Induction hob device, induction hob and method for operating an induction hob device

Abstract

In order to provide a generic device with improved properties in terms of reliability, an induction hob device (10) is proposed with an induction unit (12) and at least one installation unit detection unit (14) for detecting an installation unit (26) above the induction unit (12), wherein the installation unit detection unit (14) has a generator unit (16) and is connected in parallel with an induction current path of the induction unit (12).

Description

[0001] The invention relates to an induction hob device.

[0002] Induction hob devices with installation unit detection units are already known from the state of the art.

[0003] The object of the invention is, in particular but not limited to, to provide a generic device with improved reliability characteristics. This object is achieved according to the invention by the features of claim 1, while advantageous embodiments and further developments of the invention can be found in the subclaims.

[0004] An induction hob device with at least one induction unit and at least one installation unit detection unit is proposed, wherein the installation unit detection unit has a generator unit and is connected in parallel with an induction current path of the induction unit.

[0005] Such a design of the induction hob device can counteract unwanted heating during detection of a placement unit above the induction unit, since the current fed into the device during detection is particularly low. Particularly precise detection can be achieved. Introduced magnetic noise can be advantageously managed, in particular without overloading the power supply paths. Particularly reliable operation under varying loads can be achieved.

[0006] The induction hob device is, in particular, at least one part, in particular a subassembly, of an induction hob. The induction hob device preferably comprises at least one part of an electrical circuit and preferably the entire electrical circuit of the induction hob. The induction hob device and / or the induction hob preferably comprise / comprises at least one housing for accommodating the circuit and / or at least one user interface for controlling at least the circuit by an operator. The user interface preferably comprises at least one, in particular mechanical or digital, operating element for controlling the induction hob, in particular the induction hob device.Alternatively, it would be conceivable for the user interface to be formed separately from the induction hob, and in particular to be at least part of a smart device, for example a smartphone or a tablet, or at least part of a computer, in particular by means of a corresponding app. The induction hob device can comprise the entire induction hob. The induction hob preferably has a support plate for supporting the support unit. The induction unit is preferably arranged in an installed position below the support plate. The support plate can be formed as a hob plate. Alternatively, the support plate can be formed as a kitchen worktop.Preferably, the kitchen worktop, in particular in contrast to the hob plate, is additionally intended to provide a food preparation area in which, for example, cutting and / or mixing and / or pounding and / or peeling of food could be carried out.

[0007] The induction unit is preferably operable to transmit inductive energy from the induction unit to the mounting unit, in particular to supply inductive energy and / or inductively heat the mounting unit, in particular in a transmission state. The induction unit preferably has at least one induction coil, above which the mounting unit can be arranged for energy transmission. The induction unit preferably has more than one induction coil, wherein in particular at least one induction coil can be assigned to at least one transmission zone, for example, precisely one transmission zone, on the mounting plate on which the mounting unit can be arranged for energy transmission.The fact that the "installation unit is arranged above the induction unit" should be understood in particular to mean that the installation unit is placed on the installation plate, in particular on the transmission zone of the installation plate, wherein the induction unit is arranged in particular below the installation plate, in particular at least below the transmission zone. Preferably, the induction hob device, in particular the induction hob, is provided for an inductive energy supply to more than one installation unit and in particular for the detection of more than one installation unit, wherein the induction hob in particular has more than one transmission zone. The induction hob can be designed as a matrix induction hob, in particular with a matrix-like distribution of the transmission zones and in particular of the induction coils. Alternatively, a discrete distribution of the transmission zones and in particular of the induction coils is conceivable."Intended" should be understood as specifically programmed, designed, and / or equipped. The fact that an object is intended for a specific function should be understood as meaning that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0008] The installation unit is preferably designed as a cooking utensil, which can be heated in particular by means of the induction unit, or as a small household appliance, which can be heated in particular by means of the induction unit and / or supplied with energy for operating the small household appliance. The small household appliance is preferably designed to be portable and can in particular be transported manually by the operator. The small household appliance is preferably designed as a small cooking appliance, in particular as a small cooking appliance. The small household appliance can, for example, be designed as a rice cooker, an air fryer, a blender, a juicer, a food processor, a kettle, a coffee machine and / or the like.The detection of the installation unit above the induction unit is, in particular, at least a detection of the presence of the installation unit above the induction unit, wherein “detection of a presence” is to be understood, in particular, as a detection of an absence of the installation unit above the induction unit in addition to a detection of an existing arrangement of the installation unit above the induction unit. The detection of the installation unit is preferably based on an impedance, in particular on an inductance and / or on a resistance, of at least part of the installation unit detection unit. In particular, at least one impedance, in particular an inductance and / or a resistance, of the induction coil is dependent on the presence, in particular on a degree of coverage, of the installation unit above the induction coil.The degree of coverage preferably characterizes an area coverage of the transmission zone by the installation unit and can depend on a material of the installation unit. The installation unit detection unit is provided in particular for detecting the presence of the installation unit above the induction unit and / or for detecting the degree of coverage and / or for detecting a type of installation unit, for example as a cooking utensil or as a small household appliance. The induction unit, in particular the at least one induction coil, is preferably part of the at least one installation unit detection unit, wherein the induction coil in the installation unit detection unit preferably functions as a detection sensor. The induction hob device preferably has more than one installation unit detection unit, in particular one installation unit detection unit for each induction coil and / or each transmission zone.Detection by means of the respective installation unit detection unit can preferably be carried out independently of one another. Detection can preferably be carried out by means of the installation unit detection unit assigned to a first induction coil simultaneously with an energy transmission, in particular for heating and / or energy supply, from a second induction coil, for example also a second induction coil adjacent to the first induction coil. Different induction coils of the induction unit can simultaneously have different states, in particular a transmission state or a detection state or a deactivated state in which, in particular, no current flows through the induction coil. Alternatively, it is conceivable that the installation unit detection units are provided only for simultaneous detection.Preferably, the at least one installation unit detection unit, in particular a plurality of installation unit detection units, is provided for detecting a position of the installation unit on the induction hob, in particular in that the detection can be carried out taking into account a position of the induction coil above which the installation unit is detected, in the induction hob, wherein preferably a position of the induction coil in the induction hob, in particular at least a relative distribution of the induction coils to one another, is stored.

[0009] The induction hob device preferably has an inverter. The induction hob device preferably has a power measuring unit for determining an output power delivered to a load, preferably the induction unit. The power measuring unit is particularly configured to measure at least one current, in particular a load current, and / or a voltage, in particular an output voltage. "Configured" should be understood in particular to mean specially programmed, designed, and / or equipped. The fact that an object is configured for a specific function should be understood in particular to mean that the object fulfills and / or executes this specific function in at least one application and / or operating state. The load current can be measured, for example, using a current transformer.The output voltage is preferably measured by a voltage divider, which is preferably arranged in circuitry at an inverter output. The output power can be calculated from an instantaneous product of the measured output voltage and the load current and their mean values. Preferably, the series resonance, in particular, can be measured analogously, whereby a load-equivalent inductance L can be determined, in particular by subtracting a known resonance capacitor value. EQ and / or a load equivalent resistance R EQ are / is determinable.

[0010] The inverter preferably has two inverter switches, in particular a low-side switch and a high-side switch. The inverter switches are designed in particular as semiconductor switches, preferably as IGBTs, as bipolar transistors with insulated gate electrodes, or as other inverter switches known to those skilled in the art. To control the high-side switch, the inverter preferably has an opto-driver, which can be supplied, for example, in a potential-free manner by means of bootstrapping. Energy for the potential-free supply is available from a low-side driver supply and can preferably be pumped to the high side when the low-side switch is activated. When both inverter switches are open, the voltage divider preferably acts as a pull-down resistor.

[0011] The generator unit is particularly intended to stimulate the induction unit, preferably the induction coil, to detect a positioning unit above the induction unit. The generator unit is preferably a waveform generator, in particular for generating a voltage with a desired voltage waveform. The positioning unit detection unit is preferably arranged at the inverter output of the inverter in terms of circuitry. The positioning unit detection unit preferably has a current amplifier, preferably to amplify the signal generated by the generator unit, preferably for transmission to a resonant load, in particular the induction unit, close to the resonant frequency. In particular, the supplied voltage and current are detected and preferably conditioned for a processing block. The series impedance introduced by the current measurement is preferably included in the loop.Especially with Hall effect or current transformer sensors, the series impedance is negligible, but with a shunt resistor it is not and must preferably be subtracted.

[0012] To avoid / counteract an inrush current surge during transmission to the installation unit detection unit, in particular at least the generator unit, which could particularly damage it, the lowest possible voltage should preferably be applied to the inverter output when the installation unit detection unit is switched on. The lowest possible voltage at the inverter output when the installation unit detection unit is switched on can be achieved, for example, by precisely dimensioning the resistors or by switching off the bootstrap branch of the inverter.

[0013] It is further proposed that the generator unit is provided to excite the induction unit with an excitation frequency which at least substantially corresponds to a resonance frequency of the induction unit, in particular of the resonance load, wherein a deviation of the excitation frequency from the resonance frequency is in particular less than 25%, preferably less than 10% and particularly preferably less than 5% of the resonance frequency. The generator unit is preferably provided to excite the induction unit with an excitation frequency of at least 10 kHz, preferably at least 15 kHz, and particularly preferably at least 20 kHz. The generator unit is preferably provided to excite the induction unit with an excitation frequency of a maximum of 60 kHz, preferably a maximum of 50 kHz, particularly preferably a maximum of 40 kHz and particularly advantageously a maximum of 30 kHz.Particularly precise detection can be achieved, particularly by reducing the sensitivity of detection to phase errors. Unwanted heating during detection of a unit above the induction unit can be counteracted.

[0014] Furthermore, it is proposed that the installation unit detection unit have a switch unit via which the generator unit is connected in parallel to the induction current path of the induction unit. Advantageously, a particularly durable and / or reliable installation unit detection unit can be provided. The switch unit is in particular designed to withstand an excitation current in the detection state, which is preferably a maximum of 5 A. The switch unit is preferably designed as a relay. In particular, the switch unit is not connected in series with the induction current. Preferably, no currents below 100 mA are transmitted at long intervals during operation, which could lead to oxidation and degradation of the switch unit, in particular the relay.The switch unit is particularly designed to withstand, in the transmission state, a voltage applied to the AC voltage output, which is preferably a maximum of 400 V. It is conceivable that the switch unit is designed and / or arranged to be switchable without current.

[0015] It is further proposed that the installation unit detection unit comprise a two-channel lock-in amplifier. This advantageously enables particularly precise and / or reliable detection. The two-channel lock-in amplifier is preferably provided for filtering the measured current and / or the measured voltage in the detection state, preferably when the required phase and quadrature signals have been generated, preferably by means of an IQ generator of the installation unit detection unit.

[0016] It is also proposed that the generator unit be configured to generate a sinusoidal voltage curve, preferably for exciting the induction unit in the detection state. This allows for particularly precise detection.

[0017] It is further proposed that the induction current path be free of relays connected in series. This allows for a particularly robust and / or durable induction hob device to be provided.

[0018] Furthermore, an induction hob with an induction hob device according to the invention is proposed. Such a design of the induction hob can counteract unwanted heating during detection of a placement unit above the induction unit, since, in particular, the current fed in during detection is particularly low. Particularly precise detection can be achieved. Incoming magnetic noise can advantageously be managed, in particular without overloading the operating supply paths. Particularly reliable operation under different loads can be achieved.

[0019] Furthermore, a method for operating an induction hob device, in particular the one already mentioned, is proposed, wherein in one method step an induction unit, in particular the one already mentioned, is excited by a generator unit, in particular the one already mentioned, which is connected in parallel to an induction current path, in particular the one already mentioned, of the induction unit. Undesired heating during detection of a setup unit above the induction unit can be counteracted because, in particular, the current fed in during detection can be particularly low. Particularly precise detection can be achieved. Advantageously, coupled-in magnetic noise can be managed, in particular without overloading operating supply paths. Particularly reliable operation under different loads can be achieved.

[0020] It is also proposed that a current from a positioning unit detection unit, in particular the one mentioned above, be fed into an inverter output. This allows for particularly precise detection. Incoming magnetic noise can advantageously be managed, particularly without overloading the operating supply paths.

[0021] Furthermore, it is proposed that the entire resonance load be measured. This allows for particularly precise detection.

[0022] The induction hob device, the induction hob, and / or the method are not intended to be limited to the application and embodiment described above. In particular, the induction hob device, the induction hob, and / or the method may have a number of individual elements, components, units, and method steps that differs from the number stated herein to fulfill a functionality described herein.

[0023] Further advantages will become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0024] They show: Fig. 1 a schematic view of an induction hob with a mounting unit in a plan view, Fig. 2 a schematic representation of part of a circuit of an induction hob device according to the invention for load measurement, Fig. 3 a current flow through the circuit Fig. 2 in a transition state, Fig. 4 a schematic equivalent circuit diagram for the circuit from Fig. 2 in a stationary state, Fig. 5 is a schematic diagram of a circuit of the induction hob device, Fig. 6 is a schematic diagram of a current flow in a detection state of the induction hob device, Fig. 7 a schematic equivalent circuit diagram for the detection state of the induction hob device, Fig. 8 an embodiment of a set-up unit detection unit of the induction hob device and Fig. 9 a schematic flow of a method for operating the induction hob device.

[0025] Fig. Figure 1 shows a schematic representation of a top view of an induction hob 22. The induction hob 22 is provided for inductive energy transfer, in particular for inductive heating and / or inductive energy transfer, of a mounting unit 26. The induction hob 22 has an induction hob device 10 (see Figure 1). Fig. 2 to 8).

[0026] The induction hob device 10 comprises at least part of an electrical circuit 30 and preferably the entire electrical circuit 30 of the induction hob 22. The induction hob device 10 and / or the induction hob comprise / comprises at least one housing 28 for accommodating the circuit 30 and / or at least one user interface 32 for controlling at least the circuit 30 by an operator.

[0027] The user interface 32 preferably has at least one, in particular mechanical or digital, operating element for controlling the induction hob 22, in particular the induction hob device 10. Alternatively, it would be conceivable for the user interface 32 to be formed separately from the induction hob and, in particular, to be at least part of a smart device, for example a smartphone or a tablet, or at least part of a computer, in particular by means of a corresponding app.

[0028] The induction hob 22 has a support plate 34 for supporting the support unit 26. The induction unit 12 is arranged in an installed position below the support plate 34. The support plate 34 can be designed as a hob plate. Alternatively, the support plate 34 can be designed as a kitchen worktop.

[0029] The induction hob device 10 has an induction unit 12. The induction unit 12 is operable to transmit inductive energy from the induction unit 12 to the installation unit 26, in particular to inductively supply energy and / or inductively heat the installation unit 26, in particular in a transmission state.

[0030] The induction unit 12 here, for example, has an induction coil (in the figures, the induction coil is represented by a coil and a resistor). The mounting unit 26 for energy transmission can be arranged above the induction coil. It is also conceivable for the induction unit 12 to have more than one induction coil, wherein in particular at least one induction coil can be assigned to at least one transmission zone, for example, precisely one transmission zone, on the mounting plate 34 on which the mounting unit 26 can be arranged for energy transmission.

[0031] The installation unit 26 is designed as a cooking utensil, which can be heated in particular by means of the induction unit 12. Alternatively, it is conceivable for the installation unit 26 to be designed as a small household appliance, for example a rice cooker, an air fryer, a blender, a juicer, a food processor, a kettle, a coffee maker, and / or the like, which can be heated in particular by means of the induction unit 12 and / or supplied with energy to operate the small household appliance.

[0032] The induction hob device 10 has a positioning detection unit 14 for detecting the positioning unit 26 above the induction unit 12. Detection of the positioning unit 26 above the induction unit 12 involves at least detecting the presence of the positioning unit 26 above the induction unit 12, in particular detecting the presence of the positioning unit 26 above the induction unit 12 and / or detecting the absence of the positioning unit 26 above the induction unit 12.

[0033] The installation unit detection unit 14 is provided for detecting the presence of the installation unit 26 above the induction unit 12 and / or for detecting a degree of coverage and / or for detecting a type of installation unit 26, for example, as a cooking utensil or as a small household appliance. The degree of coverage indicates the area covered by the installation unit 26 in a transmission zone and can depend on the material of the installation unit 26.

[0034] The induction unit 12, in particular the at least one induction coil, is part of the installation unit detection unit 14. The induction unit 12 functions as a detection sensor in the installation unit detection unit 14. The installation unit detection unit 14 is provided for detecting a position of the installation unit 26 on the induction hob 22, in particular by performing the detection in the induction hob 22 taking into account a position of the induction coil above which the installation unit 26 is detected. Preferably, a position of the induction coil is stored in the induction hob 22.

[0035] The induction hob device 10 has an inverter 40. The induction hob device 10 has a power measuring unit 42 for determining an output power delivered to a load, preferably the induction unit 12. The power measuring unit 42 is configured to measure at least one current, in particular a load current, and / or one voltage, in particular an output voltage. Fig. 1 and Fig. 2 are provided to illustrate the power measuring unit 42, in particular the installation unit recognition unit 14 is shown in the Fig. 1 and Fig. 2 not shown.

[0036] The load current can be measured, for example, with a current transformer 44. The output voltage can be measured by a voltage divider 46, which is arranged in circuitry at an inverter output 48. The output power can be calculated from an instantaneous product of the measured output voltage and the load current and their mean values. Preferably, the series resonance, in particular, can be measured analogously, whereby a load-equivalent inductance L EQ and / or a load equivalent resistance R EQ are / is determinable.

[0037] The inverter has two inverter switches 50, in particular a low-side switch 52 and a high-side switch 54. The inverter holders 50 are designed as semiconductor switches, preferably as IGBTs, as insulated-gate bipolar transistors, or as other inverter switches known to those skilled in the art. To control the high-side switch 54, the inverter 40 has an opto-driver 56, which can be supplied in a potential-free manner, for example, by means of bootstrapping. Energy for the potential-free supply is available from a low-side driver supply and can preferably be pumped to the high side when the low-side switch 52 is activated. When both inverter switches 50 are open, the voltage divider 46 acts as a pull-down resistor.

[0038] When both inverter switches 50 are opened, in particular switched off, a transient phase follows, in particular a transition state. Fig. 3, current paths in the transition state are shown with dashed lines. Energy for the high side can be stored in a preferably potential-free bootstrap capacitor 60. The bootstrap capacitor has a capacitance of at least 100 nF and a maximum of 10 µF. A current-limiting resistor 62 has a value of at least 1 ohm and a maximum of 100 ohms. A resistor 64 represents a current consumption of the opto-driver 56. A typical current is, for example, approximately 1 mA, which ideally corresponds to about 20 kOhms for a 20 V supply voltage. An entire resonance capacitor 66 has, for example, a value of at least 400 nF and a maximum of 1.5 µF and is preferably divided into two halves. A bus capacitor 68 preferably represents an overall filter capacitor for the inverter 40, which typically has a value of at least 4.7 µF and a maximum of 10 µF.A bus discharge resistor 70 is provided for safe manipulation and secure construction and preferably has a value of at least 50 kOhm and a maximum of 1 MOhm. A voltage divider resistor 72 represents the total resistance of the voltage divider 46, which here is 300 kOhm, for example.

[0039] In a stationary state, the capacitors, in particular the resonance capacitor 66 and / or the bus capacitor 68, behave like an open circuit, while the inductances behave in particular like short circuits. A voltage at the inverter output 46 is determined by the voltage divider resistor 72, preferably not by the capacitors, in particular the resonance capacitor 66 and / or the bus capacitor 68 (an equivalent circuit is shown in Fig. 4). As a result, a residual voltage V0 may occur at the inverter output 46 when both inverter switches 50 are open. The residual voltage V0 is: V0 = VCC_DRV · ((R BUS ||R VOLT ) / (R BOOT + R DRIVER +R BUS ||R VOLT )) ≈ V CC_DRV · (R BUS ||R VOLT ) / (R DRIVER + R BUS ||R VOLT ). R BUS corresponds to the bus discharge resistor 70. V CC_DRV corresponds to an input voltage, especially supply voltage. R VOLT corresponds to the voltage divider resistor 72. R DRIVER entspricht the resistance 64. R BUS corresponds to the bus discharge resistor 70.

[0040] The installation unit detection unit 14 has a generator unit 16. The installation unit detection unit 14 is connected in parallel with an induction current path of the induction unit 12. The generator unit 16 is provided to excite the induction unit 12, preferably the induction coil, to detect the installation unit 26 above the induction unit 12. The generator unit 16 is a waveform generator, in particular for generating a voltage with a desired voltage waveform. The generator unit 16 is configured to generate a sinusoidal voltage curve.

[0041] The installation unit detection unit 14 is arranged circuit-wise at the inverter output 48 of the inverter 40. The installation unit detection unit 14 has a current amplifier 58, preferably for amplifying the signal generated by the generator unit 16, preferably for transmission to a resonant load, in particular the induction unit 12, close to the resonant frequency. The supplied voltage and current are detected and preferably conditioned for a processing block. The series impedance introduced by the current measurement is preferably included in the loop. In particular, with Hall-effect or current transformer sensors, the series impedance is negligible; with a shunt resistor, it is not, and must preferably be subtracted.

[0042] In order to avoid / counteract an inrush current surge, for example due to the residual voltage V0, in the transmission state to the installation unit detection unit 14, in particular at least the generator unit 16, which can particularly damage the latter, the lowest possible voltage should preferably be applied to the inverter output 46 when the installation unit detection unit 14 is switched on. The lowest possible voltage at the inverter output 46 when the installation unit detection unit 14 is switched on can be achieved, for example, by precisely selecting the dimensioning of the resistors or by switching off the bootstrap branch of the inverter 40.

[0043] The generator unit 16 is designed to excite the induction unit 12 with an excitation frequency that at least substantially corresponds to a resonant frequency of the induction unit 12. In this case, the generator unit 16 is designed to excite the induction unit 12 with an excitation frequency of at least 20 kHz and a maximum of 30 kHz. Alternatively, a different excitation frequency, for example, 40 kHz, is conceivable.

[0044] The installation unit detection unit 14 has a switch unit 18. The generator unit 16 is connected in parallel to the induction current path of the induction unit 12 via the switch unit 18. The switch unit 18 is designed to withstand an excitation current in the detection state, which is preferably a maximum of 5 A. The switch unit 18 is designed as a relay. In particular, the switch unit 18 is not connected in series with the induction current. During operation, no currents below 100 mA are transmitted at long intervals, which could lead to oxidation and degradation of the switch unit 18, in particular of the relay. The switch unit 18 is designed to withstand a voltage in the transmission state, which is applied to the AC voltage output 46 and is preferably a maximum of 400 V. It is conceivable that the switch unit 18 is designed and / or arranged so that it can be switched off when there is no current.The induction current path is free of relays connected in series.

[0045] The installation unit detection unit 14 has a two-channel lock-in amplifier 20. The two-channel lock-in amplifier 20 is provided for filtering the current 88 and / or a measured voltage 90, in particular measured by means of a current sensor 86, in the detection state, preferably when the required phase and quadrature signals have been generated, preferably by means of an IQ generator 74 of the installation unit detection unit 14.

[0046] A measured impedance Z (f) corresponds to a series resonant load whose resistance and inductance are to be estimated, but which includes the resonant capacitor 66, in particular the resonant capacitors 66, the voltage divider and the current sensor 86 (cf. Fig. 6, in which the corresponding current paths are shown in dashed lines).

[0047] Near resonance, the impedance of the resonant load is largely determined by its resistive component, which is typically less than 5 ohms, so that no significant current flows through the voltage divider resistor 72, which is typically in the range of hundreds of kOhms. For a typical 15nF damping capacitor, the impedance modulus at 30 kHz is 1 / (2πfC) = 354 ohms >> 5 ohms. An equivalent circuit is shown in Fig. 7 is shown with a schematically illustrated voltage bias 98, a voltage measurement 92 of the setup unit detection unit 14, a current measurement 94 of the setup unit detection unit 14, an intrinsic diode 96 of the low-side inverter switch 54, with an equivalent inductance 100 of the load, an equivalent resistance 102 of the load, two damping capacitors 104 and two resonant capacitors 106.

[0048] Damping capacitors 104 are connected in parallel with the resonant load, so the actual impedance is half of the previously calculated values. When a minimum excitation voltage is 0.7 V below ground, intrinsic diode 96 introduces some distortion. Voltage bias 98 is provided to prevent this distortion.

[0049] Fig. 8 shows a particularly advantageous, cost-effective, implementation variant of the Fig. 5 and Fig. 6 conceptually depicted setup unit detection unit 14. The two-channel lock-in amplifier 20 is based on a mixed-signal solution, in particular based on a solution according to WO 2022233661 A1, which is particularly equivalent to multiplying the input waveforms by square waves. The generator unit 16 has very low total harmonic distortion (THD).

[0050] The current exhibits even higher purity because the load behaves like a bandpass filter. A shift register-based implementation is proposed for synthesizing the voltage waveform. The register behaves like a digital-to-analog converter (DAC) controlled by the clock provided by a microcontroller 110. The clock frequency is the synthesized frequency multiplied by the selected oversampling, which determines the stages of a shift register 108. The higher the purity, the higher the number of stages in the shift register 108 and the higher the clock frequency. Both the digital phase and quadrature waveforms can be easily obtained at the corresponding flip-flop outputs of the shift register 108. A low-pass filter 114 can then be used to extract the first harmonic from the staircase-synthesized waveform.

[0051] Current amplifier 58 may have a class AB configuration, such as a diamond buffer configuration. Current amplifier 58 is capable of driving the low impedance provided by equivalent resistor 102 and a shunt resistor while maintaining a high input impedance. A shunt resistor 116 and a differential amplifier 118 are used as current sensor 86.

[0052] The two-channel lock-in amplifier 20 consists of four analog SPDT switches (single-pole double-throw switches) that select between the current or voltage signal and its zero value. A virtual zero value here corresponds in particular to an average supply value. Then, the outputs 124 of the SPDT switches are low-pass filtered (low-pass filter 120), in particular to obtain a DC value, and sampled by an analog-to-digital converter (ADC) 122 of the microcontroller 110 to perform the necessary calculations.

[0053] Fig. 9 shows a schematic flow of a method for operating the induction hob device 10.

[0054] In a method step 76, both inverter switches 50 are opened, in particular switched off. In a method step 78, the opto-driver 56 is disconnected, for example by means of a transistor or a relay. In a method step 80, the system waits until the residual voltage V0 at the inverter output 46 is zero. In a method step 82, the switch unit 18 is closed, preferably with zero current and limited inrush current. In a method step 24, the induction unit 12 is excited by the generator unit 16, which is connected in parallel to the induction current path of the induction unit 12. A current from the installation unit detection unit 14 is fed to the inverter output 48. In a method step 84, detection is performed by the two-channel lock-in amplifier 20. A total resonant load is measured. Reference symbol 10 Induction hob device 12 Induction unit 14 Installation unit detection unit 16 Generator unit 18 Switch unit 20 two-channel lock-in amplifiers 22 induction hob 24 process steps 26 Installation unit 28 housings 30 circuit 32 User interface 34 mounting plate 36 coil 38 Resistance 40 inverters 42 Power measurement unit 44 current transformers 46 voltage dividers 48 Inverter output 50 inverter switches 52 low-side switches 54 high-side switches 56 opto drivers 58 power amplifiers 60 Bootstrap capacitor 62 Current limiting resistor 64 Resistance 66 Resonance capacitor 68 Bus capacitor 70 Bus discharge resistor 72 voltage divider resistor 74 IQ Generator 76 process steps 78 Process step 80 process steps 82 Process step 84 Process step 86 Current sensor 88 Measured current 90 Measured voltage 92 Voltage measurement 94 Current measurement 96 Intrinsic Diode 98 Voltage bias 100 equivalent inductance 102 Equivalent resistance 104 Damping capacitor 106 Resonance capacitor 108 shift registers 110 microcontrollers 112 phase and / or quadrature waveforms 114 Low-pass filters 116 Shunt resistance 118 differential amplifiers 120 low-pass filters 122 analog-to-digital converters 124 Exit QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2022233661 A1

[0049]

Claims

[1] Induction hob device (10) with an induction unit (12) and at least one installation unit detection unit (14) for detecting an installation unit (26) above the induction unit (12), wherein the installation unit detection unit (14) has a generator unit (16) and is connected in parallel with an induction current path of the induction unit (12). [2] Induction hob device (10) according to claim 1, characterized by that the generator unit (16) is provided to excite the induction unit (12) with an excitation frequency which at least substantially corresponds to a resonance frequency of the induction unit (12). [3] Induction hob device (10) according to claim 1 or 2, characterized by that the installation unit detection unit (14) has a switch unit (18) via which the generator unit (16) is connected in parallel to the induction current path of the induction unit (12). [4] Induction hob device (10) according to one of the preceding claims, characterized by that the installation unit detection unit (14) has a two-channel lock-in amplifier (20). [5] Induction hob device (10) according to one of the preceding claims, characterized by that the generator unit (16) is designed to generate a sinusoidal voltage curve. [6] Induction hob device (10) according to one of the preceding claims, characterized by that the induction current path is free of relays connected in series. [7] Induction hob (22) with an induction hob device (10) according to one of the preceding claims. [8] Method for operating an induction hob device (10) according to one of claims 1 to 6, characterized byin that in a method step (24) an induction unit (12) is excited by a generator unit (16) which is connected in parallel to an induction current path of the induction unit (12). [9] Method according to claim 8, characterized by that a current of a setup unit detection unit (14) is fed to an inverter output. [10] Method according to one of claims 8 or 9, characterized by that a total resonance load is measured.

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