Switching device, domestic installation, and method for operating a heating device

Abstract

The invention provides a switching device (10) for operating an external heating device (20) for heating a medium (F) by means of a plurality of heating elements (21-i) of the heating device (20), a domestic installation (100), and various methods for heating a medium (F). The switching device (10) can, if heating elements (21-i) of the heating device (20) are interconnected at a common star point (22) and can be connected to the switching device (10) independently of one another, be configured to be supplied by at least one current phase (L) and include a control device (11) which is configured to switch the heating elements (21-i) independently of one another via at least one associated switch (Ki, Kia, KN) of the switching device (10) for the staged adjustment of the total heating power generated by the heating device (20) according to a respective heating stage.

Description

Field of invention

[0001] The invention relates to a switching device and a method for operating or controlling a heating device for heating a medium, as well as a domestic heating system with such a switching device and such a heating device. The medium can be, in particular, a fluid, i.e., a gas or a liquid, e.g., water. The heating device can therefore, in particular, have a plurality of heating elements to heat water in a water tank. For example, the switching device can operate a three-phase heating element for a water tank in a domestic heating system. Technical background

[0002] The optimal utilization of available electrical power is also steadily increasing in importance with the growing prevalence of renewable energy sources. Energy storage, in particular, is a key component in this.

[0003] It is known that many media, especially fluids such as water or molten salt, can be used to store energy in the form of heat. Particularly in households, where hot water is constantly needed, water in a tank can be preheated when there is a surplus of electrical power available. For this purpose, it is advantageous if the heating power used to heat the medium can be adjusted as precisely as possible in a cost-effective manner, so that the available surplus power can be used optimally.

[0004] Existing domestic hot water systems are typically already equipped with a water tank and heating element, often a single-phase or three-phase heating element. However, power electronics to operate such heating elements with precisely adjustable electrical output are usually not present and would be relatively expensive to retrofit. Summary of the invention

[0005] In light of the foregoing, it is therefore an object of the present invention to provide a switching device with which even an existing heating system can be switched in a cost-effective manner in order to provide different heating levels and thus desired heating outputs. A further object is to provide a method for operating an existing heating system in the manner described, as well as an improved domestic heating system for better utilization of available electrical power, particularly from renewable energy sources.

[0006] These problems are solved by the subject matter of the independent patent claims.

[0007] Accordingly, according to a first aspect of the invention, a switching device for operating an external heating device for heating a medium by means of a plurality of heating elements of the heating device is provided, which are interconnected at a common star point (in a star configuration) and can be connected (or are connected) to the switching device independently of one another, wherein the switching device is configured to be supplied by at least one current phase and comprises a control device which is configured to switch the heating elements independently of one another via at least one associated switch of the switching device for the staged adjustment of a heating power generated by the heating device as a whole according to a respective heating stage.

[0008] It can be arranged that the control unit is informed of a desired heating output value (i.e., a total heating output setpoint), and the control unit then selects a heating stage that optimally achieves the communicated total heating output setpoint. Alternatively, it can also be arranged that the control unit is only informed of a heating stage (for example, by a higher-level energy management system). The information about which heating stage corresponds to which total heating output can accordingly be stored in the energy management system and / or in the switching device, in particular the control unit. The boundaries can also be fluid, as the energy management system can be integrated into the switching device or vice versa.

[0009] A similar principle applies to the selection of a specific switching combination to achieve a desired heating level; that is, it can be specified by a higher-level system (e.g., the energy management system) or selected by the control device itself. For improved compatibility of the switching device with existing energy management systems, it can be advantageous if the energy management system only informs the switching device of the desired total heating output (i.e., the total heating output setpoint), and the switching device then selects and sets the heating level and a suitable switching combination for its implementation.

[0010] This approach enables optimal utilization of available electrical energy, particularly energy from renewable sources. However, this does not necessarily mean complete utilization, as other parameters and constraints may play a role, such as a desired upper temperature threshold for the water, the priority of charging a battery connected to the home's electrical system (e.g., an electric vehicle battery for an upcoming trip), and so on. In some models, the battery can be considered a renewable energy source, while in others it can be considered separately.

[0011] The present solution is also cost-effective to implement, as it requires little hardware and can also be advantageously combined with existing heating systems.

[0012] Advantageously, the controllable switches of the switching device have relays or (preferably) semiconductor switches, or each consist of a relay or (preferably) a semiconductor switch.

[0013] According to some preferred embodiments, variants, or refinements of embodiments, the switching device is configured to switch between at least five heating stages, particularly preferably at least seven heating stages, with different heating power levels. In this way, many control programs can already be implemented with comparatively high precision. Switching devices with nine, eleven, twelve, thirteen, or even more achievable heating stages are also advantageous.

[0014] According to some preferred embodiments, variants, or refinements of embodiments, a diode is connected in parallel to at least one switch, optionally only this diode, or preferably a series connection of the diode and another switch. A half-wave of alternating current can be filtered out via the parallel-connected diode to enable additional heating stages. This diode can also be selectively switched on or off by the additional switch to enable further heating stages.

[0015] According to some preferred embodiments, variants, or refinements of embodiments, the switching device has one output for each heating element to be connected, with the switch belonging to the corresponding heating element being connected in series with the output. Advantageously, each switch can be individually controlled by the control unit. However, other variants are also conceivable in which some outputs are connected differently, for example, by means of a toggle switch that can switch between a live phase and the neutral conductor. In this way, additional heating stages can be implemented even with existing heating device hardware. The outputs of the switching device can be implemented mechanically in a common socket or in separate sockets.

[0016] According to some preferred embodiments, variants, or refinements of embodiments, the control device is also configured to periodically or sequentially switch between realizations of the same heating power using different switching combinations (i.e., combinations of switch positions). As will be explained below, there are often heating stages that can be implemented using several switching combinations. Periodic switching ensures that the individual heating elements of the heating device, as well as the switches of the switching device, wear evenly to maximize the service life of the heating device. Additionally or alternatively, it can also be provided that, with each new setting of a heating stage with multiple implementation possibilities, the control device cyclically cycles through the different switching combinations sequentially.This method also ensures particularly even wear of the heating elements, switches, etc.

[0017] According to some preferred embodiments, variants, or refinements of embodiments, the switching device, in particular the control unit, is configured to receive a current power value from a renewable energy source (especially a PV system) and to adjust a current heating stage at least based on the received current power value. This allows for optimal utilization of the power currently provided by the renewable energy source. This can include adjusting an overall heating power setpoint by the switching device.

[0018] According to some preferred embodiments, variants, or refinements of embodiments, the control device is configured to also adjust the current heating stage based on an overall heating output setpoint. In this way, the switching device according to the invention can advantageously be used within the framework of an energy management system or a managed building system according to a control or regulation method. The instructions (or: control commands) for adjusting the current heating stage can therefore be generated, for example, by the energy management system.

[0019] According to some preferred embodiments, variants, or refinements of embodiments, the control device is configured to adjust the current heating stage such that the difference between the total heating output generated by the heating device and the total heating output setpoint is minimized. The switching device can also be used in a control or regulation system in this way.

[0020] According to some preferred embodiments, variants, or refinements of embodiments, the control device is designed to perform a measurement procedure to determine which heating stages are available and / or what total heating power is achieved with each of the available heating stages. For this purpose, a test voltage can be applied to each switch of the switching device, every possible switching combination can be cycled through, and the power consumed by the heating device can be determined for each switching combination.

[0021] This method allows us to determine which switching combinations belong to the same heating stage, i.e., achieve the same total heating output, and what that total heating output is numerically. The measurement procedure can be performed automatically, for example, during each initialization of the switching device, or upon user request. The measurement procedure can also determine whether the heating element is connected to the switching device via a single-phase or three-phase connection. This makes the switching device particularly versatile and easy to install, as it can acquire the necessary information itself.

[0022] According to a second aspect, the present invention provides a domestic installation comprising a switching device according to an embodiment of the first aspect of the present invention, as well as a heating device connected to (or wired to) the switching device and configured to operate the switching device. The domestic installation may also include a medium to be heated, e.g., a heat-radiating material of an infrared heating panel, and / or a fluid tank for storing a fluid, wherein the fluid in the fluid tank can be heated by means of the heating device. In particular, the fluid may be water.

[0023] According to some preferred embodiments, variants, or refinements of embodiments, the heating elements are arranged in an infrared heating panel, an instantaneous water heater, or a fluid tank. In the case of the fluid tank, the heating elements can, for example, be arranged in a wall opening of the fluid tank, and in particular, screwed into it.

[0024] According to some preferred embodiments, variants, or refinements of embodiments, the domestic system also includes a user interface by means of which one or more setpoint parameters of the heating device, the medium, and / or a fluid tank for the medium can be set. The parameter may, for example, be a setpoint temperature of the medium, an upper threshold for the temperature of the medium, a total heating output setpoint, a heating energy setpoint, and / or the like.

[0025] The user interface can also be used to adjust other parameters of the building system, such as a charge level threshold for a battery in the building system, or similar settings. The user interface can be integrated into the switching device or an energy management system of the building system, or it can be a separate unit. The user interface can be a graphical user interface, which is implemented – for example, as part of an application – on a smartphone, tablet, desktop PC, or similar device.

[0026] According to some preferred embodiments, variants, or refinements of embodiments, several heating elements, e.g., at least two, more than 50% of the heating elements, or all heating elements of the heating device have the same electrical heating resistance value. If all heating elements have the same heating resistance value, this can also be described as a symmetrical variant S. This is frequently the case with existing heating devices, e.g., 3-phase heating elements, resulting in high synergy effects with the numerous switching combinations and correspondingly realizable heating stages of the switching device according to the invention. Alternatively, some or all heating elements can have different electrical heating resistances. This allows for additional heating stages. If all heating elements have different heating resistance values, this can also be described as an asymmetrical variant A.

[0027] According to some preferred embodiments, variants, or refinements of embodiments, the domestic system also includes a battery and an energy management system configured to monitor the battery's state of charge and to allow or prevent energy from being drawn from the battery to operate the heating system based on the state of charge. This allows for optimal interaction between the two energy sinks or energy storage devices, namely the medium on the one hand and the battery on the other.

[0028] The energy management system can be configured to control the switching device and set a higher heating level than the current one. For this purpose, or independently of this, the energy management system can, for example, provide, according to a user-configurable or preset priority, additional power from a renewable energy source within the building's electrical system and / or from a battery within the building's electrical system, and / or additional power from the public power grid, and / or the power consumption of at least one local consumer within the building's electrical system is reduced. In particular, the power consumption of local consumers connected to the building's (multi-pole) electrical system ("building electrical system") can be reduced. Such a local consumer could be, for example, a heat pump or a well or pool pump.

[0029] The energy management system can also be configured to control the switching device and set a lower heating level than the current one. For this purpose, the aforementioned measures can be reversed or terminated accordingly.

[0030] The energy management system can also be set up to monitor the state of charge of a battery in the building system and only allow the drawing of additional power from the battery if the state of charge of the battery is above a user-adjustable or preset state of charge threshold.

[0031] The building's heating system can be configured so that the switching device switches to a lower heating level than the current one if insufficient power is available (from the building's renewable energy sources). For this purpose, the energy management system can either instruct the switching device's control unit to reduce the heating level if insufficient power is available. Alternatively, the energy management system can provide information about the available power to the control unit, which in turn can be configured to adjust the heating level accordingly, i.e., increase or decrease it.

[0032] According to a third aspect, the present invention provides a switching device for operating an external heating device for heating a medium by means of at least one heating element of the heating device, wherein the switching device is configured to be supplied by at least one current phase and comprises a control device which is configured to switch the heating element via at least one associated switch of the switching device for (stage) adjustment of a total heating power generated by the heating device according to a respective heating stage, wherein a diode is connected in parallel to the switch.

[0033] In this way, by selectively bridging or not bridging the diode using the switch, at least one additional heating stage can be realized, since the diode filters out one of the half-waves of alternating electrical voltage.

[0034] According to a fourth aspect, the invention provides a method for operating a heating device (or: for heating a medium by means of a heating device) with a plurality of heating elements which are interconnected at a common star point (in a star configuration) and can be connected (or are connected) independently to an energy source. The method comprises at least the following steps: Determining a desired total heating output, i.e., a total heating output setpoint; determining a heating stage that corresponds as closely (or exactly) to the desired heating output (i.e., the total heating output setpoint), i.e., in particular, that comes as close as possible to it; and switching the heating elements independently of each other via at least one associated switch for (stepped) adjustment of the specific heating stage.

[0035] According to a fifth aspect, the invention provides a method for operating a heating device with at least one heating element (or: for heating a medium by means of at least one heating element of a heating device). The method comprises at least the following steps: Determining a desired total heating output, i.e., a total heating output setpoint; determining a heating stage that best corresponds to the desired total heating output (i.e., the total heating output setpoint); and switching at least one switch, which is arranged between a current phase and the at least one heating element of the heating device, and which is connected in parallel with a diode (optionally with a series circuit of the diode and another switch), for the (stepped) adjustment of the determined heating stage.

[0036] According to a sixth aspect, the invention provides a computer program product which includes executable program code which, when executed (e.g. by means of a computing device), is configured to execute the method according to an embodiment of the fourth or fifth aspect of the present invention.

[0037] According to a seventh aspect, the invention provides a non-volatile, computer-readable data storage medium comprising executable program code which, when executed (e.g. by means of a computing device), is configured to execute the method according to an embodiment of the fourth or fifth aspect of the present invention.

[0038] The non-volatile, computer-readable data storage medium can, for example, be a semiconductor memory, such as an SSD. The data storage medium can also be a CD, DVD, Blu-ray disc, or a magnetic storage device.

[0039] According to an eighth aspect, the invention provides a data stream which includes executable program code or is configured to generate program code which, when executed (e.g. by means of a computing device), is configured to execute the method according to an embodiment of the fourth or fifth aspect of the present invention.

[0040] A computing device can be any device designed and configured for digital computing, in particular for executing software, an application, or an algorithm. For example, a computing device can include at least one processor unit (e.g., at least one CPU), at least one graphics processing unit (e.g., at least one GPU), at least one field-programmable gate array (FPGA), and / or at least one application-specific integrated circuit (ASIC), and / or any combination of the aforementioned elements. The computing device can also include main memory and / or non-volatile data storage, which are operationally linked to each other and / or to some or all of the aforementioned elements.The computing facility can be implemented partially or completely in a local unit (for example, a personal computer, PC, laptop, notebook, or the like) and / or partially or completely in a distributed system, e.g., a cloud computing platform or a geographically separate server. Brief description of the characters

[0041] The invention is explained in more detail below with reference to exemplary embodiments shown in the figures of the drawings. These show: Fig. 1 is a schematic block diagram of a switching device and a building installation according to embodiments of the present invention; Figs. 2 to 15 show various possible circuits that can be realized by switching devices according to the invention; Fig. 16 is a schematic flowchart to explain a method according to one embodiment of the present invention; Fig. 17 is a schematic flowchart to explain a method according to a further embodiment of the present invention; Fig. 18 is a schematic block diagram of a computer program product according to yet another embodiment of the present invention; Fig. 19 is a schematic block diagram of a data storage medium according to yet another embodiment of the present invention; and Fig. 20 is a schematic flowchart to explain a method according to yet another embodiment of the present invention.

[0042] In all figures, identical or functionally equivalent elements and devices are designated with the same reference numerals, unless otherwise indicated. The designation and numbering of the process steps do not necessarily imply a sequence, but serve for better differentiation, although in some variants the sequence may correspond to the numbering sequence. Detailed description of the figures

[0043] Fig. 1Figure 1 shows a schematic block diagram of a switching device 10 and a building automation system 100 according to embodiments of the present invention. The switching device 10 can also be used or provided independently of the building automation system 100. The various components of the building automation system 100 are optional and can be included or omitted depending on the intended use or existing infrastructure. Furthermore, additional components not shown can, of course, be added.

[0044] The switching device 10 is designed to operate an external heating device 20 (relative to the switching device 10), which is designed to heat a medium. In this document, a fluid F in a fluid tank 50 (here, in particular, water in a water tank) is used as an example of such a medium. The heating device 20 can, for example, be arranged in a wall opening of the fluid tank 50, in particular by being screwed in. It is understood, however, that a wide variety of other media can also be heated, such as the radiant heater of an infrared panel or the like.

[0045] As will be explained in more detail below, the switching device 10 is designed such that it can switch the heating device 20 to one of a plurality of possible heating stages, each heating stage advantageously being associated with a different heating output of the heating device 20. It is particularly advantageous that the switching device 10 is also compatible with existing, relatively simple heating devices 20.

[0046] The switching device 10 comprises a control unit 11, which can be implemented by any computing unit, for example, a microcontroller, an application-specific integrated circuit (ASIC), a programmable logic controller (PLC), and / or the like. The control unit 11 can, in particular, be implemented partly in hardware and partly in software.

[0047] The switching device 10 is also configured to be supplied via at least one electrical line 34 by at least one current phase L, which can be a single current phase (L1, L2, L3) of a 3-phase alternating current, or two, or all of these current phases. The switching device 10 can also be connected to a neutral conductor N and / or a protective conductor PE via the at least one electrical line.

[0048] The switching device 10 also has a plurality of switches K1, K2, K3, which are hereinafter sometimes referred to collectively (or when it is irrelevant which specific switch is meant) as Ki. The control device 11 is configured to switch the switches Ki, i.e., in particular to open or close each switch Ki independently of the others (or: to switch it on or off).

[0049] Each of the switches Ki is designed to be connected to a heating device 20 with a single heating element 21-1, 21-2, 21-3, in particular such that the corresponding heating element 21-i heats up when the corresponding switch Ki is closed, and does not heat up when the corresponding switch Ki is open. For this purpose, each switch Ki can be electrically connected to a (in particular: exactly one) corresponding terminal 16-i on a housing of the switching device 10, so that each heating element 21-i only needs to be electrically connected to one of the corresponding terminals 16-i.

[0050] At each output of the heating elements 21-1, 21-2, 21-2 facing away from the switches K1, K2, K3, the heating elements 21-i are connected to a common star point 22, i.e., they are star-coupled.

[0051] A neutral conductor N can be connected to a terminal 17 of the switching device 10, which can optionally be switched by the control unit 11 via a switch KN of the switching device 10. Which switches Ki, KN can be switched can vary from installation location to installation location depending on the applicable rules, standards, or laws, and can be configured in the control unit 11. The switches K1, K2, K3 can be designed as relays or semiconductor switches, or can include a relay or a semiconductor switch.

[0052] The invention is described here by way of example with three (preferably semiconductor) switches K1, K2, K3 for operating exactly three heating elements 21-i. It is understood, however, that fewer (for example, two switches Ki) or more switches Ki are also possible. This applies to each of the embodiments described herein. It is advantageous if the number of switches Ki is equal to, or at least greater than, the number of heating elements 21-i.

[0053] Each heating element 21-i contributes its own heating power P i to heat the fluid F, whereby a maximum total heating power P max = P 1 + P 2 + P 3 is provided when all switches Ki are closed. Advantageously, the control unit 11 has information about which heating power P i can be supplied to which switch Ki or which of the connections 16-i is available.

[0054] This information (which individual heating output P i can be provided) can be programmed into the switching device via a user interface 12 or selected from a table. It is also conceivable that the control unit 11 contains a database of common models of the heating device 20, from which the user can then select the appropriate model with its corresponding individual heating outputs P i.

[0055] The user interface 12 can be provided, instead of and / or in addition to the switching device 10, for example also on an energy management system 40 of the building system 100, which is coupled to the switching device 10 for data communication. The energy management system 40 of the building system 100 can also be integrated into the switching device 10 or vice versa.

[0056] For models of heating devices 20 which have different heating powers P i of their heating elements 21-i, the user may additionally be required to specify, when installing the switching device 10, at which terminal 16-i which heating power P i (or: which heating resistance) is applied.

[0057] However, the control device 11 is particularly preferably designed to perform a measurement procedure (e.g., for current, voltage, and / or frequency) to determine which heating resistances are present, which heating stages are available, and / or which total heating power P is achieved with each of the available heating stages. For this purpose, the control device 11 can apply a test voltage to each switch K1, K2, K3 of the switching device 10, cycle through every possible switching combination, and determine the power consumed by the heating device 20 for each switching combination.

[0058] In this way, it is possible to determine which switching combinations belong to the same heating stage, i.e., realize the same total heating output P, ​​and what this total heating output P is numerically (or quantitatively) in each case. The measurement procedure can be carried out automatically, e.g., during each initialization of the switching device 10, or upon request by a user via the user interface 12. As part of the measurement procedure, it can also be determined whether the heating device 20 is connected to the switching device 10 via a 3-phase or a 1-phase connection.

[0059] If the control unit 11 has the information about which heating stage corresponds to which total heating output, it is advantageous to only be informed of a total heating output setpoint (for example, by the energy management system 40). The control unit 11 then independently determines which heating stage best corresponds to this total heating output setpoint, selects a corresponding switching combination, and then sets it. Accordingly, we will mainly refer to the desired heating stage in the following, whereby it is understood that this can be determined in each case to achieve the best possible realization of a total heating output setpoint.

[0060] The total heating output setpoint can be determined, for example, depending on how much electrical power is currently generated by renewable energy sources, how much electrical power remains after deducting the total consumption of consumers 32, what the current electricity price is, and / or similar factors.

[0061] The following mainly describes the case where all heating elements 21-i have the same heating power P i ("symmetrical variant", S), since this is a common design for heating devices 20. However, it is understood that everything said can also be applied analogously to heating devices 20 which have different heating elements 21-i with different heating powers P i.

[0062] The heating elements 21-i can each have (at least) one heating resistor or consist of one. The total number of all resistors in a heating element 21-i used for heating provides the heating power P i of the corresponding heating element 21-i.

[0063] The exact interconnection of the heating elements 21-i with each other and with current phases of a power supply is described in Fig. 1 The diagram is only schematic. Actual possible circuits that can be implemented using the switching device 10 will be explained in more detail below.

[0064] However, it is already evident that the control device 11 is designed to switch the heating elements 21-i independently of each other via at least one associated switch Ki of the switching device 10 for the staged adjustment of a total heating power P to be generated (or: generated) by the heating device 20 according to a respective heating stage.

[0065] The inventive house system 100 comprises at least the switching device 10 and the heating device 20. The switching device 10 is supplied with electrical power via a power grid 30 (for example, a multi-pole house power grid of a household). The power grid 30 can have a grid connection point 31 for connection to the public power grid 35 and at least one consumer 32, for example, a heat pump.

[0066] The combination of the switch positions of the switches Ki and the connection of the terminals 16-i by the switching device 10 results in a hierarchy of heating stages, with the lowest heating stage (all switches Ki open) corresponding to a heating power of 0 watts, and the highest heating stage (all switches Ki closed) corresponding to a maximum total heating power of P max .

[0067] The following section will first present a series of possible wiring configurations based on the Figs. 2 to 15The following will be described to demonstrate the diverse possibilities of the present invention. The corresponding hierarchy of heating stages will also be explained in each case. Subsequently, it will be explained how the heating stages can be used for the efficient utilization of available energy, particularly from renewable energy sources. It is already evident, however, that the large number of available heating stages allows the current total heating output P of the heating device 20 to be adjusted particularly appropriately and flexibly. This minimizes the difference between the total heating output generated by the heating device 20 and the total heating output setpoint.

[0068] Fig. 2 Figure 1 shows a possible wiring configuration using the switching device 10 according to one embodiment. Here, the switching device 10 (in Fig. 2(not fully shown) Each of the three terminals 16-1, 16-2, 16-3 is connected to a corresponding current phase L1, L2, L3 of a 3-phase alternating current, while the star point 22 is connected to a neutral conductor N, or directly to the output 17 of the switching device 10. The heating elements 21-i each have a heating resistor R1, R2, R3.

[0069] In this variant, no switch KN is required on the neutral conductor N and can therefore also be omitted from the switching device 10; i.e., the neutral conductor N can remain without a switch. This is advantageous in areas where switching the neutral conductor N is prohibited.

[0070] In a first variant S ("symmetrical"), which corresponds to the operation of a conventional 3-phase heating element, R1=R2=R3=R (not shown). This configuration allows for four different heating levels, each corresponding to a different total heating power P. Table 1 below lists the individual switch settings in the first three columns (0 corresponds to "switch open", 1 corresponds to "switch closed"). The corresponding set (or: selected) total heating powers P are given in the fourth column as a fraction of the maximum total heating power Pmax. Thus, the four different achievable heating levels correspond, for example, to total heating powers of 0, 1 / 3 Pmax, 2 / 3 Pmax, and Pmax. The fifth column gives, for example, corresponding wattage values ​​with a heating resistance R = 26.45 Ω and a voltage of 230 V (N to Li, i.e.,from neutral conductor to phase) and a maximum total heating output of P max = 6 kW. Table 1: Available heating levels of variant S from Fig. 2 Wiring according to Fig. 2 Variant S: 4 heating levels K1 K2 K3 P R1=R2=R3=26.45 Ω 0 0 0 0 P max 0 0 0 1 1 / 3 P max 2000 W 0 1 0 1 / 3 P max 2000 W 0 1 1 2 / 3 P max 4000 W 1 0 0 1 / 3 P max 2000 W 1 0 1 2 / 3 P max 4000 W 1 1 0 2 / 3 P max 4000 W 1 1 1 P max 6000 W

[0071] The two intermediate heating levels, corresponding to the total heating outputs 1 / 3 P max and 2 / 3 P max, can each be achieved through three different switching combinations of the switches Ki. Thus, the control unit 11 can be configured, when one of these two heating levels is set, to periodically and / or cyclically select a different switching combination of the switches Ki in succession, in order to evenly stress and wear the corresponding heating elements 21-i and the switches 16-i. This also applies to each of the embodiments discussed below, provided they have at least one heating level that can be realized by more than one switching combination. Therefore, switching between the switching combinations can be performed periodically and / or cyclically.

[0072] In a second variant A ("asymmetric"), R1, R2, and R3 are all different, as in Fig. 2This circuit configuration allows for seven different heating levels, each with a different total heating power P. According to Table 2 below, the seven achievable heating levels correspond, for example, to the total heating powers 0, 1 / 6 P max, 1 / 3 P max, 1 / 2 P max, 2 / 3 P max, 5 / 6 P max, and P max when R2 = R1 / 3 and R3 = R1 / 2. The fifth column gives, for example, corresponding wattage values ​​with heating resistances of R1 = 52.9 Ω, R2 = 17.63 Ω, and R3 = 26.45 Ω, at a voltage of 230 V (LN). Table 2: Available heating levels of variant A from Fig. 2 Wiring according Fig. 2 Variant A: 7 heating levels K1 K2 K3 P R1 = 52.9 Ω / R2 = 17.63 Ω / R3 = 26.45 Ω 0 0 0 0 P max 0 0 0 1 1 / 2 P max 3000 W 0 1 0 1 / 3 P max 2000 W 0 1 1 5 / 6 P max 5000 W 1 0 0 1 / 6 P max 1000 W 1 0 1 2 / 3 P max 4000 W 1 1 0 1 / 2 P max 3000 W 1 1 1 P max 6000 W

[0073] Here and in the following, without loss of generality, the case is described where, in the asymmetrical variants, R1 has the highest ohmic resistance. It is understood, however, that other permutations are also possible. The resistor labeled R1 can also be connected to terminal 16-2 or 16-3, and so on in any permutation.

[0074] Fig. 3 The diagram shows a circuit through the switching device 10 according to a further embodiment. Here, the heating device 20 to be operated is a 3-phase heating element, which, however – unlike the variants of Fig. 2 - is to be operated with a single-phase power supply. Accordingly, all three terminals 16-i can be connected to the L1 current phase via the switching device 10. The heating stages achievable in this way for the symmetrical variant S with R=R1=R2=R3 or an asymmetrical variant correspond again to those in Table 1 and Table 2.

[0075] Fig. 4 Figure 1 shows a circuit through the switching device 10 according to a further embodiment. This embodiment differs from the one shown in Figure 2. Fig. 2 because the switching device 10 here has the switch KN on the neutral conductor N. Accordingly, a total of 5 heating stages according to the following Table 3 are available for the symmetrical variant with R1=R2=R3=R (in Fig. 4 (shown) available: Table 3: Available heating levels of variant S from Fig. 4 Wiring according Fig. 4 Variant S: 5 heating levels K1 K2 K3 KN P R = 26.45 Ω 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 1 1 1 / 3 P max 2000 W 0 1 0 0 0 0 0 1 0 1 1 / 3 P max 2000 W 0 1 1 0 1 / 2 P max 3000 W 0 1 1 1 2 / 3 P max 4000 W 1 0 0 0 0 0 1 0 0 1 1 / 3 P max 2000 W 1 0 1 0 1 / 2 P max 3000 W 1 0 1 1 2 / 3 P max 4000 W 1 1 0 0 1 / 2 P max 3000 W 1 1 0 1 2 / 3 P max 4000 W 1 1 1 0 P max 6000 W 1 1 1 1 P max 6000 W

[0076] The five heating levels correspond to the total heating outputs P of 0 (5 switching combinations), 1 / 3 P max (3 switching combinations), 1 / 2 P max (3 switching combinations), 2 / 3 P max (4 switching combinations), and P max (2 switching combinations). An asymmetrical version would result in correspondingly more heating levels. This also applies to the wiring according to... Fig. 4 Is it possible to operate a single-phase heating element by replacing L2 and L3 in Fig. 4 L1 is also set (not shown).

[0077] Fig. 5 Figure 1 shows a circuit through the switching device 10 according to a further embodiment. This embodiment differs from the one shown in Figure 2. Fig. 2or 4, by the fact that the switching device 10 here has the switch KN on the neutral conductor N, and that the output 16-2 can be switched between a connection to L2 or a connection to the neutral conductor N via the switch K2 (toggle switch). Accordingly, a total of 7 heating stages are available according to Table 4 below for the symmetrical variant S with R1=R2=R3=R (not shown), or 12 heating stages are available according to Table 5 for the asymmetrical variant A (shown): Table 4: Available heating levels of variant S from Fig. 5 Wiring according Fig. 5 Variant S: 7 heating levels K1 K2 K3 KN P R1=R2=R3=R= 26.45 Ω 0 N 0 0 0 0 0 N 0 1 0 0 0 N 1 0 1 / 6 P max 1000 W 0 N 1 1 1 / 3 P max 2000 W 0 L2 0 0 0 0 0 L2 0 1 1 / 3 P ampf 2000 W 0 L2 1 0 1 / 2 P max 3000 W 0 L2 1 1 2 / 3 P max 4000 W 1 N 0 0 1 / 6 P max 1000 W 1 N 0 1 1 / 3 P max 2000 W 1 N 1 0 5 / 9 P max 3333 W 1 N 1 1 2 / 3 P max 4000 W 1 L2 0 0 1 / 2 P max 3000 W 1 L2 0 1 2 / 3 P max 4000 W 1 L2 1 0 P max 6000 W 1 L2 1 1 P max 6000 W

[0078] The seven heating levels each correspond to the total heating power P of 0, 1 / 6 P max , 1 / 3 P max , 1 / 2 P max , 5 / 9 P max , 2 / 3 P max , and P max .

[0079] This variant illustrates the general case where the switching device 10 can have a switch (here: K2) which can be switched between one of the current phases L1, L2, L3, i.e., a live conductor, on the one hand, and the neutral conductor N on the other. That is, the corresponding heating element 21-2 with its heating resistor R2 is alternatively connected to the corresponding current phase L1, L2, L3 or the neutral conductor N. Table 5: Available heating levels of variant A from Fig. 5 Wiring according Fig. 5 Variant A: 12 heating levels K1 K2 K3 KN P R1 = 52.9Ω / R2 = 26.45Ω / R3 = 17.63Ω 0 N 0 0 0 0 0 N 0 1 0 0 0 N 1 0 1 / 5 P max 1200 W 0 N 1 1 1 / 2 P max 3000 W 0 L2 0 0 0 0 0 L2 0 1 1 / 3 P max 2000 W 0 L2 1 0 3 / 5 P max 3600 W 0 L2 1 1 5 / 6 P max 5000 W 1 N 0 0 1 / 9 P max 666 W 1 N 0 1 1 / 6 P max 1000 W 1 N 1 0 10 / 31 P max 1935 W 1 N 1 1 2 / 3 P max 4000 W 1 L2 0 0 1 / 3 P max 2000 W 1 L2 0 1 1 / 2 P max 3000 W 1 L2 1 0 11 / 12 P max 5500 W 1 L2 1 1 P max 6000 W

[0080] The twelve heating levels that can be implemented here using R1=2R2=3R3 as an example each correspond to the total heating power P of 0, 1 / 9 P max , 1 / 6 P max , 1 / 5 P max , 10 / 31 P max , 1 / 3 P max , 1 / 2 P max , 3 / 5 P max , 2 / 3 P max , 5 / 6 P max , 11 / 12 P max , and P max .

[0081] Fig. 6 shows a circuit through the switching device 10 according to a further embodiment, which is a variant of the circuit of Fig. 5 represents. Fig. 6 The heating device 20 to be operated is again a 3-phase heating element, which, however, is to be operated with a 1-phase power supply. Accordingly, all three terminals 16-i are connected to the L1 current phase by the switching device 10. This makes six heating stages possible, which are listed in the following Table 6. Although in Fig. 6Where a symmetrical variant S is shown, it is understood that an asymmetrical variant with partially or completely different heating resistances R1, R2, R2 can also be provided. Table 6: Available heating levels of variant S from Fig. 6 Wiring according Fig. 6 Variant S: 6 heating levels K1 K2 K3 KN P R1=R2=R3=R= 26.45 Ω 0 N 0 0 0 0 0 N 0 1 1 / 3 P max 2000 W 0 N 1 0 0 0 0 N 1 1 2 / 3 P max 4000 W 0 L2 0 0 0 0 0 L2 0 1 0 0 0 L2 1 0 1 / 6 P max 1000 W 0 L2 1 1 1 / 3 P max 2000 W 1 N 0 0 0 0 1 N 0 1 2 / 3 P max 4000 W 1 N 1 0 0 0 1 N 1 1 P max 6000 W 1 L2 0 0 1 / 6 P max 1000 W 1 L2 0 1 1 / 3 P max 2000 W 1 L2 1 0 2 / 9 P max 1333 W 1 L2 1 1 2 / 3 P max 4000 W

[0082] The six heating levels each correspond to the total heating power P of 0, 1 / 6 P max , 1 / 3 P max , 2 / 3 P max , 2 / 9 P max , and P max .

[0083] The following sections will show and explain embodiments, each of which has at least one diode connected in parallel with a respective switch.

[0084] The diodes make it possible to implement additional heating stages by blocking half-waves.

[0085] Fig. 7 Figure 1 shows a circuit connection via the switching device 10 according to a further embodiment. In this simple variant, a single-phase heating device 20 is operated, which comprises a single heating element 21-i with a heating resistor R (or a sum of heating resistors, which can be represented with R as the equivalent resistance).

[0086] The switching device 10 can be designed for such single-phase heating devices 20 with only two connections 16-1, 17 for the L1 live conductor and the neutral conductor, or be programmed to supply only these connections with power.

[0087] At terminal 16-1, which is intended for the L1 current conductor or the L1 current phase, the switching device 10 has a switch K1, which can be controlled by the control unit 11, and a diode 14 connected in parallel to this switch K1. In this way, three heating stages can be realized, as listed below in Table 7: 0, 1 / 2 P max, and P max. Table 7: Available heating levels of the variant shown in Fig. 7 Wiring according Fig. 7 : 3 Heating levels K1 KN P R=26.45 Ω 0 0 0 0 0 1 1 / 2 P max 1000 W 1 0 0 0 1 1 P max 2000 W

[0088] Fig. 8 shows a circuit through the switching device 10 according to a further embodiment, which is a variant of the embodiment according to Fig. 7This variant can be described as follows: In this version, the switching device 10 has a series circuit connected in parallel with the switch K1, consisting of another switch K1a, controllable by the control unit 11, and the diode 14. The switch K1a forms a series circuit with the diode 14. In this way, as listed in Table 8 below, three heating stages can also be implemented: 0, 1 / 2 P max, and P max. Table 8: Available heating levels of the variant shown in Fig. 8 Wiring according Fig. 8 : 3 Heating levels K1 K1a P R=26.45 Ω 0 0 0 0 0 1 1 / 2 P max 1000 W 1 0 P max 2000 W 1 1 P max 2000 W

[0089] The diode 14 (either alone in parallel with a switch K1, K2, K3 as in Fig. 7 , or in a series circuit with another switch K1a, wherein this series circuit is connected in parallel to a switch K1, K2, K3, as in Fig. 8 ) can also be advantageously combined with other variants, in particular with 3-phase heating systems 20.

[0090] Fig. 9 shows a variant of the wiring Fig. 2 , which differs from this by a diode 14 connected in parallel with the switch K1 and the missing connection of the star point 22 to the neutral conductor N. Accordingly, the switching device 10 can also be configured without the connection 17 and thus, for example, have only exactly one connection 16-1, 16-2, 16-3 per current phase L1, L2, L3.

[0091] In a symmetrical variant S with R1=R2=R3=R (not shown) 5 heating stages can be realized in this way, as listed in Table 9: Table 9: Available heating levels of variant S from Fig. 9 Wiring according Fig. 9 Variant S: 5 heating levels K1 K2 K3 P R1=R2=R3=R= 26.45 Ω 0 0 0 0 0 0 0 0 1 / 4 P max 1500 W 0 0 1 1 / 4 P max 1500 W 0 0 1 3 / 4 P max 4500 W 0 1 0 0 0 0 1 0 1 / 2 P max 3000 W 0 1 1 1 / 2 P max 3000 W 1 1 1 P max 6000 W

[0092] The five heating levels that can be achieved in this way are therefore: 0, 1 / 4 P max , 1 / 2 P max , 3 / 4 P max , and P max .

[0093] In an asymmetrical variant A (shown) with three different resistors R1, R2, R3, 7 heating stages can be realized, as listed in Table 10: Table 10: Available heating levels of variant A from Fig. 9 Wiring according Fig. 9 Variant A: 7 heating levels K1 K2 K3 P R1 = 52.9Ω / R2 = 26.45Ω / R3 = 17.63Ω 0 0 0 0 0 0 0 0 56 / 275 P max 1120 W 0 0 1 2 / 11 P max 1000 W 0 0 1 91 / 110 P max 4550 W 0 1 0 0 0 0 1 0 9 / 22 P max 2250 W 0 1 1 4 / 11 P max 2000 W 0 1 1 P max 5500 W

[0094] The seven heating levels that can be realized in this way with R1=2R2=3R3 are therefore: 0, 2 / 11 P max, 56 / 275 P max, 4 / 11 P max, 9 / 22 P max, 91 / 110 P max, and P max.

[0095] Fig. 10 shows a single-phase operated (or: single-phase coupled) variant of the circuit. Fig. 9 The neutral conductor N can be connected to switch K2 and terminal 16-2 (shown) or to switch K3 and terminal 16-3 (not shown).

[0096] In a symmetrical variant S with R1=R2=R3=R (not shown) 5 heating stages can be realized in this way, as listed in Table 11: Table 11: Available heating levels of variant S from Fig. 10 Wiring according Fig. 10 Variant S: 5 heating levels K1 K2 K3 P R1=R2=R3=R= 26.45 Ω 0 0 0 0 0 0 0 0 0 0 0 0 1 3 / 8 P max 500 W 0 0 1 22 / 25 P max 1175 W 0 1 0 0 0 0 1 0 0 0 0 1 1 3 / 4 P max 1000 W 0 1 1 P max 1333 W

[0097] The five heating levels that can be achieved in this way are therefore: 0, 3 / 8 P max , 3 / 4 P max , 22 / 25 P max , and P max .

[0098] In an asymmetric variant A (shown in Fig. 10 ) with three different resistors R1, R2, R3, five heating stages can also be implemented, as listed in Table 12: Table 12: Available heating levels of variant A from Fig. 10 Wiring according Fig. 10 Variant A: 5 heating levels K1 K2 K3 P R1 = 52.9Ω / R2 = 17.63Ω / R3 = 26.45Ω 0 0 0 0 0 0 0 0 1 / 4 P max 375 W 0 0 1 0 0 0 0 1 9 / 10 P max 1350 W 0 1 0 0 0 0 1 0 1 / 2 P max 750 W 0 1 1 0 0 1 1 1 P max 1500 W

[0099] The five heating levels that can be implemented in this way using R1=3R2=2R3 are therefore: 0, 1 / 4 P max , 1 / 2 P max , 9 / 10 P max , P max .

[0100] Fig. 11 shows a variant of the wiring Fig. 9 , wherein the circuit or switching device 10 consists of Fig. 11 in contrast to the wiring or switching device 10 from Fig. 9 has a neutral conductor N connected to the terminal 17 of the switching device 10, which can be switched by a switch KN ("neutral conductor switch") of the switching device 10.

[0101] In a symmetrical variant S with R1=R2=R3=R (not shown) 9 heating stages can be realized in this way, as listed in Table 13: Table 13: Available heating levels of variant S from Fig. 11 Wiring according Fig. 11 Variant S: 9 heating levels K1 K2 K3 KN P R1=R2=R3=R= 26.45 Ω 0 0 0 0 0 0 0 0 0 1 1 / 6 P max 1000 0 0 1 0 1 / 4 P max 1500 0 0 1 1 1 / 2 P max 3000 0 1 0 0 1 / 4 P max 1500 0 1 0 1 1 / 2 P max 3000 0 1 1 0 3 / 4 P max 4500 0 1 1 1 5 / 6 P max 5000 1 0 0 0 0 0 1 0 0 1 1 / 3 P max 2000 1 0 1 0 1 / 2 P max 3000 1 0 1 1 2 / 3 P max 4000 1 1 0 0 1 / 2 P max 3000 1 1 0 1 2 / 3 P max 4000 1 1 1 0 P max 6000 1 1 1 1 P max 6000

[0102] The nine heating levels that can be achieved in this way are therefore: 0, 1 / 6 P max , 1 / 4 P max , 1 / 3 P max , 1 / 2 P max , 2 / 3 P max , 3 / 4 P max , 5 / 6 P max and P max .

[0103] In an asymmetrical variant A (shown) with three different resistors R1, R2, R3, 13 heating stages can be realized, as listed in Table 14: Table 14: Available heating levels of variant A from Fig. 11 Wiring according Fig. 11 Variant A: 13 heating levels K1 K2 K3 KN P R1 = 52.9Ω / R2 = 26.45Ω / R3 = 17.63Ω 0 0 0 0 0 0 0 0 0 1 1 / 12 P max 500 0 0 1 0 3 / 16 P max 1125 0 0 1 1 7 / 12 P max 3500 0 1 0 0 1 / 6 P max 1000 0 1 0 1 5 / 12 P max 2500 0 1 1 0 91 / 120 P max 4550 0 1 1 1 11 / 12 P max 5500 1 0 0 0 0 0 1 0 0 1 1 / 6 P max 1000 1 0 1 0 3 / 8 P max 2250 1 0 1 1 2 / 3 P max 4000 1 1 0 0 1 / 3 P max 2000 1 1 0 1 1 / 2 P max 3000 1 1 1 0 11 / 12 P max 5500 1 1 1 1 P max 6000

[0104] The thirteen heating levels that can be realized in this way using R1=2R2=3R3 are therefore: 0, 1 / 12 P max , 1 / 6 P max , 3 / 16 P max , 1 / 3 P max , 3 / 8 P max , 5 / 12 P max , 1 / 2 P max , 7 / 12 P max , 2 / 3 P max , 91 / 120 P max , 11 / 12 P max , and P max .

[0105] Fig. 12 shows a single-phase operated variant of the wiring. Fig. 11 .

[0106] In a symmetrical variant S with R1=R2=R3=R (not shown) 7 heating stages can be realized in this way, as listed in Table 15: Table 15: Available heating levels of variant S from Fig. 12 Wiring according Fig. 12 Variant S: 7 heating levels K1 K2 K3 KN P R1=R2=R3=R= 26.45 Ω 0 0 0 0 0 0 0 0 0 1 1 / 6 P max 1000 0 0 1 0 0 0 0 0 1 1 1 / 2 P max 3000 0 1 0 0 0 0 0 1 0 1 1 / 2 P max 3000 0 1 1 0 0 0 0 1 1 1 5 / 6 P max 5000 1 0 0 0 0 0 1 0 0 1 1 / 3 P max 2000 1 0 1 0 0 0 1 0 1 1 2 / 3 P max 4000 1 1 0 0 0 0 1 1 0 1 2 / 3 P max 4000 1 1 1 0 0 0 1 1 1 1 P max 6000

[0107] The seven heating levels that can be achieved in this way are therefore: 0, 1 / 6 P max , 1 / 3 P max , 1 / 2 P max , 2 / 3 P max , 5 / 6 P max , and P max .

[0108] In an asymmetrical variant A (shown) with three different resistors R1, R2, R3, 9 heating stages can be realized, as listed in Table 16: Table 16: Available heating levels of variant A from Fig. 12 Wiring according Fig. 12 Variant A: 9 heating levels K1 K2 K3 KN P R1 = 52.9Ω / R2 = 26.45Ω / R3 = 17.63Ω 0 0 0 0 0 0 0 0 0 1 1 / 12 P max 500 0 0 1 0 0 0 0 0 1 1 7 / 12 P max 3500 0 1 0 0 0 0 0 1 0 1 5 / 12 P max 2500 0 1 1 0 0 0 0 1 1 1 11 / 12 P max 5500 1 0 0 0 0 0 1 0 0 1 1 / 6 P max 1000 1 0 1 0 0 0 1 0 1 1 2 / 3 P max 4000 1 1 0 0 0 0 1 1 0 1 1 / 2 P max 3000 1 1 1 0 0 0 1 1 1 1 P max 6000

[0109] The nine heating levels that can be realized in this way with R1=2R2=3R3 are therefore: 0, 1 / 12 P max , 1 / 6 P max , 5 / 12 P max , 1 / 2 P max , 7 / 12 P max , 2 / 3 P max , 11 / 12 P max , and P max .

[0110] Fig. 13 shows a variant of the wiring Fig. 11This differs from the previous version in that diode 14 is switched in place of switch KN in the neutral conductor N; furthermore, the symmetrical variant S is shown. This means that another switch K1a is connected in series with diode 14, by means of which diode 14 (and preferably only diode 14) can be connected in parallel to switch K1 when switch K1a is closed. When switch K1a is open, the diode plays no role in the circuit.

[0111] In a symmetrical variant S with R1=R2=R3=R (shown) 7 heating stages can be realized in this way, as listed in Table 17: Table 17: Available heating levels of variant S from Fig. 13 Wiring according Fig. 13 Variant S: 7 heating levels K1 K2 K3 K1a P R1=R2=R3=R= 26.45 Ω 0 0 0 0 0 0 0 0 0 1 1 / 6 P max 1000 0 0 1 0 1 / 3 P max 2000 0 0 1 1 1 / 2 P max 3000 0 1 0 0 1 / 3 P max 2000 0 1 0 1 1 / 2 P max 3000 0 1 1 0 2 / 3 P max 4000 0 1 1 1 5 / 6 P max 5000 1 0 0 0 1 / 3 P max 2000 1 0 0 1 1 / 3 P max 2000 1 0 1 0 2 / 3 P max 4000 1 0 1 1 2 / 3 P max 4000 1 1 0 0 2 / 3 P max 4000 1 1 0 1 2 / 3 P max 4000 1 1 1 0 P max 6000 1 1 1 1 P max 6000

[0112] The seven heating levels that can be achieved in this way are therefore: 0, 1 / 6 P max , 1 / 3 P max , 1 / 2 P max , 2 / 3 P max , 5 / 6 P max , and P max .

[0113] Also with the symmetrical variant S with R1=R2=R3=R (shown in Fig. 13 ), but with a single-phase connection (i.e., L1=L2=L3, not shown) seven heating stages can be realized, as listed in Table 18: Table 18: Available heating levels of variant S from Fig. 13 with single-phase connection Wiring according Fig. 13 Variant S, single-phase: 7 heating levels K1 K2 K3 K1a P R1=R2=R3=R= 26.45 Ω 0 0 0 0 0 0 0 0 0 1 1 / 6 P max 1000 0 0 1 0 1 / 3 P max 2000 0 0 1 1 1 / 2 P max 3000 0 1 0 0 1 / 3 P max 2000 0 1 0 1 1 / 2 P max 3000 0 1 1 0 2 / 3 P max 4000 0 1 1 1 5 / 6 P max 5000 1 0 0 0 1 / 3 P max 2000 1 0 0 1 1 / 3 P max 2000 1 0 1 0 2 / 3 P max 4000 1 0 1 1 2 / 3 P max 4000 1 1 0 0 2 / 3 P max 4000 1 1 0 1 2 / 3 P max 4000 1 1 1 0 P max 6000 1 1 1 1 P max 6000

[0114] The seven heating levels that can be achieved in this way are therefore: 0, 1 / 6 P max , 1 / 3 P max , 1 / 2 P max , 2 / 3 P max , 5 / 6 P max , and P max .

[0115] Fig. 14 shows a variant of the wiring Fig. 13, with the two differences that it is a single-phase connection and an asymmetrical variant A.

[0116] In this asymmetric variant A with exemplary R1=2R2=3R3, 11 heating stages can be realized, as shown in the following Table 19: Table 19: Available heating levels of variant A from Fig. 14 with single-phase connection Wiring according Fig. 14 Variant A, single-phase: 11 heating levels K1 K2 K3 K1a P R1 = 52.9Ω / R2 = 26.45Ω / R3 = 17.63Ω 0 0 0 0 0 0 0 0 0 1 1 / 12 P max 500 0 0 1 0 1 / 2 P max 3000 0 0 1 1 7 / 12 P max 3500 0 1 0 0 1 / 3 P max 2000 0 1 0 1 5 / 12 P max 2500 0 1 1 0 5 / 6 P max 5000 0 1 1 1 11 / 12 P max 5500 1 0 0 0 1 / 6 P max 1000 1 0 0 1 1 / 6 P max 1000 1 0 1 0 2 / 3 P max 4000 1 0 1 1 2 / 3 P max 4000 1 1 0 0 1 / 2 P max 3000 1 1 0 1 1 / 2 P max 3000 1 1 1 0 P max 6000 1 1 1 1 P max 6000

[0117] The eleven heating levels that can be achieved in this way are therefore: 0, 1 / 12 P max , 1 / 6 P max , 1 / 3 P max , 5 / 12 P max , 1 / 2 P max , 7 / 12 P max , 2 / 3 P max , 5 / 6 P max , 11 / 12 P max , and P max .

[0118] With a 3-phase connection (not shown) of the asymmetrical variant, the same heating stages would be possible.

[0119] Fig. 15shows a variant of the wiring Fig. 13 , with the difference that on all current phases L1, L2, L3, a series circuit consisting of diode 14 and an additional switch K1a, K2a, K3a is arranged in parallel to the respective switch K1, K2, K3 (and not only to switch K1 as in Fig. 13 ).

[0120] The heating levels achievable in this way are the same as with regard to Fig. 13 as described in Table 17 (symmetrical variant S, 3-phase) and Table 18 (symmetrical variant S, 1-phase). However, each heating stage can be selected in the variant from Fig. 15 This can be achieved with more different switching combinations.

[0121] The variant from Fig. 15Furthermore, it enables phase-accurate switching, so that the phase-accurate consumption of the heating device 20 can also be set accordingly. If an unbalanced load occurs at the mains connection point 31 and / or in the (internal) electrical network 30, i.e., if one or more phases L1, L2, L3 have a significantly different load than one or more of the other phases L1, L2, L3, then the switching device 10 can be controlled (e.g., by an energy management system 40) in such a way (or can control itself) that the unbalanced load is counteracted by selecting a suitable heating stage and / or a suitable switching combination of switches K1, K1a, K2, K2a, K3, K3a.

[0122] The detection of the unbalanced load can be carried out by the energy management system 40, which either directly controls the switching device 10 accordingly, or transmits the necessary information to the switching device 10 so that the switching device 10 can perform the necessary control itself.

[0123] The variant from Fig. 15 This is also useful in the event of emergency power, for example, if the public power grid 35 fails or is switched off. In this case, the inverter often establishes an emergency power supply in the local power grid 30 with a frequency of, for example, 53 Hz, which is detected by the control unit 11 via frequency measurement, whereas in normal operation, the frequency of, for example, the public power grid 35 is 50 Hz.

[0124] In this situation, often only a few appliances are in operation, and it can be important to be able to precisely select how much power is drawn from each phase (L1, L2, L3). The variant from Fig. 15 This allows a user to manually activate one (or more) of the current phases L1, L2, L3 of the heating device 20 via a user interface 12 (of the switching device 10, the energy management system 40, or the like), for example, at the lowest heating level with a heating power greater than zero, in order to avoid overloading the emergency power supply. If an overload or failure of the emergency power supply nevertheless occurs, the user can again select a different current phase L1, L2, L3 for a second or third attempt.

[0125] Similar options are available to the user for the other wiring variants described above.

[0126] In the inventive household appliance 200, in asymmetrical wiring configurations where a diode 14 is connected to at least one terminal 16-i (either in parallel with the corresponding switch Ki and / or in series with the further switch Kia), it is preferred that this terminal 16-i is connected to a heating element 21-i which has the lowest heating power or the highest heating resistance (usually R1 in the examples). This ensures that an additional heating stage is provided, or can be provided, by using the diode 14 (and corresponding switching).

[0127] Fig. 16Figure 1 shows a schematic flowchart to explain a method according to an embodiment of the present invention, namely a method for operating a heating device 20 or for heating a medium, in particular a fluid F, by means of a heating device 20 with a plurality of heating elements 21-i, which are connected to each other in a star configuration at a common star point 22 and can be connected independently to an energy source.

[0128] The method is carried out by means of the switching device 10 and / or the house system 100 according to one embodiment (in particular according to one of the Figures 1-6 and 9-15The method can be carried out in conjunction with the present invention, but also independently thereof. Accordingly, the method is adaptable to all embodiments, variants, options, and further developments described with reference to the switching device or the building system according to the invention, and vice versa. An energy management system 40 that performs this method can, for example, also be integrated into a switching device 10 according to the invention.

[0129] In step S100, a desired total heating output P of the heating device 20 is detected, for example, by a user interface 12, an energy management system 40, or the like. Determining the total heating output setpoint can include determining the total heating output setpoint, in particular calculating it.

[0130] In step S200, a heating stage is determined (for example, by the energy management system 40 or the control unit 11 of the switching device 10) that corresponds as closely as possible to the detected total heating output setpoint. This allows the difference between the total heating output generated by the heating device 20 and the total heating output setpoint to be advantageously kept to a minimum. Alternatively, it can also be provided that (according to one option) the lower heating stage closest to the total heating output setpoint is selected in each case, or (according to another option) the heating stage closest to the total heating output setpoint is selected in each case.

[0131] In step S300, heating elements 21-i of the heating device 20 are switched independently of one another, each via at least one associated switch Ki; K1a, for the (stepped) setting of the specific heating stage. Examples of such and other switching operations as process steps can be found in the description of the Figures 1-6 and 9-15 and result in particular from the tables listed there.

[0132] Fig. 17Figure 1 shows a schematic flowchart to explain a method according to an embodiment of the present invention, namely a method for operating a heating device 20 or for heating a medium F by means of at least one heating element 21-i of a heating device 20. The method can be carried out using the switching device 10 and / or the building system 100 according to an embodiment of the present invention, but also independently thereof. Accordingly, the method can be adapted according to all embodiments, variants, options and further developments described with reference to the switching device or the building system according to the invention, and vice versa.

[0133] In step S400, a desired total heating output P of the heating device 20, i.e., a total heating output setpoint, is recorded, for example from a user interface 12, from an energy management system 40, from a thermostat, or the like.

[0134] In step S500, a heating stage is determined which corresponds as closely as possible (or exactly) to the recorded total heating power setpoint, i.e., in particular, comes as close as possible to it.

[0135] In step S600, for the (step-by-step) setting of the specific heating stage, at least one first switch K1 connected in series with at least one heating element 21-i is switched, which is connected in parallel with a diode 14, wherein the switch is arranged between a current phase L1 and the at least one heating element 21-i.

[0136] In an optional additional step S700, a further switch K1a, connected in series with diode 14 and in parallel with the first switch K1, is also switched for (stepped) adjustment of the specific heating stage. This parallel connection is thus also arranged between a current phase L1 and the at least one heating element 21-i.

[0137] Examples of such and other switching operations, as in process steps S600 and S700, can be found in the description of the Figures 7-15 and result in particular from the tables listed there.

[0138] Fig. 18 Figure 1 shows a schematic block diagram of a computer program product 200 according to an embodiment of the present invention. The computer program product 200 comprises executable program code 250, which, when executed, is configured to perform the method according to an embodiment of the present invention, for example, according to Fig. 16 or Fig. 17 .

[0139] Fig. 19Figure 1 shows a schematic block diagram of a non-volatile, computer-readable data storage medium 300 according to an embodiment of the present invention. The data storage medium 300 comprises executable program code 350, which, when executed, is configured to perform the method according to an embodiment of the present invention, for example, according to Fig. 16 or Fig. 17 .

[0140] The non-volatile, computer-readable data storage medium 300 can, for example, be designed as or comprise a semiconductor memory, e.g., an SSD. The data storage medium 300 can also comprise or include a CD, DVD, Blu-ray disc, or a magnetic storage device.

[0141] Referring again to Fig. 1It will now be explained how the switching device 10 according to the invention can be advantageously integrated into a house installation 100 according to the invention and operated there. Accordingly, the methods according to Fig. 16 or Fig. 17 in all their variants and embodiments, they are adapted accordingly to control the house system 100, and / or specifically the switching device 10.

[0142] The building system 100 can have an energy management system 40, which can in particular control flows of electrical energy via the power grid 30, especially between power sources and / or electricity consumers, such as the grid connection point 31, at least one consumer 32, a battery 60 of the building system 100, a renewable energy source 70 (for example a PV system) of the building system 100, an inverter 80 of the building system 100 and / or the like.

[0143] In principle, the possibilities and common programs of such energy management systems are known. For example, for various reasons, it is generally desirable that the electrical energy generated by a renewable energy source be consumed within the building's electrical system. If this is not possible, it should be stored in the battery. If this is also no longer possible, it should be fed into the public electricity grid from the building's electrical system via the grid connection point. However, other schemes are also conceivable, for example, schemes based on a current electricity price that attempt to generate a financial profit through electricity trading.

[0144] Fig. 19Figure 1 shows a schematic flowchart illustrating a possible method for selecting heating levels, wherein the selected heating levels can be implemented by the various embodiments of the present invention. Accordingly, the switching device 10 and / or the building system 100 can be configured to carry out such a method, or the methods according to Figure 1 can be implemented as described above. Fig. 16 or Fig. 17 They must be designed or modified in such a way as to include such a procedure.

[0145] The description begins with a starting step S1; however, it is understood that the described procedure is usually carried out cyclically, i.e., it always starts again from the beginning, as shown by the arrow paths.

[0146] In step S1, a target temperature for the medium, here (only as an example) a fluid F in a fluid tank 50, is first recorded. The target temperature can be specified directly by a user, for example via a user interface 12 in a smart home control application. Alternatively, the target temperature can also be determined by an algorithm that can take into account, for example, the time of day, the season, and / or user input. Recording in step S1 can also consist of maintaining a previously specified target temperature.

[0147] In step S2, the current temperature of fluid F in fluid tank 50 is recorded, specifically measured. This temperature can be determined using a temperature sensor from the building system 100, which can, for example, be integrated into fluid tank 50.

[0148] In step S3, it is checked whether the actual temperature of the fluid F in the fluid tank 50 is lower than a target temperature.

[0149] Here and in the following, it is understood that whenever a comparison with a reference or threshold value (here: with the target temperature) is mentioned, a tolerance range can always be provided within which the process continues as if there were no difference. This prevents constant switching back and forth or other unstable control behavior. The tolerance ranges can be arranged symmetrically or asymmetrically around the reference or threshold value. The latter can be used, for example, to achieve a hysteresis effect, such that a larger deviation from the threshold is required to revise a decision than was necessary to trigger the decision in the first place. In the following, corresponding tolerance ranges will not be explicitly mentioned every time in order to keep the explanations concise.

[0150] If, according to the check in step S3 (as mentioned, optionally taking a tolerance range into account), the actual temperature is lower than the target temperature (plus sign, "+", in the diagram), then in step S4 it is checked whether there is excess power in the building system 100, initially from renewable energy sources 70, e.g., from a PV system. Preferably, only renewable energy sources 70 of the building system 100 are considered. For the check, a current power value from at least one renewable energy source 70 can be obtained during step S4. Optionally, further power values, e.g., power consumed by consumers 32, etc., can also be received. From the received power values, it can be calculated in a known manner whether excess power from renewable energy sources 70 of the building system 100 is present.

[0151] If excess electrical power is present (plus sign, "+", in the diagram), step S5 checks whether the state of charge of battery 60 is above a state of charge threshold. This state of charge threshold can, for example, specify a state of charge above which states of charge are generally undesirable, either to preserve battery 60, or because such a high state of charge is considered unnecessary, or for similar reasons.

[0152] If the state of charge exceeds this first threshold (plus sign, "+", in the drawing), the energy management system 40 controls the home system 100 in such a way that in step S6 an output power available at the battery 60 and released (e.g. by the customer) is added to the excess power.

[0153] Regardless of whether this occurs or not (in house systems 100 without battery 60, steps S4 and S5 are omitted), the next step, S7, checks whether the now determined excess power is sufficient to switch the heating device 20 to a higher heating level. Thus, bidirectional communication can be established between the switching device 10 and the energy management system 40, so that, on the one hand, the energy management system 40 knows the currently set heating level and / or the total heating power setpoint, and, on the other hand, it can specify a heating level and / or the total heating power setpoint to be set for the switching device 10. A higher heating level is understood to be a heating level that, all other things being equal, provides greater heating power than a lower heating level.In the preceding examples, the lowest heating level was reached when all switches were open (P=0), and the highest heating level was reached when all switches were closed (P=P max ).

[0154] If a higher heating level is not possible (minus sign, "-" in the diagram), for example because the excess power is insufficient or because no higher heating level is available, the process continues from step S1. If a higher heating level is possible (plus sign, "+" in the diagram), a higher heating level is set in step S8. For this purpose, the switching device 10 is instructed, for example, by the energy management system 40 (or it decides itself) to set a higher heating level, and then the corresponding heating level is set by the switching device 10 by switching the switches Ki, KN, and Kia accordingly. Afterwards, the process continues again from step S1.

[0155] If step S4 determines that no excess power from renewable energy sources 70 is available (minus sign, "-", in the diagram), step S9 checks whether electricity is currently being consumed from the grid, i.e., whether it is flowing into the building's electrical system 100 at the grid connection point 31. If this is not the case (minus sign, "-", in the diagram), the current heating level is maintained and the process continues from step S1.

[0156] If this is the case (plus sign, "+", in the drawing at step S9), step S10 checks whether a lower heating level is available (i.e., whether the lowest heating level, i.e., with zero power, is currently set). If no lower heating level is available (minus sign, "-", in the drawing at step S10), this heating level remains, and the process continues at step S1. If a lower heating level is available (plus sign, "+", in the drawing), the heating level is reduced in step S11. For this purpose, for example, the switching device 10 is instructed by the energy management system 40 (or it decides itself) to set a lower heating level, and then the corresponding heating level is set by the switching device 10 by switching the switches Ki, KN, and Kia accordingly. The process then continues again at step S1.

[0157] However, if in step S3 it is determined that the actual temperature is not lower than the target temperature (i.e., the actual temperature is equal to, greater than, or possibly within a tolerance range around the target temperature), represented by a minus sign, "-", to the left of step S3 in the drawing, then in step S12 it is checked whether the actual temperature is lower than a user-adjustable or predefined upper temperature threshold, which is higher than the target temperature.

[0158] If this is the case (plus sign, "+", in the diagram below step S12), step S13 checks whether excess power is available, initially from renewable energy sources. If this is not the case (minus sign, "-", in the diagram), the process continues with step S9, as already explained. If excess power from renewable energy sources is available (plus sign, "+", in the diagram below step S13), the process continues with step S7, i.e., checking whether a higher heating level is possible.

[0159] If the result of the test in step S12 is negative, i.e., the current temperature (actual temperature) is equal to or greater than the upper temperature threshold (symbol "-" in the figure at step S12), the lowest heating level of the heating device 20 is set in step S14. This will usually be the heating level with power P=0, i.e., the heating device 20 is switched off. Then, the process continues with step S1.

[0160] The procedure according to Fig. 20This allows the heating of the medium F (e.g., in the fluid tank 50) to be used for storing thermal energy. However, this should ideally not be done with electricity from the public power grid 35, but only with electrical power from renewable energy sources 70 of the building system 100, and only if the actual temperature does not exceed the upper temperature threshold. Furthermore, a state of charge of the battery 60 of the building system 100 above the threshold can be utilized (step S5). It is understood that the person skilled in the art can adapt the method according to Fig. 20f in various ways to add or omit individual steps in order to achieve a desired regulation or control.

[0161] In particular, depending on the building system 100 and the current situation, step S8 of increasing the heating level can alternatively be replaced or supplemented by a step of switching on at least one consumer 32, e.g., a heat pump. Likewise, depending on the building system 100 and the current situation, step S11 of decreasing the heating level can alternatively be replaced or supplemented by a step of switching off at least one consumer 32, e.g., a heat pump. Switching on or off can also be replaced by increasing or decreasing energy consumption.

[0162] From the preceding description, it is evident how the step-by-step adjustability of the heating power of the heating device 20 by means of the switching device 10 according to the invention makes it possible to implement complex control and regulation processes such as the one described in the invention in a cost-effective manner and without significant hardware effort. Fig. 20to carry out, even with simple, already installed heating equipment 20.

Claims

1. Switching device (10) for operating an external heating device (20) for heating a medium (F) by means of a plurality of heating elements (21-i) of the heating device (20), which heating elements are interconnected at a common star point (22) and can be connected to the switching device (10) independently of one another, wherein the switching device (10) is designed to be supplied by at least one current phase (L) and comprises a control device (11) which is designed to switch the heating elements (21-i) independently of one another via at least one associated switch (Ki, Kia, KN) of the switching device (10) for the stepwise adjustment of a total heating power generated by the heating device (20) according to a respective heating stage.

2. Switching device (10) according to claim 1, designed to switch between at least five heating levels, preferably at least seven heating levels, of different heating power.

3. Switching device (10) according to one of the preceding claims 1 or 2, wherein a diode (14) is connected in parallel to at least one switch (Ki, KN).

4. Switching device (10) according to one of claims 1 to 3, comprising an output (16-i) for each heating element (21-i) to be connected, wherein the switch (Ki) associated with the corresponding heating element (21-i) is connected in series with the output (16-i).

5. Switching device (10) according to one of claims 1 to 4, wherein the control device (11) is further configured to switch periodically and / or cyclically between realizations of the same heating power by means of different switch combinations of the switches (Ki, KN).

6. Switching device (10) according to one of claims 1 to 5, wherein the control device (11) is configured to receive (S4, S13) a current power value of a renewable energy source (70) and to adapt (S8) a current heating level at least based on the received current power value.

7. Switching device (10) according to claim 6, wherein the control device (11) is configured to further adjust the current heating level based on a total heating power setpoint.

8. Switching device (10) according to claim 7, wherein the control device (11) is configured to set the current heating level such that a difference between the total heating power generated by the heating device (20) and the total heating power setpoint becomes minimal.

9. Switching device (10) according to claim 7 or 8, wherein the control device (11) is designed to carry out a measuring method in order to determine which heating levels are available and / or which total heating power is realized with each of the available heating levels.

10. A domestic system (100) comprising a switching device (10) according to one of claims 1 to 9 and a heating device (20) connected to the switching device (10), for the operation of which heating device the switching device (10) is arranged.

11. Domestic system (100) according to claim 10, comprising a user interface (12) by means of which a target parameter of the heating device (20), the medium (F) and / or a fluid tank (50) for the medium (F) can be set, for example a target temperature of the medium (F).

12. Domestic system (100) according to one of claims 10 or 11, comprising an electrical connection (31) to a power grid (35), wherein the star point (22) of the heating device (20) is connected to a neutral conductor (N) of the power grid (30) via an associated switch (KN) and / or is switchable via an associated switch (KN).

13. Switching device (10) for operating an external heating device (20) for heating a medium (F) by means of at least one heating element (21-i) of the heating device (20), wherein the switching device (10) is designed to be supplied by at least one current phase (L) and comprises a control device (11) which is designed to switch the heating element (21-i) via at least one associated switch (Kia) of the switching device (10) for the stepwise adjustment of a total heating power generated by the heating device (20) according to a respective heating stage, wherein a diode (14) is connected in parallel to the at least one associated switch (Kia).

14. A method for heating a medium (F) by means of a heating device (20) having a plurality of heating elements (21-i) which are interconnected at a respective first connection end at a common star point (22) and which are switchable independently of one another at a respective second connection end, comprising: detecting (S100) a total heating power setpoint; determining (S200) a heating level which best corresponds to the desired total heating power setpoint; and switching (S300) the heating elements (21-i) independently of one another via at least one associated switch (Ki, Kia, KN) to set the determined heating level.

15. A method for heating a medium (F) by means of at least one heating element (21-i) of a heating device (20), comprising: detecting (S400) a total heating power setpoint; determining (S500) a heating level that best corresponds to the desired total heating power setpoint; and switching (S600) at least one switch (Kia), which is arranged between a current phase (L1) and at least one heating element (21-i) of the heating device (20), and which is connected in parallel with a diode (14), optionally with a series circuit comprising the diode (14) and a further switch (K1a), to set the determined heating level.

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