Heating element and method for operating a heating element for heating water or as a heat generator for heating in a building by means of electrical energy

Abstract

Heating rod (40) for hot water preparation and / or as a heat generator for heating in a building by means of electrical energy, comprising: - one or more heating resistors (R1, R2, R3, R4), - a power setpoint generator (42) for providing a power setpoint, - a controller (41) for controlling a power supply to the one or more heating resistors (R1, R2, R3, R4) as a function of the power setpoint, characterized in that the controller (41) is designed to control a power supply to a heating resistor of the one or more heating resistors (R1, R2, R3, R4) as a function of the power setpoint by means of wave packet control and by means of phase control or phase trailing edge control.

Description

Technical background

[0001] During operation, heating elements (cartridge heaters) convert electrical energy into thermal energy using heating resistors. Heating elements are often used as a short-term and flexible interim solution, for example, as additional heating in the event of a failure or replacement of a main heating system, etc. Other examples of applications include locally flexible radiators, boilers, and instantaneous water heaters.

[0002] Heating elements are known from the state of the art in which the heating output can be varied stepwise using wave packet control. However, wave packet control systems have the disadvantage that a flicker limit is exceeded at a heating output of approximately 350 watts. Accordingly, a maximum heating output of 350 watts * 3 = 1150 watts can be achieved with a three-phase connection without exceeding standard specifications.

[0003] Alternative control systems for heating elements using pulse-width modulation are known from the state of the art. These have the disadvantage, among other things, that due to the pulses having frequencies of several kHz, the clock-frequency harmonics contribute to significant interference emissions.

[0004] Phase-angle control systems are also known from the state of the art. However, these have the disadvantage that, at heat outputs above 750 watts in particular, harmonics exceeding a certain limit are generated, which can lead to exceeding permissible limits of the power grid.

[0005] Power grids are already subject to massive fluctuations due to a multitude of unpredictable power consumers. Consequently, it is desirable to maintain as constant an energy consumption as possible to avoid overlapping peaks or valleys in consumption.

[0006] DE 33 04 322 A1 describes an electric instantaneous water heater with several electric radiators and a control device. A control signal is converted into a binary digital signal based on an analog signal. Based on individual bits of the binary digital signal, the power supply to the several electric radiators is controlled based on the flow rate of the instantaneous water heater. The outputs of the radiator stages from the first to the penultimate radiator stage are each twice the output of the previous radiator stage.

[0007] DE 10 2017 002 193 A1 describes a method for the remote-controlled utilization of electricity with boilers. An electric heating system installed in a boiler is remotely switched on or off, thereby completely or partially taking over heat generation. The fossil-fuel-powered heat generator is switched off or downgraded accordingly.

[0008] DE 10 2016 108 232 A1 discloses a circuit comprising a mechanical relay and a solid-state relay. The mechanical relay is configured to switch a first supply current of the first heating element in a first supply line. The solid-state relay is configured to switch a second supply current of a second heating element in a second supply line.

[0009] Furthermore, heating elements with a particularly flexible heating output are desirable in order to increase the possible area of ​​application and to avoid unnecessary overheating of hot water or heating water due to a lack of control options. Description of the invention

[0010] Based on the above-mentioned problems, it is the object of the invention to provide a heating rod that can be continuously controlled over a relatively large power range compared to conventional heating rods, or a method for controlling a corresponding heating rod.

[0011] The problem is solved by the features of the independent patent claims. The dependent patent claims relate to particular embodiments of the invention.

[0012] A heating rod according to the invention for hot water preparation and / or as a heat generator for heating in a building by means of electrical energy comprises one or more heating resistors, a power setpoint generator for providing a power setpoint, and a controller for controlling an energy supply to the one or more heating resistors as a function of the power setpoint.

[0013] The building may, for example, comprise one or more rooms. The heating element may, for example, be a cartridge heater. The heating element may, for example, be designed to be arranged, with at least a portion of the heating element, in a boiler or buffer tank, or to be inserted into a boiler or buffer tank.

[0014] A heating resistor can be separated from a medium to be heated, preferably a liquid medium, by means of an insulator. The medium to be heated or warmed can be, for example, water, antifreeze, (treated) heating water, domestic water, gray water, etc.

[0015] The insulator preferably has good to very good thermal conductivity. In some embodiments, a heating resistor can be U-shaped. In some embodiments, a heating resistor can comprise a spiral section.

[0016] A power supply can, for example, be a mains voltage, in particular with an effective voltage of approximately 220V or 230V, or within a legally prescribed deviation therefrom. The power supply can, for example, be in the form of an alternating voltage, in particular with a frequency of 50Hz or 60Hz, or within a legally prescribed deviation therefrom.

[0017] The power setpoint device can, for example, be a control unit for regulating the temperature of one or more rooms in a building, in particular a house. In some embodiments, the power setpoint device can comprise a human-machine interface (HMI), for example in the form of a control element that can be adjusted by rotation, a display input, or a slider. The power setpoint can, for example, be specified as a function of the heating power to be provided by the heating element. In some embodiments, the power setpoint can be a control variable of a control loop.

[0018] In some embodiments, the power setpoint generator may comprise an analog-to-digital converter. In some embodiments, the power setpoint generator may comprise a digital-to-analog converter.

[0019] The power setpoint may represent a value for the heat output to be delivered by one or more heating resistors.

[0020] Advantageously, the power supply can be in the form of an alternating voltage. In some embodiments, the power supply can be in the form of an alternating current. In some embodiments, the heating element can be configured to convert a direct voltage / current into an alternating voltage / current.

[0021] According to the invention, the control is designed to control a power supply of a heating resistor of the one or more heating resistors as a function of the power setpoint by means of wave packet control and by means of phase control or phase trailing edge control.

[0022] With phase-angle control, after a zero crossing of the AC voltage (alternating current) of the power supply, a current flow to / from the heating resistor can be prevented until one phase of the AC voltage (alternating current) exceeds a specified phase value. The specified phase value is determined depending on the power setpoint. The phase (phase angle) indicates the current position in the sequence of a periodic process.

[0023] With trailing edge phase control, after a phase of the alternating voltage exceeds a further predefined phase value until a zero crossing of the alternating voltage is reached, a current flow from / to the heating resistor can be prevented, whereby the further predefined phase value is determined depending on the power setpoint.

[0024] A phase control or a phase control has the advantage that voltage fluctuations (flicker) are avoided and in particular are not generated.

[0025] In wave packet control, a current flow from / to the heating resistor can be interrupted for a predetermined number of whole or half periods of the alternating voltage after a zero crossing of the alternating voltage within a predetermined period of time, wherein the predetermined period of time and the predetermined number of whole or half periods within the predetermined period of time are determined as a function of the power setpoint, in particular a ratio between the predetermined number of whole or half periods within the predetermined period of time to the predetermined period of time can be determined as a function of the power setpoint.

[0026] Wave packet control has the advantage that harmonics that can enter a mains supply (power grid) are avoided or not generated.

[0027] A combination of wave packet control and phase-angle control, or phase-trailing control, has the advantage of allowing particularly precise control of heating output over a wide heating output range. Furthermore, it allows heating output to be easily controlled beyond a conventionally controllable heating output range.

[0028] In particularly elegant embodiments, the control system can additionally be configured to control the energy supply of the heating resistor by means of wave packet control and by means of phase control and phase trailing edge control depending on the power setpoint.

[0029] This can have the advantage of reducing harmonics due to phase-angle control or trailing-edge control, while elegantly defining the preset phase value and the further preset phase value depending on the power setpoint. Furthermore, voltage fluctuations (flicker) can be avoided.

[0030] In particularly high-performance embodiments, the controller can be configured to control the supply of electrical energy to a further heating resistor of the plurality of heating resistors by connecting the further heating resistor to a power supply (energy source). For example, the controller can be configured to continuously generate heat by means of the further heating resistor by supplying electrical energy to a further heating resistor of the plurality of heating resistors, beyond a heat output range of the heating resistor. This can have the advantage that the heat output of the heating element can be adjusted over a wide heat output range without excessive voltage fluctuations (flicker) and without generating excessive harmonics.

[0031] This allows the heating element to be used extremely flexibly across a wide heat output range. Furthermore, the heating element's heat output can be adjusted very precisely and thus particularly efficiently, as unnecessary overheating can be avoided. This can also extend the lifespan of the heating element, as it negatively impacts the buildup of dirt and limescale on the heating element. In the long term, this leads to more efficient heat transfer between the heating element and the medium (to be heated).

[0032] In a particularly advantageous embodiment, the controller can be configured to make changes to the power supply of a heating resistor, particularly due to a change in a power setpoint, during a zero crossing of a current and / or voltage curve of the power supply. This can prevent the generation of harmonics. As a result, the normative requirements for the heating element, particularly with regard to harmonics, for connecting the heating element to a power grid can be more easily met.

[0033] In particularly efficient embodiments, a maximum heating output P n,max an nth heating resistor of the several heating resistors must be dimensioned as follows: Pn,max≤∑j=1n−1Pj,max. This can have the advantage that the heating power of the heating element can be adjusted continuously.

[0034] In particularly efficient embodiments, the control unit can be configured to adjust the heating power P1 of the heating resistor continuously by means of wave packet control and by means of phase control and / or phase trailing edge control and to adjust the heating power P j of another heating resistor by simply pressing a switch.

[0035] When dimensioning the heating power of the heating element’s heating resistors as Pn,max≤∑j=1n−1Pj,max A given heating output range can be continuously adjusted using a minimal number of heating resistors. This can have the advantage of reducing the number of heating resistors, thus saving costs and space.

[0036] In a particularly advantageous embodiment, one or more heating resistors can be separated from the medium to be heated by insulators. This can prevent, for example, electric shock to people.

[0037] Advantageously, the insulator can exhibit particularly good thermal conductivity compared to other insulators. Advantageously, the insulator can exhibit electrical insulation properties, preventing current flow (electrical transmission) between the heating resistor and the medium to be heated. In specially shielded embodiments, the electrical insulation properties can be particularly high compared to other insulators.

[0038] In particularly efficient embodiments, the control system can be configured to continuously regulate a power supply of a first heating resistor by means of wave packet control and by means of phase control and / or phase trailing edge control such that a heating power P1 of the heating resistor is in a range between a minimum heating power P 1,min and a maximum heating output P 1,max a value depending on the power setpoint of the power setpoint generator.

[0039] Preferably, the minimum heating power P 1,min of the heating resistor is 0 watts. In this context, stepless can mean continuously variable. In preferred embodiments, the minimum heating power P 1,min and / or the maximum heating output P 1,max of the heating resistor depending on harmonic and flicker requirements.

[0040] This can have the advantage that the heating element's heat output can be adjusted very precisely to the required heat output. This prevents the generation of heat beyond the required heat demand. As a result, limescale and dirt deposits can be minimized. This leads to a long-term improvement in heat transfer from the heating elements to the medium being heated.

[0041] In particularly low-harmonic and low-flicker embodiments, the controller can be configured to generate heat with a heating power P2 by connecting a power supply to a further heating resistor. The heating power P2 can preferably be constant, i.e., it has a deviation smaller than a predetermined deviation.

[0042] Connecting the additional heating resistor to a power supply can, in some embodiments, preclude control by wave packet control and / or by phase-angle control and / or by phase-angle control. By simply connecting the additional heating resistor, the heating power of the heating element can be increased in a simple manner without generating flicker or harmonics.

[0043] In particularly simple embodiments, the controller can be configured to continuously (continuously) regulate a heating power P1 of the heating resistor by means of wave packet control and phase control and / or trailing edge control, depending on the power setpoint of the power setpoint controller, and to connect additional heating resistors of the plurality of heating resistors to a power supply depending on the power setpoint of the power setpoint controller. This allows the heating power of the heating element to be continuously controlled over a wide heating power range with minimal control effort.

[0044] A continuous control option has the advantage over a discrete control option that the heating output can be regulated more precisely to the setpoint. This prevents unnecessary overheating of the medium being heated. As a result, dirt and limescale deposits on the heating element can be reduced, leading to a long-term improvement in the heating element's efficiency.

[0045] A method according to the invention for operating a heating element for hot water preparation and / or as a heat generator for heating in a building by means of electrical energy comprises the steps of providing a heating element, wherein the heating element comprises one or more heating resistors; providing a power setpoint; and controlling a power supply of a heating resistor of the one or more heating resistors as a function of the power setpoint by means of wave packet control and by means of phase control or phase trailing edge control.

[0046] The method has the advantage that, thanks to the combination of wave packet control and phase-angle control, or trailing-edge control, the heating output of the heating element can be adjusted with particular precision. Furthermore, the heating output can be adjusted continuously over a wider heating output range compared to conventional control methods, particularly without exceeding flicker and harmonic limits. Flicker (voltage fluctuations), for example, can occur due to wave packet control, and harmonics can occur, particularly as a result of phase-angle control or trailing-edge control.

[0047] In particularly advantageous embodiments, the control of the energy supply (energy supply / energy source) of the heating resistor can be carried out as a function of the power setpoint by means of wave packet control and by means of phase control and phase trailing edge control.

[0048] In embodiments with a particularly broad range of applications, the method may include a step of controlling a power supply to a further heating resistor of the plurality of heating resistors by connecting the further heating resistor to a power supply. This allows the heating power of the heating element to be easily adjusted, preferably continuously, within a wide heating power range.

[0049] In particularly advantageous embodiments, the method can include a step of detecting a zero crossing of a current and / or voltage waveform of the power supply. The control of a power supply to a heating resistor of the one or more heating resistors can then be carried out as a function of the power setpoint using wave packet control and as a function of a detected zero crossing of a current and / or voltage waveform of the power supply using phase control and / or phase trailing edge control. This has the advantage that harmonics can be avoided.

[0050] In embodiments with a particularly precise control, the energy supply of the heating resistor can be continuously regulated when controlling the heating resistor, so that a heating power P1 of the heating resistor can be set in a range between a minimum heating power P 1,min and a maximum heating output P 1,maxa value depending on the power setpoint.

[0051] In particularly advantageous embodiments, the method may comprise a step of connecting a further heating resistor of the plurality of heating resistors to a power supply as a function of the power setpoint.

[0052] In particularly flexible embodiments, the method can comprise the steps of continuously controlling a heating power P1 of the heating resistor by means of wave packet control and by means of phase control and / or phase trailing edge control depending on the power setpoint, and connecting further heating resistors of the plurality of heating resistors to a power supply depending on the power setpoint.

[0053] The control of the heating power P1 of the heating resistor by means of wave packet control and by means of phase control and / or phase trailing edge control depending on the power setpoint and the connection of further heating resistors with heating powers P j with j≠1 of the one or more heating resistors with a power supply depending on the power setpoint can be carried out, for example, by means of a lookup table in which, for example, upper and / or lower limit values ​​are entered. In some embodiments, for example, a relationship between a power setpoint and a control or a connection of a heating resistor with a heating power P j of one or more heating resistors using one or more mathematical functions. Description of the characters Fig. 1 schematically shows a heating element according to an embodiment of the invention. Fig. 2 schematically shows a process flow of a method according to an embodiment of the invention. Fig. 3 schematically shows a process flow diagram of a method according to an embodiment of the invention. Fig. 4 schematically shows a heating element according to an embodiment of the invention. Fig. Figure 5 shows a schematic overview of compliance with flicker limits of different control methods depending on maximum power. Fig. Figure 6 shows a schematic overview of the compliance with flicker limits of different control methods depending on the level of control. Fig. Figure 7 shows a table with harmonic measurements as a function of a percentage modulation and as a function of a maximum power of a heating resistor. Fig. 8a shows an example of a combination of the wave packet control with the phase control and / or the phase cut control according to embodiments of the invention. Fig. 8b shows an example of a combination of wave packet control with phase angle control according to an embodiment of the invention.

[0054] Fig. 1 schematically shows a heating element 10 according to one embodiment of the invention. The heating element 10 comprises a controller 11 and a power setpoint generator 12. The power setpoint generator 12 provides a power setpoint, which represents a heating power to be generated by the heating element 10, to the controller 11. In some embodiments, the power setpoint generator 12 can be connected to sensors and / or actuators of a heating system for this purpose. In some embodiments, the power setpoint generator 12 can comprise a human-machine interface (HMI).

[0055] In some embodiments, the power setpoint generator 12 can be part of the controller 11. The controller is connected to a power supply 16. In some embodiments, the power supply can be a current source or a voltage source. Preferably, the power supply is an AC voltage source or an AC current source. In preferred embodiments, the power supply 16 is part of a (power) supply network. The power supply 16 can, for example, be configured to provide an AC voltage of approximately 220 or 230 volts. The AC voltage can preferably have a frequency of approximately 60 Hz or 50 Hz.

[0056] Heating resistors can, for example, additionally be connected via ground to the power supply (energy source) 16 to form an electrical circuit.

[0057] The controller 11 is connected to a first heating resistor 13 and optionally to additional heating resistors 14, 15. The controller 11 is configured to supply the first heating resistor 13 with energy from the power supply 16 by means of wave packet control and by means of phase control and / or phase trailing edge control depending on the power setpoint of the power setpoint generator 12. A heating resistor of the heating resistors 13, 14, 15 can, for example, be U-shaped, in particular U-shaped with a spiral at the connecting piece of the legs of the U-shaped heating resistor.

[0058] In some embodiments, the controller may be configured to control the energy supply to the heating resistor 13 by means of wave packet control, phase control and phase trailing edge control depending on the power setpoint.

[0059] In some embodiments, the controller can be configured to supply a further heating resistor of the heating element 10 with energy from the energy supply 16 by means of wave packet control and by means of phase control and / or phase trailing edge control depending on the line setpoint of the power setpoint generator 12.

[0060] In some embodiments, the controller 11 is configured to supply energy to, for example, a further heating resistor 15 as a function of the power setpoint of the power setpoint generator 12 by connecting the heating resistor 15 to the power supply 16.

[0061] In some embodiments, the controller may be configured to supply heating resistors 13, 14, 15 of the heating rod 10 with electrical energy by means of different conductors of a power supply, for example a three-phase current.

[0062] In some embodiments, the controller may be configured to supply heating resistors of the heating rod with electrical energy by means of a conductor of the power supply 16.

[0063] With phase-angle control, after a zero crossing of an alternating voltage (alternating current) from the power supply, a current flow to / from the heating resistor can be prevented until one phase of the alternating voltage (alternating current) exceeds a specified phase value. The specified phase value is determined depending on the power setpoint. The phase (phase angle) indicates the current position in the sequence of a periodic process.

[0064] With trailing edge phase control, after a phase of the alternating voltage exceeds a further predefined phase value until a zero crossing of the alternating voltage is reached, a current flow from / to the heating resistor can be prevented, whereby the further predefined phase value is determined depending on the power setpoint.

[0065] In wave packet control, a current flow from / to the heating resistor can be interrupted for a predetermined number of whole or half periods of the alternating voltage after a zero crossing of an alternating voltage (alternating current) within a predetermined period of time. The predetermined period of time and the predetermined number of whole or half periods within the predetermined period of time are determined depending on the power setpoint. In particular, a ratio between the predetermined number of whole or half periods within the predetermined period of time and the predetermined period of time can be determined depending on the power setpoint.

[0066] Half and full periods in which a power supply to a heating resistor is interrupted can be alternated within the time interval of half and full periods in which a power supply to the heating resistor is present, based on algorithms.

[0067] Fig. Figure 2 schematically shows a process flow of a method according to one embodiment of the invention. In some embodiments, steps of the method can be swapped, modified, executed in parallel, and their order changed without losing the essence of the invention. In some embodiments, steps can be split or combined.

[0068] In a first step S21, a heating rod comprising one or more heating resistors is provided. A heating resistor can be U-shaped, for example, in particular U-shaped with a spiral at the connecting piece of the legs of the U-shaped heating resistor.

[0069] In a further step S22, a power setpoint is provided. This can be done, for example, based on a heat request from a heating control system, based on a hot water request from a hot water control system, based on a user setting, etc.

[0070] In a further step S23, a power supply of one or more heating resistors of the one or more heating resistors is controlled as a function of the power setpoint by means of wave packet control and by means of phase control and / or phase trailing edge control.

[0071] Steps S24 and S25 are optional and independent of each other. In step S24, the heating resistor can be additionally controlled using either trailing edge or leading edge phase control depending on the power setpoint. This can reduce harmonics.

[0072] In a step S25, one or more additional heating resistors can be connected to a power supply depending on the power setpoint.

[0073] Fig. 3 schematically shows a process flow diagram of a method according to an embodiment of the invention. Fig. 3 differs from the procedure shown in Fig. 2 in that, after step S22, a step S31 detecting a zero crossing of a current or voltage curve of the power supply is inserted. Furthermore, step S23 is changed to step S23a, namely, the control of a power supply of a heating resistor of the one or more heating resistors takes place as a function of the power setpoint by means of wave packet control and by means of phase control or phase trailing edge control as a function of the detected zero crossing of a current and / or voltage curve of the power supply (energy source).

[0074] Analogously, the optional step S24 can be changed to an optional step S24a, namely that the control of the heating resistor depending on the power setpoint can additionally be carried out by means of trailing edge control or by means of leading edge control depending on the detected zero crossing of the current and / or voltage curve of the power supply.

[0075] Furthermore, the optional step S25 can be changed to an optional step S25a, namely that the connection of a further heating resistor can be carried out as a function of the power setpoint as a function of the detected zero crossing of the current and / or voltage curve of the energy supply (energy source).

[0076] Preferably, the control of a heating resistor of the one or more heating resistors can be carried out as a function of a zero crossing of a current and / or voltage curve of an energy source to which the heating resistor is / will be connected or from which the heating resistor is disconnected.

[0077] Fig. Figure 4 schematically shows a heating element 40 according to one embodiment of the invention. The heating element 40 comprises heating resistors R1, R2, R3, R4, a controller 41, and a power setpoint controller 42. In this embodiment, for example, the power setpoint of the power setpoint controller 42 can be set by a user via a rotary control. In some embodiments, the power setpoint can be set, for example, by a heating controller, an external unit, a remote control, etc.

[0078] The heating resistor R1 can, for example, have a maximum heating power P 1,maxof 375 watts. The heating resistor R2, for example, can also have a maximum heating power P 2,max of 375 watts. The maximum heating power P 3,max The heating resistor R3 can be 750 watts and the maximum heating power P 4,max The heating resistor R4 can be, for example, 1500 watts. When dimensioning the heating resistors as shown above, the equation Pn,max≤∑j=1n−1Pj,max fulfilled.

[0079] In some embodiments, the controller can only control the heating power P1 of the heating resistor R1 using wave packet control and / or phase-angle control and / or trailing-edge control. In some embodiments, the control unit can also be configured to regulate the heating power of additional heating resistors, in particular by controlling the power supply, using wave packet control, phase-angle control and / or trailing-edge control.

[0080] As in Fig. As can be seen in Figure 4, a heating resistor can comprise one or more turns or windings 44 (see the shape of the heating resistor R4). Individual turns or windings 44 are preferably spaced apart from one another, so that heat transfer to a medium to be heated (to be heated) can be particularly efficient. Examples of a medium to be heated (to be heated) include water, antifreeze, (treated) heating water, domestic water, gray water, a combination thereof, etc.

[0081] In embodiments in which the energy supply (energy source) is in the form of a three-phase alternating current (three-phase current), the heating resistors can be connected to the conductors of the three-phase alternating current in such a way that the load is distributed as evenly as possible across the conductors.

[0082] If an energy supply (energy source) is in the form of a three-phase alternating current (three-phase current), for example with a power setpoint of less than 1500 watts, the first heating resistor R1 can be connected to a first conductor of the three-phase alternating current, the second heating resistor to a second conductor of the three-phase alternating current and the third heating resistor R3 to a third conductor of the three-phase alternating current.

[0083] If the power setpoint P soll For example, with a 1500 watt system, the first and second heating resistors R1 and R2 can be connected to a first conductor, the third heating resistor R3 to a second conductor, and the fourth heating resistor R4 to a third conductor of the three-phase alternating current. This allows for a reasonably even load distribution across the three conductors of the three-phase alternating current. As a result, unbalanced loads are avoided.

[0084] In some embodiments, the heating resistors R1, R2, R3, R4 may be connected in a star configuration, such as in Fig. 1. Advantageously, the star center point can be connected to a neutral conductor. In some embodiments, the heating resistors R1, R2, R3, and R4 can be connected in a delta circuit. This allows a higher voltage to be applied to the heating resistors R1, R2, R3, and R4.

[0085] In some embodiments, all heating resistors of the heating rod can be connected to a power supply conductor, particularly in the form of a three-phase alternating current. This can be advantageous, for example, when using multiple heating rods.

[0086] Fig. Figure 5 shows a schematic overview of compliance with flicker limits for various control methods as a function of maximum power. The left-hand side shows the maximum power of a heating resistor, i.e., the heating resistor consumes 2000 W, 1500 W, and 750 W, respectively, when directly connected to a power supply (without phase-angle control and wave packet control).

[0087] The second column refers to a full-wave control, the third column to a half-wave control and the fourth column to a phase control with regard to voltage fluctuations (flicker) generated in the supply network.

[0088] As in Fig. As shown in Figure 5, full-wave control is considered very critical at a maximum heating resistor value of 750 watts, as well as at 1500 watts and 2000 watts. Similarly, half-wave control is considered very critical at a maximum heating resistor power of 2000 watts and 1500 watts. However, at a maximum heating resistor power of 750 watts, half-wave control may be possible with a suitable algorithm selection. 52

[0089] A phase control, on the other hand, is to be regarded as uncritical 53 regardless of the maximum heating power of the heating resistor, in particular for the maximum heating powers of the heating resistor of 2000 watts, 1500 watts and 750 watts.

[0090] In general, the flicker limits are met at a threshold of about 400W and lower maximum powers.

[0091] Fig. Figure 6 shows a schematic overview of compliance with flicker limits for various control methods depending on the control level. The results are based on simulations using heating resistors with a maximum heating power of 500 watts.

[0092] In Fig. Figure 6 shows that up to 25% full-wave control, compliance with the normative limits can only be achieved with special measures. When the heating output of a heating resistor is reduced between 30 and 100% using full-wave control, the voltage fluctuations exceed the legal requirements.

[0093] With half-wave control, the normative specifications can be met up to a heating output of 40% of the maximum heating output of a heating resistor, see section 53. In a range between 45 and 55% of the maximum heating output, the legal limit values ​​can be met using half-wave control with special measures, such as special algorithms, see section 52. In a range between 60% and 100% of the maximum heating output of a heating resistor, the legal specifications can no longer be met, see section 51.

[0094] As already known, phase control does not produce any, or at least no significant, flicker, see section 53.

[0095] Fig. Figure 7 shows a table with harmonic measurements as a function of a percentage modulation and as a function of a maximum power of a heating resistor. Fig. Figure 7 shows that for a heating resistor with a maximum power of 750 watts, both the limit value of the 13th harmonic of 0.21 A and the limit value of the 15th harmonic of 0.17 A are complied with at both a modulation of 20% and a modulation of 50%.

[0096] Likewise, the Fig. 7 shows that for maximum powers of 1500 watts or 2000 watts of a heating resistor for different percentage modulations (50%, 90%, 10%), both the limit value of the 13th harmonic of 0.21 A and the limit value of the 15th harmonic of 0.17 A cannot be met.

[0097] Fig. Figure 8a shows an example of a combination of wave packet control with phase control and / or phase cut control according to embodiments of the invention. Fig. 8a shows a coordinate system 80. On the x-axis, a heating output setpoint P sollof a heating element. On the y-axis, the actual heating power value P ist plotted. The coordinate system shows a curve of a phase-angle control 81 and a curve of a wave packet control 82. Furthermore, a curve 83 is shown, which is intended to represent a possible combination of the phase-angle control 81 with the wave packet control 82.

[0098] In Fig. Figure 8a illustrates that a wave packet controller 82 can only control discrete power values. Therefore, the curve of the wave packet controller 82 has a stepped profile with discrete values. Fig. 8a also shows that a wave packet control, in order to achieve the best possible results, in a range 85 the heating power exceeds a desired heating power P sollto achieve the control target as best as possible (minimal control error). The curve of the phase control 81, on the other hand, forms a power setpoint P soll exactly to a power actual value P ist with identical values.

[0099] Curve 83 shows that the Fig. 8a, a heating power of a heating resistor is controlled by means of the wave packet control so that a power setpoint P soll is set as the control target without changing the power setpoint P soll A difference between an actual power value achieved by means of wave packet control and the power setpoint P soll is compensated by means of the phase control, i.e. the difference in power is generated by means of the phase control in the heating resistor.

[0100] A trailing-edge phase control behaves analogously to the curve of the phase-angle control 81. Consequently, curve 83 can be achieved by combining wave packet control with trailing-edge phase control and / or phase-angle control.

[0101] In some embodiments, the Fig. 8b shows an exemplary control comprising a combination of the wave packet control with the phase angle control on the Fig. 8a, comprising a combination of phase control and wave packet control.

[0102] Fig. 8b shows an example of a combination of wave packet control with phase angle control according to an embodiment of the invention. Fig.Figure 8b shows a schematic coordinate system. The x-axis represents the phase value of an alternating voltage from a power supply (energy source). If the frequency of the alternating voltage of the power supply is known, the x-axis can be scaled accordingly as a time axis. The y-axis represents a current flow I. ist by a heating resistor which is controlled by phase angle control and wave packet control depending on a power setpoint.

[0103] The wave packet control in this embodiment is a half-wave control, with the period duration for the control method being 5π (five half-waves). During the half-waves, the heating resistor controlled by wave packet control and phase angle control is connected to the power supply due to the half-wave control, so that a current I istflows through the heating resistor. The half-waves are due to the phase-angle control.

[0104] It is particularly evident that in this embodiment, an actual power below one of the power setpoints is generated by means of the wave packet control 82 and the power difference to the power setpoint is converted by means of the phase control 81 in the heating resistor.

[0105] It is particularly noteworthy that in this embodiment only one half-wave during the period of five half-waves is cut by the phase control, which reduces the generation of harmonics.

[0106] In some embodiments, a half-wave can be controlled by phase control and a further half-wave can be controlled by phase control, in particular depending on the power setpoint P sollIn some embodiments, a half-wave can be controlled both by phase control and by phase control, in particular depending on the power setpoint P soll In some embodiments, the half-wave can be cut off depending on an algorithm. In particularly advantageous embodiments, half-waves / full-waves can have no cut-off by a phase-angle control and / or a phase-angle control. This has the advantage that no harmonics are generated.

[0107] Advantageously, positive (positive current flow I ist ) and negative (negative current flow I ist ) Half-waves (preferably balanced). This avoids direct current due to transformer saturation.

[0108] As a result, by combining wave packet control and phase control, the heating power of a heating resistor can be precisely adjusted to a power setpoint P soll The heating resistor is controlled in such a way that flicker and harmonic limits can be easily complied with, yet the heat output of a heating resistor can be continuously adjusted (value-continuously) over the widest possible heat output range.

[0109] In some embodiments, alternatively or in addition to the phase control, a phase control can be used instead of the phase control or combined with the phase control in order to regulate a heat output of a heating resistor to a power setpoint.

[0110] Preferably, the heating element or the method for controlling a heating element can be used for generating hot water in a house or for heating one or more rooms in a house, in particular with a connection to a (legally regulated / normatively regulated) electrical energy supply network (power supply network / mains supply).

Claims

[1] Heating rod (40) for hot water preparation and / or as a heat generator for heating in a building by means of electrical energy, comprising: - one or more heating resistors (R1, R2, R3, R4), - a power setpoint generator (42) for providing a power setpoint, - a controller (41) for controlling a power supply to the one or more heating resistors (R1, R2, R3, R4) as a function of the power setpoint, characterized by that the controller (41) is designed to control a power supply of a heating resistor of the one or more heating resistors (R1, R2, R3, R4) as a function of the power setpoint by means of wave packet control and by means of phase control or phase trailing edge control. [2] Heating rod (40) according to claim 1, wherein the controller (41) is configured to control the energy supply of the heating resistor by means of wave packet control, phase control and phase cut-off control as a function of the power setpoint. [3] Heating rod (40) according to claim 1 or 2, wherein the controller (41) is configured to control a power supply of a further heating resistor of the plurality of heating resistors (R1, R2, R3, R4) with electrical energy by connecting the further heating resistor to a power supply (16). [4] Heating rod (40) according to one of claims 1 to 3, wherein the controller (41) is configured to make changes in the power supply of a heating resistor in a zero crossing of a current and / or voltage curve of the power supply. [5] Heating rod according to one of claims 1 to 4, wherein a maximum heating power P n,maxan n-th heating resistor of the several heating resistors (R1, R2, R3, R4) is dimensioned as follows: Pn,max≤∑j=1n−1Pj,max. [6] Heating rod according to one of claims 1 to 5, wherein one or more heating resistors are separated from a medium to be heated by insulators. [7] Heating rod (40) according to one of claims 1 to 6, wherein the controller (41) is designed to continuously regulate a power supply of a first heating resistor (R1) such that a heating power P1 of the heating resistor is in a range between a minimum heating power P 1,min and a maximum heating output P 1,max a value depending on the power setpoint of the power setpoint generator (42). [8] Heating rod (40) according to claim 7, wherein the controller (41) is configured to set a constant heating power P2 of the second heating resistor by connecting a power supply (16) to a further heating resistor (R2, R3, R4). [9] Heating rod (40) according to one of claims 1 to 8, wherein the control (41) is arranged to to control a heating power P1 of the heating resistor (R1) continuously by means of wave packet control and by means of phase control and / or phase trailing edge control depending on the power setpoint of the power setpoint generator (42), and depending on the power setpoint of the power setpoint generator (42), to connect further heating resistors (R2, R3, R4) of the plurality of heating resistors (R1, R2, R3, R4) to a power supply (16). [10] Method for operating a heating rod (40) for hot water preparation and / or as a heat generator of a heating system in a building by means of electrical energy, comprising the steps: Providing a heating rod (40), the heating rod (40) comprising one or more heating resistors (R1, R2, R3, R4); Providing a power setpoint; Controlling a power supply of a heating resistor of the one or more heating resistors (R1, R2, R3, R4) as a function of the power setpoint by means of wave packet control and by means of phase control or phase trailing edge control. [11] Method according to claim 10, wherein the control of the energy supply of the heating resistor is carried out as a function of the power setpoint by means of wave packet control, phase control and phase trailing edge control. [12] Method according to claim 10 or 11 comprising a step: Controlling a power supply of a further heating resistor of the plurality of heating resistors (R1, R2, R3, R4) by connecting the further heating resistor to a power supply (16) and / or comprising a step Connecting a further heating resistor of the plurality of heating resistors (R1, R2, R3, R4) to a power supply (16) depending on the power setpoint. [13] Method according to one of claims 10 to 12 comprising a step: Detecting a zero crossing of a current and / or voltage curve of the power supply, whereby the control of a power supply of a heating resistor of the one or more heating resistors (R1, R2, R3, R4) is carried out as a function of the power setpoint by means of wave packet control and by means of phase control and / or phase trailing edge control as a function of a detected zero crossing of a current and / or voltage curve of the power supply. [14] Method according to one of claims 10 to 13, wherein in the control of the heating resistor, the energy supply of the heating resistor is continuously regulated so that a heating power P1 of the heating resistor is in a range between a minimum heating power P 1,min and a maximum heating output P 1,max a value depending on the power setpoint. [15] Method according to one of claims 10 to 14 comprising the steps: Continuous control of a heating power P1 of the heating resistor by means of wave packet control and by means of phase control and / or phase trailing edge control depending on the power setpoint, and Connecting further heating resistors of the plurality of heating resistors (R1, R2, R3, R4) to a power supply (16) depending on the power setpoint.

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