DE102019134631A1 - Operating an on-board power supply system for a vehicle - Google Patents

Abstract

A method is used to operate an on-board power supply system (1) of a vehicle (E), in which an impedance spectrum is automatically determined in the on-board power supply system (1) when a change in state occurs in the on-board power supply system (1) and then an impedance spectrum connected to the on-board power supply system (1) Impedance matching circuit (14) is adapted in such a way that at least one impedance amplitude is reduced at at least one critical resonance point which has been determined from the impedance spectrum. An impedance matching device (7) has an impedance matching circuit (14) each with a plurality of ohmic resistances, capacitances (Ci) and / or inductances (Li) that can be optionally switched on and off, the impedance matching device (7) having a control device (15), which is set up to switch on or off at least one of these discrete electrical components (Ci, Li) in order to adapt it. A vehicle (E) is set up to carry out the method. The invention is particularly advantageously applicable to electric vehicles.

Description

The invention relates to a method for operating an on-board power supply system of a vehicle. The invention also relates to an impedance matching device, having at least one impedance spectroscopy device and an impedance matching circuit, the impedance spectroscopy device having power electronics which are set up to apply a current pulse to the on-board power supply, in particular a second sub-on-board network, and having an evaluation device in order to to determine the impedance spectrum generated by means of the current pulse and to determine setting parameters of the impedance matching circuit from the impedance spectrum so that at least one impedance amplitude is reduced at at least one critical resonance point that has been determined from the impedance spectrum accordingly operable on-board power supply. The invention is particularly advantageously applicable to partially or purely electrically powered vehicles, especially to vehicles with a first sub-on-board network with a first, higher on-board network voltage and a second sub-on-board network with a second, lower on-board network voltage, the second sub-on-board network being fed from the first sub-on-board network via a DC voltage converter becomes.

It is known that, for example, during switching operations in on-board power systems and with mechanical load jumps on a machine supplied by the on-board power supply, such as a steering and / or a brake, (“transient”) transient processes with high voltage peaks are generated. The voltage peaks can damage electrical components, reduce their performance, lead to malfunctions and / or impair the voltage stability of the on-board power supply system.

So far, the voltage peaks have mainly been covered by the large capacity of the electrochemical energy store that supplies the on-board power system with power.

In addition, suppressor diodes can be used to reduce voltage peaks or overvoltages. Disadvantageously, however, these are only suitable for reducing overvoltages to a tolerable level, not for further disturbances such as voltage drops due to high demand for power.

• Avalur, K.: „Power management IC architecture in automotive environment: Case study of rear view camera“, TENCON 2017 IEEE Conference ;
• Bai, H.: „The Short-Time-Scale Transient Processes in High-Voltage and High-Power Isolated Bidirectional DC-DC Converters“, IEEE Transactions on Power Electronics 2008; Diez, T.: „Transient voltage characterization for automotive 42 volt power systems“, IEEE International Symposium on Electromagnetic Compatibility 2000 ;
• Frazier, R.: „Comparison of ISO 7637 transient waveforms to real-world automotive transient phenomena“, 2005 International Symposium on Electromagnetic Compatibility ;
• ISO Central Secretary: „Road vehicles - Electrical disturbances from conduction and coupling - Part 2: Electrical transient conduction along supply lines only“, en. Standard ISO 7637 -2:2011 ;
• Klötzl, J.: „Stabilität automobiler Leistungsbordnetze“, Doktorarbeit, Universität der Bundeswehr München, 2012 ;
• Nasim, S.: „Cost-effective means of protecting electronics from voltage transients and overvoltages in an automotive network“, 2009 IEEE Student Conference on Research and Development (SCOReD) ;
• Ruf, F.: „Auslegung und Topologieoptimierung von spannungstabilen Energiebordnetzen“, Doktorarbeit, Technische Universität München, Oktober 2015 .

A structure of an on-board power supply system with an electrochemical low-voltage energy store and a description of transient processes of such on-board power supply systems in vehicles is given, for example, in:

• Avalur, K .: "Power management IC architecture in automotive environment: Case study of rear view camera", TENCON 2017 IEEE Conference ;
• Bai, H .: “The Short-Time-Scale Transient Processes in High-Voltage and High-Power Isolated Bidirectional DC-DC Converters”, IEEE Transactions on Power Electronics 2008; Diez, T .: "Transient voltage characterization for automotive 42 volt power systems", IEEE International Symposium on Electromagnetic Compatibility 2000 ;
• Frazier, R .: "Comparison of ISO 7637 transient waveforms to real-world automotive transient phenomena", 2005 International Symposium on Electromagnetic Compatibility ;
• ISO Central Secretary: "Road vehicles - Electrical disturbances from conduction and coupling - Part 2: Electrical transient conduction along supply lines only", en. Standard ISO 7637-2: 2011 ;
• Klötzl, J .: “Stability of automotive power systems”, doctoral thesis, University of the Federal Armed Forces, Munich, 2012 ;
• Nasim, S .: "Cost-effective means of protecting electronics from voltage transients and overvoltages in an automotive network", 2009 IEEE Student Conference on Research and Development (SCOReD) ;
• Ruf, F .: "Design and topology optimization of voltage-stable on-board power systems", doctoral thesis, Technical University of Munich, October 2015 .

There are vehicles with an on-board network architecture with a first sub-board network ("high-voltage on-board network") with a first, higher on-board network voltage ("high-voltage voltage", e.g. of 60 V or more, e.g. of 120 V, 400 V or 800 V) and a second sub-board network (“Low-voltage vehicle electrical system”) with a second, lower vehicle electrical system voltage (“Low-voltage voltage”, e.g. of up to 60 V, e.g. of 12 V, 24 V or 48 V). There are also efforts - especially for purely electrically powered vehicles - to dispense with the low-voltage energy storage device ("low-voltage storage device") in order to save costs and installation space. However, the resulting limited power availability is particularly critical to safety, especially in the case of highly automated driving functions, since if the low-voltage storage device is omitted, the effects of the transient voltage peaks in the low-voltage on-board power supply must be covered by the DC / DC converter as the only continuously available power source in order to ensure stable operation of the on-board power supply. This disadvantageously results in particularly high demands on the dynamics of the DC voltage converter. However, the dynamics of the - typically digitally controllable - DC / DC converter, for example due to its regulation with delay times and dead times, usually only limited. This only enables it to a limited extent to compensate for transient processes or undesired network perturbations, which has a negative impact on voltage stability.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art and, in particular, to provide an improved possibility of reducing or practically completely avoiding voltage peaks generated by transient processes in an on-board power supply system of a vehicle and thereby a particularly voltage-stable operation of the on-board power supply system to reach.

This object is achieved according to the features of the independent claims. Advantageous embodiments are the subject matter of the dependent claims, the description and the drawings.

• - mit einem Auftreten einer Zustandsänderung in dem Energiebordnetzes automatisch ein Impedanzspektrum in dem Energiebordnetzes bestimmt wird und folgend
• - eine mit dem Energiebordnetzes verbundene Impedanz-Anpassungsschaltung so angepasst oder eingestellt wird, dass mindestens eine Impedanzamplitude an mindestens einem kritischen Resonanzpunkt, der aus dem Impedanzspektrum bestimmt worden ist, reduziert wird.

The object is achieved by a method for operating an on-board power supply system of a vehicle

• - When a change in state occurs in the on-board power supply, an impedance spectrum is automatically determined in the on-board power supply and then follows
• an impedance matching circuit connected to the on-board power supply system is adapted or set in such a way that at least one impedance amplitude is reduced at at least one critical resonance point that has been determined from the impedance spectrum.

This method has the advantage that transient disturbances in the on-board power supply are reduced or even completely prevented, which reduces voltage peaks and dips and thus stabilizes the voltage in the on-board power supply, in particular in a frequency range of up to 100 kHz. The voltage stabilization also reduces the risk of failure of safety-relevant consumers.

Another advantage is that power loss from harmonics can be reduced. It is taken into account that the on-board power supply system consists of interconnected clocked / switching / power electronic components, which results in current and voltage ripples or "ripples" in the on-board network. The impedance matching offers the possibility of reducing these ripples, which in turn reduces the requirements for internal voltage stabilization of the individual components and thus costs, e.g. by reducing the size of otherwise oversized intermediate circuit capacitors of individual components.

In addition, the advantage is achieved that data analysis and diagnosis are made easier. A validation of simulation models using recorded and stored network spectra (for different vehicle equipment, types and operating states of the on-board network) and / or a so-called "Time Domain Response" (TDR) analysis for the detection and diagnosis of errors and signs of aging (e.g. cable breaks, corrosion, etc.).

The method for operating an on-board power supply system can also be referred to as a method for voltage stabilization of an on-board power supply system.

The vehicle is in particular a partially electrically powered vehicle (hybrid vehicle) or a purely electrically powered electric vehicle.

The determination of an impedance spectrum, e.g. by means of an impedance spectroscopy method, is known in principle. It is also known to determine or identify at least one resonance point (i.e. at least one resonance point and / or at least one anti-resonance point) at which a critical resonance or high impedance amplitude occurs from the impedance spectrum. The critical resonance points can in particular correspond to critical frequencies at which high current peaks, which cause voltage collapses, occur. In addition, an adjustment of an impedance matching circuit in such a way that the impedance amplitude (s) is reduced at the at least one resonance point is known in principle.

The impedance matching circuit can also be referred to as a variable impedance filter.

• - mit einem Auftreten einer Zustandsänderung in dem zweiten Teilbordnetz automatisch ein Impedanzspektrum in dem zweiten Teilbordnetz bestimmt wird und folgend
• - eine mit dem zweiten Teilbordnetz verbundene Impedanz-Anpassungsschaltung so angepasst wird, dass mindestens eine Impedanzamplitude an mindestens einem kritischen Resonanzpunkt, der aus dem Impedanzspektrum bestimmt worden ist, reduziert wird.

In one embodiment, the on-board power supply system has a first on-board sub-network with a first, higher on-board network voltage and a second, energy-storage-reduced sub-on-board network with a second, lower on-board network voltage, the second sub-on-board network being fed from the first sub-on-board network via a DC voltage converter and wherein

• - When a change of state occurs in the second sub-on-board network, an impedance spectrum is automatically determined in the second sub-on-board network and then follows
• - An impedance matching circuit connected to the second sub-electrical system so it is adapted that at least one impedance amplitude is reduced at at least one critical resonance point which has been determined from the impedance spectrum.

This method has the advantage that transient disturbances can be reduced or even completely prevented, especially in the second sub-on-board network, which reduces voltage peaks and voltage dips there and stabilizes the voltage in the second sub-on-board network, in particular in a frequency range up to 100 kHz. As a result, local resonances at the output of the DC voltage converter can in turn be reduced, as a result of which the DC voltage converter is advantageously relieved with regard to transient processes that place great strain on its bidirectional control dynamics. In particular, distributed capacities in the on-board power supply network (e.g. in the input circuits of the individual components) can now serve as a sufficient power reserve.

Another advantage is that a power loss for peak powers can be reduced, since a peak power requested on the component side can take a shortened route to a high-performance component, to be precise instead of a route from a low-voltage storage device to the component. High peak powers can be compensated for, for example, by the capacitance of the impedance matching circuit.

The first vehicle electrical system voltage (“high voltage”) is higher than the second vehicle electrical system voltage (“low voltage”). The high voltage can be e.g. 60 V, 120 V, 400 V, 800 V, etc. The low voltage can be, for example, 12 V, 24 V, 48 V, etc.

The fact that the second sub-on-board network is an energy-storage-reduced sub-on-board network includes in particular that the second sub-on-board network has either no electrochemical low-voltage storage or an electrochemical low-voltage storage with a reduced capacity compared to a conventional low-voltage sub-on-board network. Such low-voltage storage devices are typically permanently available and are used to supply power to the components or loads supplied by the second sub-on-board network, such as power steering, a braking system, etc. Electrochemical energy storage devices include, for example, battery cells, but no capacitors. Under an electrochemical energy store with reduced capacity, for example, a battery group with a capacity of not more than 40 Ah, in particular not more than 30 Ah, in particular not more than 20 Ah, in particular not more than 10 Ah, in particular not more than 5 Ah, be understood.

The DC voltage converter is in particular a high-voltage-low-voltage DC voltage converter.

In one embodiment, the change in state that triggers an adaptation of the impedance matching circuit is a change in a switching state or a switching process in the on-board power supply, in particular a second sub-on-board network, or on a component supplied with electrical power by the on-board power supply, in particular a connection an electrical consumer to the on-board power supply system, disconnecting an electrical consumer from the on-board power supply and / or changing the expansion of the on-board power supply, for example by connecting network segments. If such a change in state is triggered or detected, an impedance adaptation to the total impedance changed by the change in state can be carried out in response thereto. The vehicle infrastructure (e.g. central on-board electronics or an on-board computer, one or more sensors, etc.) can determine or report that there is a change in status.

In order to communicate with the vehicle infrastructure, the impedance matching circuit is connected to the vehicle infrastructure in terms of communication technology. For example, the impedance matching circuit can be coupled to the rest of the vehicle infrastructure in terms of communication technology via communication means customary in the automotive industry, such as, for example, a CAN bus, a Flexray bus, an Ethernet line, etc.

However, other changes in state can in principle also be determined by the vehicle infrastructure and used as a trigger for adapting the impedance matching circuit. Such changes in state can include, for example, power jumps that result in equalization processes in the on-board power supply system, which can cause critical undervoltage. A high demand for power from a neighboring component of a steering system can lead to a voltage drop at the input terminals of the steering system, which can lead to a malfunction.

One embodiment is that to determine the impedance spectrum, impedance spectroscopy is carried out on the on-board power supply, in particular the second sub-on-board network, and the critical resonance points are determined from the impedance spectrum determined by means of impedance spectroscopy.

In order to carry out the impedance spectroscopy, a current pulse can in particular be fed into or injected into the second sub-on-board network and a Current and voltage response to the current pulse measured. Using a Laplace transformation on the measured currents and voltages, a frequency-dependent impedance or the (actual) impedance spectrum is calculated for the current switching or operating state. The resonance and anti-resonance points can be filtered out of the impedance spectrum. From this, in turn, a target impedance spectrum can be calculated in which the resonance and antiresonance points are no longer present or only present with a noticeably reduced amplitude. The impedance matching circuit can then be adapted or set in such a way that the target impedance spectrum or the corresponding target total impedance results at least approximately for the second sub-vehicle electrical system. The impedance matching circuit can be matched in such a way that its desired impedance (hereinafter also referred to as "target filter impedance"), which causes the desired target impedance spectrum of the second sub-electrical system, is based on the known mathematical relationship between target filter impedance, target Impedance spectrum and actual impedance spectrum is calculated. The setting values of the impedance matching circuit (for example RLC values) can then be set in such a way that they approximate the target filter impedance as closely as possible. These setting values can be determined using a parameter estimation method such as the least squares method, etc., for example.

The method can also be referred to as a method for reducing transient interference in on-board power systems or a method for voltage stabilization in on-board power systems.

• - die Impedanzspektroskopie-Vorrichtung eine Leistungselektronik, die dazu eingerichtet ist, einen Strompuls auf ein Energiebordnetz, insbesondere ein zweites Teilbordnetz, aufzugeben, und eine Auswerteeinrichtung aufweist, um ein mittels des Strompulses erzeugte Impedanzspektrum zu bestimmen und aus dem Impedanzspektrum Einstellparameter der Impedanz-Anpassungsschaltung so zu bestimmen, dass mindestens eine Impedanzamplitude an mindestens einem kritischen Resonanzpunkt, der aus dem Impedanzspektrum bestimmt worden ist, reduziert wird, wobei
• - die Impedanz-Anpassungsschaltung jeweils mehrere wahlweise zu- und herausschaltbare ohmsche Widerstände, Induktivitäten und/oder Kapazitäten als Einstellparameter aufweist und wobei
• - die Impedanzanpassungsvorrichtung eine Steuereinrichtung aufweist, die dazu eingerichtet ist, zu ihrer Anpassung mindestens einen dieser diskreten elektrischen Bauteile zuzuschalten oder herauszuschalten.

The object is also achieved by an impedance matching device, having at least one impedance spectroscopy device and an impedance matching circuit, wherein

• - The impedance spectroscopy device has power electronics that are set up to apply a current pulse to an on-board power supply system, in particular a second sub-board network, and have an evaluation device to determine an impedance spectrum generated by means of the current pulse and, from the impedance spectrum, to set parameters for the impedance matching circuit to determine that at least one impedance amplitude is reduced at at least one critical resonance point that has been determined from the impedance spectrum, wherein
• the impedance matching circuit has a plurality of ohmic resistances, inductances and / or capacitances that can be optionally switched on and off as setting parameters, and wherein
• the impedance matching device has a control device which is set up to connect or disconnect at least one of these discrete electrical components for its adaptation.

The impedance matching device can be designed analogously to the method and produces the same advantages.

The fact that the impedance matching circuit has the resistances, inductances and / or capacitances as setting parameters can in particular mean that switching on (e.g. parameter value "1") and switching off (e.g. parameter value "0") of these R, L and / or C-links can be selected. The R, L and / or C links can be switched on or off mechanically (e.g. via relays) or electronically (e.g. via transistors, triacs, etc.), for example.

The impedance matching device can also be referred to as a device for reducing transient interference in on-board power systems or a device for voltage stabilization in on-board power systems.

It is an embodiment that the impedance matching circuit is designed as a Pi circuit or an analog circuit such as a T circuit.

One embodiment is that the impedance matching device has a data transmission interface by means of which the impedance matching device can receive information about the occurrence of a change in the state of the on-board power supply system, and the impedance matching device is set up to apply the current pulse to the on-board power supply system on the basis of receiving the information in order to determine the impedance spectrum , and set the setting parameters of the impedance matching circuit from the impedance spectrum.

It is a further development that the device is an independent device, unit or module that can be connected to the on-board power supply system. This can in particular be installed in a vehicle at a later date. In particular, the module then only needs to be connected to an access point (e.g. a live line of the on-board power supply), to a reference potential (e.g. ground) and to a communication connection of the vehicle, which makes it particularly easy to install it in a vehicle at night.

The object is also achieved by a vehicle having an on-board power supply and one connected to the on-board power supply Impedance matching device, which has at least one impedance spectroscopy device and an impedance matching circuit, the vehicle being set up to carry out the method as described above by means of the impedance matching device. The vehicle can be designed analogously to the method and has the same advantages.

In one embodiment, the on-board power supply system has a first on-board sub-network with a first, higher on-board network voltage and a second, energy-storage-reduced sub-on-board network with a second, lower on-board network voltage, the second sub-on-board network being fed via a DC voltage converter from the first sub-on-board network, and the impedance matching device is connected to the second sub-electrical system.

In one embodiment, the impedance spectroscopy device has power electronics that are set up to apply a current pulse to the vehicle electrical system.

It is an embodiment that the impedance spectroscopy device has an evaluation device in order to determine an actual impedance spectrum from the current and voltage response generated by means of the current pulse, to determine critical resonance points present therein, to calculate a target impedance spectrum in which the critical Resonance points are at least dampened (i.e. the amplitudes at the corresponding frequencies are noticeably reduced), a target filter impedance of the impedance matching circuit can be calculated from the actual impedance spectrum and the target impedance spectrum and setting parameters of the impedance matching circuit can be calculated from the target filter impedance , by means of which the target impedance spectrum can be approximated as closely as possible. The impedance matching circuit can then be adapted, e.g. by means of a control device, by setting the setting parameters calculated in this way.

The impedance spectroscopy device also advantageously has at least one current measuring device and a voltage measuring device in order to measure the current and voltage response.

One embodiment is that the impedance matching circuit has a plurality of discrete passive electrical components that can optionally be switched on and off, such as ohmic resistors, capacitors and / or coils, and the impedance matching device has a control device which is designed to match at least one resistor, at least to connect or disconnect a capacitor and / or at least one coil. These components can be switched on or off using switches (e.g. relays, semiconductor switches). By connecting permanently installed capacitors in parallel (e.g. capacitors), the total capacitance of the impedance matching circuit can be increased and / or by adding permanently installed inductances (e.g. coils) connected in series, the total inductance of the impedance matching circuit can be increased. In other words, a total inductance, a total capacitance and / or a total resistance of the impedance matching circuit can each be set to discrete values.

The impedance matching circuit can be in the form of a pi circuit (series inductances with resistance, transverse capacitances with resistance). This results in the advantage that the structure of the impedance matching circuit can be designed in a particularly simple manner. Instead of a pi-circuit, any other functionally corresponding circuit types or topologies can also be used, e.g. a T-circuit.

One embodiment is that the impedance matching device is designed as a module that can be connected to the second sub-on-board network. In this way, a particularly simple possibility is provided of providing an impedance matching without major structural adaptations to the second sub-on-board network. In particular, the impedance matching can be retrofitted particularly easily in this way.

• 1 zeigt ein vereinfachtes Blockschaltbild eines Energiebordnetzes eines Fahrzeugs;
• 2 zeigt ein funktionales Blockdiagramm einer Impedanzanpassungsvorrichtung; und
• 3 zeigt ein Ersatzschaltbild einer möglichen Variante einer Impedanz-Anpassungsschaltung der Impedanzanpassungsvorrichtung aus 2.

The properties, features and advantages of this invention described above and the manner in which they are achieved will become clearer and more clearly understandable in connection with the following schematic description of an exemplary embodiment which is explained in more detail in connection with the drawings.

• 1 shows a simplified block diagram of an on-board power supply system of a vehicle;
• 2 Figure 3 shows a functional block diagram of an impedance matching device; and
• 3 FIG. 12 shows an equivalent circuit diagram of a possible variant of an impedance matching circuit of the impedance matching device from FIG 2 .

1 shows a greatly simplified equivalent circuit diagram of a block diagram of an on-board power supply system 1 of a vehicle, here an electric vehicle E. . The on-board power supply 1 has a first sub-electrical system 2 with a first, higher vehicle electrical system voltage U_h (e.g. from 48 V). The first sub-electrical system 2 has a rechargeable electrochemical energy store 3 , for example a battery group with several battery cells to operate the electric vehicle E. on, in particular also to carry out a driving operation of the electric vehicle E. . The energy storage 3 can, for example, be charged using a charging station.

The on-board power supply 1 also has a second sub-electrical system 4th with a second, lower vehicle electrical system voltage U.N (e.g. from 12 V). On the second sub-electrical system 4th is at least one consumer such as an electrically powered power steering 5 , a braking system, etc. and is connected via the second sub-electrical system 4th supplied with operating power. The second part of the electrical system 4th is reduced in energy storage in the sense that it has no or at least only small dedicated, permanently available electrochemical energy storage such as a rechargeable battery, the one or more of the consumers 5 supplied with operating power. Rather, the second sub-electrical system is 4th to supply the consumers connected to it 5 from the first sub-electrical system 2 powered by a DC / DC converter 6th .

The electric vehicle E. further comprises an impedance matching device 7th on that here to the second sub-electrical system 4th is connected and is provided to an impedance of the power supply system 1 , in particular of the second sub-electrical system 4th , to different states, in particular switching states, in the second sub-on-board network 4th adapt in such a way that overvoltages in the on-board power supply system caused by "transient" changes in state 1 , in particular in the second sub-electrical system 4th , reduced or even practically completely prevented.

The impedance matching device 7th is designed here as a separately connectable, in particular retrofittable component, in particular a module, and in the connected state can be used as an independent functional unit and / or as a functional part of the second sub-on-board network 4th be considered. The impedance matching device 7th is here between an access point AP and a reference potential GND connected. The access point AP can, for example, be based on an operating voltage of the at least one consumer 5 lie, in particular on the second vehicle electrical system voltage U.N .

The impedance matching device 7th also has a data interface 16 for communication-related connection to a data line 17 of the vehicle E. e.g. for connection to an on-board computer (not shown). The data line can be, for example, a CAN bus, Flexray bus or Ethernet network.

2 Figure 3 shows a functional block diagram of the impedance matching device 7th out 1 . The impedance matching device 7th is only available with a first connection 8th at the access point AP and with a second connection 9 at the reference potential GND connected.

The impedance matching device 7th has an impedance spectroscopy device 10 with power electronics 11 , a current / voltage measuring device 12th and an evaluation device 13th on. The power electronics 11 is set up for this via the connections 8th , 9 a current pulse to the second sub-electrical system 4th give up while the current / voltage measuring device 12th is set up to measure the current and voltage response generated by means of the current pulse. The current / voltage measuring device 12th a current measuring device (not shown) and a voltage measuring device (not shown), which have one between the connections 8th , 9 flowing current or one between the connections 8th , 9 Measure the applied voltage.

The evaluation device 13th is set up for this, for example programmed, from the measured values of the current / voltage measuring device 12th to determine an impedance spectrum, to determine critical resonance points therefrom and, in turn, to use this to determine setting parameters of an impedance matching circuit 14th to determine which is a best approximation for adapting the total impedance (of the second sub-electrical system 4th including the impedance matching circuit 14th ) so that overvoltages in the second sub-electrical system 4th reduced or even practically completely prevented.

The impedance matching device 7th also has a control device 15th which is set up for this purpose by the evaluation device 13th to adopt certain setting parameters and the impedance matching circuit 14th adjust or adjust accordingly.

The above procedure for matching the impedance matching circuit 14th can by receiving information that there is a change in state in the on-board power supply system, in particular in the second subnetwork 4th , has taken place. The information can be a command to trigger the method.

3 shows an equivalent circuit diagram of a possible variant of the impedance matching circuit 14th . The impedance matching circuit 14th is constructed here as a pi-circuit, which has a first variable ohmic resistance in the longitudinal direction Rv1 and connected in series with a variable (series) inductance Lv having. In the transverse direction there are two series connections with a second variable ohmic resistor Rv2 and a first variable (lateral) capacity Cv1 or a third variable ohmic resistor Rv3 and a second variable (transverse) capacitance Cv2. The Both longitudinal branches or longitudinal paths are connected to the connections 8th , 9 connected.

The variable inductance Lv In one variant, several optionally via switch Sw such as relays or electronic switches (e.g. transistors, triacs, etc.), permanently installed individual inductances that can be individually switched on and off Li with 1 ≤ i ≤ n and n ≥ 2. The switches Sw are by means of the control device 15th switchable. The individual inductances Li are shown here as an electrical series circuit, but can basically be interconnected in any series and / or parallel circuit. At least two individual inductances Li can have the same inductance and / or at least two individual inductances Li have a mutually different inductance.

The respective variable capacity can be analogous Cv1 and Cv2 several optionally via switch Sw such as relays or electronic switches (e.g. transistors, triacs, etc.), permanently installed individual capacitors that can be individually switched on and off Ci with 1 ≤ i ≤ n and n ≥ 2. The switches Sw are also here by means of the control device 15th switchable. The individual inductances Li are shown as an electrical parallel connection, but can in principle be connected to one another in any series and / or parallel connection. At least two individual capacities Ci can have the same inductance and / or at least two individual capacitances Ci have a mutually different inductance.

Analogous to the variable inductance Lv and / or the variable capacity (s) Cv1 , Cv2 can be the respective variable ohmic resistance Rv1 , Rv2 or. Rv3 several optionally via switch Sw such as relays or electronic switches have permanently installed individual resistors (not shown) that can be individually switched on and off and that can basically be connected to one another in any series and / or parallel connection. At least two individual resistors can have the same resistance value and / or at least two individual resistors can have a mutually different resistance value.

Of course, the present invention is not restricted to the exemplary embodiment shown.

A functionally equivalent T-circuit can be used instead of the pi-circuit.

In addition, the pi-circuit can also be interposed in a current path of the second sub-on-board network.

Furthermore, it is basically also possible to additionally or alternatively connect an impedance matching device to the first sub-on-board network and / or to also use the method described above for the first sub-on-board network.

In general, “a”, “one” etc. can be understood as a singular or plural number, in particular in the sense of “at least one” or “one or more” etc., as long as this is not explicitly excluded, for example by the expression “exactly a "etc.

A numerical specification can also include exactly the specified number as well as a customary tolerance range, as long as this is not explicitly excluded.

List of reference symbols

1

On-board power supply

2

First part of the electrical system

3

Electrochemical energy storage

4th

Second part of the electrical system

5

Power steering

6th

DC voltage converter

7th

Impedance matching device

8th

First connection of the impedance matching device

9

Second connection of the impedance matching device

10

Impedance spectroscopy device

11

Power electronics

12th

Current / voltage measuring device

13th

Evaluation device

14th

Impedance matching circuit

15th

Control device

16

Data interface

AP

Access point

Ci

i-th individual capacity

Cv1

First variable capacity

Cv1

Second variable capacity

Li

i-th single inductance

E.

Electric vehicle

GND

Reference potential

Lv

Variable (series) inductance

Li

i-th single inductance

Rv1

First variable ohmic resistance

Rv2

Second variable ohmic resistance

Rv3

Third variable ohmic resistance

Sw

counter

U_h

First, higher on-board voltage

U.N

Second, lower vehicle electrical system voltage

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Non-patent literature cited

• Avalur, K .: "Power management IC architecture in automotive environment: Case study of rear view camera", TENCON 2017 IEEE Conference [0005]
• Bai, H .: “The Short-Time-Scale Transient Processes in High-Voltage and High-Power Isolated Bidirectional DC-DC Converters”, IEEE Transactions on Power Electronics 2008; Diez, T .: "Transient voltage characterization for automotive 42 volt power systems", IEEE International Symposium on Electromagnetic Compatibility 2000 [0005]
• Frazier, R .: "Comparison of ISO 7637 transient waveforms to real-world automotive transient phenomena", 2005 International Symposium on Electromagnetic Compatibility [0005]
• ISO Central Secretary: "Road vehicles - Electrical disturbances from conduction and coupling - Part 2: Electrical transient conduction along supply lines only", en. Standard ISO 7637-2: 2011 [0005]
• Klötzl, J .: "Stability of automotive power supply systems", doctoral thesis, University of the Federal Armed Forces, Munich, 2012 [0005]
• Nasim, S .: "Cost-effective means of protecting electronics from voltage transients and overvoltages in an automotive network", 2009 IEEE Student Conference on Research and Development (SCOReD) [0005]
• Ruf, F .: "Design and topology optimization of voltage-stable on-board power systems", doctoral thesis, Technical University of Munich, October 2015 [0005]

Claims (13)

Method for operating an on-board power supply system (1) of a vehicle (E), in which - When a change of state occurs in the on-board power supply system (1), an impedance spectrum is automatically determined in the on-board power supply system (1) and then follows - An impedance matching circuit (14) connected to the on-board power supply system (1) is adapted in such a way that at least one impedance amplitude is reduced at at least one critical resonance point which has been determined from the impedance spectrum. Procedure according to Claim 1 , in which the on-board power supply (1) has a first sub-on-board network (2) with a first, higher on-board network voltage (U_h) and a second, energy-storage-reduced sub-on-board network (4) with a second, lower on-board network voltage (U_n), the second sub-on-board network (4) is fed (2) via a DC voltage converter (6) from the first sub-on-board network and with the method - with an occurrence of a state change in the second sub-on-board network (4) automatically an impedance spectrum in the second sub-on-board network (4) is determined and following - one with the impedance matching circuit (14) connected to the second sub-on-board network (4) is adapted in such a way that at least one impedance amplitude is reduced at at least one critical resonance point which has been determined from the impedance spectrum. Method according to one of the preceding claims, in which the change of state comprises a change of a switching state in the on-board power supply system (1), in particular in the second sub-board network (4). Method according to one of the preceding claims, in which an impedance spectroscopy is carried out on the on-board power supply system (1), in particular the second sub-board network (4), to determine the impedance spectrum, and the critical resonance points are determined from the impedance spectrum determined by means of the impedance spectroscopy. Impedance matching device (7), comprising at least one impedance spectroscopy device (10) and an impedance matching circuit (14), wherein - The impedance spectroscopy device (10) has power electronics (11) which are set up to apply a current pulse to an on-board power supply system (1), in particular a second sub-board network (4), and have an evaluation device (13) in order to be able to use the To determine the impedance spectrum generated by the current pulse and to determine setting parameters of the impedance matching circuit (14) from the impedance spectrum in such a way that at least one impedance amplitude is reduced at at least one critical resonance point that has been determined from the impedance spectrum, wherein - The impedance matching circuit (14) each has a plurality of ohmic resistances, capacitances (Ci) and / or inductances (Li) that can optionally be switched on and off as setting parameters, and wherein - The impedance matching device (7) has a control device (15) which is set up to switch on or off at least one of these discrete electrical components (Ci, Li) for its adaptation. Impedance matching device (7) according to Claim 5 , wherein the impedance matching circuit (14) is designed as a Pi circuit. Impedance matching device (7) according to one of the Claims 5 to 6th , in which the impedance matching device (7) has a data transmission interface, by means of which the impedance matching device (7) can receive information about the occurrence of a change in the state of the on-board power supply system (1), and the impedance matching device (7) is set up to receive the current pulse on the basis of the information received abandon the on-board power supply system (1), determine the impedance spectrum, and set the setting parameters of the impedance matching circuit (14) from the impedance spectrum. Impedance matching device (7) according to one of the Claims 5 to 7th , wherein the impedance matching device (7) is designed as a module that can be connected to the on-board power supply system (1), in particular the second sub-board network (4). Vehicle (E), having an on-board power supply (1) and an impedance matching device (7) connected to the on-board power supply (1), which has at least one impedance spectroscopy device (10) and an impedance matching circuit (14), the vehicle (E) is set up, the method according to one of the Claims 1 to 4th to be carried out by means of the impedance matching device (7). Vehicle (E) after Claim 9 , wherein the on-board power supply (1) has a first sub-on-board network (2) with a first, higher on-board network voltage (U_h) and a second, energy-storage-reduced sub-on-board network (4) with a second, lower on-board network voltage (U_n), the second sub-on-board network (4) having a DC voltage converter (6) is fed from the first sub-on-board network (2), and the impedance matching device (7) is connected to the second sub-on-board network (2). Vehicle (E) after one of the Claims 9 to 10 , wherein the impedance spectroscopy device (10) has power electronics (11) which are set up to apply a current pulse to the second sub-on-board network (4) and an evaluation device (13) in order to determine and output the impedance spectrum generated by means of the current pulse to calculate the impedance spectrum setting parameters of the impedance matching circuit (14). Vehicle (E) after one of the Claims 9 to 11 , wherein the impedance matching device (7) is an impedance matching device (7) according to one of Claims 5 to 8th is. Vehicle (E) after one of the Claims 9 to 12th , wherein the impedance matching device (7) is a module connected to the second sub-on-board network (4).

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