Induction device

Abstract

The invention relates to an induction device (10a; 10b; 10c), in particular an induction cooking device, comprising a plurality of independently controllable induction areas (12a, 14a, 16a, 18a; 12b, 14b, 16b, 18b; 12c, 14c, 16c, 18c) and comprising at least one control unit (20a; 20b) which is provided to repetitively control the induction areas (12a, 14a, 16a, 18a; 12b, 14b, 16b, 18b; 12c, 14c, 16c, 18c) within a control period (22a; 22b) formed by a first control interval (26a; 26b) and at least one second control interval (28a; 28b) with at least one AC frequency (24a; 24b) and to supply same with energy. In order to provide a generic device with improved characteristics in terms of safe and / or comfortable operation, in the first control interval (26a; 26b), the control unit (20a; 20b) operates at least two of the induction areas (12a, 14a, 16a, 18a; 12b, 14b, 16b, 18b; 12c, 14c, 16c, 18c) with a first phase shift (32a; 32b) in order to minimise interferences.

Description

[0001] The invention relates to an induction device according to the preamble of claim 1 and a method for operating an induction device according to the preamble of claim 11.

[0002] An induction cooking appliance device with at least one control and / or regulating unit is already known from the prior art, which is provided to repetitively control and supply with energy at least one induction target in at least one periodic continuous heating operating state, to which at least one operating period is assigned, and to operate the induction target in at least one switch-on interval of the operating period with a heating power, in particular a target heating power or a power surplus compared to a target heating power, wherein the control and / or regulating unit is provided to vary a heating current frequency for the induction target in the switch-on interval of the operating period in the continuous heating operating state in order to thus enable low-noise operation.

[0003] EP 3 484 242 A1 describes an induction cooking device with at least two induction heating elements and with at least one control unit which, in at least one operating state, operates the induction heating elements in at least a first time interval with a phase shift.

[0004] EP 3 001 773 A1 describes a cooking appliance device with at least two inverters, which are each provided to operate at least one inductor, and with a control unit which is provided to operate the at least two inverters jointly in at least one time window of a continuous operating state and to divide the at least one time window into at least two time intervals.

[0005] Furthermore, an induction cooking appliance device with at least two induction heating elements and with at least one control unit is already known from the prior art, which in at least one operating state operates the induction heating elements in at least one first time interval with a first phase shift and in at least one second time interval different from the first time interval with a second phase shift different from the first phase shift, in order to thus enable improved heat distribution.

[0006] The object of the invention is, in particular but not limited to, to provide a generic device with improved properties regarding safe and / or convenient operation. This object is achieved according to the invention by the features of claims 1 and 11, while advantageous embodiments and further developments of the invention can be found in the subclaims.

[0007] The invention is based on an induction device, in particular an induction cooking device, with a plurality of independently controllable induction targets and with at least one control unit which is provided to repeatedly control the induction targets with at least one alternating current frequency and to supply them with energy within a control period consisting of a first control interval and at least one second control interval.

[0008] It is proposed that the control unit operates at least two of the induction targets with a first phase shift in the first control interval in order to minimize interference.

[0009] The inventive design makes it possible to provide a generic cooking appliance with improved properties regarding safe and / or comfortable operation, in particular low-noise operation and / or in particular with regard to compliance with EMC standards and / or flicker conformity. In particular, noise resulting from intermodulation can be advantageously minimized. This makes it possible to avoid, in particular, an adverse acoustic impact on an operator, thereby achieving a high level of operating comfort and, in particular, a positive operating impression for the operator, particularly with regard to acoustic quality.Furthermore, an induction device with improved compliance with legal guidelines, in particular guidelines regarding EMC compliance and / or flicker compliance, can advantageously be achieved using simple technical means. Furthermore, stricter EMC compliance limits planned for the future can also be met now.

[0010] An "induction device" is understood to mean, in particular, at least one part, in particular a subassembly, of an induction device that has a primary function in the form of energy transmission to at least one external unit. The induction device could, for example, be designed as a part and / or a subassembly of an induction charger, wherein the external unit could have at least one receiving element, for example, a secondary coil, and could, for example, be designed as a handheld power tool, such as a drill and / or an electric screwdriver and / or a hammer drill and / or a saw, or as a mobile device such as a smartphone and / or tablet and / or laptop. Alternatively or additionally, the induction device could be designed as part of a transformer and, in particular, comprise at least one primary coil of a transformer.Preferably, the induction device is designed as an induction cooking appliance device, for example as an induction oven device or as an induction grill device, and particularly preferably as an induction hob device and is provided for heating the external unit, which can in particular be designed as a cooking utensil.

[0011] According to the invention, an "induction target" is to be understood as an inductor or a plurality of inductors, which is / are part of the induction device and which can be jointly controlled by the control unit. An "inductor" is to be understood here, in particular, as an element that has at least one induction coil and is intended to supply energy, in particular in the form of an alternating magnetic field, to at least one receiving element, in particular a receiving element of the external unit, in at least one operating state. In the case of an induction device designed as an induction cooking appliance, an induction target can be intended, in particular, to supply energy to the receiving element for the purpose of heating.In this case, the external unit could, for example, be designed as a cooking utensil and have at least one secondary coil as a receiving element for receiving the energy provided by the inductor. Alternatively or additionally, the receiving element could also be designed as a metallic heating means, in particular as an at least partially ferromagnetic heating means, for example as a ferromagnetic base of a cooking utensil, in which, in the operating state, eddy currents and / or remagnetization effects are induced by the inductor, which are converted into heat. In particular, the plurality of inductors can be arranged in a matrix, wherein the matrix-like inductors can form a variable cooking surface. In particular, at least one inverter unit is assigned to each of the induction targets, which can in particular be designed as a resonant inverter and / or as a dual half-bridge inverter.The inverter unit comprises, in particular, at least two switching elements, which can be individually controlled by the control unit. A "switching element" is understood, in particular, to be an element that is intended to establish and / or break an electrically conductive connection between two points, in particular contacts of the switching element. The switching element preferably has at least one control contact via which it can be switched. In particular, the switching element is designed as a semiconductor switching element, in particular as a transistor, for example as a metal oxide semiconductor field-effect transistor (MOSFET) or organic field-effect transistor (OFET), advantageously as a bipolar transistor with a preferably insulated gate electrode (IGBT). Alternatively, it is conceivable for the switching element to be designed as a mechanical and / or electromechanical switching element, in particular as a relay.

[0012] A "control unit" is understood, in particular, to be an electronic unit that is at least partially integrated into the induction device and is intended, in particular, to control at least one of the inverter units. The control unit preferably comprises a computing unit and, in particular, in addition to the computing unit, a memory unit with at least one control program stored therein, which is intended to be executed by the computing unit. A "control period" is understood, in particular, to be a period of time in which the control unit repetitively controls the induction targets using at least one control strategy.A "control strategy" is understood to mean, in particular, a specific control of a unit, in particular of at least two induction targets, and / or a specific method and / or a specific algorithm applied to the unit, in particular to the induction targets. The control strategy can, in particular, comprise at least one phase shift. A "control interval" is understood to mean, in particular, a sub-period of the control period in which the control unit controls the induction targets using precisely one specific control strategy and maintains this control strategy throughout this sub-period. During a control interval, in particular, the number of induction targets simultaneously operated by the control unit remains constant.In the context of the control interval, the terms "first," "second," and "further" are to be understood as purely naming conventions to better distinguish the respective control intervals and do not imply any chronological order and / or ranking of the respective control intervals. For example, the first control interval may be subordinate to the second control interval and / or other control intervals, or vice versa. In particular, the first control interval may be longer or shorter than the second control interval and / or other control intervals, or all control intervals may each last the same length of time.

[0013] An "alternating current frequency" is to be understood in particular as a frequency of an alternating electrical current in a range from 20 kHz to 150 kHz, preferably from 30 kHz to 75 kHz, with which at least one inductor of an induction target is controlled to generate an alternating magnetic field.

[0014] Interference can be particularly noticeable and perceived as undesirable by a user and / or prohibited by law. For example, interference could take the form of flicker. Alternatively or additionally, interference could be undesirable acoustic influences, particularly in a frequency range between 20 Hz and 20 kHz perceptible to the average human ear. Interference could be caused, in particular, by intermodulation and manifest itself in acoustically perceptible noise. "Intermodulation" is understood to mean, in particular, the sum and / or difference products of individual alternating current frequencies or their nth harmonics, where n represents an integer greater than zero.Interference can also be caused, alternatively or additionally, by the occurrence of a ripple current, i.e., an alternating current of any frequency and waveform superimposed on a direct current, resulting in an undesirable hum. Interference in this context does not include, in particular, technical malfunctions, defects, and / or other undesirable phenomena, such as uneven heat distribution.

[0015] A "phase shift" is to be understood, in particular, as meaning that an oscillation of a control signal of a first inverter unit, with which a first induction target is controlled, and an oscillation of a further control signal of a further inverter unit, with which a further induction target is controlled, have spaced-apart zero crossings. In particular, the phase shift assumes an amount that corresponds to the distance between the zero crossings and is specified as a phase angle. The amount of the phase shift will be considered below based on the control signal by which the control unit first controls and supplies energy to a specific induction target in the relevant control interval.In the context of the term phase shift, the terms "first," "second," and "further" are to be understood as purely naming conventions to better distinguish phase shifts that differ in terms of magnitude and / or the respective induction targets and / or the respective control interval. Furthermore, the terms "first," "second," and "further" in the context of a phase shift serve to assign a particular control interval to a particular control interval in which a specific phase shift applies. For example, a first phase shift and a further first phase shift each apply in a first control interval. In particular, the term "first phase shift" does not necessarily imply the presence of a second and / or further phase shift.

[0016] "Intended" should be understood in particular to mean specifically programmed, designed, and / or equipped. The fact that an object is intended for a specific function should be understood in particular to mean that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0017] It is further proposed that the control unit operate the at least two induction targets in the second control interval with a second phase shift that differs from the first phase shift. For example, it would be conceivable for the control unit to operate exactly two of the induction targets simultaneously with the first phase shift in the first control interval, for example, offset by a phase angle of 90° from one another, and to operate the two induction targets in the second control interval with the second phase shift, for example, offset by a phase angle of 60° from one another. This advantageously minimizes interference in different operating situations, for example, when the induction targets have different power outputs.

[0018] It is also proposed that the control unit operate at least one additional induction target with a further first phase shift in the first control interval. For example, it would be conceivable for the control unit to operate three induction targets simultaneously in the first control interval, namely a second induction target with the first phase shift relative to a first induction target and a further induction target with the further first phase shift relative to the first induction target. This advantageously minimizes interference in different operating situations, for example, when a different number of induction targets are to be operated simultaneously.

[0019] Furthermore, it is proposed that the control unit operate at least one further induction target with a further second phase shift in the second control interval. For example, it would be conceivable for the control unit to operate exactly two induction targets simultaneously with the first phase shift in the first control interval and three induction targets simultaneously in the second control interval, namely a second induction target with the second phase shift relative to a first induction target and a further induction target with the further second phase shift relative to the first induction target. This advantageously minimizes interference in different operating situations, for example, when a different number of induction targets are operated simultaneously.

[0020] It is further proposed that the duration of at least one of the control intervals, in particular of all control intervals, be shorter than half a period of an AC mains voltage. This advantageously allows the control unit to react, particularly very quickly and automatically, to a changed operating situation, for example, the switching on and / or off of individual induction targets by a user, while simultaneously minimizing interference. Furthermore, it is proposed that the duration of the control period be shorter than half a period of an AC mains voltage. This advantageously allows flicker compliance to be improved.

[0021] It is also proposed that, in at least one of the control intervals, the control unit controls at least one of the induction targets with the alternating current frequency and at least one other of the induction targets with a further alternating current frequency different from the alternating current frequency. For example, it is conceivable that, in the first control interval, the control unit controls the at least two induction targets with the alternating current frequency, and in the second control interval, controls one of the two identical induction targets with the alternating current frequency and the other of the two identical induction targets with the further alternating current frequency.Alternatively, it is conceivable for the control unit to drive the at least two induction targets at the alternating current frequency in the first control interval, and to drive one of the same two induction targets at the alternating current frequency in the second control interval, and another induction target, which was not driven in the first control interval, at the additional alternating current frequency. This advantageously allows multiple induction targets to be operated simultaneously at different output powers, while simultaneously minimizing interference.

[0022] For example, it would be conceivable for the alternating current frequency and the additional alternating current frequency to be spaced apart by a certain amount, in particular by an amount of at least 20 kHz, without the alternating current frequency and the additional alternating current frequency having a common integer multiple. To advantageously enable a phase shift even in the case of two induction targets operated at different alternating current frequencies, it is proposed that the additional alternating current frequency be an integer multiple of the alternating current frequency. For example, the alternating current frequency at which the first two induction targets are operated could be 35 kHz, and the additional alternating current frequency at which a further induction target is operated could be 70 kHz.This advantageously minimizes interference, particularly in cases where at least two induction targets of the induction device have to be operated with different alternating current frequencies for technical reasons, for example due to differing output powers.

[0023] It is further proposed that the control unit operates at least two of the induction targets, in particular the at least two induction targets, at the same alternating current frequency in at least one of the control intervals, in particular the first control interval. With the same alternating current frequency, a phase shift can advantageously be realized using particularly simple technical means, while simultaneously minimizing interference.

[0024] Furthermore, the inventive solution comprises the control unit calculating a phase angle of the first phase shift from a quotient of 180° and a number of induction targets to be operated simultaneously within the first control interval. In particular, the control unit calculates all phase angles of all phase shifts from 180° and a number of induction targets to be operated simultaneously within the first control interval. To calculate the phase angle, the control unit comprises, in particular, a computing unit. For example, two induction targets could be operated simultaneously in one of the control intervals, so that the computing unit of the control unit calculates the phase angle, 180° divided by two, to be 90°.In this way, interference, which can vary considerably depending on the number of induction targets operated simultaneously within a control interval, can advantageously be minimized by the control unit, in particular automatically.

[0025] In an alternative embodiment not according to the invention, it is proposed that the control unit selects at least one suitable phase angle for the first phase shift from a catalog of suitable phase angles based on a number of induction targets to be operated simultaneously within the first control interval. In particular, the control unit selects at least one suitable phase angle for the respective phase shift from a catalog of suitable phase angles based on a number of induction targets to be operated simultaneously within a respective control interval. The control unit in particular comprises at least one memory unit in which the catalog is stored so that it can be retrieved by the control unit. The catalog can in particular contain a multiplicity of suitable phase angles, in particular those determined experimentally through tests.In particular, it is conceivable that, in addition to the number of induction targets to be operated simultaneously, further factors, for example a number of inductors assigned to the respective induction targets and / or a diameter and / or number of windings of a coil of an inductor, are taken into account in the plurality of phase angles stored in the catalog. In particular, it is conceivable that the phase angles contained in the catalog are adapted to a specific application of the induction device, for example a specific operating mode. In particular, a first catalog of a first induction device, which is part of a first induction device, can differ from a second catalog of a second induction device, which is part of a second induction device that is different from the first, in particular with regard to a field of application.In particular, it is conceivable that the catalogue can be expanded and / or adapted to include further suitable phase angles, so that new empirical findings regarding suitable phase angles can be added, for example through a software update.

[0026] The invention further relates to a method for operating an induction device, in particular an induction cooking device, having a plurality of independently controllable induction targets, wherein the induction targets are repetitively controlled and supplied with energy with at least one alternating current frequency within a control period of at least two consecutive control intervals.

[0027] To minimize interference in at least one of the control intervals, it is proposed that at least two of the induction targets be operated with a phase shift. This advantageously allows for particularly quiet operation of the induction device.

[0028] The induction device is not intended to be limited to the application and embodiment described above. In particular, the induction device may have a number of individual elements, components, and units that differs from the number stated herein to fulfill a functionality described herein.

[0029] 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.

[0030] They show: Fig. 1 is a schematic representation of an induction device with an induction device which has a plurality of induction targets and a control unit, Fig. 2 is a circuit diagram of the induction device in a schematic representation, Fig. 3 is a schematic representation of the induction device with a connection to a mains voltage source, Fig. 4 is a schematic representation of a control period of the induction device, Fig. 5 is a schematic representation of a method for operating the induction device, Fig. 6 is a schematic representation of a control period of an induction device of an embodiment not according to the invention and Fig. 7 is a circuit diagram of a further alternative embodiment of an induction device in a schematic representation.

[0031] Figure 1shows an induction appliance 100a with an induction device 10a. The induction appliance 100a is designed as an induction cooking appliance, specifically as an induction hob. The induction device 10a is designed as an induction cooking appliance. The induction device 10a has a plurality of induction targets 12a, 14a, 16a, 18a. The induction device 10a has a control unit 20a. The induction targets 12a, 14a, 16a, 18a can be controlled independently by the control unit 20a. The control unit 20a is provided to control the induction targets 12a, 14a, 16a, 18a within a control period 22a (cf. Figure 4 ) repetitively with at least one alternating current frequency 24a and to supply it with energy. The control unit 20a has a computing unit 92a and a memory unit 94a.

[0032] Figure 2shows a circuit diagram of the induction device 10a in a schematic representation. Each of the induction targets 12a is assigned an inverter unit 38a. Each of the inverter units 38a has a first switching element 40a and a second switching element 42a. The first switching element 40a and the second switching element 42a are each designed as transistors, specifically as bipolar transistors with an insulated gate electrode. In an operating state, the control unit 20a repetitively controls the respective induction targets 12a, 14a, 16a, 18a via the inverter units 38a assigned to the respective induction targets 12a, 14a, 16a, 18a at the alternating current frequency 24a.

[0033] Figure 3shows the induction device 10a in a schematic representation. The induction device 10a is connected to an AC mains voltage source 70a. The AC mains voltage source 70a provides an AC mains voltage 72a or an AC mains current 74a. The induction device 10a has a filter unit 76a and a rectifier unit 78a. The rectifier unit 78a converts the AC mains voltage 72a into a DC voltage 80a. The DC voltage 80a has a period 84a, which corresponds to a period of the AC mains voltage 72a. A duration 88a of the control period 22a is shorter than half a period 86a of the AC mains voltage 72a. The control period 22a consists of several control intervals 26a, 28a, 30a. The duration of all tax intervals 26a, 28a and 30a together results in the duration of tax period 22a (cf. Figure 4). Consequently, the duration of all control intervals 26a, 28a, 30a is shorter than half the period 86a of the AC mains voltage 72a.

[0034] Figure 4shows a synopsis of several diagrams illustrating the control period 22a of the control unit 20a in an exemplary operating state of the induction device 10a. A time is plotted on an abscissa axis 46a of a first diagram. A total power inductively provided by the induction targets 12a, 14a, 16a, 18a is plotted on an ordinate axis 44a of the first diagram. The control period 22a comprises a first control interval 26a, a second control interval 28a, and two further control intervals 30a. A time is plotted on an abscissa axis 50a of a second diagram. A power provided by the induction target 12a of the induction targets 12a, 14a, 16a, 18a is plotted on an ordinate axis 48a of the second diagram. A time is plotted on an abscissa axis 54a of a third diagram. On an ordinate axis 52a of the third diagram, a power provided by the induction target 14a is plotted.A time is plotted on an abscissa axis 58a of a fourth diagram. A power provided by the induction target 16a is plotted on an ordinate axis 56a of the fourth diagram. A time is plotted on an abscissa axis 62a of a fifth diagram. A power provided by the induction target 18a is plotted on an ordinate axis 60a of the fifth diagram. A time is plotted on an abscissa axis 66a of a sixth diagram. A phase angle 36a of a phase shift is plotted on an ordinate axis 64a of the sixth diagram. In the first control interval 26a, the control unit 20a operates the first induction target 12a and the second induction target 14a at the same AC frequency 24a. In the first control interval 26a, the control unit 20a operates the induction target 14a with a first phase shift 32a relative to the induction target 12a in order to minimize interference.

[0035] Using the computing unit 92a, the control unit 20a calculates the phase angle 36a of the first phase shift 32a from a quotient of 180° and a number of induction targets 12a, 14a, 16a, 18a to be operated simultaneously within the first control interval 26a. In the first control interval 26a, the induction target 12a and the induction target 14a are to be operated simultaneously by the control unit 20a, so that the number of induction targets 12a, 14a to be operated simultaneously is two. The computing unit 92a of the control unit 20a then calculates the phase angle 36a from the quotient of 180° and two and determines an amount of 90° for the phase angle 36a of the first phase shift 32a in the first control interval 26a.

[0036] In the second control interval 28a, the control unit 20a operates the induction target 14a, the induction target 16a, and the induction target 18a simultaneously, each at the same AC frequency 24a. In the second control interval 28a, the control unit 20a operates the induction target 16a with a second phase shift 34a relative to the induction target 14a and the induction target 18a with the second phase shift 34a relative to the induction target 14a. The second phase shift 34a differs from the first phase shift 32a.

[0037] Figure 5shows a schematic representation of a method for operating the induction device 10a with a plurality of independently controllable induction targets 12a, 14a, 16a, 18a. In a first method step 102a, the control unit 20a determines a number of induction targets 12a, 14a, 16a, 18a to be operated simultaneously within the first control interval 26a. In a second method step 104a, at least two of the induction targets 12a, 14a, 16a, 18a are repetitively controlled with the alternating current frequency 18a within the control period 22a and supplied with energy. To minimize interference, two of the induction targets 12a, 14a, 16a, 18a are operated with the first phase shift 32a in the first control interval 26a.

[0038] In the Figure 7 A further embodiment of the invention is shown. In the Figure 6A further alternative embodiment is shown which is not in accordance with the invention. The following descriptions are essentially limited to the differences between the embodiments, with reference to the description of the embodiment of the Figures 1 to 5 To distinguish the embodiments, the letter a in the reference numerals of the embodiment in the Figures 1 to 5 by the letters b and c in the reference numerals of the embodiment of the Figures 6 and 7 With regard to components with the same designation, in particular with regard to components with the same reference numerals, reference can generally also be made to the drawings and / or the description of the embodiment of the Figures 1 to 5 be referred to.

[0039] The Figure 6relates to an embodiment of an induction device 10b not according to the invention. The induction device 10b is designed identically to the induction device 10a in terms of its structural design and differs only in terms of programming of a control unit 20b. Figure 6shows a synopsis of several diagrams illustrating a control period 22b of the control unit 20b in an exemplary operating state. The control period 22b comprises a first control interval 26b, a second control interval 28b, and two further control intervals 30b. A time is plotted on an abscissa axis 46b of a first diagram. A total power inductively provided by the induction targets 12b, 14b, 16b, 18b is plotted on an ordinate axis 44b of the first diagram. A time is plotted on an abscissa axis 50b of a second diagram. A power provided by the induction target 12b is plotted on an ordinate axis 48b of the second diagram. A time is plotted on an abscissa axis 54b of a third diagram. A power provided by the induction target 14b is plotted on an ordinate axis 52b of the third diagram.A time is plotted on an abscissa axis 58b of a fourth diagram. A power provided by the third induction target 16b is plotted on an ordinate axis 56b of the fourth diagram. A time is plotted on an abscissa axis 62b of a fifth diagram. A power provided by the induction target 18b is plotted on an ordinate axis 60b of the fifth diagram. A time is plotted on an abscissa axis 66b of a sixth diagram. A phase angle 36b of a phase shift is plotted on an ordinate axis 64b of the sixth diagram. In the first control interval 26b, the control unit 20b operates the induction targets 14b and 16b at an alternating current frequency 24b and the induction target 18b at a further alternating current frequency 90b. The further alternating current frequency 90b is different from the alternating current frequency 24b.The further alternating current frequency 90b is an integer multiple of the alternating current frequency 24b.

[0040] In the first control interval 26b, the control unit 20b operates the induction target 14b and the induction target 16b with a first phase shift 32b. From a catalog stored in a memory unit 94b of the control unit 20b, the control unit 20b determines a suitable phase angle 36b for the first phase shift 32b from a number of induction targets 12b, 14b, 16b, 18b to be operated simultaneously in the first control interval 26b.

[0041] In the first control interval 26b, the control unit 20b operates the further induction target 18b with a further first phase shift 96b. In the second control interval 28b, the control unit 20b operates the induction target 14b, the induction target 16b, and the induction target 18b, each at the same AC frequency 24b. The control unit 20b operates the induction target 14b and the induction target 16b with a second phase shift 34b. The second phase shift 34b is different from the first phase shift 32b. In the second control interval 28b, the control unit 20b operates the further induction target 18b with a further second phase shift 98b relative to the induction target 14b.

[0042] Figure 7shows a circuit diagram of an alternative induction device 10c in a schematic representation. The induction device 10c has four induction targets 12c, 14c, 16c, 18c. Each of the induction targets is supplied with electrical energy in a matrix multi-inverter topology. Each of the induction targets 12c, 14c, 16c, 18c has five inductors 106c. Each of the induction targets 12c, 14c, 16c, 18c is assigned an inverter unit 38ac. Each of the inverter units 38c has a first switching element 40c and five second switching elements 42c. Each of the switching elements 40a, 42c is designed as a transistor, specifically as an insulated-gate bipolar transistor. By means of the switching elements 42c, a separate control of the individual inductors 106c of the respective induction targets 12c, 14c, 16c, 18c is possible. Reference symbol

[0043] 10 Induction device 12 First induction target 14 Second induction target 16 Third induction target 18 Fourth induction target 20 Control unit 22 Control period 24 AC frequency 26 First control interval 28 Second control interval 30 Further control interval 32 First phase shift 34 Second phase shift 36 Phase angle 38 Inverter unit 40 First switching element 42 Second switching element 44 Ordinate axis 46 Abscissa axis 48 Ordinate axis 50 Abscissa axis 52 Ordinate axis 54 Abscissa axis 56 Ordinate axis 58 Abscissa axis 60 Ordinate axis 62 Abscissa axis 64 Ordinate axis 66 Abscissa axis 70 Mains AC voltage source 72 Mains AC voltage 74 Mains AC current 76 Filter unit 78Rectifier unit 80DC voltage 84Period 86Half period 88Duration 90Further AC frequency 92Arithmetic unit 94Storage unit 96Further first phase shift 98Further second phase shift 100Induction device 102First process step 104Second process step 106Inductor

Claims

1. Induction device (10a; 10c), in particular induction cooking appliance device, having a plurality of induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) which can be controlled independently and at least one control unit (20a), which is provided to control the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) within a control period (22a) from a first control interval (26a) and at least one second control interval (28a) repetitively with at least one alternating current frequency (24a) and to supply the same with energy, wherein the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) are embodied as individual inductors or as a plurality of inductors (106c) which can be controlled jointly by the control unit (10a), wherein in the first control interval (26a), for the purpose of minimizing interferences, the control unit (20a) operates at least two of the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) with a first phase shift (32a), characterised in that the control unit (20a) calculates a phase angle (36a) of the first phase shift (32a) from a quotient of 180° and a number of inductors (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) to be operated simultaneously within the first control interval (26a).

2. Induction device (10a; 10c) according to claim 1, characterised in that in the second control interval (28a) the control unit (20a) operates the at least two induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) with a second phase shift (34a) which differs from the first phase shift (32a).

3. Induction device (10a; 10b; 10c) according to claim 1 or 2, characterised in that in the first control interval (26a; 26b) the control unit (20a; 20b) operates at least a further one of the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) with a further first phase shift.

4. Induction device (10a; 10c) according to one of the preceding claims, characterised in that in the second control interval (28a; 28b) the control unit (20a) operates at least a further one of the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) with a further second phase shift.

5. Induction device (10a; 10c) according to one of the preceding claims, characterised in that a duration of at least one of the control intervals (26a, 28a, 30a), in particular all control intervals (26a, 28a, 30a), is in each case shorter than half a cycle time (86a) of a mains alternating voltage (72a).

6. Induction device (10a; 10c) according to one of the preceding claims, characterised in that a duration (88a) of the cycle time (22a; 22b) is shorter than half a cycle time (86a) of a mains alternating voltage (72a).

7. Induction device (10a; 10c) according to one of the preceding claims, characterised in that in at least one of the control intervals (26a; 28a, 30a) the control unit (20a) controls at least one of the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) with the alternating current frequency (24a) and at least a further one of the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) with a further alternating current frequency which differs from the alternating current frequency (24a).

8. Induction device (10a; 10c) according to claim 7, characterised in that the further alternating current frequency is an integral multiple of the alternating current frequency (24a).

9. Induction device (10a; 10c) according to one of claims 1 to 6, characterised in that in at least one of the control intervals (26a; 28a, 30a), in particular the first control interval (26a), the control unit controls at least two of the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c), in particular the at least two induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c), with the same alternating current frequency (24a).

10. Induction cooking appliance (100a), in particular an induction hob, with an induction device (10a; 10c) according to one of the preceding claims.

11. Method for operating an induction device (10a; 10c), in particular an induction cooking appliance device, in particular according to one of claims 1 to 9, having a plurality of induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) which can be controlled independently of one another and are embodied as an inductor or a plurality of inductors, wherein the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) within a control period (22a) from at least two consecutive control intervals (26a, 28a, 30a) are controlled repetitively with at least one alternating current frequency (24a) and supplied with energy, wherein in order to minimise interference influences in at least one of the control intervals (26a, 28a, 30a), at least two of the induction areas (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) are operated with a phase shift (32a), characterised in that a phase angle (36a) of the first phase shift (32a) is calculated from a quotient from 180° and a number of inductors (12a, 14a, 16a, 18a; 12c, 14c, 16c, 18c) to be operated simultaneously within the first control interval (26a).

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