EP3030041B1 - Cooking hob device and method for operating a cooking hob device - Google Patents

Description

The invention is based on a hob device according to the preamble of claim 1 and a method for operating a hob device according to the preamble of claim 11. From the prior art induction hobs are known, the at least one inductor, at least one inverter for operating the inductor and a capacitance voltage measuring unit, wherein the capacitance voltage measuring unit is provided to measure a capacitance voltage of a resonant capacitance. For determining a power output of the inductor, however, an output voltage and / or an output current of the inverter is evaluated. Such induction hob is, for example, in EP 2 437 573 A1 disclosed. The object of the invention is in particular to provide a generic device with improved properties in terms of efficiency. The object is solved by the characterizing features of claims 1 and 11, while advantageous embodiments and modifications of the invention can be taken from the dependent claims.

The invention is based on a cooktop device, in particular an induction cooktop device, with at least one heating module, comprising at least two, preferably in series and preferably identical to each other, inverter switch, which are switched periodically in particular in an operating state, and which is provided to provide at least one heating current, with at least one of the heating module associated resonance capacity, with at least one, preferably exactly one capacitance voltage measuring unit, which is intended to measure a capacitance voltage of the resonant capacitor and with at least one control unit.

It is proposed that the control unit is provided to determine in at least one operating state from the capacitance voltage a power output of the heating module, preferably exactly one heating element of the heating module, and in particular not from an operating voltage, in particular an input and / or output voltage, of the inverter , and / or an operating current, in particular an input and / or output current, of the inverter. In this context, a "cooktop device" should be understood as meaning, in particular, at least one part, in particular a subassembly, of a cooktop, in particular an induction cooktop. In particular, the hob device may also comprise the entire hob, in particular the entire induction hob. The heating module has in particular a, preferably designed as an inductor, heating element and is particularly intended to heat by eddy current and / or Ummagnetisierungseffekte a cookware. In particular, the heating module can also comprise a plurality, in particular at least two, at least three and / or at least four, heating elements and / or at least one switching arrangement, in particular for switching on, switching off and / or switching over the heating elements. The inverter is in particular provided to provide and / or to generate an oscillating electric current, in particular a heating current, preferably with a frequency of at least 1 kHz, in particular of at least 10 kHz and advantageously of at least 20 kHz, in particular for operation of the heating module , In this context, an "inverter switch" is to be understood as meaning, in particular, a switching unit which is preferably bidirectional and unipolar. A "switching unit" is to be understood in particular as meaning a unit, preferably an electronic unit, which comprises a switching element and preferably a diode, in particular connected in parallel with the switching element. In addition, the switching unit can in particular have a capacitance, in particular a damping capacitance, connected in particular to the switching element and / or to the diode in parallel. The switching element can be embodied as any switching element which appears sensible to a person skilled in the art, preferably a semiconductor switching element, for example as a transistor, preferably as a FET, as a MOSFET and / or as an IGBT. By "provided" is intended to be understood in particular specially programmed, designed and / or equipped. The fact that an object is intended for a specific function should in particular mean that the object fulfills this specific function in at least one application and / or operating state and / or performs. The resonance capacitance is advantageously embodied as a resonance capacitor and, in particular, provided to form, in at least one operating state with the heating module, at least one part of an electrical oscillating circuit and / or preferably an electrical oscillating circuit. In particular, the resonance capacity has a capacity of at least 0.1 nF, preferably of at least 1 nF and particularly preferably of at least 10 nF and in particular of at most 100 uF, preferably of at most 50 uF and particularly preferably of at most 10 uF. By the phrase "an object is assigned to another object", it should be understood in particular that in at least one operating state at least one, preferably direct, electrically conductive connection exists between the object and the further object. Furthermore, a "control unit" should be understood as meaning, in particular, an electrical and / or electronic unit which is provided to control and / or regulate an operation of the cooktop apparatus, in particular of the inverter. For this purpose, the control unit preferably comprises a computing unit and in particular, in addition to the arithmetic unit, a memory unit with a control and / or regulating program stored therein, which is in particular provided for being executed by the arithmetic unit. Furthermore, the capacitance voltage measuring unit can be designed as any voltage measuring unit that appears appropriate to a person skilled in the art, in particular electrical and / or electronic. However, the capacitance voltage measuring unit preferably comprises at least one voltage divider and / or at least one analog-to-digital converter and, in particular in at least one operating state, has at least one electrically conductive connection to the control unit and / or an evaluation unit of the control unit. In this context, a "capacitance voltage" should be understood as meaning, in particular, a voltage stored in a capacitor, in particular the resonant capacitance, and / or a voltage dropping across the capacitor, in particular the resonant capacitance. The capacitance voltage may correspond in particular to a voltage between two defined potential values and / or a voltage between a defined potential value and a, preferably grounded, ground potential. Furthermore, a "power output" is to be understood as meaning, in particular, a power, in particular heating power, in particular of at least one heating element of the heating module, which is supplied in at least one operating state, a cookware set up, in particular on a cooktop of the cooktop device, and in particular for heating the cooking appliance cookware serves. Furthermore, the term "determine" should be understood to mean, in particular, reading out and / or calculating.

With this configuration, a cooktop device having improved properties in terms of efficiency, in particular time efficiency, measurement efficiency and / or cost efficiency can be provided. In particular, a measurement accuracy, in particular by using a resonance capacity with a precise capacitance value and / or due to an advantageously simple calibration of the resonance capacity, can be improved. Furthermore, can be dispensed with additional components, such as voltage and / or current meter units, which space can be saved and / or costs can be reduced. Alternatively, when using additional voltage and / or current measuring units even in an error operating state, in particular an operating state in which a determination of the power output and / or other operating data fails and / or is not possible based on the capacitance voltage, safe operation and in particular a secure determination the power output and / or the operating data are guaranteed. In addition, a control algorithm of the hob device can be advantageously simplified.

Furthermore, it is proposed that the control unit be provided for evaluating and / or taking into account only the capacitance voltage, in particular values, in particular voltage values, of the capacitance voltage for determining the power output, in particular in at least one operating state. The control unit is provided to evaluate only the values, in particular measured values, of the capacitance voltage measuring unit for determining the power output. As a result, an uncomplicated measurement and / or evaluation can be achieved.

If the capacitance voltage measuring unit is provided to measure exactly two values, in particular voltage values, of the capacitance voltage, in particular at least two different times of the switching period duration, during a switching period duration of at least one of the inverter switches Control algorithm advantageously be designed simply. A "switching period duration" is to be understood in particular as a period of time, in particular periodic, in which each switching unit, in particular each inverter switch, is located exactly once in the closed and / or conducting state. The term "during a period of time" should be understood in particular simultaneously with a beginning and / or end of the period of time and / or at any time within the period of time.

Preferably, the capacitance voltage measuring unit is provided to measure exactly two values, in particular voltage values, of the capacitance voltage, in particular at least two different times of the switch-on time, during a switch-on time of one of the inverter switches. In this context, a "switch-on time" of an inverter switch should be understood as meaning, in particular, a time duration in which the inverter switch is in particular in a closed and / or electrically conducting state. In particular, a sum of the turn-on time of the inverter switch and a turn-off time of the same inverter switch corresponds to a switching period of the inverter switch. In this context, a "switch-off time" of an inverter switch should be understood in particular to be a time duration in which the inverter switch is in particular in an open and / or electrically non-conducting state. Preferably, a sum of the switch-on times of the inverter switches corresponds to at least substantially one switching cycle duration of the inverter switches. By "a sum of the switch-on times of the inverter switches at least substantially corresponds to a switching period" is to be understood in particular that a deviation between the sum of the switch-on of the inverter switch and the switching period corresponds to a maximum of 15%, preferably at most 10% and more preferably at most 5% , As a result, in particular a measuring efficiency can be further improved.

In one embodiment of the invention it is proposed that the capacitance voltage measuring unit is provided to a value, in particular voltage value, of the capacitance voltage at the beginning of a switch-on one of Inverter switch to measure. The term "at the beginning of a switch-on time" should be understood in particular immediately after a start of the switch-on time and / or preferably at the same time as a start of the switch-on time. In this way, in particular, an advantageously simple and in particular reproducible measurement can be achieved.

The capacitance voltage measuring unit is preferably provided to measure a value, in particular a further value, in particular a further voltage value, of the capacitance voltage at the end of a switch-on time of one of the inverter switches. The term "at the end of a switch-on time" should be understood in particular immediately before an end of the switch-on time and / or at the same time as an end of the switch-on time. Advantageously, the capacitance voltage measuring unit is provided to measure in each case a value, in particular voltage value, of the capacitance voltage at the beginning of a switch-on time and at the end of the same switch-on time, in particular the same inverter switch. As a result, in particular a control algorithm can be further simplified.

Furthermore, it is proposed that the control unit be provided to evaluate at least two values, in particular voltage values, of the capacitance voltage for determining the power output. In particular, the control unit is provided to evaluate at least the value measured at the beginning of the switch-on time, in particular the voltage value, the capacitance voltage and at least the value measured at the end of the switch-on time, in particular further voltage value, of the capacitance voltage for determining the power output. Particularly preferably, the control unit is provided to evaluate exactly two values, in particular voltage values, of the capacitance voltage for determining the power output per switching cycle duration. As a result, an advantageously simple, precise and reproducible measurement method can be provided.

In a preferred embodiment of the invention, it is proposed that the control unit is provided to determine an average value of the capacitance voltage from the capacitance voltage. In particular, the control unit is intended to to evaluate only the capacitance voltage to determine the mean value of the capacitance voltage. An "average value of the capacitance voltage" should be understood in particular to mean a time-averaged capacitance voltage, which corresponds in particular to an arithmetic mean value of the capacitance voltage in a defined time range. As a result, a power output can advantageously be easily determined.

It is also proposed that the control unit is provided to determine from the capacitance voltage an average value of a rectified mains voltage. In particular, the control unit is provided to evaluate only the capacitance voltage for determining the mean value of the rectified mains voltage. In this context, a "rectified mains voltage" should be understood to mean, in particular, a mains voltage, in particular bus voltage and / or voltage applied to the inverter, preferably rectified by a rectifier unit of the hob device. A "mean value of the rectified mains voltage" should be understood in particular to mean a time-average rectified mains voltage, which in particular corresponds to an arithmetic mean value of the rectified mains voltage in a defined time range. As a result, it is possible in particular to dispense with additional stress measuring units, which in particular allows costs to be reduced.

Furthermore, it is proposed that the control unit is provided for determining the mean value of the capacitance voltage and / or the mean value of the rectified mains voltage from at least three values, in particular voltage values, of the capacitance voltage. In particular, the capacitance voltage measuring unit could be provided to measure at least three values, in particular voltage values, of the capacitance voltage, in particular at least three different times of the switching period duration, during a switching period duration and / or during a switch-on time of at least one of the inverter switches. Alternatively and / or additionally, the control unit could be provided with at least three values, in particular voltage values, of Capacitance voltage from at least two, preferably immediately consecutive, to evaluate switching period durations. As a result, in particular without the use of additional measuring units, advantageously simple operating data of the hob device can be determined.

In addition, the invention is based on a method for operating a hob device, according to claim 11.

Fig. 1

ein als Induktionskochfeld ausgebildetes Kochfeld mit einer Kochfeldvorrichtung in einer schematischen Draufsicht,

Fig. 2

ein vereinfachtes Schaltbild der Kochfeldvorrichtung,

Fig. 3

ein schematisches Schaubild einiger Signale zur Steuerung der Kochfeldvorrichtung und

Fig. 4

ein vereinfachtes Schaltbild einer weiteren Kochfeldvorrichtung.

Show it:

Fig. 1

a hob designed as an induction hob with a hob device in a schematic plan view,

Fig. 2

a simplified circuit diagram of the hob device,

Fig. 3

a schematic diagram of some signals for controlling the hob device and

Fig. 4

a simplified circuit diagram of another hob device.

FIG. 1 shows an exemplary hob designed as an induction hob 26a in a schematic plan view. The hob 26a has in the present case a hob plate with four heating zones 28a. Each heating zone 28a is intended to heat exactly one cookware element (not shown).

In addition, the hob 26a includes a hob device. The hob device has an operating unit 30a. The operating unit 30a serves to input and / or select various parameters, such as a power level, by a user. To control operation, the cooktop apparatus includes a control unit 24a. The control unit 24a has an arithmetic unit, a memory unit and an operating program stored in the memory unit, which is intended to be executed by the arithmetic unit.

FIG. 2 shows a schematic diagram of the hob device. The hob device has a heating module 10a. In the present case, the heating module 10a comprises exactly one heating element. The heating element is designed as an inductor. The heating module 10a is associated with one of the heating zones 28a in the present case. Alternatively, it is conceivable that a heating module comprises a plurality of heating elements, in particular designed as inductors, and / or a switching arrangement for switching between the heating elements. In this case, the heating module could be assigned to several and / or all heating zones.

In addition, the cooktop apparatus includes an energy source (not shown). The energy source is designed in the present case as a grid connection. Furthermore, the hob device comprises a rectifier unit (not shown). The rectifier unit is intended to rectify a mains voltage of the power source and a To supply energy storage unit 32 a of the hob device. Alternatively, it is conceivable to use an energy source other than a mains connection, in particular a voltage source. Furthermore, in particular when using a DC voltage source, it would also be possible to dispense with a, in particular additional, rectifier unit.

In addition, the hob device comprises an inverter 12a. The inverter 12a includes two inverter switches 14a, 16a. The inverter switches 14a, 16a are identical to each other. The inverter switches 14a, 16a are designed as bidirectional, unipolar semiconductor switches. In the present case, each of the inverter switches 14a, 16a comprises an inverter switching element 34a designed as an IGBT with a diode 36a connected in parallel thereto and a buffer capacitor 38a connected in parallel therewith. Each of the inverter switches 14a, 16a is electrically connected to a center tap 40a of the inverter 12a. The inverter 12a is intended to convert a pulsed rectified mains voltage v _{B of} the energy storage unit 32a into a high-frequency heating current i ₀ , to provide it to the center tap 40a and in particular to feed it to the heating module 10a. Alternatively, it is also conceivable to design inverter switches differently and / or to dispense with a diode and / or buffer capacitor connected in parallel with an inverter switching element.

Further, the cooktop device comprises a resonant capacitor 18a. The resonance capacitor 18a is formed as a capacitor. The resonance capacitance 18a in the present case has a capacitance C _r of 1440 nF. The resonance capacity 18a is associated with the heating module 10a. Accordingly, the resonance capacity 18a is part of an electrical resonant circuit and can be charged via the inverter 12a.

In the present case, a first terminal of the inverter 12a is connected to a first terminal of the energy storage unit 32a. The term "connected" should be understood to mean electrically connected here and below. A second terminal of the inverter 12a is connected to a second terminal of Energy storage unit 32a connected. Furthermore, the second terminal of the inverter 12a is connected to a second terminal of the resonance capacitor 18a. The center tap 40a of the inverter 12a is connected to a first terminal of the heating module 10a. Further, a second terminal of the heating module 10a is connected to a first terminal of the resonance capacitor 18a. Thus, the heating module 10a is disposed in the bridge branch between the center tap 40a and the resonance capacitance 18a. The heating module 10a is operated in the present case in a half-bridge circuit. Alternatively, it is conceivable to operate a heating module in a full bridge circuit.

Furthermore, the cooktop device comprises a capacitance voltage measuring unit 22a. The capacitance voltage measuring unit 22a in the present case comprises a voltage divider and a downstream analog-to-digital converter. In addition, the capacitance voltage measuring unit 22a has a data connection to the control unit 24a. The capacitance voltage measuring unit 22a is provided to measure a capacitance voltage v _{c of} the resonance capacitance 18a and to transmit it to the control unit 24a. In the present case, the hob device is free of further measuring units, in particular voltage and / or current measuring units. Alternatively, however, it is also conceivable for a cooktop device, in particular in addition to a capacitance voltage measuring unit, to comprise further measuring units, in particular voltage and / or current measuring units, in particular in order to increase operational safety.

FIG. 3 shows a schematic diagram of some signals for controlling the hob device. An ordinate axis 42a is shown as a size axis. The time is shown on an abscissa axis 44a. A curve 46a illustrates the switching states of a first inverter switch 14a of the inverter 12a. A curve 48a illustrates the switching states of a second inverter switch 16a of the inverter 12a. A "0" level defines a non-conductive and / or an open state, while a "1" level describes a conductive and / or a closed state. A curve 50a shows an output voltage v _{0 of} the inverter 12a. A curve 52a shows a time profile of the heating current i ₀ .

The control unit 24a is provided to switch the inverter switches 14a, 16a in an operating state alternately and periodically. The control unit 24a is provided to switch the inverter switches 14a, 16a in an operating state with a switching frequency _fsw . The switching frequency f _sw in the present case is about 75 kHz. Thus, at least a first time, the first inverter switch 14a is open and the second inverter switch 16a is closed and the first inverter switch 14a closed and the second inverter switch 16a open for at least a second time, in particular different from the first time.

In the present case, the control unit 24 is provided to determine ₀ the heating module 10a from the capacitor voltage V _c of the resonance capacitor 18a has a power output P. The power output P ₀ corresponds to a heating power of the heating module 10 a, which is supplied in at least one operating state, a set up on the cooking plate cookware and serves to heat the cookware. In this case, the control unit 24a is provided to evaluate only the capacitance voltage v _{c of} the resonance capacitance 18a for determining the power output P ₀ .

The capacitance voltage measuring unit 22a is provided to measure exactly two values of the capacitance voltage V _c during a switching period T _sw of the first inverter switch 14a. The capacitance voltage measuring unit 22a is provided during each switching period T _sw of the first inverter switch 14a to measure exactly two values of the capacitor voltage V _c. In this case, the capacitor voltage measuring unit 22a is provided to each on-time during T ₀ of the first inverter switch 14a accurately measure two values of the capacitor voltage V _c. A duty cycle D of the first inverter switch 14a in the present case is 0.5. The capacitance voltage measuring unit 22a is provided in the present case to measure a value of the capacitance voltage v _c at a switch-on time t _{1 of} the first inverter switch 14a. Thus, the capacitance voltage measuring unit 22a is provided to set a value of Capacitance voltage v _c to measure simultaneously with a start of a turn-on time T _{0 of} the first inverter switch 14a. Furthermore, the capacitance voltage measuring unit 22a is provided to measure a further value of the capacitance voltage v _c at a switch-off time t _{2 of} the first inverter switch 14a. Accordingly, the capacitance voltage measuring unit 22a is provided to measure a further value of the capacitance voltage v _c simultaneously with an end of a switch-on time T _{0 of} the first inverter switch 14a. Alternatively, it is conceivable that a capacitance voltage measuring unit is provided to measure at least three, at least four and / or at least five values of a capacitance voltage during a switching period duration and / or during a switch-on time of at least one of the inverter switches. In addition, it is conceivable to determine values of a capacitance voltage at a switch-on time and / or a switch-off time of a second inverter switch. Furthermore, a capacitance voltage measuring unit could be provided to measure at least one value of a capacitance voltage at another time.

Die Leistungsabgabe P₀ setzt sich dabei aus der Schaltfrequenz f_sw und/oder der Schaltperiodendauer T_sw, der Kapazität C_r, dem Tastgrad D, einem Mittelwert V_Mc der Kapazitätsspannung v_c sowie einer Differenz des am Ende der Einschaltzeit T₀ gemessenen weiteren Werts der Kapazitätsspannung v_c und des zu Beginn der Einschaltzeit T₀ gemessenen Werts der Kapazitätsspannung v_c zusammen. Gleichung 1 lässt sich dabei insbesondere aus folgenden Gleichungen für die Leistungsabgabe P₀ und die Kapazitätsspannung v_c ableiten. $$P_0=f_{\mathit{sw}}\cdot {\int }_0^{T_{\mathit{sw}}}{v}_0\cdot i_0\left(t\right)\mathit{dt}=f_{\mathit{sw}}\frac{V_{\mathit{Mc}}}{D}\cdot {\int }_0^{{\mathit{DT}}_{\mathit{sw}}}{i}_0\left(t\right)\mathit{dt}$$

$$v_c\left(t\right)=V_{\mathit{Mc},0}+\frac{1}{c_r}{\int }_t{\mathit{i}}_0\left(t\right)\mathit{dt}$$

Dabei ist die Steuereinheit 24a ferner dazu vorgesehen, aus der Kapazitätsspannung v_c den Mittelwert V_Mc der Kapazitätsspannung v_c zu bestimmen. Der Mittelwert V_Mc der Kapazitätsspannung v_c ergibt sich dabei durch folgenden Zusammenhang: $$V_{\mathit{Mc}}=f_{\mathit{sw}}{\int }_t{\mathit{v}}_c\left(t\right)\mathit{dt}$$

Des Weiteren ist die Steuereinheit 24a dazu vorgesehen, den Mittelwert V_Mc der Kapazitätsspannung v_c aus zumindest drei Werten der Kapazitätsspannung v_c zu bestimmen. Im vorliegenden Fall ist die Steuereinheit 24a dazu vorgesehen, die zumindest drei Werte der Kapazitätsspannung v_c aus zumindest zwei unmittelbar aufeinanderfolgenden Schaltperiodendauern T_sw auszuwerten. Alternativ könnten jedoch auch mehrere Werte einer Kapazitätsspannung pro Schaltperiodendauer bestimmt werden.In the present case, the control unit 24a is provided to evaluate exactly two values of the capacitance voltage v _c for determining the power output P ₀ per switching cycle duration T _{sw of} one of the inverter switches 14a, 16a. The control unit 24a is provided in the present case to a measured at the beginning of the switch-on time T ₀ of the capacitor voltage V _c and a measured at the end of the on time T ₀ further value of the capacitance voltage V _c for determining the power output P ₀ of the heating module 10a analyze. The control unit 24a is provided for determining the power output P _{0 of} the heating module 10a on the basis of the following equation, which depends in particular only on one variable, in particular the capacitance voltage v _c : $${\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_0=\frac{f_{\mathit{sw}}\cdot C_r\cdot V_{\mathit{Mc}}}{D}\cdot \left[v_c\left(t={\mathit{DT}}_{\mathit{sw}}\right)-v_c\left(t=0\right)\right]$$

The power output P ₀ is made up of the switching frequency f _sw and / or the switching period T _sw , the capacitance C _r , the duty cycle D, an average value V _{Mc of} the capacitance voltage v _c and a difference of the further value measured at the end of the switch-on time T ₀ the capacitance voltage v _c and the value of the capacitance voltage v _c measured at the beginning of the switch-on time T ₀ . Equation 1 can be derived in particular from the following equations for the power output P ₀ and the capacitance voltage v _c . $${\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_0=f_{\mathit{sw}}\cdot {\int }_0^{{\mathrm{<figure-callout\; id="0"\; label="T\; sw\; v"\; filenames="imgf0002.png"\; state="\{\{state\}\}">T\; </figure-callout>}}_{\mathit{sw}}}{v}_{}{}_0\cdot i_0\left(t\right)\mathit{dt}=f_{\mathit{sw}}\frac{V_{\mathit{Mc}}}{D}\cdot {\int }_0^{{\mathit{DT}}_{\mathit{sw}}}{i}_0\left(t\right)\mathit{dt}$$

$$v_c\left(t\right)=V_{\mathit{Mc}.0}+\frac{1}{c_r}{\int }_t{\mathit{i}}_0\left(t\right)\mathit{dt}$$

In this case, the control unit 24a is further provided to determine the mean value V _{Mc of} the capacitance voltage v _c from the capacitance voltage v _c . The mean value V _{Mc of} the capacitance voltage v _c is given by the following relationship: $$V_{\mathit{Mc}}=f_{\mathit{sw}}{\int }_t{\mathit{v}}_c\left(t\right)\mathit{dt}$$

Furthermore, the control unit 24a is provided to determine the mean value V _{Mc of} the capacitance voltage v _c from at least three values of the capacitance voltage v _c . In the present case, the control unit 24a is provided to evaluate the at least three values of the capacitance voltage v _c from at least two immediately consecutive switching period durations T _sw . Alternatively, however, several values of a capacitance voltage per switching cycle duration could also be determined.

Ferner ist die Steuereinheit 24a im vorliegenden Fall dazu vorgesehen, insbesondere lediglich, aus der Kapazitätsspannung v_c den Heizstrom i₀ zu bestimmen. Zudem ist die Steuereinheit 24a im vorliegenden Fall dazu vorgesehen, insbesondere lediglich, aus der Kapazitätsspannung v_c die Ausgangsspannung v₀ des Wechselrichters 12a zu bestimmen. Hierdurch können sämtliche Betriebsdaten des Kochfelds 26a ausgewertet werden, wobei auf zusätzliche Messeinheiten verzichtet werden kann.Furthermore, the control unit 24a is provided to determine an average value V _{MB of} a rectified mains voltage v _B from the capacitance voltage v _c . Where: $$V_{\mathit{MB}}=\frac{V_{\mathit{Mc}}}{D}$$

Furthermore, the control unit 24a is provided in the present case, in particular only, to determine the heating current i ₀ from the capacitance voltage v _c . In addition, the control unit 24a is provided in the present case, in particular only, from the capacitance voltage v _c to determine the output voltage v _{0 of} the inverter 12a. As a result, all operating data of the hob 26a can be evaluated, it being possible to dispense with additional measuring units.

In the FIG. 4 a further embodiment of the invention is shown. The following description and the drawing are essentially limited to the differences between the exemplary embodiments, with respect to the same reference components, in particular with respect to components with the same reference numerals, in principle also to the drawing and / or the description of the other embodiment, in particular of FIGS. 1 to 3 , can be referenced. To distinguish the embodiments of the letter a is the reference numerals of the embodiment in the FIGS. 1 to 3 readjusted. In the embodiment of FIG. 4 the letter a is replaced by the letter b.

The further embodiment of the FIG. 4 differs from the previous embodiment, at least substantially by a number of resonance capacitances 18b, 20b.

In the present case, the cooktop apparatus comprises a first resonant capacitance 18b and a second resonant capacitance 20b. The resonance capacitances 18b, 20b are connected in series. The resonance capacitances 18b, 20b are identical to each other. A center tap 54b of the resonant capacitances 18b, 20b is connected to a second terminal of a heating module 10b. In this case, a capacitance voltage v _c corresponds to a voltage between a defined potential value at the center tap 54 b and a ground potential.

reference numeral

10

heating module

12

inverter

14

Inverter switch

16

Inverter switch

18

resonant capacitance

20

resonant capacitance

22

Capacitance voltage measurement unit

24

control unit

26

hob

28

heating zone

30

operating unit

32

Energy storage unit

34

Inverter switching element

36

diode

38

buffering capacity

40

center tap

42

axis of ordinates

44

abscissa

46

Curve

48

Curve

50

Curve

52

Curve

54

center tap

C _r

capacity

D

duty cycle

f _sw

switching frequency

i ₀

heating

P ₀

power output

T ₀

on time

T _sw

Cycle time

t ₁

switch-on

t ₂

off time

v ₀

output voltage

v _B

rectified mains voltage

v _c

capacitance voltage

V _Mc

Average

V _MB

Average

Claims (11)

1. Cooking hob device with at least one heating module (10a; 10b), with at least one inverter (12a; 12b) which comprises at least two inverter switches (14a, 16a; 14b, 16b) and which is intended to provide at least one heating current (i₀), with at least one resonance capacitor (18a; 18b, 20b) associated with the heating module (10a; 10b), with at least one capacitance voltage measurement unit (22a; 22b) which is intended to measure a capacitance voltage (v_c) of the resonance capacitor (18a; 18b, 20b) and with at least one control unit (24a; 24b) which is intended to determine, in at least one operating state, an output power (P₀) of the heating module (10a; 10b) from the capacitance voltage (v_c), characterised in that the control unit (24a; 24b) is intended merely to evaluate the capacitance voltage (v_c) for the determination of the output power (P₀).
2. Cooking hob device according to claim 1, characterised in that the capacitance voltage measurement unit (22a; 22b) is intended to measure exactly two values of the capacitance voltage (v_c) during a switching period (T_sw) of at least one of the inverter switches (14a, 16a; 14b, 16b).
3. Cooking hob device according to one of the preceding claims, characterised in that the capacitance voltage measurement unit (22a; 22b) is intended to measure exactly two values of the capacitance voltage (v_c) during a turn-on time (T₀) of one of the inverter switches (14a, 16a; 14b, 16b).
4. Cooking hob device according to claim 2 or 3, characterised in that the capacitance voltage measurement unit (22a; 22b) is intended to measure a value of the capacitance voltage (v_c) at the start of a turn-on time (T₀) of one of the inverter switches (14a, 16a; 14b, 16b).
5. Cooking hob device according to claim 2 to 4, characterised in that the capacitance voltage measurement unit (22a; 22b) is intended to measure a value of the capacitance voltage (v_c) at the end of a turn-on time (T₀) of one of the inverter switches (14a, 16a; 14b, 16b).
6. Cooking hob device according to one of the preceding claims, characterised in that the control unit (24a; 24b) is intended to evaluate at least two values of the capacitance voltage (v_c) for the determination of the output power (P₀).
7. Cooking hob device according to one of the preceding claims, characterised in that the control unit (24a; 24b) is intended to determine a mean value (V_Mc) of the capacitance voltage (v_c) from the capacitance voltage (v_c).
8. Cooking hob device according to one of the preceding claims, characterised in that the control unit (24a; 24b) is intended to determine a mean value (V_MB) of a rectified mains voltage (V_B) from the capacitance voltage (v_c).
9. Cooking hob device according to claim 7 or 8, characterised in that the control unit (24a; 24b) is intended to determine the mean value (V_Mc)) of the capacitance voltage (v_c) and/or the mean value (V_MB) of the rectified mains voltage (V_B) from at least three values of the capacitance voltage (v_c).
10. Cooking hob (26a; 26b) with at least one cooking hob device according to one of the preceding claims.
11. Method for operating a cooking hob device, in particular according to one of claims 1 to 9, with at least one heating module (10a; 10b), with at least one inverter (12a; 12b) which comprises at least two inverter switches (14a, 16a; 14b, 16b) and which is intended to provide a heating current (i₀), with at least one resonance capacitor (18a; 18b, 20b) associated with the heating module (10a; 10b) and with at least one capacitance voltage measurement unit (22a; 22b) which is intended to measure a capacitance voltage (v_c) of the resonance capacitor (18a; 18b, 20b), wherein, in at least one operating state, an output power (P₀) of the heating module (10a; 10b) is determined from the capacitance voltage (v_c), characterised in that merely the capacitance voltage (v_c) is evaluated for the determination of the output power (P₀).

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