Method for operating a system for converting electrical energy

Abstract

The present invention relates to a method for operating a system (1) for converting electrical energy from an on-board network (101) of a drive train (100) into heat. The system (1) comprises a switching device (3) and 2 consumers (2), wherein the switching device (3) connects the consumers (2) individually to the vehicle electrical system (101) and to each other for the conversion of electrical energy from the vehicle electrical system (101). The invention also relates to a system (1) operated in this manner and to a computer program product for carrying out the method.

Description

[0001] The present invention relates to a method for operating a system for converting electrical energy from an on-board electrical system. The invention also relates to a computer program for carrying out the method and to a system operated in this manner.

[0002] The powertrain of a partially or fully electric vehicle typically includes an electric motor connected to the vehicle's electrical system. This system usually operates on direct current (DC). An inverter is generally located between the electrical system and the electric motor.

[0003] There may be excess electrical energy in the drivetrain that needs to be dissipated. This excess electrical energy can, for example, originate from the electric machine when it is operating in generator mode.

[0004] To dissipate excess electrical energy, a system with consumers can be used that convert electrical energy into heat when an electric current flows through it, thus consuming and dissipating it.

[0005] Such a system is known from WO 2023 / 036510 A1. The system is connected to the vehicle's electrical system via an inverter. The inverter can connect a total of three loads to the vehicle's electrical system, each of which converts electrical energy from the system into heat when connected.

[0006] The object of the present invention is to provide an improved or different method for operating a system of the aforementioned type. Furthermore, the object of the invention is to provide improved or different embodiments of such a system and of a computer program product for operating such a system.

[0007] The problem is solved using the features of the independent claims. Advantageous variants are the subject of the dependent claims.

[0008] The core idea of ​​the invention is therefore to connect two consumers for converting electrical energy into heat to the vehicle's electrical system by means of a switching device, in order to operate a system for converting electrical energy from the vehicle's electrical system into heat. The switching device can connect the consumers to the electrical system either individually or in parallel. Thus, depending on the connection of the consumers to the electrical system, different amounts of energy are converted from the electrical system. This allows for flexible use of the consumers for converting electrical energy into heat and therefore demand-based dissipation of electrical energy from the electrical system. Consequently, the core idea leads to an adaptable conversion of electrical energy from the vehicle's electrical system into heat with simple implementation.

[0009] The core idea is advantageously implemented in a method for operating such a system. The system comprises two consumers, which are hereinafter referred to as the first consumer and the second consumer. Each consumer generates heat when an electric current flows through it, i.e., when energized, thus converting electrical energy from the vehicle's electrical system into heat. The system also includes a switching device capable of electrically connecting the consumers to the vehicle's electrical system and to each other. This switching device is preferably part of a power electronics unit. The switching device allows the system to operate in two modes, which are hereinafter referred to as the first operating mode and the second operating mode. In the first operating mode, the switching device connects only one of the consumers to the vehicle's electrical system, so that only this consumer receives power.In the second operating mode, the consumers are connected in parallel by means of the switching device and connected to the vehicle electrical system, so that they are powered in parallel.

[0010] The system is conveniently connected, or connectable, to the vehicle's electrical system via the switching device. The switching device selectively establishes the electrical connection of the respective load to the vehicle's electrical system in order to direct, as described, a current flowing through the vehicle's electrical system through the at least one load connected to the system, so that this load converts the electrical energy into heat. The system thus consumes electrical energy and consequently power, which is hereinafter also referred to as power consumption. In a lossless system, the power consumption corresponds to the square of the voltage U of the vehicle's electrical system divided by the total resistance R_total of the loads connected to the vehicle's electrical system, hereinafter also referred to as total resistance R_total. Therefore, P = U 2 / R_total, where P corresponds to the power consumption. The power consumption is therefore inversely proportional to the total resistance.

[0011] If neither of the electrical consumers is powered, for example, if both consumers are disconnected from the vehicle's electrical system, no conversion of electrical energy takes place via the consumers. Therefore, no power is consumed.

[0012] In the second operating mode, the total resistance R_total is minimized, and thus the power consumption is maximized. The second operating mode can therefore also be referred to as the high-power operating mode.

[0013] In the first operating mode, the total resistance R_total is higher compared to the second operating mode. Consequently, the first operating mode results in reduced power consumption compared to the second. The first operating mode can therefore also be described as the average power operating mode.

[0014] Preferably, the system can be operated in a further operating mode, which is subsequently also referred to as the third operating mode. In the third operating mode, the loads are connected in series via the switching device and connected to the vehicle's electrical system, so that they are energized in series. The total resistance R_total is therefore lower than that in the first operating mode. Consequently, the power consumption in the third operating mode is lower than in the first operating mode. The third operating mode can therefore also be referred to as the low-power operating mode. This results in further flexibility in the consumption of electrical energy from the vehicle's electrical system.

[0015] The respective consumer can be of any design, provided that it generates heat when an electric current from the vehicle's electrical system flows through it, and thus consumes electrical energy. The respective consumer is therefore, in particular, an electrical load.

[0016] For example, at least one of the consumers can be a coil or at least have a coil which, when energized, inductively converts electrical energy from the vehicle electrical system into heat through eddy currents.

[0017] Likewise, at least one of the consumers could be a heating element or similar device.

[0018] In advantageous versions, at least one of the consumers, and in particular the respective consumer, is a power resistor. This leads to simple implementation and scalable heat generation in a compact design. In particular, the generated heat can thus be easily dissipated, for example, to supply another application, such as an air conditioner.

[0019] The switching device can be designed in any way you like, as long as it can connect the consumers to each other and to the vehicle's electrical system as described.

[0020] In advantageous versions, the switching device is part of an inverter or at least incorporates such an inverter for individually connecting the loads to each other and / or to the vehicle's electrical system. This allows the switching device to be operated at higher frequencies. Furthermore, this design simplifies the system and makes it more compact.

[0021] The power electronics, in particular the switching device, preferably has two connections to the vehicle's electrical system, which are hereinafter also referred to as vehicle electrical system connections or simply mains connections. The power electronics thus have a first mains connection and a second mains connection.

[0022] The respective consumer preferably has two connections that allow the consumer to be powered and are hereinafter also referred to as consumer connections.

[0023] The first consumer connection of the first consumer is hereinafter also referred to as the first primary consumer connection, and a second consumer connection of the first consumer is also referred to as the second primary consumer connection. Similarly, the first consumer connection of the second consumer is hereinafter also referred to as the first secondary consumer connection, and a second consumer connection of the second consumer is also referred to as the second secondary consumer connection.

[0024] In preferred variants, the second primary consumer connection is connected to the second secondary consumer connection, so that the consumers are connected in series.

[0025] Preferably, in the first operating mode, the switching device connects the first primary load connection to the first mains connection and the second primary load connection to the second mains connection, and disconnects the first secondary load connection from the mains connections. Alternatively, in the first operating mode, the switching device connects the first secondary load connection to the first mains connection and the second secondary load connection to the second mains connection, while disconnecting the first primary load connection from the mains connections.

[0026] In the second operating mode, the switching device preferably connects the first primary consumer connection and the first secondary consumer connection to the first mains connection, and the second primary consumer connection and the second secondary consumer connection to the second mains connection.

[0027] Preferably, in the third operating mode, the switching device connects the first primary consumer connection to the first mains connection and the first secondary consumer connection to the second mains connection, whereby the second primary consumer connection and the second secondary consumer connection are disconnected from the mains connections, so that the consumers are energized in series.

[0028] In preferred embodiments, the loads are supplied with a uniform current periodically in the respective operating mode. This leads to uniform aging and / or stress on the loads and thus to an overall increased service life of the system. Furthermore, heat is generated uniformly within the system in this way. The latter simplifies the use and / or dissipation of the generated heat. Moreover, this results in a comparatively homogeneous heat distribution within the system.

[0029] It is understood that, in addition to the method for operating the system, a system operated in this manner as such is also part of the scope of this invention.

[0030] The system may include a suitably designed control unit for executing the procedure.

[0031] The process is preferably carried out using a computer program.

[0032] The computer program product therefore comprises instructions which, when the computer program product is executed by a computer, cause it to carry out the procedure.

[0033] The computer can be part of the control system, or vice versa. Alternatively, the computer can be the control system itself.

[0034] It goes without saying that the computer program product itself is also part of the scope of this invention.

[0035] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0036] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0037] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components. They show, schematically, each one Fig. 1 a highly simplified, circuit diagram-like representation of a drive train with an on-board electrical system and a system for converting electrical energy from the on-board electrical system, Fig. 2 a highly simplified, circuit diagram-like representation of the system and the vehicle electrical system, Fig. 3. A circuit diagram-like representation of a switching device and consumers of the system in a first operating mode of the system. Fig. 4 the representation from Fig. 3 in a second operating mode of the system, Fig. 5 the representation from Fig. 3 in a third operating mode of the system, Fig. 6. A diagram to illustrate the operation of the system using the first operating mode. Fig. 7. A diagram to illustrate the operation of the system using the first operating mode. Fig. 8 a diagram to illustrate the operation of the system using the second operating mode, Fig. 9 a diagram to illustrate the operation of the system using the second operating mode, Fig. 10. A diagram to illustrate the operation of the system using the third operating mode.

[0038] One in the Fig. 1 and Fig. 2 and 3 to 5, the exemplary system 1 shown serves to convert, in particular to reduce, electrical energy from an electrical and into the Fig. 1 and Fig. 2 exemplary drive train 100 of a merely in Fig. 1 motor vehicle 200, which is indicated but not shown otherwise.

[0039] The electric powertrain 100, hereinafter also referred to simply as powertrain 100, features, as described in the Fig. 1 and Fig. Figure 2 shows an on-board electrical system 101, which serves to supply an electric machine 102 of the drive train 100. System 1 serves to convert electrical energy from the on-board electrical system 101 into heat. The on-board electrical system 101 makes it possible to supply the electric machine 102 with electricity when it is operating as a motor to drive the vehicle 200. Furthermore, the on-board electrical system 101 can be used to draw off electrical energy generated in the electric machine 102 when it is operating as a generator. In the illustrated embodiments, the on-board electrical system 101 is a high-voltage on-board electrical system 101 operated with direct current / direct voltage. An inverter 103 is connected upstream of the electric machine 102.In the illustrated embodiments, the drive train 100 also includes a traction battery 104, which is connected to the electric machine 102 via the vehicle electrical system 101 and the inverter 103.

[0040] The conversion, in particular the reduction, of electrical energy with system 1 takes place through a connection of consumers 2 (see for example Fig. 1) of system 1 with the vehicle electrical system 101, such that a current flowing through the vehicle electrical system 101 flows through the respective consumer 2 connected to the vehicle electrical system 101, thus energizing them. System 1 has two consumers 2, namely a first consumer 2, 2a, and a second consumer 2, 2b. Each consumer 2 generates heat when energized, resulting in the aforementioned conversion of electrical energy into heat. In the illustrated embodiments, the consumers 2 are, purely by way of example, each configured as a power resistor 20. In the illustrated embodiments, the consumers 2 are, purely by way of example, identical components, i.e., they have, in particular, the same resistance R.

[0041] The connection of the respective consumer 2 to the vehicle electrical system 101 is made via a connection in the Fig. 1 to 5 are examples of switching device 3 of system 1. The switching device 3 is part of a power electronics system 21.

[0042] This heat, generated by consumers 2, can be transferred by means of a [unclear] in Fig. The coolant is discharged from the cooler 4 shown in the diagram. For this purpose, the cooler 4 has fluid connections 5, allowing a coolant to flow through it. The consumers 2 are fluidically separated from the coolant and can be, as shown in the diagram, Fig. 3 can be removed, and are located in the cooler 4.

[0043] The switching device 3 can only be used in the Fig. 3 to 5 show the capacitance 6, in the illustrated embodiments in the form of a capacitor 7. The switching device 3 can, as in the embodiment shown, Fig. 1 and Fig. Figures 2 and 3 to 5 show that they are part of an inverter 8. As shown below, based on the Fig. As explained in sections 3 to 5 by way of example, the switching device 3 is designed in such a way that it can connect the consumers 2 individually to the vehicle electrical system 101 and to each other.

[0044] The switching device 2, in particular the inverter 8, can be controlled by pulse width modulation. Pulse width modulation, hereinafter also referred to as "PWM", is carried out at a frequency and thus a period C (compare Fig. 6 to 10). This period C is subsequently also referred to as the PWM cycle C.

[0045] In the illustrated embodiments, the respective consumer 2 indicates the need for power supply, such as... Fig. As can be seen from Figure 2, a first connection 9 and a second connection 10 are provided. The first connection 9, 9a of the first consumer 2, 2a is hereinafter also referred to as the first primary consumer connection 9, 9a, and the first connection 9, 9b of the second consumer 2, 2b as the first secondary consumer connection 9, 9b. Similarly, the second connection 10, 10a of the first consumer 2, 2a is hereinafter also referred to as the second primary consumer connection 10, 10a, and the second connection 10, 10b of the second consumer 2, 2b as the second secondary consumer connection 10, 10b. The second primary consumer connection 10, 10a and the second secondary consumer connection 10, 10b are connected to each other, so that the consumers 2 are connected in series.

[0046] How especially the Fig. As can be seen from Figure 2, the switching device 3 in the illustrated embodiments has two connections 11 that can be connected to or are connected to the vehicle electrical system 101, which are hereinafter also referred to as vehicle electrical system connections 11 or, in short, mains connections 11. The switching device 3 thus has a first mains connection 11, 11a and a second mains connection 11, 11b.

[0047] In the illustrated embodiments, the switching device 3, in particular the inverter 8, also has three connections 12 for the loads 2, which are hereinafter also referred to as switching connections 12. In the illustrated embodiments, as in the Fig. Figures 2 to 5 show the first primary consumer connection 9, 9a of the first consumer 2, 2a being connected to a first switch terminal 12, 12a, and the first secondary consumer connection 9, 9b of the second consumer 2, 2b being connected to a second switch terminal 12, 12b of the switching device 3. The second primary consumer connection 10, 10a of the first consumer 2, 2a and the second secondary consumer connection 10, 10b of the second consumer 2, 2b are connected to a third switch terminal 12, 12c of the switching device 3.

[0048] The switching device 3 can be switched between different positions 13, 14, 15, thus allowing the system 1 to operate in different operating modes 16, 17, 18. In the different operating modes 16, 17, 18, the loads 2 are connected to and energized by the vehicle electrical system 101 in different ways, resulting in varying amounts of electrical energy from the vehicle electrical system 101 being converted into heat. In this process, the system 1 consumes electrical energy and thus a power P, which is subsequently also referred to as power consumption P. In a lossless system, the power consumption P therefore corresponds to the square of the voltage U of the vehicle electrical system 101 divided by the total resistance R_total of the loads 2 connected to the vehicle electrical system, i.e., P = U 2 / R_ges.

[0049] In an exemplary in Fig. In the first operating mode 17 shown in Figure 3, the switching device 3 connects only one of the consumers 2 to the vehicle electrical system 101, so that only this consumer 2 is energized. In the first operating mode 17, the switching device 3 is in a position 14 in the illustrated embodiments, which is hereinafter also referred to as the first position 14. The power consumption P is therefore given by P = U 2 / R.

[0050] How Fig. As can be seen from Figure 3, in the illustrated embodiments, the switching device 3, in the first operating mode 17, connects the first primary consumer connection 9, 9a to the first mains connection 11, 11a and the second primary consumer connection 10, 10a to the second mains connection 11, 11b, whereas the first secondary consumer connection 9, 9b is disconnected from the mains connections 11. Likewise, in the first operating mode 17, the switching device 3 can connect the first secondary consumer connection 9, 9b to the first mains connection 11, 11a and the second secondary consumer connection 10, 10b to the second mains connection 11, 11b, as well as disconnect the first primary consumer connection 9, 9a from the mains connections 11 (not shown).

[0051] In an exemplary in Fig. In the second operating mode 18 shown in Figure 4, the switching device 3 connects the loads 2 in parallel and to the vehicle electrical system 101, so that the loads 2 are energized in parallel. In the second operating mode 18, the switch 3 is in a position 15 in the illustrated embodiments, which is also referred to below as the second position 15. The power consumption P is therefore P = 2U 2 / R.

[0052] How Fig. 4 can be taken from the illustrations shown, in the second operating mode 18 the switching device 3 connects the first first consumer connection 9, 9a and the first second consumer connection 9, 9b to the first mains connection 11, 11a and the second first consumer connection 10, 10a as well as the second second consumer connection 10, 10b to the second mains connection 11, 11b.

[0053] Furthermore, the switching device 3 can be integrated into a Fig. In the third operating mode 16 shown in Figure 5, the consumers 2 are connected in series and to the vehicle electrical system 101, so that the consumers 2 are energized in series. In the third operating mode 16, the switching device 3 is in a position 13 in the illustrated embodiments, which is hereinafter also referred to as the third position 13. Thus, the power consumption P is given by P = U 2 / 2R.

[0054] How Fig. As can be seen from Figure 5, in the illustrated embodiments, the switching device 3, in the third operating mode 16, connects the first primary consumer connection 9, 9a to the first mains connection 11, 11a and the first secondary consumer connection 9, 9b to the second mains connection 11, 11b. Furthermore, in the third operating mode 16, the switching device 3 disconnects the second primary consumer connection 10, 10a and the second secondary consumer connection 10, 10b from the mains connections 11.

[0055] The switching device 3 can also be switched in various positions not shown, in which no power is consumed. For example, it is possible to disconnect the power resistors 2 from the vehicle electrical system 101.

[0056] In the illustrated embodiments, and preferably, the consumers 2 are periodically and uniformly supplied with current in the respective operating mode 16, 17, 18.

[0057] The operation of System 1 is described below using the following examples: Fig. The control of the switching device 3, as shown in sections 6 to 10, is explained. Fig. Figures 6 to 10 each show a diagram in which time t is plotted along the abscissa and power consumption P along the ordinate. In the Fig. Figures 6 to 10 also show the power consumption P of the first consumer 2, 2a with the vehicle electrical system 101 with a solid line L1 and the power consumption of the second consumer 2, 2b with a dashed line L2. More precisely, the Fig. 6 to 10, which determine the maintenance duration of the corresponding operating modes 16, 17, 18 over a period T. In the Fig. From 6 to 10, the PWM cycle C is indicated by vertically running, dashed lines.

[0058] How the Fig. The operating modes 16, 17, and 18 shown in the illustrated embodiments are periodically repeated for twice the duration of the PWM cycle C. The states in the respective operating modes 16, 17, and 18 are thus repeated periodically with a period T, which, for example, corresponds to twice the duration of the PWM cycle C for a duty cycle of 100%. By selecting the appropriate operating mode depending on the on-board voltage U and a required power consumption P, the so-called ripple currents and voltage ripple on the on-board network 101 are reduced. Advantageously, the control frequency is also varied to achieve an optimum for the respective operating point.The power consumption P is modulated by the duty cycle, which is advantageously selected as large as possible by choosing the appropriate operating modes in order to achieve the desired effects of minimizing voltage ripple with all its associated benefits, such as reduced shield currents, EMC, eddy current losses, unwanted heating of critical components, and the like. This results in reduced amplitudes of the discharge currents during switching and the distribution of the discharge currents across two PWM cycles C, and thus two phases for controlling the switching device 3. The result is a reduction in the so-called ripple currents in the drive train 100 and, in particular, in the vehicle electrical system 101. In addition to improved operation of the drive train 100, components of system 1, especially the capacitor 6, can therefore be made smaller while still maintaining reduced ripple currents.This results in improved operation and a more compact and cost-effective training of System 1.

[0059] The Fig. 6 and Fig. Figure 7 shows the control of the switching device 3 using the first operating mode 17. More precisely, the figures show Fig. 6 and Fig. 7 the maintenance duration of the first operating mode 17 over a period T. In these embodiments, no overlapping connection of the consumers 2 to the vehicle electrical system 101 is provided. This means that only one of the consumers 2 is connected to and energized by the vehicle electrical system 101 at any given time. In the embodiments shown, as for example Fig. 6 can be taken from the consumer 2, which is alternately connected to the vehicle electrical system 101 at equal time intervals. During the Fig. In the exemplary embodiment shown in Figure 6, the consumers 2 are connected to the vehicle electrical system 101 one after the other for a connection duration that corresponds to a maximum of one-eighth of the period T, with the connection durations being evenly distributed over the period T. The alternating connection of the consumers 2 to the vehicle electrical system 101 results in the electrical energy converted into heat being distributed between both consumers 2. This leads, for example, to reduced wear on the system 1.

[0060] At the in Fig. In the embodiment shown in Figure 6, the consumers 2 are alternately connected to the vehicle electrical system 101 for one-eighth of the period T and disconnected from it for the following seven-eighths of the period T. In the illustrated embodiment, the first consumer 2, 2a is connected to the vehicle electrical system 101 for the first eighth of the period T and disconnected for the following seven-eighths of the period T. Furthermore, the second consumer 2, 2b is connected to the vehicle electrical system 101 for the fifth-eighth of the period T and disconnected for the remaining eighths of the period T.

[0061] At the in Fig. In the embodiment shown in Figure 7, the consumers 2 are each connected to the vehicle electrical system 101 for one-sixteenth of the period T, disconnected from the vehicle electrical system 101 for the following twelve-sixteenths of the period T, connected to the vehicle electrical system 101 for the next sixteenth of the period C, and disconnected from the vehicle electrical system 101 for the remaining sixteenths of the period T. In the illustrated embodiment, the first consumer 2, 2a is connected to the vehicle electrical system 101 for the first sixteenth and the thirteenth sixteenth of the period T and disconnected from the vehicle electrical system 101 for the remaining sixteenths of the period T. Furthermore, the second consumer 2, 2b is connected to the vehicle electrical system 101 for the fifth and the ninth sixteenth of the period T and disconnected from the vehicle electrical system 101 for the remaining sixteenths of the period T.

[0062] In these embodiments, the converted energy E during a period T can thus be (1 / 5)TxP, where P corresponds to the power consumption of a consumer 2, i.e., the power consumption P in the first operating mode 17.

[0063] The Fig. 8 and Fig. Figure 9 shows the control of the switching device 3 using the second operating mode 18. In the illustrated embodiments, the consumers 2 are operated in the second operating mode 18, i.e., connected in parallel and energized, for at least six-eighths, i.e., three-quarters, of the period T. In the illustrated embodiments, each consumer 2 is connected to the vehicle electrical system 101 for a maximum of seven-eighths of the period T. Furthermore, the consumers 2 are alternately disconnected from the vehicle electrical system 101, whereby only one of the consumers 2 may be energized at a time, and thus the first operating mode 17 may be present.

[0064] At the in Fig. In the embodiment shown in Figure 8, the respective consumer 2 is connected to the vehicle electrical system 101 for a total of seven eighths of the period T and disconnected from the vehicle electrical system 101 for the other eighth of the period T, whereby the disconnections of the consumers 2 are equally spaced in time from each other.

[0065] At the in Fig. In the embodiment shown in Figure 9, the respective consumer 1 is connected to the vehicle electrical system 101 for a total of six eighths of the period T and disconnected from the vehicle electrical system 101 for the other two eighths of the period T, wherein in each eighth of the period T one of the consumers 2 is disconnected from the vehicle electrical system 101.

[0066] In the control systems of the exemplary embodiments of the Fig. 8 and Fig. 9 The converted energy E during a period T can thus be (17 / 10)TxP, where P corresponds to the power consumption of a consumer 2 in the first operating mode 17.

[0067] Fig. Figure 10 shows the control of the switching device 3 using the third operating mode 16. The third operating mode 16 is alternately established and interrupted for a quarter of the period T, and thus for half the PWM cycle C. In the illustrated embodiment, the third operating mode 16 is maintained for the first quarter of the period T, for the next quarter of the period T the consumers 2 are disconnected from the vehicle electrical system 101, for the following quarter of the period T the third operating mode 16 is maintained, and so on.

[0068] When controlling the exemplary embodiment of the Fig. 10 The converted energy E during a period T can thus be (1 / 4)TxP, where P corresponds to the power consumption of a consumer P in the first operating mode 17.

[0069] System 1 can only be in Fig.The system 1 has an indicated control device 19 for operating the system 1, in particular for controlling the switching device 3. The control device 19 is designed accordingly.

[0070] The operation of System 1 is preferably implemented by means of a computer program product containing corresponding instructions. Preferably, when the computer program product is executed by a computer (not shown) and / or by the control unit 19, the instructions cause the computer and / or the control unit 19 to operate System 1 as described. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] WO 2023 / 036510 A1

[0005]

Claims

[1] Method for operating a system (1) for converting electrical energy from an on-board network (101) of a powertrain (100) into heat, - with a first consumer (2, 2a) and a second consumer (2, 2b) for generating heat, - with a power electronics unit (21) comprising a switching device (3) for connecting the consumers (2) to the vehicle electrical system (101) and to each other, in particular electrically, - where • in a first operating mode (17) only one of the consumers (2) is connected to the vehicle electrical system (101) by means of the switching device (3), • in a second operating mode (18) the consumers (2) are connected in parallel and to the vehicle electrical system (101) by means of the switching device (3). [2] Method according to claim 1, characterized by, that in a third operating mode (16) the consumers (2) are connected in series and to the vehicle electrical system (101) by means of the switching device (3). [3] Method according to claim 1 or 2, characterized by , - that the first consumer (2, 2a) has a first primary consumer connection (9, 9a) and a second primary consumer connection (10, 10a), - that the second consumer (2, 2b) has a first secondary consumer connection (9, 9b) and a second secondary consumer connection (10, 10b), - that the second primary consumer connection (10, 10a) is connected to the second secondary consumer connection (10, 10b) so that the consumers (2) are connected in series, - that the power electronics (21) is connected or connectable to the vehicle electrical system (101) via a first mains connection (11, 1a) and a second mains connection (11, 11b), - that the switching device (3) is in the first operating mode: • connects the first primary consumer connection (9, 9a) to the first network connection (11, 11a) and the second primary consumer connection (10, 10a) to the second network connection (11, 11b) and disconnects the first secondary consumer connection (9, 9b) from the network connections (11), or • connects the first secondary consumer connection (9, 9b) to the first network connection (11, 11a) and the second secondary consumer connection (10, 10b) to the second network connection (11, 11b) and disconnects the first primary consumer connection (9, 9a) from the network connections (11), - that the switching device (3) in the second operating mode (18) connects the first primary consumer connection (9, 9a) and the first secondary consumer connection (9, 9b) to the first mains connection (11, 11a) and connects the second primary consumer connection (10, 10a) and the second secondary consumer connection (10, 10b) to the second mains connection (11, 11b). [4] Method according to claims 2 and 3, characterized by , that the switching device (3) in the third operating mode (16) connects the first primary consumer connection (9, 9a) to the first mains connection (11, 11a) and the first secondary consumer connection (9, 9b) to the second mains connection (11, 11b) and disconnects the second primary consumer connection (10, 10a) and the second secondary consumer connection (10, 10b) from the mains connections (11). [5] Method according to any one of claims 1 to 4, characterized by , that the consumers (2) are periodically and uniformly supplied with current in at least one of the operating modes (16, 17, 18). [6] Computer program product comprising instructions which, when the computer program product is executed by a computer, cause it to execute the method according to any one of claims 1 to 5. [7] System (1), - with a drive train (100) having an on-board electrical system (101), - with a first consumer (2, 2a) and a second consumer (2, 2b) for converting electrical energy from the on-board network (101) into heat, - with a power electronics (21) comprising a switching device (3) for selectively connecting the consumers (2) to the vehicle electrical system (101) and to each other, - with a control device (19) which is connected to the switching device (3) and is designed to operate the system (1) according to any one of claims 1 to 5. [8] System according to claim 7, characterized by , - that the first consumer (2, 2a) has a first primary consumer connection (9, 9a) and a second primary consumer connection (10, 10a), - that the second consumer (2, 2b) has a first secondary consumer connection (9, 9b) and a second secondary consumer connection (10, 10b), - that the second primary consumer connection (10, 10a) is connected to the second secondary consumer connection (10, 10b) so that the consumers (2) are connected in series, - that the power electronics (21) is connected or connectable to the vehicle electrical system (101) via a first mains connection (11, 1 a) and a second mains connection (11, 11b). [9] System according to claim 7 or 8, characterized by , that at least one of the consumers (2) is a power resistor (20). [10] System according to any one of claims 7 to 9, characterized by , that the switching device (3) is part of an inverter (8) or has an inverter (8).

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