EP3001774B1 - Domestic appliance and method for operating a domestic appliance - Google Patents

Description

The invention is based on a cooking device with a domestic appliance device according to the preamble of claim 1 and on a method for operating a cooking appliance with a domestic appliance device according to the preamble of claim 12.

Induction hobs are known from the prior art, comprising an inverter with two switching units and a driver circuit with a bootstrap unit, wherein a control voltage of at least one of the switching units is set via the bootstrap unit.

From the European patent application EP 2 753 147 A2 There is already known an induction heating cooker which converts a rectifying element which converts an input voltage into a DC output voltage, an inverter which switches the DC voltage generated by the rectifying element to generate an AC voltage, a first heating element driven by the AC voltage from the inverter a second heating element connected in parallel with the first heating element, the second heating element being operated with the alternating voltage from the inverter, and a switching signal generating element controlling a respective operating state of the first and second heating elements of the inverter in accordance with an externally set operation mode. The switching signal generating element has an inverter drive with a bootstrap circuit.

The object of the invention is in particular to provide a generic cooking appliance with improved properties in terms of switching behavior. The object is solved by the characterizing features of claims 1 and 12, while advantageous embodiments and further developments of the invention can be taken from the dependent claims.

The invention relates to a cooking appliance with a domestic appliance device, in particular an induction hob device, which has a switching unit and a driver circuit, which comprises a bootstrap unit and is provided to set and / or provide a control voltage for the switching unit.

It is proposed that the bootstrapping unit comprises an adaptation unit which is provided for changing, and / or preferably adapting at least one, preferably electronic, parameter of the bootstrapping unit, in particular dynamically. In this context, a "domestic appliance device" is to be understood as meaning, in particular, at least one part, in particular a subassembly, of a cooking device, preferably a cooktop, and particularly preferably an induction cooktop. In particular, the home appliance device may also comprise the entire cooking appliance, preferably the entire hob, and particularly preferably the entire induction hob. In particular, the home appliance device may further comprise a Control unit, an inverter and / or at least one heating element, in particular at least one inductor include. The inverter is preferably provided to provide and / or to generate an oscillating electrical current, preferably with a frequency of at least 1 kHz, in particular of at least 10 kHz and advantageously of at least 20 kHz, in particular for operation of the at least one heating element. Advantageously, the inverter comprises the switching unit. By "provided" is intended to be understood in particular specially programmed, designed and / or equipped. The fact that an object is intended for a specific function should in particular mean that the object fulfills and / or executes this specific function in at least one application and / or operating state. In this context, a "switching unit" is to be understood as meaning in particular a unit, preferably an electronic unit, which comprises a switching element and in particular is intended to interrupt a line path, in particular comprising at least part of the switching unit. In this case, the switching element is preferably designed as a circuit breaker and in particular provided to switch a current of at least 0.5 A, preferably at least 4 A and particularly preferably at least 10 A, in particular periodically. Advantageously, the switching unit is designed as a bidirectional unipolar switching unit and in particular comprises a control input and a reference voltage terminal, wherein a switching state of the switching unit is controllable in particular by a control voltage between the control terminal and the reference voltage terminal. In particular, the reference voltage terminal may be at a floating potential. The switching element of the switching unit can be embodied as any switching element which appears sensible to a person skilled in the art, preferably a semiconductor switching element, such as a transistor, preferably as a FET, as a MOSFET and / or as an IGBT. In particular, a switching unit may also comprise a plurality of control inputs, reference voltage connections and / or switching elements. In this context, a "conduction path" is to be understood in particular to mean an element which at least temporarily produces an electrically conductive connection between at least two points and / or at least two components. A "floating potential" should in particular be understood to mean a potential which is at least 10 V, preferably at least 50 V, preferably at least 75 V, and particularly preferably at its potential value, preferably periodically at least 100V changes. The driver circuit preferably has a converter unit. In this context, a "converter unit" should be understood to mean in particular an electronic unit, which in particular comprises a converter input, a converter output and / or preferably two supply voltage connections and is provided in particular in at least one operating state, in particular in an operating state in which one voltage applied to the two supply voltage terminals exceeds a limit value, in particular at least 8 V, preferably at least 10 V, to amplify a voltage signal and / or potential, in particular of the control unit, in particular applied to the converter input and in particular to supply it to the control terminal of the switching unit. In particular, the converter unit can also have a plurality of converter inputs, converter outputs and / or more than two supply voltage connections. A "bootstrap unit" is to be understood in particular as meaning a unit which comprises a bootstrapping capacity and in particular is intended to generate and / or provide a bootstrap voltage and in particular to supply the two supply voltage terminals, whereby a switching state of the switching unit can preferably be controlled. In particular, the bootstrap voltage corresponds to the supply voltage of the converter unit, in particular applied to the two supply voltage terminals. Preferably, the bootstrapping unit further comprises a bootstrap resistor and / or at least one bootstrap diode. In this context, a "bootstrap capacity" should be understood to mean, in particular, a unit which comprises at least one capacity and advantageously at least two capacities, and in particular is intended to store energy, in particular the bootstrap voltage, in particular to supply the converter unit. Advantageously, the at least one capacitance is designed as a capacitor. Furthermore, a "bootstrap resistor" should be understood to mean, in particular, a unit which comprises at least one resistance component and advantageously at least two resistance components, and in particular is intended to limit a current flowing into the bootstrap capacitance and / or through the at least one bootstrap diode. The term "adapting" should in particular be understood to mean optimization and / or equalizing to an advantageous operation. In particular, a home appliance device may also include a plurality of switching units, driver circuits and / or Include inverters. Furthermore, the driver circuit may comprise a plurality of converter units and / or a plurality of bootstrap units.

By virtue of this configuration, a generic household appliance device having improved properties with respect to a switching behavior can be provided. In particular, a fast response time of the switching unit can be achieved, whereby in particular a control and / or an efficiency of the home appliance device can be improved. Also, an operational safety and / or a service life of the domestic appliance device can be advantageously increased since negative influences of stray impedances, in particular on the converter unit and / or the switching unit, can be effectively reduced. Furthermore, costs can advantageously be kept low.

If the adaptation unit is provided for changing and / or preferably adapting the at least one parameter as a function of a bootstrap voltage, in particular the bootstrap voltage, preferably the voltage present in particular at the two supply voltage terminals, an advantageously simple control can be achieved.

It is also proposed that the at least one parameter corresponds to a charging time constant of the bootstrap unit. In this context, a "charging time constant" should be understood to mean, in particular, a charging time of the bootstrapping capacity and / or a time duration after which the bootstrap capacity has in particular a voltage value and / or an effective voltage value which is at least 63% of a maximum voltage value and / or maximum effective voltage value the bootstrap capacity corresponds. As a result, an advantageously simple and, in particular, cost-effective adaptation of the bootstrap unit to different operating states can be achieved.

Preferably, the at least one parameter has a value between 10 ^-9 s and 10 ^-5 s, and preferably between 10 ^-8 s and 10 ^-6 s, at least in a start operating state. In this context, a "start operating state" is to be understood as meaning, in particular, an operating state which, in particular immediately after starting the household appliance device and / or a selection of a Operating program and / or a change of an operating program starts. The bootstrap capacity is completely discharged, in particular at the beginning of the start operating state, in particular over a relatively long period of time, in particular at least 1 ms, advantageously at least 0.5 s, preferably at least 1 s and particularly preferably at least 5 s. In particular, a maximum voltage value stored in the bootstrap capacity and / or an effective voltage value and / or a maximum bootstrap voltage in the start operating state changes and at least between two switching operations of the switching unit and preferably between all switching operations of the switching unit. As a result, in particular a fast response of the home appliance device can be achieved.

Furthermore, it is proposed that the at least one parameter has a value between 10 ^-7 s and 10 ^-3 s, and preferably between 10 ^-6 s and 10 ^-4 s, at least in a continuous operating state. In this context, a "continuous operating state" is to be understood in particular to mean an operating state which, preferably directly, is followed by the start operating state. In particular, a maximum stored in the bootstrap capacity and / or effective voltage value and / or a maximum bootstrap voltage in the continuous operation state at least substantially constant between two switching operations of the switching unit and preferably between all switching operations of the switching unit. In this context, the term "at least substantially constant" is to be understood as meaning, in particular, a change of not more than 5%, preferably of not more than 2% and particularly preferably of not more than 1%. In this way, in particular an advantageous filtering effect, in particular filtering of a supply voltage and / or the bootstrap voltage can be achieved, whereby possible leakage currents and / or leakage voltages, which are caused in particular by stray impedances, can be effectively minimized.

The at least one parameter could, for example, be given by an inductance value of the bootstrap unit. However, the at least one parameter preferably corresponds to a capacity value and / or an effective capacity value of the bootstrap unit. As a result, an advantageously simple and uncomplicated adaptation of the bootstrap unit can take place.

Alternatively and / or additionally, it is proposed that the at least one parameter corresponds to a resistance value and / or an effective resistance value of the bootstrap unit. As a result, in particular a flexibility of the home appliance device can be increased.

In one embodiment of the invention it is proposed that the matching unit comprises at least two capacitors or at least two resistance components which are connected in parallel in at least one operating state, in particular in the start operating state and / or the continuous operating state. In this way, in particular a simple construction can be achieved.

It is also proposed that the matching unit comprises at least two capacitors or at least two resistance components which are connected in series in at least one operating state, in particular in the start operating state and / or the continuous operating state. In this way, the home appliance device can be adapted in particular flexibly to different requirements.

The adaptation unit comprises a bridging switching element which is provided to bridge and / or bypass at least one component, in particular at least one capacitor and / or at least one resistance component, the bootstrapping unit in at least one operating state, in particular in the start operating state and / or the continuous operating state , the at least one parameter can advantageously be adapted simply and in particular during operation of the household appliance device. The bridging switching element can be designed as any switching element which appears sensible to a person skilled in the art, preferably a semiconductor switching element, such as a transistor, preferably as a FET, as a MOSFET and / or as an IGBT. In particular, the adaptation unit can also have a plurality of, preferably identical, bridging switching elements.

The adaptation unit and / or the bypass switching element could be controlled, for example, by a control signal of the control unit. Preferably, however, the adaptation unit and / or the bridging switching element is designed to be self-controlling. Under that an object is "self-controlling" is designed, in particular be understood that the object in at least one operating state, its state, in particular switching state, automatically and / or automatically, in particular depending on a, in particular momentary, voltage value and / or current value of the driver circuit and / or the bootstrap unit changes. In particular, the adaptation unit and / or the bridging switching element is free from a, in particular direct, connection to the control unit. In this way, in particular an advantageously simple, cost-effective and safe control can be achieved.

Furthermore, a method is proposed for operating a household appliance device, in particular an induction hob device, with a switching unit and with a driver circuit, which comprises a bootstrapping unit and by means of which a control voltage for the switching unit is set.

It is proposed that at least one parameter, preferably a charging time constant, advantageously a capacitance value and / or a resistance value, of the bootstrapping unit, in particular as a function of a bootstrap voltage, be changed. As a result, a switching behavior can be improved, wherein a response time can be lowered and an operating time can be increased.

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawing, the description and the claims contain numerous features in combination.

Fig. 1

ein als Induktionskochfeld ausgebildetes Hausgerät mit einer Hausgerätevorrichtung in einer schematischen Draufsicht,

Fig. 2

ein vereinfachtes Prinzipschaltbild der Hausgerätevorrichtung mit einem eine Bootstrapeinheit aufweisenden Treiberschaltkreis,

Fig. 3

ein schematisches Schaubild verschiedener Signale zur Steuerung der Hausgerätevorrichtung,

Fig. 4

eine konkrete Ausgestaltung einer Bootstrapeinheit einer weiteren Hausgerätevorrichtung mit zwei zumindest in einem Betriebszustand in Reihe geschalteten Kondensatoren,

Fig. 5

eine konkrete Ausgestaltung einer weiteren Bootstrapeinheit einer weiteren Hausgerätevorrichtung mit zwei zumindest in einem Betriebszustand parallel geschalteten Kondensatoren,

Fig. 6

eine konkrete Ausgestaltung einer weiteren Bootstrapeinheit einer weiteren Hausgerätevorrichtung mit zwei zumindest in einem Betriebszustand parallel geschalteten Widerstandsbauelementen,

Fig. 7

eine konkrete Ausgestaltung einer weiteren Bootstrapeinheit einer weiteren Hausgerätevorrichtung mit zwei zumindest in einem Betriebszustand in Reihe geschalteten Widerstandsbauelementen und

Fig. 8

eine konkrete Ausgestaltung einer weiteren Bootstrapeinheit einer weiteren Hausgerätevorrichtung.

Show it:

Fig. 1

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

Fig. 2

a simplified schematic diagram of the home appliance device with a bootstrap unit having a driver circuit,

Fig. 3

a schematic diagram of various signals for controlling the home appliance device,

Fig. 4

a concrete embodiment of a bootstrap unit of a further domestic appliance device with two capacitors connected in series, at least in one operating state,

Fig. 5

a concrete embodiment of a further bootstrap unit of a further domestic appliance device with two capacitors connected in parallel, at least in one operating state,

Fig. 6

a concrete embodiment of a further bootstrap unit of a further domestic appliance device with two resistance components connected in parallel at least in one operating state,

Fig. 7

a concrete embodiment of another bootstrap unit of another home appliance device with two in at least one operating state in series resistor components and

Fig. 8

a concrete embodiment of another bootstrap unit of another home appliance device.

FIG. 1 shows an exemplary trained as an induction hob home appliance 32 in a schematic plan view. In the present case, the domestic appliance 32 has a hob plate with four heating zones 34. Each heating zone 34 is intended to heat exactly one cookware element (not shown). In addition, the household appliance 32 includes a home appliance device. In order to control an operation of the domestic appliance 32, the domestic appliance apparatus comprises a control unit 36. The control unit 36 has an arithmetic unit, a memory unit and an operating program stored in the memory unit, which is intended to be executed by the arithmetic unit.

FIG. 2 shows a simplified schematic diagram of the home appliance device. Concrete embodiments of the home appliance devices, however, are in the FIGS. 4 to 8 shown. The home appliance device has a heating unit 38. The heating unit 38 may include a plurality of inductors (not shown). In addition, the heating unit 38 may include a switching arrangement (not shown) to operate the inductors alternately and / or in common, for example in a time-multiplexed method. For supplying the heating unit 38, the household appliance device comprises a main energy source 40. Furthermore, the household appliance device comprises an inverter 42. The inverter 42 comprises two switching units 10, 12. The switching units 10, 12 12 are formed identical to each other. The switching units 10, 12 each comprise a control input. In addition, the switching units 10, 12 each comprise a switching element. The switching elements are designed as IGBTs. Furthermore, the switching units 10, 12 each comprise a freewheeling diode and a snubber capacitor, which are in particular connected in parallel to the switching elements. Alternatively, it is also conceivable that a home appliance device has multiple inverters. In addition, it is conceivable that at least one inverter has different switching units.

A first terminal of the main energy source 40 is connected to an emitter terminal of a first switching unit 10 of the switching units 10, 12 and / or the switching element of the first switching unit 10 electrically conductive. In addition, a second terminal of the main energy source 40 is electrically conductively connected to a collector terminal of a second switching unit 12 of the switching units 10, 12 and / or the switching element of the second switching unit 12. The inverter 42 is designed to convert a pulsed rectified mains voltage of the main energy source 40 into a high-frequency heating current and in particular to supply the heating unit 38. The heating unit 38 is arranged in a bridge branch between a center tap 44 of the inverter 42 and a resonance unit 46.

In addition, the domestic appliance device comprises a driver circuit 14. The driver circuit 14 is provided to set a control voltage for the switching units 10, 12. For this purpose, the driver circuit 14 comprises a secondary energy source 48. The secondary energy source 48 has a voltage between 10 V and 25 V. In the present case, a first connection of the secondary energy source 48 is electrically conductively connected via a first conduction path 54 to the first connection of the main energy source 40. Furthermore, the driver circuit 14 comprises two converter units 50, 52. The converter units 50, 52 are formed identical to one another. Alternatively, it is also conceivable to use different converter units. For example, galvanic (optical, magnetic, or capacitive) isolation may be used only where necessary, or as a discrete implementation, or through integrated circuit of the converter unit. In the case where only high-side galvanic isolation and compact implementation of the whole set are needed, the converter units 50, 52 are formed as a high-voltage integrated circuit (IC). Each of the converter units 50, 52 has one Converter input and a converter output. In addition, each of the converter units 50, 52 has two supply voltage connections. A first converter unit 50 of the converter units 50, 52 is provided to operate the first switching unit 10. A second converter unit 52 of the converter units 50, 52 is provided to operate the second switching unit 12. For this purpose, the inputs of the converter units 50, 52 are each electrically connected to the control unit 36. The outputs of the converter units 50, 52 are each electrically conductively connected to the control inputs of the switching units 10, 12. In addition, the driver circuit 14 has a bulk capacitor 56. The bulk capacitor 56 is designed as an energy buffer. The bulk capacitor 56 has a capacitance value that is sufficiently higher than the maximum capacity of the bootstrap unit 16. By "sufficiently higher" should be understood in this context in particular at least 4 times higher, advantageously 10 times higher. Usually, the bulk capacitor 56 has a capacitance value between 100 nF and 47 μF. The bulk capacitor 56 is provided to provide a substantially constant supply voltage for the first converter unit 50. For this purpose, a first connection of the bulk capacitor 56, in particular via the first conduction path 54, is electrically conductively connected to the first connection of the secondary energy source 48. The first connection of the bulk capacitor 56 is electrically conductively connected, in particular via the first conduction path 54, to a first supply voltage connection of the first converter unit 50. In addition, the first connection of the bulk capacitor 56, in particular via the first conduction path 54, is electrically conductively connected to the emitter connection of the first switching unit 10. The first conduction path 54 thus serves as a reference voltage terminal for the first switching unit 10. The first conduction path 54 is at a fixed potential. A second terminal of the bulk capacitor 56 is electrically connected to a second terminal of the secondary power source 48. The second terminal of the bulk capacitor 56 is electrically conductively connected to a second supply voltage terminal of the first converter unit 50.

Furthermore, the driver circuit 14 comprises a bootstrap unit 16. The bootstrap unit 16 comprises a bootstrap diode 58. The bootstrap unit 16 comprises a bootstrap capacity 60. The bootstrap capacity 60 is designed as an energy buffer. Bootstrap capacity 60 has an effective capacitance value between 33 nF and 3.3 μF on. The bootstrap capacity 60 has a voltage-dependent capacitance value. In addition, the bootstrap unit 16 includes a bootstrap resistor 62. The bootstrap resistor 62 is provided to limit a current flowing into the bootstrap capacitance 60 and through the bootstrap diode 58. The bootstrap resistor 62 has an effective resistance between 0.5 Ω and 50 Ω. The bootstrap resistor 62 has a voltage-dependent resistance value. Alternatively, it is also conceivable to dispense with a bootstrap resistance. Furthermore, a bootstrap resistance or a bootstrap capacity could also be voltage-independent.

The bootstrap diode 58 is electrically conductively connected to the second terminal of the secondary power source 48 with an anode terminal. The bootstrap diode 58 is electrically connected to a cathode terminal to a first terminal of the bootstrap resistor 62. A second terminal of the bootstrap resistor 62 is electrically connected to a first terminal of the bootstrap capacitance 60. Furthermore, the second terminal of the bootstrap resistor 62 is electrically conductively connected to a first supply voltage terminal of the second converter unit 52. A second connection of the bootstrap capacity 60 is electrically conductively connected to the center tap 44 via a second line path 64. Accordingly, the bootstrap capacity 60 is electrically connected to a collector terminal of the first switching unit 10 and / or the switching element of the first switching unit 10 and an emitter terminal of the second switching unit 12 and / or the switching element of the second switching unit 12. Furthermore, the bootstrap capacity 60, in particular via the second conduction path 64, is electrically conductively connected to a second supply voltage terminal of the second converter unit 52. The second conduction path 64 serves as a reference voltage terminal for the second switching unit 12. The second conduction path 64 is at a floating potential. The second conduction path 64 is in an operating state in which the switching units 10, 12 are alternately switched, alternately at a reference potential of the first conduction path 54 and a mains voltage potential V ₀ . The bootstrap capacity 60 is intended to provide a bootstrap tension V _BS . The bootstrap voltage V _{BS in} this case corresponds to a supply voltage of the second converter unit 52 and, in particular in at least one operating state, is applied to the supply voltage terminals of the second converter unit 52.

In the present case, the converter units 50, 52 are further equipped with an undervoltage cut-off protection (UVLO). Consequently, the converter units 50, 52 are inoperative at a supply voltage below a limit value, in particular at the supply voltage terminals. In the present case, the limit value is between 9 V and 16 V. The converter units 50, 52 are thus provided, in an operating state in which a voltage applied to the supply voltage terminals exceeds the limit value, to amplify a voltage signal of the control unit 36 applied to the converter input ,

FIG. 3 shows a schematic diagram of various signals for controlling the home appliance device in a start mode and a, in particular to the start mode, subsequent continuous mode. An ordinate axis 68 is shown as a size axis. The time is shown on an abscissa axis 66. The abscissa axis 66 has two time segments with an interruption, wherein a first time segment represents a start operating state and a second, in particular temporally later, time period represents a continuous operating state. A curve 70 illustrates the switching states of the switching element of the first switching unit 10. A curve 72 illustrates the switching states of the switching element of the second switching unit 12. A "0" level defines a non-conductive state. A curve 74 shows the mains voltage potential V _{0 of} the main energy source 40. The mains voltage _potential V ₀ is superimposed in the present case with a creeping voltage V _LEAK . The creeping _voltage V _LEAK shows a curve 76. The creeping _voltage V _LEAK can occur due to stray inductances of connecting lines, in particular of connecting _cables and / or printed conductors, in particular after closing of the switching unit 12. Furthermore, a curve 78 shows an input voltage of the bootstrap unit 16, while a curve 80 represents the bootstrap voltage V _BS . The input voltage of the Bootstrapeinheit 16 corresponds to a superimposition of the AC voltage potential V ₀ and the voltage potential of the secondary power source 48. The Bootstrapspannung V _BS corresponds at least substantially an envelope of the input voltage and in particular a supply voltage of the second converter unit 52. A particular set by a manufacturer information, optimum Supply voltage of the second converter unit 52 defines a curve 81. Accordingly, the bootstrap voltage V _{BS is} in a comparison to the optimum one Supply voltage of the second converter unit 52 increases at least in the start operating state, which in particular can lead to destruction and / or malfunction of the second converter unit 52. According to the invention, the bootstrap voltage V _BS in the continuous operating state at least substantially corresponds to the optimum supply voltage of the second converter unit 52, whereby destruction and / or malfunction of the second converter unit 52 can be advantageously counteracted.

In an operating state, the switching units 10, 12 are switched alternately. Thus, at least a first time, the first switching unit 10 is open and the second switching unit 12 is closed and at least a second, in particular different from the first time, the first switching unit 10 is closed and the second switching unit 12 open. At this time, the bulk capacitor 56 and the bootstrap capacity 60 are alternately charged and discharged. The bulk capacitor 56 is discharged during activation of the first switching unit 10. The bulk capacitor 56 is charged during activation of the second switching unit 12. The bootstrap capacity 60 is discharged during activation of the second switching unit 12. Bootstrap capacity 60 is charged during activation of first switching unit 10 via bootstrap diode 58 and bootstrap resistor 62.

In the present case, the bootstrap unit 16 further comprises an adaptation unit 18. The adaptation unit 18 is provided to change a parameter of the bootstrap unit 16 in dependence on the bootstrap voltage V _BS . The parameter is given by a charging time constant T, in particular the bootstrap capacity 60. The charging time constant T is given by: $$\mathsf{\tau }={\mathrm{R}}_{\mathrm{boat}}\cdot {\mathrm{C}}_{\mathrm{boat}}$$

A variable R _boat corresponds to the resistance value of the bootstrap resistor 62, while a variable C _boot corresponds to the capacitance value of the bootstrap capacity 60.

In the present case, the adaptation unit 18 is provided to dynamically adjust the resistance value of the bootstrap resistor 62 and the capacitance value of the bootstrap capacitance 60, and in particular during operation of the home appliance device.

Alternatively, it is also conceivable to dynamically adapt a resistance value of a bootstrap resistor or a capacitance value of a bootstrap capacity.

In the present case, the parameter in the start operating state has a value between 1 × 10 ^-8 s and 1 × 10 ^-6 s. If the bootstrap voltage V _BS exceeds a limit value of approximately 12 V, then the adaptation unit 18 is provided to change a value of the parameter, for example by switching between at least two resistors of the bootstrap resistor 62 and / or between at least two capacitors of the bootstrap capacitance 60 Continuous mode, the parameter has a higher value than in the start operating state. In the steady state, the parameter has a value between 1 × 10 ^-6 s and 1 × 10 ^-4 s. As a result, a fast response of the second switching unit 12 can be achieved in the start operating state, since the bootstrap capacity 60 already reaches a required voltage limit value in a first switching pulse, which is required for operation of the second converter unit 52. In the continuous operating state, by contrast, an enlargement of the charging time constant T can achieve an advantageous filtering effect. In particular, bootstrap capacity 60 and bootstrap resistance 62 correspond to a low pass filter. In the continuous operating state, voltage peaks in the supply voltage of the second converter unit 52, in particular due to the creeping _voltage V _LEAK , can be filtered, in particular by adapting the charging time constant T of the bootstrap unit 16 by the adaptation unit 18. In this way, a destruction and / or an operating time reduction of the second converter unit 52 can be prevented by an excessive operating voltage. Alternatively, however, it is also conceivable to provide an additional filter unit in a domestic appliance device, for example between a secondary energy source and a bootstrapping unit, which is bridged and / or bridged in particular in a start operating state.

In the FIGS. 4 to 8 concrete embodiments of the bootstrap unit 16 are shown. The following description and the drawing are essentially limited to the differences between the basic example and the concrete exemplary embodiments, with reference in principle to components and components denoted by the same reference symbols, in principle to the drawing and / or the description of the basic example, in particular of the FIGS. 1 to 3 can be referenced. To distinguish the embodiments are in the concrete embodiments of the FIGS. 4 to 8 the letters a to e are readjusted.

The embodiment of FIG. 4 the letter a is readjusted. In the FIG. 4 is a first concrete embodiment of a bootstrap unit 16a of a further, in particular only partially illustrated, home appliance device, shown.

A bootstrap resistor 62a in the present case consists of a single resistance component 24a. The resistance component 24a has a, in particular fixed, resistance value of 15 Ω. A bootstrap capacity 60a comprises two capacitors 20a, 22a. A first capacitor 20a of the capacitors 20a, 22a has a capacitance value of 2.2 μF. A second capacitor 22a of the capacitors 20a, 22a has a capacitance value of 68 nF. Further, the bootstrap capacity 60a includes an adjustment unit 18a. The matching unit 18a has a bypass switching element 28a with a parallel-connected diode 82a. The bypass switching element 28a is formed as an n-channel MOSFET. Further, the matching unit 18a includes a zener diode 84a. The Zener diode 84a is formed as a blocking element. The Zener diode 84a is provided to block the bypass switch element 28a below a voltage limit of about 12V. In addition, the matching unit 18a includes a resistor 86a which sets an operating point of the lock-up switching element 28a.

A first terminal of the first capacitor 20a is electrically conductively connected to a first supply voltage terminal of a second converter unit 52a. The first terminal of the first capacitor 20a is electrically connected to a cathode terminal of the zener diode 84a. Further, the first terminal of the first capacitor 20a is connected to the bootstrap resistor 62a. A second terminal of the first capacitor 20a is electrically connected to a drain terminal of the bypass switching element 28a. Further, the second terminal of the first capacitor 20a is connected to a first terminal of the second capacitor 22a. Thus, the capacitors 20a, 22a are connected in series. The first terminal of the second capacitor 22a is thus also electrically conductively connected to the drain terminal of the bypass switching element 28a. Further, a second terminal of the second capacitor 22a is connected to a second one Supply voltage terminal of the second converter unit 52a electrically conductively connected. The second terminal of the second capacitor 22a is electrically connected to a source terminal of the bypass switching element 28a. In addition, the second terminal of the second capacitor 22a is electrically conductively connected to a second terminal of the resistor 86a.

An anode terminal of the zener diode 84a is further electrically connected to a base terminal of the bypass switching element 28a. The anode terminal of the Zener diode 84a is also electrically connected to a first terminal of the resistor 86a.

In a starting operation state, a capacity value of the bootstrap capacity 60a is given by an effective capacity value from the capacities of the two capacitors 20a, 22a. The effective capacitance value in the starting operating state in the present case is about 66 nF. In the starting operation state, a charging time constant T of the bootstrap unit 16a is about 1 μs. Above the voltage threshold, the zener diode 84a reaches its passband so that the bypass switch element 28a turns on. As a result, the adaptation unit 18a is designed to be self-controlling and, in particular, free from connection to a control unit 36a. Alternatively, however, it is also conceivable to control a matching unit by means of a signal of a control unit. In the steady state condition, the bypass switching element 28a is provided to bridge a device 30a. In the present case, the bypass switching element 28a is provided to bridge the second capacitor 22a. The effective capacitance value in the steady-state condition is therefore 2.2 μF. In the steady state, a charging time constant T of the bootstrap unit 16a is about 33 μs.

In the FIG. 5 a further embodiment of the invention is shown. The embodiment of FIG. 5 the letter b is added. The further embodiment of the FIG. 5 differs from the previous embodiments by a bootstrap unit 16b.

A bootstrap capacity 60b comprises two capacitors 20b, 22b. In the present case, the capacitors 20b, 22b are connected in parallel.

A first terminal of the first capacitor 20b is electrically conductively connected to a first supply voltage terminal of a second converter unit 52b. The first terminal of the first capacitor 20b is electrically connected to a cathode terminal of a Zener diode 84b. The first terminal of the first capacitor 20b is connected to a bootstrap resistor 62b. Further, the first terminal of the first capacitor 20b is connected to a first terminal of the second capacitor 22b. A second terminal of the first capacitor 20b is electrically connected to a drain terminal of a bypass switching element 28b. The first terminal of the second capacitor 22b is also electrically conductively connected to the first supply voltage terminal of the second converter unit 52b. A second terminal of the second capacitor 22b is electrically conductively connected to a second supply voltage terminal of the second converter unit 52b. The second terminal of the second capacitor 22b is electrically connected to a source terminal of the bypass switching element 28b. Furthermore, the second terminal of the second capacitor 22b is electrically conductively connected to a first terminal of a resistor 86b.

In a starting operation state, a capacity value of the bootstrap capacity 60b is given by a capacitance value of the second capacitor 22b. In the starting mode, the bypass switching element 28b is provided to bypass the first capacitor 20b. The capacity value in the startup mode is 68 nF. Above the voltage threshold, the zener diode 84b reaches its passband so that the bypass switch element 28b turns on. In this steady-state condition, a capacity value of the bootstrap capacity 60b is given by an effective capacity value from the capacities of the two capacitors 20b, 22b. The effective capacitance value in the steady state condition is about 2.3 μF. In the steady state, a charging time constant T of the bootstrap unit 16a is about 34 μs.

In the FIG. 6 a further embodiment of the invention is shown. The embodiment of FIG. 6 the letter c is adjusted. The further embodiment of the FIG. 6 differs from the previous embodiments by a bootstrap unit 16c.

A bootstrap capacity 60c in the present case consists of a single capacitor 20c. A bootstrap resistor 62c includes two resistor devices 24c, 26c. The resistance components 24c, 26c are connected in parallel. A bypass switching element 28c is provided in the present case to bridge a first resistance component 24c of the resistance components 24c, 26c in a continuous mode of operation.

In the FIG. 7 a further embodiment of the invention is shown. The embodiment of FIG. 7 the letter d is readjusted. The further embodiment of the FIG. 7 differs from the previous embodiments by a bootstrap unit 16d.

A bootstrap resistor 62d includes two resistor devices 24d, 26d. The resistance components 24d, 26d are connected in series. A bypass switching element 28d is provided to bridge a second resistance device 26d of the resistance devices 24d, 26d in a startup mode of operation.

In the FIG. 8 a further embodiment of the invention is shown. The embodiment of FIG. 8 the letter e is readjusted. The further embodiment of the FIG. 8 differs from the previous embodiments by a bootstrap unit 16e.

FIG. 8 shows a cascaded bootstrap capacity 60e. The bootstrap capacity 60e consists essentially of n consecutively connected bootstrap capacities 60b FIG. 5 Wherein the first capacitors 20e ₁ - _n 20e, 84e, the Zener diodes ₁ - _n, and the resistors 84e 86e ₁ - 86e have _n such varying values that a charging time constant T, at least during a starting operation state is continuously increasing. Alternatively, it is also conceivable to provide a cascaded bootstrap resistor. Furthermore, it is conceivable to combine a cascaded bootstrap capacity with a cascaded bootstrap resistor and / or with a bootstrap resistor from the FIGS. 6 and / or 7. In addition, it is conceivable, a cascaded bootstrap resistor with a bootstrap capacity from the FIGS. 4 and / or 5 to combine.

reference numeral

10

switching unit

12

switching unit

14

Driver circuit

16

Bootstrapeinheit

18

matching unit

20

capacitor

22

capacitor

24

resistance component

26

resistance component

28

Bridging switching element

30

module

32

Cooking appliance

34

heating zones

36

control unit

38

heating unit

40

GGS

42

inverter

44

center tap

46

resonance unit

48

Secondary power source

50

converter unit

52

converter unit

54

conduction path

56

Bulk capacitor

58

Bootstrapdiode

60

Bootstrapkapazität

62

Bootstrapwiderstand

64

conduction path

66

abscissa

68

axis of ordinates

70

Curve

72

Curve

74

Curve

76

Curve

78

Curve

80

Curve

81

Curve

82

diode

84

Zener diode

86

resistance

C _boat

variable

R _boat

variable

T

Charging time constant

V _BS

Bootstrapspannung

V ₀

Mains voltage potential

V _Leak

Leakage

Claims (12)

1. Cooking device having a domestic appliance, in particular having an induction hob device which has a switching unit (12; 12a - 12e) and a driver circuit (14; 14a - 14e) which comprises a bootstrap unit (16; 16a - 16e) and which is provided to set a control voltage for the switching unit (10; 10a - 10e), characterised in that the bootstrap unit (16; 16a - 16e) comprises an adjustment unit (18; 18a - 18e) which is provided for changing at least one parameter of the bootstrap unit (16; 16a - 16e).
2. Cooking device according to claim 1, characterised in that the adjustment unit (18; 18a - 18e) is provided for changing the at least one parameter as a function of a bootstrap voltage (V_BS).
3. Cooking device according to claim 1 or 2, characterised in that the at least one parameter corresponds to a charging time constant T of the bootstrap unit (16; 16a - 16e).
4. Cooking device according to claim 2, characterised in that the at least one parameter has, at least in a start-up operating state, a value between 10^-9 s and 10^-5 s.
5. Cooking device according to claim 2 or 3, characterised in that the at least one parameter has, at least in a continuous operating state, a value between 10^-7 s and 10^-3 s.
6. Cooking device according to one of the preceding claims, characterised in that the at least one parameter corresponds to a capacitance value of the bootstrap unit (16; 16a; 16b; 16e).
7. Cooking device according to one of the preceding claims, characterised in that the at least one parameter corresponds to a resistance value of the bootstrap unit (16; 16c; 16d).
8. Cooking device according to one of the preceding claims, characterised in that the adjustment unit (18b; 18c; 18e) comprises at least two capacitors (20b, 22b; 20e, 22e) or at least two resistance elements (24c, 26c) which are connected in parallel in at least one operating state.
9. Cooking device according to one of the preceding claims, characterised in that the adjustment unit (18a; 18d) comprises at least two capacitors (20a, 22a) or at least two resistance elements (24d, 26d) which are connected in series in at least one operating state.
10. Cooking device according to one of the preceding claims, characterised in that the adjustment unit (18a - 18e) comprises a bridging switching element (28a - 28e) which is provided for bridging at least one element (30a - 30e) of the bootstrap unit (16a - 16e) in at least one operating state.
11. Cooking device according to one of the preceding claims, characterised in that the adjustment unit (18a - 18e) is designed to be self-controlling.
12. Method for operating a cooking device having a domestic appliance, in particular having an induction hob device, in particular according to one of claims 1 to 11, which has a switching unit (10; 10a - 10e) and a driver circuit (14; 14a - 14e) which comprises a bootstrap unit (16; 16a - 16e), and by means of which a control voltage for the switching unit (10; 10a - 10e) is set, characterised in that at least one parameter of the bootstrap unit (16; 16a - 16e) is changed.

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