Hob device, hob, and method for operating a hob device

Abstract

The invention relates to a hob device (10a) comprising at least one circuit (12a), said circuit (12a) having at least one inverter (14a; 14b) and at least one filter unit (16a). The aim of the invention is to improve at least the efficiency of the filter unit (16a). This is achieved in that the filter unit (16a) has a notch filter (26a) and / or a band-stop filter in order to filter at least one signal with respect to the inverter (14a; 14b).

Description

[0001] Hob device, hob and method for operating a hob device

[0002] The invention relates to a hob device according to the preamble of claim 1, a hob according to claim 10 and a method for operating a hob device according to claim 11.

[0003] A circuit for a hob is already known from the prior art, which comprises a filter unit, in particular an EMC and / or EMI filter, for filtering electromagnetic interference between a mains supply and a frequency converter of the circuit. The filter unit is known to be designed as a low-pass filter, which filters out high interference frequencies. However, in order to filter out interference signals at a comparatively low frequency, in particular at an operating frequency of 20 kHz to 50 kHz typical for a hob, the low-pass filter must meet high requirements, for example with regard to an inductance filter component, which means that the low-pass filter must be designed particularly cost-intensively and / or have a particularly large filter size and / or the interference signals are only attenuated to a slight extent at the operating frequency.Furthermore, the use of notch filters for RF communication in a frequency range of over 700 MHz up to the terahertz range is known, for example from US 5226057 A, and in a motor application to reduce electromagnetic interference (EMI) at a constant frequency from EP 2876794 A1.

[0004] The object of the invention is, in particular but not limited to, to provide a generic device with improved properties with respect to at least one aspect of efficiency. This object is achieved according to the invention by the features of claim 1, while advantageous embodiments and further developments of the invention can be found in the subclaims.

[0005] The invention is based on a cooktop device with at least one circuit, wherein the circuit has at least one inverter and at least one filter unit. It is proposed that the filter unit has a notch filter and / or a band-stop filter for filtering at least one signal related to the inverter.

[0006] Such a configuration allows the at least one signal to be attenuated particularly efficiently. Advantageously, a particularly strong attenuation of the signal can be achieved using a particularly simple filter unit. In particular, a particularly space-efficient and / or cost-efficient filter unit and, in particular, circuit can be achieved, which, in particular, meets regulations regarding electromagnetic compatibility (EMC).

[0007] The hob device is in particular at least one part, in particular a subassembly, of a hob. The hob device could also comprise the entire hob. The hob device is in particular designed as an induction hob device, wherein the hob is in particular designed as an induction hob. The hob, in particular the hob device, preferably has at least one inductor unit, which in particular has at least one induction coil, which is preferably provided in at least one operating state of the hob device for transmitting inductive energy to at least one installation unit placed on the hob, in particular to a cooking utensil and / or a small household appliance, for example a rice cooker, a blender, a kettle or the like.In the operating state, in particular in a heating mode and / or supply mode, the inductor unit is preferably provided for inductive heating and / or for an inductive power supply of the installation unit. The circuit preferably has at least one inductor unit. In the operating state, the inverter is particularly provided to generate an alternating current for the operation of the inductor unit. The circuit is particularly designed as an electrical and / or electronic circuit and preferably has at least part of an entire electrical and / or electronic circuit of the hob for the operation of the inductor unit for applying an external voltage to the circuit. The circuit preferably has a connection unit, wherein the connection unit is particularly provided for connection to a voltage source.The voltage source in particular provides the external voltage at the connection unit. The voltage source, for example in the form of a household socket, preferably provides a mains voltage or can be designed as a battery and / or a rechargeable battery, for example with a voltage source inverter. The connection unit is preferably provided for applying the external voltage to the connection unit to supply power to the circuit. The connection unit preferably provides a useful signal by means of the voltage source, by means of which the circuit can be operated in the operating state. The useful signal is in particular designed as a main current and / or a main voltage of the circuit. The useful signal is in particular designed differently at different positions in the circuit and can preferably be changed by means of the electrical and / or electronic components of the circuit.The circuit preferably comprises the entire electrical and / or electronic circuit of the hob and is particularly designed as such. The circuit is preferably formed on a printed circuit board, whereby a particularly space-efficient and / or cost-effective printed circuit board can be provided, in particular by means of the filter unit.

[0008] The signal relating to the inverter is in particular designed as an electromagnetic interference signal, which can be generated by at least the inverter in the operating state. In particular, the signal comprises at least one interference voltage and / or one interference current or is designed as such. The signal is preferably designed as an interference signal generated by electromagnetic incompatibility and / or electromagnetic interference of the inverter, in particular with another device and / or element and / or at least part of a remainder of the circuit. The signal can be designed as a signal modulated onto the useful signal of the circuit. The signal is preferably designed as a harmonic current due to the electromagnetic incompatibility and / or the electromagnetic interference relating to the inverter.The filter unit is preferably designed as the notch filter and / or the band-stop filter and in particular has only the notch filter and / or the band-stop filter.

[0009] Alternatively, it is conceivable for the filter unit to have at least one further electrical and / or electronic element that would be deemed appropriate by a person skilled in the art. The filter unit, in particular the notch filter and / or the band-stop filter, is / are provided in particular for filtering out and / or attenuating the signal. Preferably, the filter unit, in particular the notch filter and / or the band-stop filter, is / are provided for filtering the frequency of the signal and / or for filtering a stop-band frequency range in which the frequency of the signal lies.

[0010] "Intended" should be understood as specifically programmed, designed, and / or equipped. The fact that an object is intended for a specific function should be understood as meaning that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0011] It is further proposed that the filter unit be set to an operating frequency of the

[0012] This allows at least one of the inverters to be switched on during operation

[0013] The signal generated by the inverter, in particular a plurality of signals generated during operation of the inverter, in particular interference signals, are attenuated particularly efficiently. In particular, interference signals relating to the inverter with a frequency which at least substantially corresponds to the operating frequency of the inverter, are generated by the inverter in the operating state with a maximum frequency with respect to a total amount of interference signals relating to the inverter. A total amount of the signals generated by the inverter, in particular the interference signals, in particular has at least substantially the operating frequency most frequently. “At least substantially the operating frequency” is to be understood in particular as a frequency which deviates from the operating frequency preferably by a maximum of 25%, preferably by less than 10% and particularly preferably by less than 5% of the operating frequency.Preferably, at least one frequency filtered by the filter unit has a value that at least substantially corresponds to the operating frequency. The stopband frequency range of the filter unit preferably has the operating frequency. Preferably, the filter unit is provided to filter at least substantially the operating frequency of the inverter, in particular to a maximum, in particular to attenuate an intensity of a signal with at least substantially the operating frequency, in particular to a maximum. The operating frequency of the inverter in particular corresponds at least substantially to an operating frequency of the inductor unit, in particular taking into account electrical and / or electronic losses and / or other changes in the operating frequency in the inductor unit and / or between the inverter and the inductor unit that are known to those skilled in the art.The operating frequency is preferably at least 10 kHz, preferably at least 15 kHz and particularly preferably at least 20 kHz and / or preferably at most 100 kHz, preferably at most 70 kHz, particularly preferably at most 50 kHz and particularly advantageously at most 40 kHz.

[0014] It is also proposed that the inverter have a fixed operating frequency. Advantageously, the signal can be filtered particularly efficiently by means of a filter unit structure with particularly low complexity. In particular, the filter unit can have a fixed filter frequency which in particular corresponds at least substantially to the operating frequency of the inverter. In particular, the filter unit can have a fixed stopband frequency range which has the operating frequency and / or a frequency which at least substantially corresponds to the operating frequency of the inverter. The inverter can, for example, have a buck-boost inverter by means of which in particular energy or power emitted by the inductor unit can bePower at the fixed operating frequency can be controlled by means of a duty cycle and / or a phase shift between branches, in particular of the circuit, or it can be designed as another inverter with a fixed, in particular unchangeable, operating frequency that appears appropriate to a person skilled in the art. Alternatively, it is conceivable for the inverter to have a variable, in particular adjustable, operating frequency, in particular for adjusting the energy or power transmitted by means of the inductor unit. For example, the inverter can have a series resonant half-bridge inverter or a single-switch inverter, for example a dual single-switch inverter, or it can be designed as such an inverter.The filter unit can have a variable, in particular adjustable, filter frequency and / or stopband frequency range, which can be adapted in particular to the operating frequency. The filter unit can in particular have adjustable electronic and / or electrical elements and / or more than one notch filter and / or band-stop filter, which are each set for the different operating frequencies of the inverter. It is further proposed that the circuit have at least one rectifier and at least one inductor unit, in particular the one mentioned above, wherein the filter unit is interposed between the rectifier and the inductor unit. Advantageously, an arrangement of the filter unit in the circuit can be achieved for which the signal with respect to the inverter can be filtered particularly efficiently.In particular, a filter function of the filter unit, as explained below, can be advantageously improved. The filter unit is preferably connected downstream of the rectifier, in particular along a main current direction of the useful signal in the circuit. The filter unit is preferably connected upstream of the inductor unit, in particular along the main current direction of the useful signal in the circuit.

[0015] It is further proposed that the circuit comprise at least one rectifier, in particular the one mentioned above, wherein the filter unit is connected between the rectifier and the inverter. Advantageously, filtering of the useful signal originating from the inverter, in particular filtering of the useful signal comprising an alternating current with the operating frequency of the inverter along the main current direction downstream of the inverter, can be avoided by means of the filter unit. In particular, the filter unit can advantageously only filter the at least one signal, in particular the interference signal. The filter unit is preferably arranged, in particular connected, in the circuit to allow the useful signal to pass through. The filter unit is preferably connected directly downstream of the rectifier, in particular along the main current direction of the useful signal in the circuit.Preferably, the filter unit is connected upstream of the inverter, in particular along the main current direction of the useful signal in the circuit, for example directly.

[0016] It is also proposed that the notch filter and / or the band-stop filter have / have an LC resonant circuit or an LCR resonant circuit, whereby in particular a particularly high filter efficiency, in particular a particularly strong attenuation of the signal, of the filter unit can be achieved, in particular for advantageous space efficiency and / or cost efficiency of the filter unit. Advantageously, a requirement for inductance components of the filter unit, in particular for at least one filter coil, can be advantageously reduced, wherein in particular a necessary inductance of the coil can be advantageously reduced for efficient filtering. In particular, the notch filter and / or the band-stop filter have / have the at least one filter coil. Preferably, the notch filter and / or the band-stop filter have / have at least one filter capacitor.The filter unit, in particular the notch filter and / or the band-stop filter, is / are preferably designed as a single-stage filter. The filter unit preferably has exactly one LC resonant circuit or exactly one LCR resonant circuit. The filter unit preferably has exactly one filter coil and / or exactly one filter capacitor. In particular, the number of inductance filter components in the circuit can be advantageously reduced. The complexity of the filter unit can advantageously be reduced and thus, in particular, the space efficiency and / or cost efficiency of the filter unit can be advantageously increased. The notch filter and / or the band-stop filter preferably have a parallel configuration, wherein, in particular, the filter capacitor is connected in parallel with at least the filter coil and / or a remainder of the circuit.Alternatively, the notch filter and / or the band-stop filter may comprise more than one LC resonant circuit or one LCR resonant circuit, in particular more than one filter coil and / or more than one filter capacitor.

[0017] Alternatively or additionally, it would be conceivable that the notch filter and / or the band-stop filter have / have at least one RC resonant circuit and are / are designed, for example, free of a filter coil.

[0018] It is further proposed that the filter unit filters at least one differential-mode interference. The signal relating to the inverter preferably comprises the at least one differential-mode interference or is configured as such. Advantageously, the signal relating to the inverter can be filtered particularly efficiently. The filter function of the filter unit is preferably to filter the at least one differential-mode interference. The at least one filter coil is provided, in particular, to provide a differential-mode inductance for filtering the differential-mode interference.

[0019] It is further proposed that the circuit have at least one further filter unit which filters at least one common-mode interference, whereby the filtering of interference signals in the circuit can advantageously be further improved. The further filter unit can filter the at least one signal, in particular the interference signal, relating to the inverter and / or at least one further signal, in particular an interference signal, relating to the inverter and / or additional signals, in particular interference signals in the circuit, which are generated in particular free from any reference to the inverter. Preferably, the further filter unit is provided to provide a different filter function than the filter unit, in particular by filtering the common-mode interference.The further filter unit can be provided, in particular, to filter frequencies higher than the frequency of the signal relating to the inverter, in particular higher than the operating frequency of the inverter. The further filter unit can be provided, in particular, to filter at least interference signals, in particular the at least one common-mode interference, emanating from the voltage source and thus the connection unit.

[0020] It is also proposed that the circuit comprise at least one rectifier and one connection unit, in particular the one mentioned above, for connection to a voltage source, in particular the one mentioned above, wherein the further filter unit is interposed between the connection unit and the rectifier. As a result, the filtering function of the further filter unit, in particular the filtering of the at least one common-mode interference, can be provided particularly efficiently. In particular, the filter unit and the further filter unit can interact particularly efficiently for overall filtering. The further filter unit filters, in particular, a current outgoing from the connection unit and / or a current flowing back to the connection unit. In particular, the further filter unit is arranged in the circuit in a manner typical for an EMC filter in a conventional circuit of a hob.The additional filter unit can be designed at least partially according to an EMC filter, in particular one known to those skilled in the art. The additional filter unit could, in particular to increase filter performance in the circuit, be designed entirely as an EMC filter known to those skilled in the art. Advantageously, at least one requirement for the additional filter unit, in particular in an embodiment as an EMC filter, can be relaxed due to the filter unit in the circuit, whereby the additional filter unit can be provided, in particular, with particularly low complexity, in particular with particularly high space efficiency and / or cost efficiency.

[0021] Furthermore, a method for operating a cooktop device, in particular the one mentioned above, with at least one circuit, in particular the one mentioned above, which has at least one inverter, in particular the one mentioned above, and at least one filter unit, in particular the one mentioned above, is provided, wherein at least one signal, in particular the one mentioned above, relating to the inverter is filtered by means of a notch filter, in particular the one mentioned above, and / or a band-stop filter, in particular the one mentioned above, of the filter unit. Advantageously, particularly efficient filtering of the signal can be achieved, in particular by means of a particularly cost-effective and / or space-efficient filter unit.

[0022] The method preferably comprises a method step, in particular a signal generation step, in which the signal is generated based on an operation of the inverter. The signal generation step is carried out, in particular, automatically by performing an induction operation of the hob, in particular the hob device. The method preferably comprises a further method step, in particular a filtering step, in which the signal is filtered by means of the filter unit.

[0023] The cooktop device, the cooktop, and the method for operating the cooktop device are not intended to be limited to the application and embodiment described above. In particular, the cooktop device, the cooktop, and the method for operating the cooktop device may have a number of individual elements, components, units, and method steps that differs from the number stated herein to fulfill a functionality described herein.

[0024] Further advantages will become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0025] They show:

[0026] Fig. 1 is a schematic view of a hob with a hob device from above,

[0027] Fig. 2 is a circuit diagram of a circuit of the hob device which has a filter unit, Fig. 3 is an exemplary graph of a frequency response of the filter unit and of two conventional low-pass filters in comparison,

[0028] Fig. 4 is a flowchart of a method for operating the hob device and

[0029] Fig. 5 shows an inverter for an alternative embodiment of a circuit of a hob device.

[0030] Figure 1 shows a top view of a cooktop 50a with an exemplary mounting unit 52a positioned on the cooktop 50a and inductively supplied with power by the cooktop 50a. The cooktop 50a is configured as an induction cooktop. The mounting unit 52a is configured, for example, as a cooking utensil that can be heated by the cooktop 50a.

[0031] The hob 50a comprises a hob device 10a. The hob device 10a is designed as an induction hob device. The hob device 10a has at least one circuit 12a. The hob device 10a can be designed as at least one printed circuit board (not shown) having the circuit 12a. Alternatively, it is conceivable, for example, for the hob device 10a to comprise the entire hob 50a.

[0032] Figure 2 shows a circuit diagram of circuit 12a. Circuit 12a has at least one inductor unit 20a. In at least one operating state of cooktop device 10a, inductor unit 20a is provided for transmitting inductive energy to mounting unit 52a. Inductor unit 20a has at least one induction coil 28a. In this case, inductor unit 20a has more than one induction coil 28a, although only one induction coil 28a is designated.

[0033] By way of example, the inductor unit 20a in the present case has exactly two induction coils 28a, but alternatively any number of induction coils 28a that appears reasonable to a person skilled in the art would be conceivable.

[0034] The circuit 12a has a connection unit 24a. The connection unit 24a is provided for connection to a voltage source 30a. The voltage source 30a provides an external voltage, in particular a mains voltage, to the connection unit 24a. The circuit 12a can be supplied with power via the connection unit 24a by the voltage source 30a. The connection unit 24a provides a useful signal in the circuit 12a by means of the voltage source 30a. The useful signal is embodied as a main current and / or a main voltage of the circuit 12a. The useful signal is embodied differently at different positions in the circuit 12a, in particular at least with regard to a frequency.

[0035] The circuit 12a has at least one rectifier 18a. The rectifier 18a is provided at least for rectifying the useful signal emanating from the connection unit 24a.

[0036] The circuit 12a has at least one inverter 14a. In the operating state, the inverter 14a is provided to generate an alternating current with an operating frequency of the inverter 14a for the inductor unit 20a. The inverter 14a is provided at least for one direction of the useful signal passing through the rectifier 18a.

[0037] The circuit 12a has at least one filter unit 16a. The filter unit 16a has a notch filter 26a for filtering at least one signal related to the inverter 14a. Alternatively or additionally, the filter unit 16a can have a band-stop filter for filtering at least the signal related to the inverter 14a. In particular, the features mentioned below regarding the notch filter 26a and / or the filter unit 16a with the notch filter 26a also apply accordingly to a band-stop filter and / or a filter unit with the band-stop filter.

[0038] The signal relating to the inverter 14a is embodied as an interference signal generated by at least the inverter 14a in the operating state. The signal is generated due to electromagnetic incompatibility and / or electromagnetic interference with the inverter 14a. The filter unit 16a is embodied here as the notch filter 26a. Alternatively, it would be conceivable for the filter unit 16a to comprise, in addition to the notch filter 26a, at least one further electrical and / or electronic element that would be deemed appropriate by a person skilled in the art.

[0039] The signal has a frequency that at least substantially corresponds to the operating frequency of the inverter 14a. The filter unit 16a is set to the operating frequency of the inverter 14a. The filter unit 16a is intended to at least substantially filter the operating frequency of the inverter 14a. The operating frequency of the inverter 14a is at least 20 kHz in this case. The operating frequency of the inverter 14a is a maximum of 30 kHz in this case (see Figure 3). Alternatively or additionally, a different operating frequency of the inverter 14a would be conceivable, in particular in a frequency range from 10 kHz to 100 kHz.

[0040] The inverter 14a is designed here as a single-switch inverter which has an adjustable operating frequency for controlling energy to be transmitted by means of the inductor unit 20a.

[0041] The filter unit 16a is connected between the rectifier 18a and the inductor unit 20a. The filter unit 16a is connected between the rectifier 18a and the inverter 14a. The filter unit 16a is arranged to pass the useful signal in the circuit 12a. In this case, the filter unit 16a is connected directly downstream of the rectifier 18a.

[0042] The notch filter 26a has an LC resonant circuit 36a. The notch filter 26a has at least one filter coil 38a. The notch filter 26a has at least one filter capacitor 40a. The filter capacitor 40a is connected in parallel with at least the filter coil 38a. The notch filter 26a is designed as exactly one LC resonant circuit 36a. The notch filter 26a has exactly one filter coil 38a. The notch filter 26a has exactly one filter capacitor 40a.

[0043] Alternatively, another number and / or arrangement of filter coils 38a and / or filter capacitors 40a in the filter unit 16a, in particular in a filter unit designed as a band-stop filter (not shown), which appears to be appropriate to a person skilled in the art, is conceivable.

[0044] The filter unit 16a filters at least one differential-mode interference. The signal relating to the inverter 14a includes the at least one differential-mode interference. The filter coil 38a is provided to provide a differential-mode inductance for filtering the differential-mode interference.

[0045] The circuit 12a has at least one further filter unit 22a, which filters at least one common-mode interference. The further filter unit 22a is connected between the connection unit 24a and the rectifier 18a. The further filter unit 22 filters a current flowing out from the connection unit 24a and a current flowing back to the connection unit 24a. The further filter unit 22a is designed at least partially according to an EMC filter known to those skilled in the art.

[0046] Figure 3 shows a graph illustrating a frequency response of the exemplary filter unit 16a and two conventional low-pass filters (not shown) in comparison. The graph has an axis 56a representing the intensity in decibels present after the filter unit 16a or the low-pass filter, respectively, versus an axis 54a representing a frequency in kilohertz.

[0047] A curve 58a describes the frequency response of the filter unit 16a. The filter coil 38a has, for example, an inductance of 75 Ω. The filter capacitor 40a has, for example, a capacitance of 470 nF.

[0048] A curve 60a describes the frequency response of a first low-pass filter with an inductance of 75 pH. A curve 62a describes the frequency response of a second low-pass filter with an inductance of 300 pH.

[0049] The graph shows that the filter unit 16a has an increased filter performance in a stopband frequency range of the filter unit 16a compared to the low-pass filters for an inductance that is equal to or lower than the inductance of the low-pass filters.

[0050] Figure 4 shows a flowchart of a method for operating the hob device 10a, wherein the at least one signal relating to the inverter 14a is filtered by means of the notch filter 26a of the filter unit 16a.

[0051] The method includes a signal generation step 100a, in which the signal is generated based on an operation of the inverter 14a. In a filtering step 102a of the method, the signal is filtered by the filter unit 16a.

[0052] Of multiple objects, only one is provided with a reference symbol in the figures.

[0053] Figure 5 shows a further embodiment of the invention. The following descriptions are essentially limited to the differences between the embodiments, whereby reference can be made to the description of the embodiment in Figures 1 to 4 with regard to identical components, features and functions. To distinguish the embodiments, the letter a in the reference numerals of the embodiment in Figures 1 to 4 has been replaced by the letter b in the reference numerals of the embodiment in Figure 5. With regard to components with the same designation, in particular with regard to components with the same reference numerals, reference can also be made to the drawings and / or the description of the embodiment in Figures 1 to 4.

[0054] Figure 5 shows an alternative embodiment of at least part of an inverter 14b of a circuit (not shown) of a cooktop device (not shown). The inverter 14b has a fixed operating frequency. The inverter 14b is at least partially designed as a buck-boost inverter, in particular a non-resonant one. The inverter 14b is provided to adjust the energy emitted at the inductor unit (not shown) in at least one operating state independently of the operating frequency of the inverter 14b. Alternatively, the inverter 14b can be designed as another inverter 14b with a fixed operating frequency that would be deemed appropriate by a person skilled in the art.

[0055] Reference symbol

[0056] 10 Hob device

[0057] 12 circuit

[0058] 14 inverters

[0059] 16 Filter unit

[0060] 18 rectifiers

[0061] 20 Inductor unit

[0062] 22 additional filter units

[0063] 24 connection unit

[0064] 26 notch filters

[0065] 28 Induction coil

[0066] 30 Voltage source

[0067] 36 LC resonant circuit

[0068] 38 filter coil

[0069] 40 filter capacitor

[0070] 50 hob

[0071] 52 Installation unit

[0072] 54 Axis

[0073] 56 Axis

[0074] 58 Curve

[0075] 60 curve

[0076] 62 Curve

[0077] 100 signal generation steps

[0078] 102 Filtering step

Claims

Claims 1. Hob device (10a) with at least one circuit (12a), wherein the circuit (12a) has at least one inverter (14a; 14b) and at least one filter unit (16a), characterized in that the filter unit (16a) has a notch filter (26a) and / or a band-stop filter for filtering at least one signal relating to the inverter (14a; 14b).

2. Hob device (10a) according to claim 1, characterized in that the filter unit (16a) is set to an operating frequency of the inverter (14a; 14b).

3. Hob device according to claim 1 or 2, characterized in that the inverter (14b) has a fixed operating frequency.

4. Hob device (10aq) according to one of the preceding claims, characterized in that the circuit (12a) has at least one rectifier (18a) and at least one inductor unit (20a), wherein the filter unit (16a) is connected between the rectifier (18a) and the inductor unit (20a).

5. Hob device (10a) according to one of the preceding claims, characterized in that the circuit (12) has at least one rectifier (18a), wherein the filter unit (16a) is connected between the rectifier (18a) and the inverter (14a; 14b).

6. Hob device (10) according to one of the preceding claims, characterized in that the notch filter (26a) and / or the band-stop filter has an LC resonant circuit (36a) or LCR resonant circuit.

7. Hob device (10a) according to one of the preceding claims, characterized in that the filter unit (16a) filters at least one differential mode interference.

8. Hob device (10a) according to one of the preceding claims, characterized in that the circuit (12a) comprises at least one further filter unit (22a) which filters at least one common-mode interference.

9. Hob device (10a) according to claim 8, characterized in that the circuit (12a) has at least one rectifier (18a) and a connection unit (24a) for connection to a voltage source (30a), wherein the further filter unit (22a) of the connection unit (24a) and the rectifier (18a) is interposed.

10. Hob (50a) with a hob device (10a) according to one of the preceding claims.

11. Method for operating a hob device (10a), in particular according to one of the preceding claims, with at least one circuit (12a) which has at least one inverter (14a; 14b) and at least one filter unit (16a), characterized in that at least one signal relating to the inverter (14a; 14b) is filtered by means of a notch filter (26a) and / or a band-stop filter of the filter unit (16a).

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