OPERATING A HOME APPLIANCE DEVICE

The invention relates to a home appliance device according to the preamble of claim 1 and a method for operating a home appliance device according to the preamble of claim 12.

It is known to use hobs comprising at least one relay and a control unit which provides a driving signal for actuating the relay. The relay is thereby driven by using a steady driving signal.

The objective of the invention is, in particular, to provide a generic home appliance device with improved characteristics regarding a switching behaviour. The objective is achieved, according to the invention, by the characterizing features of claims 1 and 12, while advantageous implementations and further developments of the invention can be obtained by the dependent claims.

The invention relates to a home appliance device, in particular a hob device, preferably an induction hob device, comprising a control unit, which is provided to actuate at least one switch and to supply at least one driving signal for completely transferring the switch in at least one first switching process from at least one, preferably exactly one, first switch position to at least one, preferably exactly one, second switch position.

It is proposed that the control unit is provided to modify, preferably optimize, in at least one operational state, in particular during operation, the driving signal for completely transferring the switch from the first switch position to the second switch position, preferably during successive first switching processes, in particular from the first switch position to the second switch position. Thereby, the driving signal is, in particular, different from a portion and/or a part of the driving signal which may vary during the first switching process. "Provided" is to be understood, in particular, as specifically programmed, designed and/or equipped. By an object being provided for a certain function, it is, in particular, to be understood that the object fulfils and/or implements this certain function in at least one application state and/or operating state. Moreover, the control unit is, particularly advantageously, provided to supply at least one further driving signal, which, in particular, may differ from the driving signal, for completely transferring the switch in at least one second switching process from the second switch position to the first switch position. Preferably, the control unit is thereby provided to modify, preferably optimize, in at least one further operational state, in particular during operation, the further driving signal for completely transferring the switch from the second switch position to the first switch position, preferably during successive second switching processes, in particular from the second switch position to the first switch position.

A "home appliance device" is to be understood, in particular, at least as a part, in particular a subassembly, of a home appliance, in particular a hob and preferably an induction hob. Moreover, the home appliance device may, in particular, also comprise the entire home appliance, in particular the entire hob and preferably the entire induction hob. The home appliance device may, in particular, comprise the switch. Thereby, the switch may, in particular, comprise further switch positions like at least one third switch position and/or at least one fourth switch position. However, advantageously the switch comprises exactly two switch positions, in particular the first switch position and the second switch position.

Moreover, a "control unit", in particular, is to be understood to mean an electrical and/or electronical unit which is provided to control and/or regulate an operation of the home appliance device. For this purpose, the control unit preferably comprises a processor unit, a memory unit and/or an operating program which is advantageously stored in the memory unit and preferably executed by the processor unit. By the expression that "the switch is completely transferred to a switch position", it is, in particular, to be understood that the switch is operatively connected, in particular electrically connected, to the switch position, in particular in such a way that a normal and/or correct operation can be achieved. Thus, in particular switching fluctuations and/or switching bounces are excluded. The term "optimize" is to be understood, in particular, as to adjust the driving signal in such a way that an advantageous operation of the home appliance device can be obtained.

In addition, the home appliance device may comprise at least one heating unit, in particular an inductor, which is, in particular, provided to generate an alternating electromagnetic field, which is converted into heat in a bottom of a cooking utensil by means of eddy currents and/or magnetization and demagnetization effects, and/or at least one inverter which is, in particular, provided to supply the heating unit with at least one, preferably high frequency, heating current. By the implementation according to the invention, a home appliance device can be obtained in particular having improved characteristics regarding a switching behaviour. Thereby, in particular a flexibility can be increased, in particular due to the fact that a switching behaviour may be optimized online and/or during operation of the home appliance device. Thus, in particular a fatigue strength and/or a durability of the home appliance device may be increased, advantageously. In addition to that, in particular, an efficiency, in particular power efficiency, component efficiency and/or cost efficiency, can be increased.

Preferably, the control unit is provided to modify, preferably optimize, the driving signal for completely transferring the switch from the first switch position to the second switch position by considering at least one switching performance determined, preferably calculated, in dependence of at least one previous, advantageously immediately previous, first switching process of the switch from the first switch position to the second switch position. Particularly preferably, the control unit is also provided to modify, preferably optimize, the further driving signal for completely transferring the switch from the second switch position to the first switch position by considering at least one further switching performance determined, preferably calculated, in dependence of at least one previous, advantageously immediately previous, second switching process of the switch from the second switch position to the first switch position. A "switching performance" is understood, in particular, to mean a quantity which is correlated with a switching process of the switch. Advantageously, the switching performance correlates and/or corresponds to a signal measured during switching which represents and/or characterizes the switching process, like a voltage signal, in particular a magnitude and/or a shape of the voltage signal, a current signal, in particular a magnitude and/or a shape of the current signal, a duration of the switching process and/or a volume of the switching process. By that, in particular a switching behaviour can be modified precisely.

Moreover, it is proposed that the home appliance device comprises a sensor unit which is provided to measure at least one signal measured during switching of the switch, in particular during and/or after a switching process, in particular the first switching process and/or the second switching process. Thereby, the signal measured during switching, in particular, correlates to the switching process, in particular a currently running switching process and/or an immediately previous switching process. In particular, the sensor unit comprises at least one sensor and preferably several, advantageously differently constructed, sensors, like at least two, at least three and/or at least four sensors. Thereby, the sensor unit may, in particular, comprise at least one voltage sensor, current sensor, acoustic sensor, position sensor, velocity sensor and/or acceleration sensor. Moreover, in particular the at least one sensor may be a resistive sensor, a capacitive sensor, an inductive sensor, an ultrasonic sensor, an optical sensor and/or a piezo-electric sensor. Thus, in particular an advantageously flexible sensor unit can be provided, which can be easily adapted to different needs and/or requirements, wherein at the same time costs may be kept to a minimum.

A straightforward control algorithm can, in particular, be provided, if the switching performance is correlated to and/or depends on the, in particular measured, signal measured during switching, in particular a signal measured during switching which is associated to the first switching process. Moreover, advantageously the further switching performance is correlated to and/or depends on a further, in particular measured, signal measured during switching, which is in particular associated to the second switching process. Additionally, it is proposed that the control unit is provided to regularly modify, preferably optimize, the driving signal for completely transferring the switch from the first switch position to the second switch position, in particular by redetermine the switching performance regularly. Moreover, advantageously the control unit is provided to regularly modify, preferably optimize, the further driving signal for completely transferring the switch from the second switch position to the first switch position, in particular by redetermine the further switching performance regularly. In this context the term "regularly", in particular, is understood to mean annually, monthly, daily, hourly and/or after a certain number of switching processes like at least one switching process, at least two switching processes, at least five switching processes and/or at least ten switching processes for example. As an alternative or additionally, it is conceivable that the control unit, in particular, is provided to modify, preferably optimize, the driving signal for completely transferring the switch from the first switch position to the second switch position and/or the further driving signal for completely transferring the switch from the second switch position to the first switch position after and/or during a defined and/or definable triggering event, like an occurrence of a service mode and/or an error mode, for example an unexpected lengthy switching process. Hence, in particular the home appliance device is adjustable to changing environmental conditions, for example due to aging of the switch and/or temperature effects.

Advantageously, the control unit is provided to modify, preferably optimize, the driving signal for completely transferring the switch from the first switch position to the second switch position in an iterative way, in particular by determining the switching performance in an iterative way. Moreover, advantageously the control unit is provided to modify, preferably optimize, the further driving signal for completely transferring the switch from the second switch position to the first switch position in an iterative way, in particular by determining the further switching performance in an iterative way. Thereby, in particular the driving signal and/or the further driving signal can continually be improved.

Further, it is proposed that the control unit is provided to modify, preferably optimize, the driving signal for completely transferring the switch from the first switch position to the second switch position and/or the further driving signal for completely transferring the switch from the second switch position to the first switch position by using an optimization algorithm, preferably a numerical and/or a derivative free optimization algorithm like cuckoo search algorithm, particle swarm optimization algorithm and/or preferably pattern search algorithm, in particular to determine the switching performance and/or the further switching performance. As a result, in particular, a particularly simple optimization can be obtained.

In one embodiment of the invention, it is proposed that the control unit is provided to determine and/or redetermine the switching performance in dependence of and/or for each first switching process of the switch. Moreover, advantageously the control unit is provided to determine and/or redetermine the further switching performance in dependence of and/or for each second switching process of the switch. Thus, in particular, an advantageously accurate controlling method may be obtained. In particular, the switch might be constructed as a semiconductor switch or the like. However, preferably it is proposed that the home appliance device comprises a switch, in particular the switch mentioned before, which is an electromechanical relay and preferably a latching relay. In this case, the switch may be formed as a single contact switch like a SPST-switch, DPST-switch, SPCO-switch and/or SPTT-switch, and/or a toggle switch like a SPDT-switch, a DPDT-switch and/or a DPCO-switch. By that, in particular, a particularly robust home appliance device may be obtained. In addition to that, advantageously costs may be reduced effectively.

Moreover, it is proposed that the home appliance device comprises a switch, in particular the switch mentioned before, which is located between at least one inverter, in particular the inverter mentioned before, and at least one heating unit, in particular the heating unit mentioned before, and is provided to connect and/or disconnect in at least one operational state at least one conduction path between the inverter and the heating unit. A "conduction path" is, in particular, to be understood as a, in particular electrically, conductive connection between at least two points. By that, in particular, a disconnection time period, in particular of the inverter, may be optimized and particularly advantageously reduced to a minimum.

Further, the invention relates to a method for operating a home appliance device, in particular a hob device, preferably an induction hob device, wherein at least one switch is in at least one first switching process completely transferred by at least one driving signal from at least one, preferably exactly one, first switch position to at least one, preferably exactly one, second switch position.

It is proposed that the driving signal for completely transferring the switch from the first switch position to the second switch position is modified, preferably optimized, in at least one operational state, in particular during operation, and preferably during successive first switching processes, in particular from the first switch position to the second switch position. Particularly advantageously, the switch is in at least one second switching process completely transferred by at least one further driving signal from the second switch position to the first switch position. Preferably, the further driving signal for completely transferring the switch from the second switch position to the first switch position is modified, preferably optimized, in at least one operational state, in particular during operation, and preferably during successive second switching processes, in particular from the second switch position to the first switch position. In particular, the driving signal and/or the further driving signal might be modified, in particular completely, via an online network connection, in particular the internet. However, advantageously the driving signal and/or the further driving signal are modified by using an, in particular autonomous, control unit which operates at least substantially offline. By that, in particular, a switching behaviour can be advantageously improved by which, in particular, a fatigue strength and/or a durability of the home appliance device may be increased, advantageously. Moreover, in particular a flexibility and/or an efficiency may be improved.

The home appliance device is herein not limited to the application and implementation described above. In particular, for the purpose of fulfilling a functionality herein described, the home appliance device can comprise a number of respective elements, structural components and units that differs from the number mentioned herein. Further advantages of the invention may be derived from the description of the figures below. The figures show one exemplary embodiment of the invention. The figures, the description and the claims contain numerous features in combination. The features may also be considered individually, and may be combined into useful further combinations.

It is shown in:

Fig. 1 a simplified schematic view of a home appliance comprising a home appliance device,

Fig. 2 a simplified schematic view of a switch of the home appliance device in a first position,

Fig. 3 the switch in a second position,

Fig. 4 an exemplary circuit diagram for controlling the switch,

Fig. 5 a controlling scheme which is used to modify a driving signal of the switch, Fig. 6 a diagram of an exemplary signal which is used to control the switch, Fig. 7 a diagram of different non-optimized signals of the home appliance device with respect to a first switching process,

Fig. 8 a diagram showing a switching performance in an iterative optimization process,

Fig. 9 a diagram of the signals shown in figure 7 after the iterative optimization process,

Fig. 10 a diagram of different signals of the home appliance device with respect to a second switching process,

Fig. 1 1 a diagram showing a further switching performance in a further iterative optimization process and

Fig. 12 a diagram of the signals shown in figure 10 after the further iterative optimization process. Figure 1 shows a top view of an exemplary home appliance 24. The home appliance 24 is formed as a hob. In the present case, the home appliance 24 is formed as an induction hob. Alternatively, it is conceivable that the home appliance is formed as an arbitrary other home appliance, like an oven, a microwave, a cooler and/or a freezer.

The home appliance 24 comprises a home appliance device. The home appliance device comprises a cooktop 26 with four heating zones. Each heating zone is provided to heat one cooking utensil (not shown). Moreover, the home appliance device comprises at least one heating unit 20. In the present embodiment, the home appliance device comprises four heating units 20, wherein for simplicity, in particular figure 1 merely shows two of the heating units 20. The heating units 20 are embodied as inductors. Each heating unit 20 is assigned to one of the heating zones. Alternatively, it is conceivable that a cooktop is formed as a matrix-cooktop and/or a flexible cooktop having a plurality of heating zones and/or heating units. Moreover, the heating units could be generally embodied as resistance-heating units, too.

Moreover, the home appliance device comprises a power supply 28. The power supply 28 is formed as a mains supply. Further, the home appliance device comprises an inverter 18. The inverter 18 comprises two semiconductor switches which are operated alternately. Each semiconductor switch is electrically connected to a center tap of the inverter 18. The inverter 18 is provided to convert a, in particular pulsating and rectified, mains voltage of the power supply 28 in a high frequency heating current which is led via the center tap to at least one of the heating units 20. In the present case, the hob device additionally comprises a rectifier (not shown) which is provided to rectify the mains voltage of the power supply 28. Alternatively, it is conceivable to refrain from using a rectifier in particular if a DC voltage source is used as power supply. The home appliance device further comprises a control unit 10. The control unit 10 comprises a processor unit, a memory unit and an operating program which is stored in the memory unit and executed by the processor unit. The control unit 10 is completely located in a housing of the home appliance device. The control unit 10 is provided for controlling an operation of the home appliance device. The control unit 10 is at least provided for controlling a cooking process by regulating a heating output of the heating units 20.

Additionally, the home appliance device comprises at least one switch 12 (cf. figures 2 and 3). The switch 12 is embodied as an electromechanical switch. The switch 12 is embodied as an electromechanical relay. In the present case, the switch 12 is embodied as a latching relay. Moreover, the switch 12 is constructed as a toggle switch, in particular a SPDT-switch. Thus, the switch 12 comprises a first switch position (cf. figure 2) and a second switch position (cf. figure 3). In the present case, the switch 12 comprises three contacts 30, 32, 34, a common terminal contact 30, a normally closed contact 32 and a normally open contact 34. The common terminal contact 30 is electrically connected to the inverter 18. The normally closed contact 32 and the normally open contact 34 are respectively electrically connected to one of the heating units 20. Thus, the switch 12 is located in a conduction path 22 between the inverter 18 and at least one of the heating units 20. Additionally, the switch 12 comprises a, in particular movable, latch 36. The latch 36 is provided to connect the common terminal contact 30 to the normally closed contact 32 and/or in at least one operational state to the normally open contact 34. In the present case, an operative connection between the common terminal 30 and the normally closed contact 32 corresponds to the first switch position while an operative connection between the common terminal 30 and the normally open contact 34 corresponds to the second switch position. Thus, the switch 12 is provided to connect and to disconnect a conduction path 22 between the inverter 18 and at least one of the heating units 20. In order to increase a lifetime of the switch 12, the switch 12 is moreover de-energized, in particular disconnected from the power supply 28, during a switching process. In particular to achieve a defined movement of the latch 36, the switch 12 further comprises a control inductance 38. The control inductance 38 is embodied as a coil. The control inductance 38 is operatively connected to the control unit 10. The control inductance 38 is provided for carrying, in at least one operational state, a current, resulting in a magnetic field. Hence, the inductance 38 is provided to attract and/or repulse the latch 36, in particular via a magnetic force, and by that change the switch positions of the switch 12. As an alternative, a switch may comprise a different number of contacts and/or may be embodied as another toggle switch and/or a single contact switch. Moreover, it is conceivable that a switch might be embodied as a semiconductor switch and/or another non-electromechanical switch.

Furthermore, the home appliance device comprises a sensor unit 16. The sensor unit 16 is provided to measure at least one signal measured during switching of the switch 12. For this purpose, the sensor unit 16 comprises at least one sensor 40, 42. In the present case, the sensor unit 16 comprises at least two sensors 40, 42. A first sensor 40 of the sensors 40, 42 is formed as a voltage sensor. The first sensor 40 is provided to measure a voltage on the normally closed contact 32 and the normally open contact 34 and by that, in particular, provide information about a switching process, in particular contact bounces and/or a number of bounces. A second sensor 42 of the sensors 40, 42 is formed as a current sensor, in particular an electric current sensor like a current transducer for instance. The second sensor 42 is provided to measure a current through the control inductance 38. Additionally or alternatively, a sensor unit may comprise further sensors, in particular voltage sensors, current sensors, time sensors, position sensors like optical sensors, ultrasonic sensors, piezo-electric sensors, inductive sensors, capacitive sensors and/or resistive sensors for example, and/or acoustic sensors like a microphone for example. Figure 4 shows one exemplary circuit diagram for controlling the switch 12.

The control unit 10 is provided to actuate the switch 12, in particular by supplying the control inductance 38. In particular by using electromechanical switches like relays, several issues may occur during a switching process of the switch 12 like a particularly noisy switching process, a particularly lengthy switching process, for example due to contact bounces, and/or a high number of contact bounces. These issues may decrease a performance of the switch 12, may lead to a reduced lifetime of the switch 12 and/or may lead to problems regarding flicker, in particular if a disconnection period is excessively long. Moreover, aging effects and/or temperature effects further complicate an optimization of a driving signal used to actuate the switch 12.

In order to minimize the aforementioned issues, the control unit 10 is provided to optimize a switching behaviour of the switch 12 during an operation of the home appliance device. In the present case, the control unit 10 is at least provided to supply a driving signal 14 for completely transferring the switch 12 in a first switching process from the first switch position to the second switch position and to modify the driving signal 14 for completely transferring the switch 12 in the first switching process from the first switch position to the second switch position, in particular during successive first switching processes from the first switch position to the second switch position. Thereby, the control unit 10 is provided to modify the driving signal 14 during normal operation of the home appliance device. Moreover, the control unit 10 is provided to regularly modify the driving signal 14 for completely transferring the switch 12 from the first switch position to the second switch position and by that optimize a switching behaviour of switch 12. Additionally or as an alternative, a control unit might be provided to modify a driving signal independently from a normal operation like for example in a special service mode and/or calibration mode. Moreover, it is conceivable to use a control unit which is at least partly outsourced in a datacentre or the like, preferably in such a way that a modification of a driving signal may be performed externally.

Next, with respect to figure 5 a general controlling scheme, which is used to modify the driving signal 14 in principle, will be explained while the figures 6 to 12 show detailed diagrams and signals of an exemplary modification process. In the present case, the control unit 10 is thereby provided to reduce a duration of contact bounces of the switch 12 and by that, in particular, an overall switching time. Additionally or as an alternative, it is conceivable that a control unit is provided to reduce a number of contact bounces of a switch and/or to reduce a switching noise.

A step 46 corresponds to a first switching process of the switch 12. Thereby, the control unit 10 is provided to actuate the switch 12 using the driving signal 14, in particular a current driving signal and/or an initial driving signal, in order to completely transfer the switch 12 from the first switch position to the second switch position.

A following step 48 corresponds to a measuring step. The sensor unit 16 and in particular the sensors 40, 42 are provided to gather information from the system. In the present case, the sensor unit 16 is provided to measure at least one signal measured during switching of the switch 12, in particular at least a voltage signal, which corresponds to and/or is related to a duration of contact bounces, in particular of an immediately previous switching process, in particular the first switching process of step 46. A following step 50 corresponds to an optimization step. Thereby, the control unit 10 is provided to determine a switching performance. The switching performance is correlated to the signal measured during switching, in particular of the immediately previous switching process, in particular the measured signal measured during switching of step 48. For this purpose, the control unit 10 defines a cost function. The cost function transforms the measured signal measured during switchings into a single value, in particular the switching performance, to be optimized, in particular minimized. In the present case, a cost function for the duration of contact bounces is formulated, which is in particular used to minimize the duration of contact bounces and by that, in particular, the overall switching time. Thereby, the cost function is optimized in an iterative way by using an optimization algorithm. In the present case, the optimization algorithm performs four experimental evaluations on the considered system. As an alternative, in particular in case a switching noise is aimed to be reduced, a cost function which corresponds to an integral over a time of an absolute value of an acoustic sensor signal can be utilized for reducing a switching noise.

A following step 52 corresponds to a modification step. Thereby, the control unit 10 is provided to modify the driving signal 14 for completely transferring the switch 12 from the first switch position to the second switch position by considering the switching performance determined in step 50 and in particular in dependence of an immediately previous first switching process of the switch 12 from the first switch position to the second switch position.

Step 52 is followed by step 46 and thus by a further first switching process, which in particular occurs after a second switching process wherein the switch 12 is completely transferred from the second switch position back to the first switch position. As a result, the control unit 10 is provided to modify the driving signal 14 for completely transferring the switch 12 from the first switch position to the second switch position in an iterative way and in particular in dependence of each first switching process of the switch 12, in particular in such a way that the switching performance converges to a minimum and by that improve the switching behaviour of the switch 12. Moreover, the control unit 10 is provided to modify the driving signal 14 for completely transferring the switch 12 from the first switch position to the second switch position by using an optimization algorithm.

Further, it has to be noted that the cost function is non-analytic so that a numerical and/or a derivative free optimization algorithm is required. In the present case, a pattern search algorithm is used as optimization algorithm. The pattern search algorithm is a known optimization algorithm and may in particular be obtained from the source "Audet, Charles and J.E. Denis Jr., Analysis of Generalized Pattern Searches, SIAM Journal on Optimization, Volume 13, Number 3, 2003, pp. 889-903". For the selection of a suitable optimization algorithm, in particular, computational requirements, a number of evaluations needed, a number of parameters and an ability of the algorithm to avoid local minima has to be considered. Hence, it is also conceivable to use other, in particular numerical and/or derivative free, optimization algorithms, like cuckoo search algorithm and/or particle swarm optimization algorithm. Additionally, the cost function is optimized in an iterative way. In the present case between 5 and 100 iteration steps, in particular consecutive first switching processes, and preferably between 10 and 50 iteration steps, in particular consecutive first switching processes, are needed in order to reach an optimal point.

In the following, the figures 6 to 12 show detailed diagrams and signals of an exemplary modification process.

Figure 6 shows a diagram of a signal of the control unit 10 which is used to control the switch 12. An axis of abscissas 54 represents a time while an axis of ordinates 56 corresponds to a value axis. A curve 58 shows a signal of the control unit 10 in order to actuate the switch 12. Thereby, a first part of the curve 58, in particular a signal of the control unit 10 between the time T ₀ and T _s , represents the driving signal 14 for completely transferring the switch 12 from the first switch position to the second switch position while a second part of the curve 58, in particular a signal of the control unit 10 between the time T _s and ΤΊ , represents a further driving signal 15 for completely transferring the switch 12 from the second switch position to the first switch position. In the present case, the driving signal 14 and the further driving signal 15 are modified during operation of the home appliance device according to the control scheme described with respect to figure 5. The driving signal 14 and the further driving signal 15 are formed of several pulses and are specifically adapted to a type of switch used. Alternatively, it is conceivable to refrain from using a further driving signal, for example in case a restoring element like a spring is used. Moreover, merely a driving signal might be modified whereas a further driving signal may be kept steady during operation.

Figure 7 shows a diagram of different non-optimized signals of the home appliance device with respect to a first switching process, in particular from the first switch position to the second switch position. An axis of abscissas 60 represents a time while an axis of ordinates 62 corresponds to a value axis. A curve 64 shows a current signal measured by the second sensor 42. A curve 66 shows a voltage signal corresponding to the current signal measured by the second sensor 42. A curve 68 shows a voltage signal measured by the first sensor 40 on the normally closed contact 32. A curve 70 shows a voltage signal measured by the first sensor 40 on the normally open contact 34.

As it can be seen from figure 7, contact bounces, in particular between the latch 36 and the normally open contact 34, occur in a time interval ti when transferring the switch 12 from the first switch position to the second switch position. The time interval ti comprises a duration of about 2 ms.

Figure 8 shows a diagram showing the switching performance being optimized in an iterative optimization process. In this case, an axis of abscissas 72 represents a number of iteration steps while an axis of ordinates 74 corresponds to a value axis. A curve 76 shows the switching performance being minimized. A minimum is thereby reached in about 8 iteration steps. In the present case, the control unit 10 is provided to modify the driving signal 14 for completely transferring the switch 12 from the first switch position to the second switch position by adjusting a duration of the pulses of the driving signal 14. Additionally or as an alternative, it is also conceivable that a control unit is provided to modify a magnitude and/or a shape of a driving signal.

Figure 9 again shows a diagram of the signals shown in figure 7 after the iterative optimization process. As a result, a duration of contact bounces, in particular between the latch 36 and the normally open contact 34, is minimized. Thereby, contact bounces, in particular between the latch 36 and the normally open contact 34, merely occur in a time interval t ₂ which is significantly shorter than the time interval ti . The time interval t ₂ comprises a duration of about 0.5 ms.

The figures 10 to 12 show in analogy with the figures 7 to 9 detailed diagrams and signals of an exemplary modification process with respect to a second switching process, in particular from the second switch position to the first switch position.

Figure 10 shows a diagram of different non-optimized signals of the home appliance device with respect to the second switching process. An axis of abscissas 78 represents a time while an axis of ordinates 80 corresponds to a value axis. A curve 82 shows a current signal measured by the second sensor 42. A curve 84 shows a voltage signal corresponding to the current signal measured by the second sensor 42. A curve 86 shows a voltage signal measured by the first sensor 40 on the normally closed contact 32. A curve 88 shows a voltage signal measured by the first sensor 40 on the normally open contact 34.

As it can be seen from figure 10, contact bounces, in particular between the latch 36 and the normally closed contact 32, occur in a time interval t ₃ when transferring the switch 12 from the second switch position to the first switch position. The time interval t ₃ comprises a duration of about 3.5 ms.

Figure 1 1 shows a diagram showing a further switching performance being optimized in a further iterative optimization process. In this case, an axis of abscissas 90 represents a number of iteration steps while an axis of ordinates 92 corresponds to a value axis. A curve 94 shows the switching performance being minimized. A minimum is thereby reached in about 6 iteration steps. In the present case, the control unit 10 is provided to modify the further driving signal 15 for completely transferring the switch 12 from the second switch position to the first switch position by adjusting a duration of the pulses of the further driving signal 15. Additionally or as an alternative, it is also conceivable that a control unit is provided to modify a magnitude and/or a shape of a further driving signal.

Figure 12 again shows a diagram of the signals shown in figure 10 after the further iterative optimization process. As a result, a duration of contact bounces, in particular between the latch 36 and the normally closed contact 32, is minimized. Thereby, contact bounces, in particular between the latch 36 and the normally closed contact 32, merely occur in a time interval t ₄ which is significantly shorter than the time interval t ₃ . The time interval t ₄ comprises a duration of about 0.1 ms.

Hence, a switching behaviour of the switch 12 and a switching time can be improved and by that a disconnection time period of the inverter 18 can be reduced to a minimum.

List of reference numbers control unit

switch

driving signal

further driving signal

sensor unit

inverter

heating unit

conduction path

home appliance

cooktop

power supply

common terminal contact

normally closed contact

normally open contact

latch

control inductance

sensor

sensor

step

step

step

step

axis of abscissas

axis of ordinates

curve

axis of abscissas

axis of ordinates

curve

curve

curve

curve 72 axis of abscissas

74 axis of ordinates

76 curve

78 axis of abscissas

80 axis of ordinates

82 curve

84 curve

86 curve

88 curve

90 axis of abscissas

92 axis of ordinates

94 curve