thus establishes a conductive connection between the emitter 46, 60 and the collector 44, 56 of the relevant switching element 10, 28, while the heating element 38 ' Electricity leads. Furthermore, the control device 11 switches a second of the switching elements 10, 28 to passage while the heating element 38 'is de-energized is. Furthermore, the control device 11 switches both switching elements 10, 28 into a blocking state, ie interrupts conductive connections which exist within both switching elements 10, 28 between the respective emitters 46, 60 and collectors 44, 56, while the heating element 38 'carries current. One of the blocking periods d ₁₂ , d ₂₂ may be a dead time of one of the switching elements 10, 28.

A second time interval switching mode differs from the first time interval switching type only in that one of the switching elements 10, 28 is switched to the blocking state, while a conductive connection between the emitter 46, 60 and the collector 44, 56 of the relevant switching element 10, 28 is de-energized. Specifically, in the first and second time interval switching modes, the controller 11 may change a first and / or a second period related time interval p ₁₂ , p ₂₂ during a heating power changing operation of the heating element 38 '. The first period-related time interval p ₁₂ is the blocking time d ₁₂ divided by the primitive period length 14. The second period-related time interval p ₂₂ is the blocking time d ₂₂ divided by the primitive period length 14.

A third time interval switching mode differs from the first time interval switching type only in that both switching elements 10, 28 are switched to passage, while the heating element 38 'is de-energized, and d ₁₂ + D ₁₂ = 0.5 applies.

A fourth time interval switch type differs from the first time interval switch type only in that d ₁₂ + D _{12 is} not equal to 0.5.

A fifth time interval switching type differs from the second time interval switching type only in that one of the switching elements 10, 28 is switched to the blocking state, while a conductive connection between the emitter 46, 60 and the collector 44, 56 of the relevant switching element 10, 28 is de-energized.

In particular, during operation of the cooktop apparatus, the controller 11 may control the switching elements 10, 28 such that the switching elements 10, 28 in each of the time intervals T ₁ , T ₂ , ..., T _{n are switched} in one of the five described time interval switching modes , wherein the time interval switching modes of the individual time intervals T ₁ , T ₂ , ..., T _n can differ.

In particular, during operation of the cooktop device, the control device 11 can change the total number n of the time intervals T ₁ , T ₂ ,..., T _n of which the period 14 exists to change a heating power of the heating element 38 '. Furthermore, during operation of the cooktop device, the control device 11 can change a quotient between one of the time intervals T ₁ , T ₂ ,..., T _n and the period 14 for changing a heating power of the heating element 38 '.

In particular, in the case of a specific operation of the cooktop apparatus, it can be said that for each time interval T ₁ , T ₂ ,..., T _{n of} a majority of the time intervals T ₁ , T ₂ ,..., T _n , a switching behavior of the two Switching elements 10, 28 in the relevant time interval T ₁ , T ₂ , ..., T _n of each switching behavior of the two switching elements 10, 28, which this in a large part of the time intervals T ₁ , T ₂ , ..., T _n own, makes a difference.

In a particular mode of operation, the control unit 12 causes the switching element 10 to periodically establish contact between the collector 44 and the emitter 46, wherein the switching element 10 makes the contact exactly once in a period 24 and interrupts once (FIG. Figures 2 and 4 ). In this mode of operation, the control unit 13 causes the switching element 28 to periodically establish the contact between the collector 56 and the emitter 60, wherein the switching element 28 makes the contact in the period 24 exactly once and interrupts once. The contact between the collector 44 and the emitter 46 is established during the period 24 continuously during a time interval 71 which starts at the beginning of the period 24 and is less than one half of the period 24. During the time interval 71 is the contact between the collector 56 and the emitter 60 is interrupted. The period 24 consists of the time interval 71 and a time interval 72. In the time interval 72, the contact between the collector 44 and the emitter 46 is interrupted and the contact between the collector 56 and the emitter 60 is established. In a further operating mode, the time intervals 71, 72 each form one half of the period 24.

FIG. 6 shows a power curve 90 of the induction heating circuit 26 'in operation, a power curve 91 of the induction heating circuit 26' in the particular mode of operation, and a power curve 92 of the induction heating circuit 26 'in the further mode of operation. The power curves 90 to 92 are each closed.

gegeben ist. Hierbei ist R ein Wert des Widerstands 68, L die Induktivität der Spule 38 und f der Wert der Frequenz.Further, the power curves 90, 91 each define an area. Along an abscissa 94 is a frequency, which for the power curve 90, the inverse of the period 14, that is one divided by the period 14 and which for the power curves 91, 92 is the inverse of the period 24 plotted. At an ordinate 96, a heating power dissipated by the coil 38 of the induction heating circuit 26 'is removed. By varying the period duration 14, the time intervals 20, 22, the total switch-on times 16, 18 and the total switch-off times 50, 52 and blocking periods, which can be inserted between the total switch-on times 16, 18 and the total switch-off times 50, 52 and which in FIG. 3a d ₂₁ , d ₂₂ and d ₁₁ , d ₁₂ are mentioned and in which both switching elements 10, 28 make no contact, it is achievable that the coil 38 of the induction heating circuit 26 'in one by a point of the surface, which is bordered by the power curve 90 is operating, described manner, namely at a defined by the point of the surface value of the period 14 yields a certain power through the point of the surface. An analogous meaning has that surface, which is bordered by the power curve 91, wherein the surface is formed by a variation of the time interval 71 and the frequency. For a given value of the frequency, the power which the coil 38 provides in the operation is different from those provided by the coil 38 in the particular mode of operation and in the further mode of operation. For the in FIG. 6 shown power curve 90, 91, 92 is a so-called power factor equal to 0.5, wherein the power factor by $\frac{\mathrm{<figure-callout\; id="2"\; label="R\; R"\; filenames="imgf0002.png"\; state="\{\{state\}\}">R\; </figure-callout>}}{\sqrt{R^{}}}$

given is. Here, R is a value of the resistor 68, L is the inductance of the coil 38 and f is the value of the frequency.

The other induction heating circuits are identical to the induction heating circuit 26 '. One of the further induction heating circuits 32 (FIG. FIGS. 1 and 5 ) has control units 34, 35 and switching elements 36, 37, which are caused by the control units 34, 35 in the operation to time periodically with the period 14 make electrical contacts and interrupt. The induction heating circuit 32 and the induction heating circuit 26 'are part of an electronic assembly consisting of the induction heating circuits 32, 26'. In this case, the Induktionsheizschaltkreis 32 works in the particular or in the other operating mode, which is achieved by the coils 38 of the Induktionsheizschaltge 26 ', 32 can be operated with different output powers and the cooktop device works very quietly. It can be advantageously avoided that the Induction heating circuits 26 'and 32 are operated with different periods. Different output powers are z. B. advantageous if the Induktionsheizschaltkreisen 32, 26 'different cookware to be heated differently.

In FIG. 7 an alternative embodiment is shown. Substantially identical components, features and functions are basically numbered by the same reference numerals. To distinguish the embodiments, however, the reference numerals of the embodiment in the FIG. 7 the letter "a" added. The following description is essentially limited to the differences from the embodiment in the FIGS. 1 to 6 , wherein with respect to the same components, features and functions on the description of the embodiment in the FIGS. 1 to 6 can be referenced.

FIG. 7 shows an alternative embodiment of a circuit 26a, namely an induction heating circuit 26'a. In contrast to the induction heating circuit 26 ', which has a so-called half-bridge topology, the induction heating circuit 26'a has a full-bridge topology. The induction heating circuit 26'a comprises control units 12a, 13a and further comprises two further control units 74a, 76a. Furthermore, the induction heating circuit 26'a comprises two additional switching elements 30a, 31a, which are formed as insulated gate bipolar transistors, and two further diodes 78a. In an operation of the induction heating circuit 26'a, the control units 12a and 76a respectively supply the voltage 42 (FIG. FIG. 3 ). In operation, the control units 13a and 74a output the voltage 58. The switching elements 10a, 28a, 30a, 31a are identical. reference numeral 10 switching element 48 gate 11 control device 50 Total break 12 control unit 52 Total break 13 control unit 54 diode 14 period 56 collector 16 Total Power 58 tension 18 Total Power 60 emitter 20 lag 62 diode 22 lag 64 gate 24 period 66 voltage source 26 circuit 68 resistance 26 ' Induktionsheizschaltkreis 70 capacitor 28 switching element 71 time interval 30 switching element 72 time interval 31 switching element 74 control unit 32 Induktionsheizschaltkreis 76 control unit 34 control unit 78 diode 35 control unit 80 electricity 36 switching element 82 Point 37 switching element 84 Point 38 Kitchen sink 86 tension 38 ' heating element 88 Just 40 Cookware support surface 90 power curve 42 tension 91 power curve 44 collector 92 power curve 46 emitter 94 abscissa 96 ordinate T ₁ time interval T ₂ time interval T _n time interval p ₁₂ lag p ₂₂ lag ₁₁ blocking time d ₂₁ blocking time d ₁₂ blocking time d ₂₂ blocking time d _1n blocking time d _2n blocking time D ₁₁ contact time D ₂₁ contact time D ₁₂ contact time D ₂₂ contact time D _1n contact time D _2n contact time

Claims (13)

1. Induction hob device having at least one switching element (10; 10a), having at least one first induction heating circuit (26'; 26'a), which has the switching element (10; 10a) and at least one further switching element (28; 28'), at least one control unit (12; 12a) which, during at least one operating process, triggers the switching element (10; 10a), essentially periodically in time, to establish and interrupt a specific electric contact between a collector (44; 44a) and an emitter (46; 46a) of the switching element (28; 28a), and a control unit (13; 13a), which, in the operating process, applies a voltage (58) between a gate (64; 64a) and an emitter (60; 60a) of the further switching element (28; 28a), wherein the voltage (58) is embodied such that it always effects a conducting contact between a collector (56) and the emitter (60; 60a) of the further switching element (28; 28a) if the contact between the emitter (46; 46a) and the collector (44; 44a) of the switching element (10; 10a) is interrupted, characterised in that
   during the operating process the control unit (12; 12a) triggers the switching element (10; 10a) to establish the specific electric contact at least twice in a primitive cycle duration (14) of the essentially periodic, in time, establishment and interruption of the specific electric contact.
2. Induction hob device according to claim 1,
   characterised in that
   at least two overall switch-on times (16; 18), during which the contact is established without interruption during the cycle duration (14), are different.
3. Induction hob device according to one of claims 1 or 2,
   characterised in that
   during the operating process the control unit (12; 12a) triggers the switching element (10; 10a) to establish the contact in at least two different time intervals (20, 22).
4. Induction hob device according to one of the preceding claims,
   characterised in that
   in at least one operating mode the control unit (12; 12a) triggers the switching element (10; 10a) to establish the contact essentially periodically, namely exactly once during a cycle duration (24).
5. Induction hob device according to one of the preceding claims,
   characterised in that
   the control unit (12; 12a) is provided to trigger the switching element (10; 10a) to interrupt the contact while the switching element (10; 10a) has no power.
6. Induction hob device according to one of the preceding claims,
   characterised by
   at least one control device (11; 11a), which is provided to trigger the switching element (10; 10a) to establish or interrupt the contact at least once, while a heating element (38', 38'a) has no power, and to trigger a further switching element (28; 28a) to establish a further contact at least once, while the heating element (38'; 38'a) conducts current.
7. Induction hob device according to one of the preceding claims,
   characterised by
   at least one control device (11; 11a) which is provided to modify a cycle-related time interval (p ₁₂) existing between a passage time span (D ₁₂) of the switching element (10; 10a) and a passage time span (D ₂₁) of a further switching element (28; 28a), which time interval (p ₁₂) exists within the primitive cycle duration (14), and a further cycle-related time interval (D ₂₂), which exists between the passage time span (D ₁₂) of the switching element (10; 10a) and a further passage time span (D ₂₂) of the further switching element (28; 28a) and elapses within the same primitive cycle duration (14), in order to change a heating power of a heating element (38'; 38'a).
8. Induction hob device according to one of the preceding claims,
   characterised in that
   the control unit (12; 12a) is provided to modify an overall number with respect to how often the contact is established during the primitive cycle duration (14).
9. Induction hob device according to one of the preceding claims,
   characterised by
   a control device (11; 11a) which, during the operational sequence, switches the switching element (10; 10a) and a further switching element (28; 28a) such that the primitive cycle duration (14) consists of at least three time intervals (T ₁, T ₂ ...., T _n), in which the switching element (10; 10a) establishes the contact exactly once and the further switching element (28; 28a) establishes a further contact exactly once and each of the time intervals (T ₁, T ₂ ..., T _n) ends at a point in time at which the further switching element (28; 28a) interrupts the further contact.
10. Induction hob device according to claim 9,
    characterised in that
    it applies for each time interval (T ₁, T ₂..., T _n) of a majority of the time intervals (T ₁, T ₂...,
    T _n) that a switching behaviour of the two switching elements (10, 28; 10a, 28a) in the relevant time interval (T ₁, T ₂..., T _n) differs from a switching behaviour of the two switching elements (10; 28; 10a; 28a) in a majority of the time intervals (T ₁, T ₂ ..., T _n).
11. Induction hob device according to one of claims 9 or 10,
    characterised in that
    the control device (11; 11a) is provided to modify a cycle-related duration of at least one of the time intervals (T ₁, T ₂..., T _n).
12. Hob having an induction hob device according to one of claims 1 to 11.
13. Induction hob control method for at least partially controlling an induction hob device according to one of claims 1 to 11, in which a specific electric contact is established and interrupted essentially periodically in time and the specific electric contact is established at least twice in a primitive cycle duration (14) of the essentially periodic, in time, establishment and interruption of the specific electric contact.

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