Method for operating an electrical system, control device, electrical system

Abstract

The invention relates to a method for operating an electrical system (1) comprising at least one power grid (2), in particular the on-board electrical system of a motor vehicle, at least one electrical energy storage device (3), in particular an intermediate circuit capacitor, connected to the power grid (2), and at least one controllable electrical component (7) connected to the power grid (2) as an electrical consumer. The power grid (2) is monitored for a discharge request relating to the power grid (2), in particular during a shutdown process and / or an emergency situation, for example an accident involving the motor vehicle. It is provided that, when such a discharge request is detected, a power loss is generated at the at least one electrical component (7) in order to increase the energy consumption of the component (7) and to discharge the energy storage device (3).

Description

The invention relates to a method for operating an electrical system which has at least one power grid, in particular the on-board power supply system of a motor vehicle, at least one electrical energy store, in particular an intermediate circuit capacitor, connected to the power grid, and at least one controllable electrical component connected to the power grid as electrical load, wherein the power grid is monitored for a discharge request relating to the power grid, in particular as part of a shutdown process and / or an emergency situation, for example an accident of the motor vehicle.The invention further relates to a control device specially designed for carrying out such a method, and to an electrical system having such a control device.Prior ArtMethods of the type mentioned at the beginning are known from the prior art. If such a discharge request occurs, the energy store is usually discharged in a targeted manner in order to put the power grid and components connected thereto into a voltage-free state. For this purpose, passive electrical resistance networks are usually used, which are provided in addition to normal, controllable electrical consumers in the power network and which otherwise do not fulfil any further task. For example, the applicant's laid-open specification DE 10 2009 055 053 A1 discloses a method and a device for discharging a corresponding energy store, in which discharge resistors are connected in parallel with the energy store or are connected as required. From the laid-open specification DE 10 2011 015 531 A1, a further method for automatically discharging components of a high-voltage electric circuit in a vehicle is known, wherein electrical energy is supplied to an occupant protection system, for example belt tensioner, and thus its power is increased.Methods are also known for specifically utilizing the waste heat of an electrical component. For example, the laid-open specification DE 10 2018 205 784 A1 discloses a method for preheating a traction battery of a motor vehicle or of a vehicle interior by the waste heat of a control unit, wherein the control unit is provided with a computer-soluble task, and wherein the waste heat produced when the task is solved is used for preheating the battery or of the interior.Finally, methods are known in which an at least short-term discharge of an energy store is accepted in order to supply an electrical load with an increased energy requirement due to the situation. For example, the published patent application DE 10 2018 218 312 A1 discloses a method in which an electrical load is supplied with an increased supply voltage for a short time when it requires it, so that a battery is discharged, wherein the discharge is limited and / or compensated by current limiting and / or current compensation.Disclosure of the InventionThe method according to the invention having the features of claim 1 is distinguished in that, if such a discharge request is detected, a power loss is generated at the at least one electrical component in order to increase the energy consumption of the component and to discharge the energy store. As a result, an active component which is already present in the power grid is advantageously used to discharge the energy store in a targeted manner by generating and distributing power loss in the power grid and to produce a voltage-safe state in which, for example, the corresponding voltage within the power grid falls below a predefined value. Establishing such a voltage-proof state is necessary, for example, for safety reasons when the motor vehicle having the electrical system has had an accident or in order to enable a service technician to access safely for carrying out a repair or maintenance. The component or components are usually operated as energy-efficiently as possible in that the invention is based on the consideration of operating the component or components in an energy-inefficient manner. If the components are arranged, for example, in a corresponding supply chain, a higher power loss is likewise generated in each component arranged upstream as a result of the power consumption which is increased on account of the power loss in one of the components at the end of the supply chain, with the result that the power loss is advantageously spatially distributed. Additional discharge devices, such as the resistor networks known from the prior art mentioned at the beginning, can thus be relieved, of smaller dimensions and / or completely omitted. The power loss is preferably generated as a thermal power, so that corresponding waste heat is produced at the component. In this respect, it is not the object of the invention to use the waste heat which arises, as is known, for example, from the prior art mentioned at the beginning, but to accept it as a type of waste product in order to discharge the energy store. Likewise, the measures provided in the prior art mentioned at the beginning, relating to the control of the control unit for achieving a task and the supply of a load with increased supply voltage, are not provided for activating a specifically provided discharge of the energy store in response to a discharge request, for example in an emergency situation. The discharge request can be made as desired, in particular in an emergency situation, and / or in the event of a regular shutdown of the system, in order to establish the described voltage-proof state in each case. As described above, the method according to the invention is provided in particular for use in an electrical system of a motor vehicle, but can likewise be used advantageously in any electrical system, for example stationary devices, such as heat pumps, refrigerators, air conditioners, etc.According to a preferred development of the invention, it is provided that a power loss is generated in each case at a multiplicity of electrical components connected to the power grid. By generating the power loss at a plurality of components, it is advantageously ensured that the power loss is spatially distributed within the power grid, in particular waste heat which arises in this case, such that in particular local overheating is avoided.It is particularly preferably provided that an electrical supply voltage of the component or at least one of the components is increased, in particular maximized, in order to generate the power loss. Increasing the supply voltage results in the advantage that the power loss is generated by a specifically more inefficient operation of the component. Thus, the component is in particular operated at a non-optimum operating point because such components have, for example, a predefined range for permissible supply voltages, wherein specific voltage levels are more energy-efficient than others. In particular, the supply voltage is increased to a permissible maximum.According to a preferred development of the invention, it is provided that the component or at least one of the components is designed as a voltage regulator, and that a voltage difference between an electrical input voltage and an electrical output voltage at the voltage regulator is increased, in particular maximized, in order to generate the power loss. By increasing the voltage difference, it is advantageously ensured that the power loss is reliably generated. Usually, the power loss increases with the voltage difference. In particular, the voltage difference is increased to a permissible maximum.It is particularly preferably provided that the component or at least one of the components is designed as a computer device, and that a processor load and / or a clock frequency of a processor of the component is increased, in particular maximized, in order to generate the power loss, in particular by executing a predefined calculation. Increasing the processor load and / or clock frequency results in the advantage that power loss is generated particularly reliably. The power consumption of the processor is increased, so that the processor generates waste heat in particular as thermal power loss. The predefined calculation comprises, in particular, an input variable that is useful for the operation of at least one of the components of the overall system, in particular of the vehicle; for example, a result of the calculation finds input in a corresponding operating method of the component.According to a preferred development of the invention, it is provided that the component or at least one of the components is designed as a computer device, and that, in order to generate the power loss, at least one memory access and / or an analog-to-digital conversion is carried out by means of the component, and / or at least one electrical output of the component is switched, in particular multiple times. Memory access, conversion and / or switching of the output advantageously ensures that a corresponding power loss is reliably generated. In particular, no object productive for operating the component at least in the current situation is fulfilled.It is particularly preferably provided that, in order to generate the power loss, communication signals are generated within the component, and / or between the or at least one of the components and at least one further component, and / or are exchanged via a communication bus. The generation of the communication signals results in the advantage that power loss is generated particularly simply and with accurate targeting. The additional communication signals thus do not serve for the coordination of the components with one another, i.e. they do not fulfil a predefined task. Even an already merely internal generation of the communication signals within the component generates a corresponding power loss, optionally these are also exchanged between the components, i.e. externally. In particular, CAN, LIN, SPI and / or UART is used as the communication bus.According to a preferred development of the invention, it is provided that the component or at least one of the components has at least one optical display device, in particular an LED and / or display, and that the display device is switched on, in particular with maximum brightness, in order to generate the power loss. By switching on the display device, it is advantageously ensured that the power loss is set to be particularly high. In particular, depending on a power loss to be achieved, the brightness, which is proportional thereto, for example, is correspondingly controlled, for example, down to a brightness to be generated at maximum by the display device.It is particularly preferably provided that the component or at least one of the components has at least one gate driver circuit, and that a clock frequency of the gate driver circuit is increased in order to generate the power loss. By increasing the clock frequency, the power loss is particularly advantageously easily generated because, for example, charge reversal losses in transistors are increased. In particular, the clock frequency is increased to a predefined maximum, for example a maximum clock frequency that can be converted by the gate driver circuit.According to a preferred development of the invention, it is provided that the power loss is generated and / or distributed to the components as a function of an amount of energy stored in the energy store, a predefined period of time for reducing the amount of energy, and / or a maximum power loss that can be generated by the component or components, in particular constantly or according to a predefined characteristic curve. By the corresponding generation and / or distribution of the power loss, it is advantageously ensured that the energy store is discharged particularly accurately and the power loss is distributed within the power grid, in particular local overheating of one of the components is reliably avoided.It is particularly preferably provided that the power loss is generated and / or distributed to the components in such a way that an amount of energy stored in the energy store is at least partially reduced to a predetermined value, in particular completely, in a predetermined period of time. By the corresponding dissipation of the amount of energy, a particularly advantageous possibility for achieving a safe state is created.The control device, which is in particular designed as a computer device or integrated into a computer device and has the features of claim 12, is characterized in that the control device is specifically designed to carry out the method according to the invention. In particular, the control device is also designed to actuate the or at least one of the components for generating the power loss. This results in the already mentioned advantages.The electrical system having the features of claim 13 has at least one power grid, in particular the on-board power supply system of a motor vehicle, at least one electrical energy store, in particular intermediate circuit capacitor, connected to the power grid, and at least one electrical component connected to the power grid as electrical load. It is distinguished by the control device according to the invention. This also results in the advantages already mentioned. In particular, the electrical system is designed as an electrical system of a motor vehicle.Further preferred features and combinations of features are evident from the description above and from the claims. The invention is explained in more detail below with reference to the drawings. This is shown by FIG. 1 shows an electrical system, and FIG. 2 shows a method for operating the system.FIG. 1 shows an electrical system 1. the electrical system 1 has a power network 2, in the present case as an on-board power system, in particular a high-voltage on-board power system, of a motor vehicle which is otherwise not shown in more detail. Alternatively, the electrical system 1 is assigned to an in particular stationary device, such as a heat pump. Furthermore, the electrical system 1 has at least one electrical energy store 3, in the present case designed as an intermediate circuit capacitor, which is connected to the power grid 2, and an electrical resistor 4 as a passive discharge resistor.In addition, the electrical system 1 has a first voltage converter 5, which is designed as a high-voltage flyback converter and is connected to the energy store 3 on the electrical input side, and a second voltage converter 6, which is designed as a DC voltage converter and is connected to the first voltage converter 5 on the electrical input side.Furthermore, the electrical system 1 has a multiplicity of controllable electrical components 7 connected to the power grid 2 as electrical loads. In this case, different types of components 7 are illustrated, wherein at least one of each type is illustrated by way of example, the electrical system 1 can have any desired number of components 7 in terms of type and number, in particular it has a plurality of components 7 of each type.In this case, a first of the components 7 is designed as a first voltage regulator 8, and a second of the components 7 is designed as a second voltage regulator 9. The voltage regulators 8, 9 are connected in parallel with one another and are each electrically connected on the input side to the second voltage converter 6.A further computer device 11 of the component 7 is designed as a processor 10, in particular a microcontroller, and is electrically connected on the input side to the first voltage regulator 8.At least one of the components 7 has a communication device 12, a sensor 13, and / or an optical display device 14, in particular an LED and / or display, wherein communication device 12, sensor 13 and display device 14 can be provided in different ones of the components 7 or a common component 7. In the present case, they are each electrically connected on the input side to the second voltage regulator 9.The communication device 12 is designed, in particular, to generate communication signals internally within the component 7 and / or to exchange them externally between a plurality of components 7 via a communication bus.At least one further component 7 has a gate driver circuit 15 which is designed to drive at least one semiconductor switch 16, in particular a transistor, for example a MOSFET, which is in particular formed as part of the same component 7. The gate driver circuit 15 is in the present case electrically connected on the input side to the first voltage converter 5, and the semiconductor switch 16 is correspondingly electrically connected on the input side to the gate driver circuit 15.Finally, the electrical system 1 has at least one control device 17, which is designed in particular to actuate at least one of the components 7, for example to generate a power loss. The control device 17 is in particular designed as a separate component and / or is in particular only connected to the system 1 and / or at least one of the components 7 by communication technology, but is for example arranged at a distance therefrom. Alternatively, the control device 17 is integrated into one of the components 7, preferably into the computer device 11.It should be noted that the components of the electrical system 1 described here are largely optional, and the interconnection of the components among one another illustrated merely represents an advantageous possibility. The method for operating the electrical system 1 to be described with reference to FIG. 2 is accordingly not limited to the specific exemplary embodiment.As a minimum requirement in order to be able to carry out the method, the electrical system 1 only has to have the power grid 2, the energy store 3 and any of the components 7. The type of device which has the electrical system 1 can also be selected as desired. The above-described assignment to a motor vehicle is only one, but by far not the only advantageous possibility.In the following, with reference to FIG. 2, the advantageous method for operating the electrical system 1 already indicated is described. For this purpose, FIG. 2 shows the method on the basis of a flow chart. In particular, the method ensures that power loss for discharging the energy store 3 is generated in a targeted manner within the electrical system 1. The method is preferably carried out with the aid of the control device 17.In a step S 1, the method begins with the power grid 2 being monitored for a discharge request relating to the power grid 2, in particular as part of a shutdown process and / or an emergency situation, in particular an accident of the motor vehicle. If such a discharge request is detected, the method continues with a step S 2.In step S 2, a power loss is generated at at least one, in particular each, of the plurality of electrical components 7 in each case, in order to increase the energy consumption of the corresponding components 7 and to discharge the energy store 3, preferably until the electrical system 1 is in a voltage-proof state, in particular supported by the electrical discharge resistor 4.The power loss is preferably generated and / or distributed to the components 7 as a function of an amount of energy stored in the energy store 3, a predefined time period for reducing the amount of energy, and / or a maximum power loss that can be generated by the component 7 or components 7, in particular constantly or according to a predefined characteristic curve.In order to generate the power loss, an electrical supply voltage of the component 7 or of at least one of the components 7 is increased, in particular maximized. For example, in order to generate the power loss, a voltage difference between an electrical input voltage and an electrical output voltage at at least one, in particular both, of the voltage regulators 5, 6 is increased.Alternatively or additionally, in order to generate the power loss, a processor load and / or a clock frequency of the processor 11 of the computer device 10 are preferably increased, in particular maximized, for example by carrying out a predefined calculation, at least one memory access and / or an analog-to-digital conversion are carried out by means of the computer device 10, and / or at least one electrical output of the computer device 10 is switched, in particular multiple times.Alternatively or additionally, for generating the power loss, communication signals are preferably generated within the component 7, and / or between the or at least one of the components 7 and at least one further component 7 and / or exchanged via a communication bus, preferably with the aid of the communication device 12.Alternatively or additionally, for generating the power loss, the display device 14 is preferably switched on, in particular with maximum brightness, and / or a clock frequency of the gate driver circuit 15 is increased, in particular maximized.For example, the power loss is generated and / or distributed to the components 7 in such a way that an amount of energy stored in the energy store is at least partially reduced to a predetermined value, in particular completely, in a predetermined period of time.In particular, a current value of the energy quantity is monitored and, if the predetermined value is undershot, the generation of the power loss 7 is ended. Alternatively, the power loss is generated until the energy store 3 is discharged and the component 7 or the components 7 can no longer be controlled. The method ends in each case with a step S 3.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2009 055 053 A1

[0003] DE 10 2011 015 531 A1

[0003] DE 10 2018 205 784 A1

[0004] DE 10 2018 218 312 A1

[0005]

Claims

Method for operating an electrical system (1) which has at least one power grid (2), in particular the on-board power supply system of a motor vehicle, at least one electrical energy store (3) connected to the power grid (2), in particular an intermediate circuit capacitor, and at least one controllable electrical component (7) connected to the power grid (2), as electrical load, wherein the power grid (2) is monitored for a discharge request relating to the power grid (2), in particular within the scope of a shutdown process and / or an emergency situation, for example an accident of the motor vehicle, characterized in that, if such a discharge request is detected, a power loss is generated at the at least one electrical component (7) in order to increase the energy consumption of the component (7) and to discharge the energy store (3).Method according to Claim 1, characterized in that a power loss is generated in each case at a multiplicity of electrical components (7) connected to the power grid (2).Method according to one of the preceding claims, characterized in that, in order to generate the power loss, an electrical supply voltage of the component (7) or of at least one of the components (7) is increased, in particular maximized.Method according to one of the preceding claims, characterized in that the component (7) or at least one of the components (7) is designed as a voltage regulator (8, 9), and in that, in order to generate the power loss, a voltage difference between an electrical input voltage and an electrical output voltage at the voltage regulator (8, 9) is increased, in particular maximized.Method according to one of the preceding claims, characterized in that the component (7) or at least one of the components (7) is designed as a computer device (10), and in that, in order to generate the power loss, a processor load and / or a clock frequency of a processor (11) of the component (7) is increased, in particular maximized, in particular by carrying out a predefined calculation.Method according to one of the preceding claims, characterized in that the component (7) or at least one of the components (7) is designed as a computer device (10), and in that, in order to generate the power loss, at least one memory access and / or an analog-to-digital conversion is carried out by means of the component (7), and / or at least one electrical output of the component (7) is switched, in particular multiple times.Method according to one of the preceding claims, characterized in that, in order to generate the power loss, communication signals are generated within the component (7) and / or between the or at least one of the components (7) and at least one further component (7) and / or are exchanged via a communication bus.Method according to one of the preceding claims, characterized in that the component (7) or at least one of the components (7) has at least one optical display device (14), in particular an LED and / or display, and in that, in order to generate the power loss, the display device (14) is switched on, in particular with maximum brightness.Method according to one of the preceding claims, characterized in that the component (7) or at least one of the components (7) has at least one gate driver circuit (15), and in that a clock frequency of the gate driver circuit (15) is increased in order to generate the power loss.Method according to one of the preceding claims, characterized in that the power loss is generated and / or distributed to the components (7) as a function of an amount of energy stored in the energy store (3), a predefined period of time for reducing the amount of energy, and / or a maximum power loss which can be generated by the component (7) or components (7), in particular constantly or in accordance with a predefined characteristic curve.Method according to one of the preceding claims, characterized in that the power loss is generated and / or distributed to the components (7) in such a way that an amount of energy stored in the energy store (3) is at least partially reduced to a predetermined value, in particular completely, in a predetermined period of time.Control device (17), in particular computer device, characterized in that the control device (17) is specifically designed to carry out the method according to one of the preceding claims, in particular is designed to actuate the or at least one of the components (7) for generating the power loss.Electrical system (1) which has at least one power grid (2), in particular the on-board power supply system of a motor vehicle, at least one electrical energy store (3), in particular intermediate circuit capacitor, connected to the power grid (2), and at least one electrical component (7) connected to the power grid (2) as electrical load, characterized bya control device (17) according to Claim 12.

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