Patent Publication Number: US-10321521-B2

Title: Hob apparatus

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is the U.S. National Stage of International Application No. PCT/IB2014/067014, filed Dec. 17, 2014, which designated the United States and has been published as International Publication No. WO 2015/092704 and which claims the priority of Spanish Patent Application, Serial No. P201331877, filed Dec. 20, 2013, pursuant to 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The invention proceeds from a hob apparatus. 
     A hob apparatus which comprises a configuration unit and is designed as an induction hob apparatus is already known from the prior art. The configuration unit has two input connections which are each intended to form a connection to at least one heating frequency unit. Furthermore the configuration unit has two output connections which are each intended to form a connection to a plurality of heating elements. In each case a switch of the configuration unit is disposed between a first of the input connections and a first of the output connections as well as between a second of the input connections and a second of the output connections. The switches are intended to switch the two heating frequency units in parallel. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of the invention consists in particular in providing a generic apparatus having improved properties in respect of high efficiency. The object is achieved by the features of the invention. 
     The invention proceeds from a hob apparatus, in particular an induction hob apparatus, having at least one configuration unit which has at least two input connections which are each intended to form a connection to at least one inverter, at least two output connections which are each intended to form a connection to at least one heating element, and at least one switch which is connected to a first input connection of the at least two input connections and at least to a first output connection of the at least two output connections, and which is intended to operate the at least two inverters in at least one operating state, in particular in at least one boost mode, in parallel to at least one of the at least two heating elements. 
     It is proposed that the at least one configuration unit has at least one bridging element which is intended to connect the first input connection and a second output connection of the at least two output connections to one another independently of a switching position of the at least one switch. A “hob apparatus” should be understood in particular to mean at least one part, in particular a subassembly, of a hob, in particular of an induction hob. In particular the hob apparatus can also comprise the entire hob, in particular the entire induction hob. A “configuration unit” should be understood in particular to mean a unit which is intended to assume different switching positions in at least two operating states different from one another. The at least one configuration unit has in particular at least one control contact which is advantageously intended to receive control signals generated in particular by a control unit and via which in particular in at least one operating state a switching position of the at least one configuration unit can be changed. An “inverter” should be understood in particular to mean an electrical unit which generates an oscillating electrical signal, preferably having a frequency of at least 1 kHz, in particular of at least 10 kHz, advantageously of at least 20 kHz and in particular of a maximum of 100 kHz for at least one heating element. In particular the inverter is intended to provide a maximum electrical output, required by the at least one heating element, of at least 100 W, in particular at least 500 W, advantageously at least 1000 W and preferably at least 1500 W. In this case the hob apparatus comprises in particular the at least two inverters. The phrase stating that a first object “is intended to form a connection to a second object” should be understood in particular to mean that in at least one operating state an electrically conductive connection exists between the first object and the second object, advantageously independently of at least one switching unit in the in particular electrically conductive connection, which in particular is disposed between the first object and the second object. A “heating element” should be understood in particular to mean an element which is intended in at least one operating state for an in particular inductive heating of a cooking container, in particular having a maximum heat output of at least 100 W, in particular of at least 500 W, preferably of at least 1000 W and particularly advantageously of at least 1500 W. In this case the hob apparatus comprises in particular the at least two heating elements, wherein the hob apparatus advantageously has a total of at least four, in particular at least six, advantageously at least eight and particularly advantageously a plurality of heating elements. A “switch” should be understood in particular to mean an element which is intended to establish and/or break an electrically conductive connection between at least two points, in particular contacts of the switch. In this case the switch is designed in particular as an electrical element and preferably has at least one control contact for receipt of a control signal, wherein the switch can be actuated via the control contact and in particular can be switched between the at least two contacts, in particular as a function of a control signal generated by a control unit. The phrase stating that a first object is “connected” to a second object should be understood in particular to mean that at least one operating state exists in which the first object and the second object are in contact with one another by means of an electrically conductive connection, wherein in particular in the at least one operating state electrical current flows between the first object and the second object via the electrically conductive connection. The phrase stating that the at least one configuration unit is intended to operate the at least two inverters in at least one operating state “in parallel to at least one of the at least two heating elements” should be understood in particular to mean that the at least one configuration unit is intended, in the at least one operating state, to connect the at least two inverters, in particular by changing a switching position of the at least one switch, simultaneously to the at least one heating element, and in particular to transfer energy generated by the at least two inverters simultaneously to the at least one heating element, in particular in order to achieve a high and advantageously higher output power of the at least one heating element. In this case the configuration unit comprises in particular an electrical connection between the second input connection and the first output connection, which in particular can be electrically switched. A “bridging element” should be understood in particular to mean an electrically conductive element which is intended to connect at least two contact points in particular directly electrically conductively to one another at least in an assembled state, in particular independently of an operating state and advantageously independently of switching positions of any switching units and/or of any switches. Different embodiments of the at least one bridging element which appear as expedient to a person skilled in the art are conceivable. For example, the at least one bridging element can be designed as a permanent connection between the at least two contact points, wherein the at least one bridging element in particular could be disposed fixedly on at least one circuit board. Likewise conceivable is that the at least one bridging element can be designed to be removable, wherein the at least one bridging element in particular enables different topologies and/or arrangements on the at least one circuit board. “Intended” should be understood in particular to mean specifically programmed, designed and/or configured. The statement that an object is intended for a specific function should be understood in particular to mean that the object fulfills and/or performs this particular function in at least one application state and/or operating state. 
     Thanks to the inventive embodiment it is possible in particular to achieve a high degree of efficiency, advantageously a high degree of electrical and/or in particular a high degree of economic efficiency. A high output power can advantageously be achieved, in particular since the at least one configuration unit is intended for high electrical currents. Because of the at least one bridging element a small electrical current through the switch can advantageously be achieved, as a result of which in particular a switch with low requirements and/or with a small size can be used. As a result, low costs can preferably be achieved. 
     The at least one switch could for example be connected exclusively to the first output connection, wherein exactly one electrical connection could exist between the first input connection and the second output connection, which in particular would be formed by the at least one bridging element. Preferably the at least one switch is however additionally connected to the second output connection, wherein in particular a “normally closed” contact of the at least one switch is connected to the second output connection. Alternatively it is conceivable for a “normally opened” contact of the at least one switch to be connected to the second output connection. This means that in particular a high degree of flexibility can be achieved. 
     For example the at least one bridging element could be intended to bridge the “normally opened” contact of the at least one switch. 
     Preferably the at least one bridging element is however intended to bridge a “normally closed” contact of the at least one switch, as a result of which in particular a high output power and/or a high current intensity can be provided at the second output connection. 
     It is further proposed that the at least one configuration unit has at least one second switch, which is connected to a second input connection of the at least two input connections and at least to the second output connection, as a result of which in particular a high degree of flexibility can be achieved. 
     For example, the at least one second switch could be connected exclusively to the second output connection, wherein advantageously exactly the one in particular switchable electrical connection could exist between the second input connection and the first output connection. Preferably the at least one second switch is however additionally connected to the first output connection, wherein the at least one second switch could form the one in particular switchable electrical connection. Various connection options of the at least one second switch to the first output connection are conceivable which appear expedient to a person skilled in the art. For example, a “normally opened” contact of the at least one switch could be connected to the first output connection. Advantageously however a “normally closed” contact of the at least one switch is connected to the first output connection. As a result further switches can in particular be dispensed with, as a result of which low costs can advantageously be achieved. 
     Furthermore it is proposed that the at least one configuration unit has at least one second bridging element which is intended to connect a second input connection of the at least two input connections and the first output connection to one another, as a result of which in particular a high degree of electrical and/or economic efficiency can be achieved. 
     If the at least one second bridging element is intended to bridge a “normally closed” contact of the at least one second switch, a component with low requirements can in particular be used for the at least one second switch, as a result of which low costs and/or a hob apparatus which can be acquired inexpensively by a customer can be achieved. 
     Furthermore it is proposed that the hob apparatus comprises a switching unit which is switched between the at least one configuration unit and the at least two heating elements. A “switching unit” should be understood in particular to mean an electronic unit which is intended to establish and/or break an electrically conductive connection at least between two contact points. The switching unit preferably has at least one control contact, via which the switching unit advantageously can be switched in at least one operating state and via which the switching unit receives in particular in at least one operating state at least one control signal, which advantageously is generated by a control unit. The phrase stating that the switching unit is switched “between” the at least one configuration unit and the at least two heating elements should be understood in particular to mean that in each operating state in which the at least two heating elements are fed with electrical current by the configuration unit the electrical current flows through the switching unit. When viewed in the direction of a cable path the switching unit is advantageously switched starting from the configuration unit upstream of the at least two heating elements. As a result in particular a high degree of flexibility can be achieved. 
     For example, the switching unit could have exactly one further switch which in particular could be intended—advantageously in the case of an incorrect switching position of the configuration unit—to break the connection between the at least one configuration unit and the at least two heating elements and in particular to perform an emergency switch-off. However, the switching unit preferably has at least two further switches which are each intended to connect one of the at least two heating elements individually to the configuration unit, wherein a number of further switches and a number of heating elements is advantageously at least substantially identical. As a result in particular a high degree of operational safety can be achieved. 
    
    
     
       Further advantages emerge from the following description of the drawing. Exemplary embodiments of the invention are illustrated in the drawing. 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 to form meaningful further combinations. 
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawing: 
         FIG. 1  shows an inventive hob having an inventive hob apparatus in a schematic planar view, 
         FIG. 2  shows the hob apparatus of the hob in a schematic illustration, 
         FIG. 3  shows a modified hob apparatus in a schematic illustration, 
         FIG. 4  shows a further modified hob apparatus in a schematic illustration, 
         FIG. 5  shows an alternative hob apparatus in a schematic illustration, 
         FIG. 6  shows a modified hob apparatus in a schematic illustration, 
         FIG. 7  shows a further modified hob apparatus in a schematic illustration, 
         FIG. 8  shows a further modified hob apparatus in a schematic illustration, 
         FIG. 9  shows an alternative modified hob apparatus in a schematic illustration, 
         FIG. 10  shows a further alternative modified hob apparatus in a schematic illustration, 
         FIG. 11  shows a further alternative hob apparatus in a schematic illustration, 
         FIG. 12  shows a further modified hob apparatus in a schematic illustration and 
         FIG. 13  shows an alternative modified hob apparatus in a schematic illustration. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION 
       FIG. 1  shows a hob  44   a , which is designed as an induction hob, having a hob apparatus  10   a  which is designed as an induction hob apparatus. The hob apparatus  10   a  has a hob plate  46   a  on which to place cooking containers. Furthermore the hob apparatus  10   a  comprises a plurality of heating elements  26   a ,  28   a  for heating cooking containers placed thereon (cf.  FIG. 2 ). The heating elements  26   a ,  28   a  are designed as induction heating elements. In a built-in position the heating elements  26   a ,  28   a  are disposed underneath the hob plate  46   a . In an assembled state the heating elements  26   a ,  28   a  are disposed in the form of a hob matrix. The heating elements  26   a ,  28   a  are disposed in a half-bridge circuit in the assembled state. The heating elements  26   a ,  28   a  are split into two groups. In this case a first group comprises the heating elements  26   a  and a second group comprises the heating elements  28   a . Alternatively to a hob matrix it is conceivable for the heating elements to be designed as movably mounted heating elements which are intended to be moved underneath the hob plate in directions aligned substantially parallel to the hob plate. Furthermore it is conceivable for the heating elements to form a traditional hob, in which each heating element in particular defines an autonomous, separate heating zone which is advantageously marked on the hob plate. 
     The hob apparatus  10   a  comprises an operating unit  48   a  for inputting and/or selecting operating parameters, for example a heat output and/or a heat output density and/or a heating zone (cf.  FIG. 1 ). The operating unit  48   a  is intended for the output of a value of an operating parameter to an operator. The hob apparatus  10   a  comprises a control unit  50   a , which as a function of operating parameters input by means of the operating unit  48   a  performs actions and/or changes settings. In one operating state the control unit  50   a  operates the heating elements  26   a ,  28   a  as a function of operating parameters input by means of the operating unit  48   a.    
     The hob apparatus  10   a  comprises a rectifier  52   a , which is intended for connection to a phase  54   a  of a domestic power supply (cf.  FIG. 2 ). Furthermore the hob apparatus  10   a  comprises two inverters  18   a ,  20   a , which are each connected to the rectifier  52   a . The inverters  18   a ,  20   a  are intended for generating a high-frequency alternating current. By means of the high-frequency alternating current generated by the inverters  18   a ,  20   a  the heating elements  26   a ,  28   a  are supplied in the operating state. As a function of the operating parameters input by means of the operating unit  48   a  the control unit  50   a  actuates the inverters  18   a ,  20   a.    
     The inverters  18   a ,  20   a  are designed to be substantially identical, which is why in this section only one of the inverters  18   a ,  20   a  is considered. The inverter  18   a  has two series-connected, bidirectional unipolar switches. The switches are formed by a transistor and a parallel-switched diode. Furthermore the inverter  18   a  has in each case a damping capacitor switched in parallel to the bidirectional unipolar switches. A voltage tap of the inverter  18   a  is disposed at a shared contact point of two bidirectional unipolar switches. 
     The hob apparatus  10   a  comprises a configuration unit  12   a  which is switched between the inverters  18   a ,  20   a  and the heating elements  26   a ,  28   a . The configuration unit  12   a  has two input connections  14   a ,  16   a , which are each intended to form a connection to one of the inverters  18   a ,  20   a . A first input connection  14   a  of the input connections  14   a ,  16   a  is connected to a first inverter  18   a  of the inverters  18   a ,  20   a . A second input connection  16   a  of the input connections  14   a ,  16   a  is connected to a second inverter  20   a  of the inverters  18   a ,  20   a . The configuration unit  12   a  has two output connections  22   a ,  24   a . A first output connection  22   a  of the output connections  22   a ,  24   a  is intended to form a connection to the heating elements  26   a . A second output connection  22   a  of the output connections  22   a ,  24   a  is intended to form a connection to the heating elements  28   a.    
     The configuration unit  12   a  has a switch  30   a  and a second switch  32   a . Alternatively to an embodiment of the configuration unit having two switches, an embodiment having exactly one switch is conceivable (cf.  FIGS. 3 and 4 ). The switches  30   a ,  32   a  are designed as changeover switches (cf.  FIG. 2 ). The switches  30   a ,  32   a  are designed as relays. The switch  30   a  is connected to the first input connection  14   a  and the first output connection  22   a . The switch  30   a  has a “changeover” contact. The “changeover” contact of the switch  30   a  is connected to the first input connection  14   a . The switch  30   a  has a “normally opened” contact and a “normally closed” contact. The “normally opened” contact of the switch  30   a  is connected to the first output connection  22   a . The “normally opened” contact of the switch  30   a  is connected to the first output connection  22   a . A “normally closed” contact of the switch  30   a  is free-standing, in particular connectionless. The second switch  32   a  is connected to the second input connection  16   a  and the second output connection  24   a . The second switch  32   a  has a “changeover” contact. The “changeover” contact of the second switch  32   a  is connected to the second input connection  16   a . The second switch  32   a  has a “normally opened” contact and a “normally closed” contact. The “normally opened” contact of the second switch  32   a  is connected to the second output connection  24   a . The “normally closed” contact of the second switch  32   a  is free-standing, in particular connectionless. 
     The configuration unit  12   a  has a bridging element  34   a  and a second bridging element  36   a . The bridging element  34   a  connects the first input connection  14   a  and the second output connection  24   a  to one another independently of a switching position of the switches  30   a ,  32   a . Independently of a switching position of the switches  30   a ,  32   a  the configuration unit  12   a  has an electrically conductive connection between the first inverter  18   a  and the second output connection  24   a . The electrically conductive connection between the first inverter  18   a  and the second output connection  24   a  is formed by the first bridging element  34   a . The second bridging element  36   a  connects the second input connection  16   a  and the first output connection  22   a  to one another independently of a switching position of the switches  30   a ,  32   a . The configuration unit  12   a  has an electrically conductive connection between the second inverter  20   a  and the first output connection  22   a  independently of a switching position of the switches  30   a ,  32   a . In this case the electrically conductive connection between the second inverter  20   a  and the first output connection  22   a  is formed by the second bridging element  36   a.    
     In the operating state the configuration unit  12   a  is intended to operate the inverters  18   a ,  20   a  in parallel to a group of the heating elements  26   a ,  28   a . For example, the configuration unit  12   a  could switch a switching position of the switch  30   a  from the “normally closed” contact to the “normally opened” contact, as a result of which the inverters  18   a ,  20   a  are operated in parallel to the heating elements  28   a . Alternatively the configuration unit  12   a  could switch a switching position of the second switch  32   a  from the “normally closed” contact to the “normally opened” contact, as a result of which the inverters  18   a ,  20   a  are operated in parallel to the heating elements  26   a . The operating state, in which the inverters  18   a ,  20   a  are operated jointly in parallel to a group of the heating elements  26   a ,  28   a , is referred to as a boost mode. In a further operating mode it is conceivable for the first group of the heating elements  26   a  to be operated on the second inverter  20   a . Likewise, in the further operating mode it is possible to operate the second group of the heating elements  28   a  on the first inverter  18   a.    
     The hob apparatus  10   a  comprises a switching unit  38   a , which is switched between the configuration unit  12   a  and the heating elements  26   a ,  28   a . The switching unit  38   a  has two input connections  56   a ,  58   a . A first input connection  56   a  of the input connections  56   a ,  58   a  of the switching unit  38   a  is connected to the second output connection  24   a  of the configuration unit  12   a . A second input connection  58   a  of the input connections  56   a ,  58   a  of the switching unit  38   a  is connected to the first output connection  22   a  of the configuration unit  12   a . The switching unit  38   a  has a plurality of output connections  60   a . A number of output connections  60   a  of the switching unit  38   a  is substantially identical to a number of heating elements  26   a ,  28   a.    
     The switching unit  38   a  has a plurality of further switches  40   a ,  42   a , which are each intended to connect one of the heating elements  26   a ,  28   a  individually to the configuration unit  12   a . The further switches  40   a ,  42   a  are split into two groups. In this case a first group has the further switches  40   a  which are associated with the first group of the heating elements  26   a . In each case a further switch  40   a  of the first group is connected to a heating element  26   a  of the first group and is intended to connect the respective heating element  26   a  individually to the configuration unit  12   a . A second group has the further switches  42   a  which are associated with the second group of the heating elements  28   a . In each case a further switch  42   a  of the second group is connected to a heating element  28   a  of the second group and is intended to connect the respective heating element  28   a  individually to the configuration unit  12   a.    
     The hob apparatus  10   a  comprises a plurality of resonance capacitors  62   a . Each resonance capacitor  62   a  is associated with one of the heating elements  26   a ,  28   a . A number of resonance capacitors  62   a  is substantially identical to a number of heating elements  26   a ,  28   a . Alternatively it is conceivable for the hob apparatus to have exactly one resonance capacitor per group of heating elements, wherein the hob apparatus in the present exemplary embodiment could in particular have two resonance capacitors which could each be associated with a group of heating elements. In the present exemplary embodiment each resonance capacitor  62   a  has two capacitors. Alternatively embodiments having a different number of capacitors are conceivable. 
       FIGS. 5 to 13  show further exemplary embodiments of the invention. The following descriptions are substantially limited to the differences between the exemplary embodiments, wherein in respect of components, features and functions which remain identical reference can be made to the description of the exemplary embodiments in  FIGS. 1 to 4 . To distinguish the exemplary embodiments the letter a in the reference characters of the exemplary embodiments in  FIGS. 1 to 4  is replaced by the letter b in the reference characters of the exemplary embodiments in  FIGS. 5 to 13 . In respect of identically designated components, in particular in reference to components having identical reference characters, reference can in principle also be made to the drawings and/or the description of the exemplary embodiments in  FIGS. 1 to 4 . 
       FIG. 5  shows a hob apparatus  10   b , which is designed as an induction hob apparatus, of a hob which is designed as an induction hob. The hob apparatus  10   b  comprises a configuration unit  12   b  which has two input connections  14   b ,  16   b . The input connections  14   b ,  16   b  are each intended to form a connection to an inverter  18   b ,  20   b  of the hob apparatus  10   b . Furthermore the configuration unit  12   b  has two output connections  22   b ,  24   b . A first output connection  22   b  of the output connections  22   b ,  24   b  is intended to form a connection to heating elements  26   b  of the hob apparatus  10   b . A second output connection  22   b  of the output connections  22   b ,  24   b  is intended to form a connection to heating elements  28   b  of the hob apparatus  10   b.    
     A switch  30   b  of the hob apparatus  10   b  is connected to a first input connection  14   b  of the input connections  14   b ,  16   b  and the first output connection  22   b . A “normally opened” contact of the switch  30   a  is connected to the first output connection  22   b . The switch  30   b  is additionally connected to the second output connection  24   b . A “normally closed” contact of the switch  30   b  is connected to the second output connection  22   b . For example, the configuration unit could have exactly the one switch (cf.  FIG. 6 ), wherein further switches, in particular a second switch, could be dispensed with. Preferably however the configuration unit  12   b  has a second switch  32   b  (cf.  FIG. 5 ), which is connected to the second input connection  16   b  and the second output connection  24   b . A “normally opened” contact of the second switch  32   b  is connected to the second output connection  24   b . The second switch  32   b  is additionally connected to the first output connection  22   b . A “normally closed” contact of the second switch  32   a  is connected to the first output connection  22   b . As shown in  FIG. 7 , the configuration unit could have exactly the one second switch, wherein the switch could be dispensed with. 
     The configuration unit  12   b  has a bridging element  34   b , which connects the first input connection  14   b  and the second output connection  24   b  to one another independently of a switching position of the switches  30   b ,  32   b . In this case the bridging element  34   b  bridges the “normally closed” contact of the switch  30   b . The configuration unit  12   b  has a second bridging element  36   b , which connects the second input connection  16   b  and the first output connection  22   b  to one another independently of a switching position of the switches  30   b ,  32   b . The second bridging element  34   b  bridges the “normally closed” contact of the second switch  32   b.    
     A switching unit  38   b  of the hob apparatus  10   b  is switched between the configuration unit  12   b  and the heating elements  26   b ,  28   b  and has a plurality of further switches  40   b ,  42   b . The respective further switches  40   b ,  42   b  are intended to connect one of the heating elements  26   b ,  28   b  individually to the configuration unit  12   b . The further switches  40   b ,  42   b  are designed as changeover switches (cf.  FIG. 5 ). The further switches  30   b ,  32   b  are designed as relays. Each further switch  40   b ,  42   b  has a “changeover” contact, a “normally opened” contact and a “normally closed” contact. In the present exemplary embodiment the “changeover” contact of the further switches  40   b ,  42   b  is in each case disposed on a side of the further switches  40   b ,  42   b  facing away from the configuration unit  12   b . Each “changeover” contact of the further switches  40   b ,  42   b  is connected to one of the heating elements  26   b ,  28   b . Each further switch  40   b ,  42   b  is connected to the configuration unit  12   b  via the “normally opened” contact. Alternatively it is conceivable for each further switch  40   b ,  42   b  to be connected to the configuration unit  12   b  via the “normally closed” contact—as shown for example in  FIG. 8 . 
     In further alternative arrangements of the further switches  40   b ,  42   b  it is conceivable for the “changeover” contact of the further switches  40   b ,  42   b  to be connected to the configuration unit  12   b  (cf.  FIGS. 9 and 10 ). In this case each further switch  40   b ,  42   b  could be connected to one of the heating elements  26   b ,  28   b  via the “normally opened” contact (cf.  FIG. 9 ). As illustrated in  FIG. 10 , each further switch  40   b ,  42   b  could however also be connected to one of the heating elements  26   b ,  28   b  via the “normally closed” contact. 
     Alternatively to an embodiment of the further switches  40   b ,  42   b  as changeover switches it is conceivable for the further switches  40   b ,  42   b  to be designed as on-off switches (cf.  FIGS. 11 and 12 ). In this case each further switch  40   b ,  42   b  could have a “changeover” contact and a “normally opened” contact. Likewise conceivable is for each further switch  40   b ,  42   b  to have a “changeover” contact and a “normally closed” contact (not illustrated). As shown in  FIG. 11 , each further switch  40   b ,  42   b  could be connected to the configuration unit  12   b  via the “normally opened” contact. In this case each further switch  40   b ,  42   b  would be connected to one of the heating elements  26   b ,  28   b  via the “changeover” contact. Alternatively to this, each further switch  40   b ,  42   b  could be connected to one of the heating elements  26   b ,  28   b  via the “normally opened” contact (cf.  FIG. 12 ). In this case each further switch  40   b ,  42   b  could be connected to the configuration unit  12   b  via the “changeover” contact. 
     It is furthermore conceivable for a switching position of the configuration unit  12   b  and a switching position of the switching unit  38   b  to be coupled to one another. This can be explained by using  FIG. 5  as an example. For example, a switching position of the “normally closed” contacts of the further switches  40   a ,  42   a  could be coupled to a switching position of the “normally opened” contacts of the switches  30   b ,  32   b  of the configuration unit  12   b . In this case, in the event that the “changeover” contact and the “normally opened” contact of the switch  30   a  are connected to one another, for each further switch  40   a  of the first group the “changeover” contact is connected to the “normally closed” contact. In the present exemplary embodiment the configuration unit  12   b  and the switching unit  38   b  are however designed independently of one another. In particular switching positions of the configuration unit  12   b  and switching positions of the switching unit  38   b  can be set independently of one another. 
     By means of the switches  30   b ,  32   b  the configuration unit  12   b  is intended in a operating state to operate the inverters  18   b ,  20   b  in parallel to a group of the heating elements  26   b ,  28   b . In this case it is conceivable for the configuration unit  12   b  in the operating mode to operate the inverters  18   b ,  20   b  in parallel to exactly one heating element  26   b ,  28   b  of a group of the heating elements  26   b ,  28   b . Alternatively the configuration unit  12   b  in the operating mode could operate the inverters  18   b ,  20   b  in parallel to a plurality of and/or all heating elements  26   b ,  28   b  of a group of the heating elements  26   b ,  28   b . Furthermore it is conceivable for the configuration unit  12   b  in a further operating mode to operate each of the inverters  18   b ,  20   b  at one of the group of heating elements  26   b ,  28   b , wherein a majority and advantageously all heating elements  26   b ,  28   b  are in operation jointly. 
     The hob apparatus  10   b  comprises a plurality of resonance capacitors  62   b . Each resonance capacitor  62   b  has capacitors. Alternatively, embodiments having a different number of capacitors are conceivable. Each resonance capacitor  62   b  is associated with one of the heating elements  26   b ,  28   b , wherein a number of resonance capacitors  62   b  is substantially identical to a number of heating elements  26   b ,  28   b . As illustrated in  FIG. 13 , it is alternatively conceivable for the hob apparatus  10   b  to have exactly one resonance capacitor  62   b  per group of heating elements  26   b ,  28   b . In this case the hob apparatus  10   b  could in particular have two resonance capacitors  62   b , which could each be associated with a group of heating elements  26   b ,  28   b.    
     Alternatively to an embodiment having two inverters, embodiments having another number of inverters are possible, in particular having more than two inverters, which could each be connected to the rectifier. In this case a number of switches of the configuration unit would be appropriately adjusted, wherein in particular an algorithm could be used for calculating a minimum required number of switches.