Method for operating an on-board electrical system

Abstract

Method for operating an on-board electrical system (10) comprising at least one energy source, at least one power distributor (14, 20, 22) and at least one consumer (24, 25, 26, 28, 30, 32), wherein each consumer (24, 25, 26, 28, 30, 32) is assigned to one of the at least one power distributors (14, 20, 22) for supply purposes, in the method an on-board electrical system power balance is created which takes into account the power provided by the at least one energy source and the consumption of the at least one consumer (24, 25, 26, 28, 30, 32), and power limits for the at least one power distributor (14, 20, 22) are defined as a function of the on-board electrical system power balance created.

Description

[0001] The invention relates to a method for operating an on-board network and to such an on-board network.

[0002] In motor vehicles, electrical consumers are typically located in an on-board electrical system. A distinction is made between safety-relevant consumers and non-safety-relevant consumers, such as quality management (QM) consumers. During operation of the on-board electrical system, it is important that the power supply is always secure, especially for safety-relevant consumers. To ensure the safety of the on-board electrical system, it is well known that the power supply in the on-board electrical system and thus in the vehicle must be monitored.

[0003] Due to the increasing power demands in vehicle electrical systems, so-called energy management functions (EEM) are being used. These serve to maintain the balance between energy demand and energy supply during vehicle operation. These are reactive measures that intervene in overload conditions and actively reduce the energy consumption of comfort consumers.

[0004] The goal of the EEM functions is to avoid extended discharge phases of the 12V battery in order to ensure a balanced or positive charge balance. To achieve this, overload is detected based on the battery condition and the intensity of the degradation of convenience consumers is determined. Typically, the state of charge, the functional status, and the battery current are used for this purpose. If, for example, the 12V battery is discharged for an extended period, the EEM initiates the degradation of convenience consumers. The degradation sequence of the consumers can vary. Consumer degradation is carried out via a degradation signal that is distributed by the EEM to the consumers via a communication interface. The affected consumers then limit their power consumption, thereby reducing the overall load in the vehicle electrical system.

[0005] In light of new assistance systems and safety-relevant aspects, electronic power distributors, such as local power distributors (LPDs) or zone control units, are increasingly being used to ensure a reliable power supply for safety-relevant consumers. For this purpose, the power distributors' outputs are typically implemented using MOSFET switches or eFuses. The LPDs control their outputs locally based on current or voltage thresholds to isolate the affected areas in the event of a fault. The LPDs provide a control interface for a higher-level EEM, potentially enabling the outputs to be controlled even during normal operation.

[0006] The publication DE 10 2020 213 357 A1 describes a method for checking the behavior of at least one group of consumers in a motor vehicle. The method checks whether the at least one group of consumers behaves according to a request to change their consumption. For this purpose, the energy consumption of the group is measured and compared with a modeled consumption. An algorithm, e.g., a maximus algorithm, a minimum algorithm, a delta algorithm, or a differential algorithm, is used for this comparison. Disclosure of the invention

[0007] Against this background, a method having the features of claim 1 and an on-board network according to claim 6 are presented. Embodiments emerge from the dependent claims and from the description.

[0008] The presented method is used to operate an on-board electrical system comprising at least one energy source, at least one power distributor, and at least one consumer, with each consumer being assigned to one of the at least one power distributors for supply. The method creates an on-board electrical system power balance that takes into account the power provided by the at least one energy source and the consumption of the at least one consumer. Depending on the created on-board electrical system power balance, power limits are defined for the at least one power distributor.

[0009] The presented method is used in particular for the power coordination of electronic power distributors in the low-voltage electrical system of a motor vehicle.

[0010] This optimizes the energy supply to components. In particular, energy storage ensures a reliable supply of energy to safety-relevant consumers, even in energy shortage scenarios.

[0011] Furthermore, the modular approach reduces complexity at the system level. Zones with power limits can be defined, with a power / energy reserve for safety-relevant consumers. Furthermore, a request for and approval of power limits can be provided. If necessary, zone-dependent downgrading of consumers takes place.

[0012] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0013] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention. Short description of the drawings Fig. 1 shows a diagram of a power supply design. Fig. 2 shows a power coordination in a block diagram. Fig. 3 shows the composition of the on-board network power. Fig. Figure 4 shows the functional principle of performance coordination for different scenarios. Fig. Figure 5 shows the composition of the power that can be provided by the system. Embodiments of the invention

[0014] The invention is illustrated schematically in the drawings using embodiments and is described in detail below with reference to the drawings.

[0015] In future on-board networks, the available power from the 12V battery and DC-DC converter will be distributed to the subordinate components via different power distributors.

[0016] Fig.1 shows a schematic representation of an embodiment of an on-board network 10 as it will be used in the future. The on-board electrical system 10, the topology 12 of which is illustrated, has a central power distributor (CPD) 14, a DC-DC converter 16, a low-voltage battery (LV battery) 18, in this case a 12V battery, a first local power distributor (LPD) 20, a second LPD 22, a first safety-relevant consumer 24 supplied by the CPD 14, a first convenience consumer 25 supplied by the CPD 14, a second safety-relevant consumer 26 supplied by the first LPD 20, a second convenience consumer 28 supplied by the first LPD 20, a third safety-relevant consumer 30 supplied by the second LPD 22, and a third convenience consumer 32 supplied by the second LPD 22.The comfort consumers 25, 28, 32 are also referred to as non-safety-relevant consumers.

[0017] The CPD 14 handles distribution at the highest level and supplies the LPDs 20, 22 and directly connected safety-relevant and non-safety-relevant loads or consumers. The LPDs 20, 22 then supply further safety-relevant and non-safety-relevant consumers. The task of the power distributors is to coordinate the power of connected components so that the applied power of consumers does not exceed the available power of the 12V battery 18 and DC-DC converter 16, ensuring sufficient power reserve for the safety-relevant consumers. Furthermore, the power distributors 14, 20, 22 perform a safety function. For this purpose, the outputs of the power distributors 14, 20, 22 are usually implemented using MOSFET switches or eFuses, for example, to isolate the affected areas in the event of a component failure. In practice, an LPD is also referred to as a zone or zone control device.

[0018] This paper proposes a control mechanism for performance coordination in CPD and LPD.

[0019] Fig. Figure 2 shows the functional principle of this power coordination. The functionality of the CPD is outlined in a block 100. In a first step 102, an on-board power balance is established. For this purpose, the CPD uses the currently available power 104 of the 12V battery, the power 106 of the DC-DC converter, and the power 108 applied by the loads. The determination of these variables is not always the subject of the presented method and is assumed to be given here.

[0020] The on-board power balance describes the current load of the on-board power system. If the power present in the on-board power system exceeds the available power of the 12V battery and / or the DC-DC converter, the on-board power system is in overload mode and is characterized by a negative power balance.

[0021] Based on the power balance, the power limits for the respective LPDs are determined in a step 110. The power limits are required to limit the applied power of the LPDs. In the event of a negative power balance, these LPDs are limited in their power to varying degrees, which will be discussed later. This results in a power limit 120 for the first LPD, a power limit 122 for the second LPD, and a power limit 124 for the nth LPD. The LPDs must adhere to the commanded power limits through local power coordination, e.g., through degradation or clocking, of the connected loads.

[0022] In the following, several terms are defined to describe the function and the functionality is explained using examples. For a simpler description of the states, the individual loads of the LDPs are summarized in the following description. The safety-relevant loads are referred to as P-SRC Sum and the non-safety-relevant loads as P-QM Sum. The principle can be Fig. 3. The individual areas shown are: P-SRC WC 150, P-SRC Reserve 152, P-SRC currently 154, P-SRC Sum 156, P-QM Sum 158, P-SRC 1 160, P-SRC 2 162, P-SRC 3 164, P-QM 1 170, P-QM 2 172, P-QM 3 174.

[0023] In the further description, terms are needed that also Fig.3. The power P-SRC WC 150 represents the maximum power required by safety-relevant loads during a worst-case maneuver. P-SRC current 154, in turn, represents the currently applied power of all safety-relevant loads. The difference between the loads P-SRC WC 150 and P-SRC current 154 results in the power reserve that currently (still) needs to be maintained for the safety-relevant loads in order to reliably supply a potential worst-case scenario with power / energy: P-SRC reserve 152.

[0024] Three more terms are needed to describe the functionality: Power ShortTerm, Power LongTerm and ΔP-LT:

[0025] Power ShortTerm represents the power that the system can provide for a short period of time. It consists of the currently available peak power of the DC-DC converter (Ppeak-DCDC) and, if present, the currently available power of the battery (P-Batt available). This can be represented mathematically as follows: Power ShortTerm=P−Batt available+Ppeak−DCDC.

[0026] However, Power ShortTerm must be at least as large as P-SRC Reserve 152. If this is not the case, the remaining power must also be provided from the rated power of the DC-DC converter. An example of this is shown in Fig. 5 (left). Mathematically, the formula then changes to: Power ShortTerm=P−SRC reserve.

[0027] The next term is Power LongTerm. This is the power that the system can provide or is available for continuous operation. It is usually composed of the currently available rated power of the DC / DC converter: Power LongTerm=Prated−DCDC.

[0028] In special cases, e.g. at low temperatures, the performance is slightly limited, see explanation of Power ShortTerm, so that Power LongTerm is calculated from the rated power of the DC-DC converter less a potential reserve from Power P-SRC Reserve 152, see Fig. 5 right.

[0029] The last term is ΔP-LT. This is the remaining (continuous) power available. This power can be calculated as follows: ΔP−LT=Power LongTerm−(P−SRC current+P−QM current).

[0030] If ΔP-LT is positive, there is still usable power available in the system that can be commanded to the LPDs. If ΔP-LT is negative, the total power supplied by all LPDs must be degraded by at least this amount.

[0031] In the following, three use cases are used to explain the value range of ΔP-LT. These are shown in Fig. 4 shown.

[0032] Fig. 4 shows a use case 1 200, a use case 2.1 202 and a use case 2.2 204. The individual blocks in the three use cases 202, 204, 204 are: P-Battery available (available) 210, Ppeak-DCDC available 212, Pnenn-DCDC available 214, Power ShortTerm 216, Power LongTerm 218, P-SRC Reserve 220, P-SRC Actual 222, P-QM Actual 224, ΔP-LT 226, ΔP-LT degrade 228.

[0033] Application case 1 200: ΔP-LT positive, this represents the normal case.

[0034] In the first example, the current power of safety-relevant consumers and non-safety-relevant consumers is less than the available continuous power: Power LongTerm−(P−SRC actual+P−QM actual)=ΔP−LT≥0.

[0035] This means that the current power supplied to the system is less than the maximum continuous power the system can deliver, and therefore an increase in load is permissible. If a consumer, e.g. the seat heating, is to be switched on, the control unit must submit a "request" to the higher-level LPD or query whether this is permissible. The LPD then checks whether the additional power requirement is within the locally assigned power limit. If this is the case, it is immediately approved and the component is switched on. If this is not the case, an increase is requested at the main distribution level (CPD). The CPD can now increase the LPD's power limit by a maximum of ΔP-LT. The LPD then checks again to determine whether the consumer can be switched on if necessary.

[0036] The entire load in the system is covered by Power LongTerm, no degradation is required.

[0037] Use Case 2.1 202: ΔP-LT negative due to an increase in SRC power. This represents the special case.

[0038] In the second example, the current power of safety-relevant consumers and non-safety-relevant consumers is greater than the available continuous power: Power LongTerm−(P−SRC actual+P−QM actual)=ΔP−LT<0.

[0039] This means that the system's current power is greater than the maximum continuous power it can deliver (Power LongTerm), and therefore, an additional load increase is not permitted. In this example, this occurs due to an increase in P-SRC Sum. The system is not overloaded in this state, as a temporary supply of Power ShortTerm is available to ensure sufficient supply.

[0040] However, if ΔP-LT for a defined time t STis less than zero, measures must be taken. This means a degradation of the LPDs by at least the amount ΔP-LT. The exact breakdown of the degradation components will be discussed later.

[0041] There is an excess of Power LongTerm due to an increase in P-SRC Actual. P-QM Actual must be degraded by the amount ΔP-LT.

[0042] Use Case 2.2 204: ΔP-LT negative due to an increase in QM. This case should not occur during normal operation.

[0043] In the third example, as in the second case, 202 Power LongTerm - (P-SRC actual + P-QM actual) = ΔP-LT < 0.

[0044] The difference to application case 2.1 202 is that ΔP-LT became less than zero due to an increase in QM.

[0045] This scenario should be avoided by setting power limits, see Use Case 1 200. Therefore, theoretically, this scenario only occurs in fault conditions, but is described for the sake of completeness, as the procedure remains unchanged. Essentially, the procedure is exactly the same as in Use Case 2.1 202: The power limits of the zones / sections are reduced by at least ΔP-LT.

[0046] There is an excess of Power LongTerm due to an increase in P-QM Actual. P-QM Actual must be degraded by the amount ΔP-LT.

[0047] Regarding a potential degradation strategy, Table 1 shows an example calculation for determining power limits for an on-board network with six LPDs. However, the principle is not limited to this specific number and power limits. Table 1: Example calculation for determining performance limits LPD Index #1 #2 #3 #4 #5 #6 Maximum power [W] 800 800 800 1000 1000 1000 Nominal power [W] 560 560 560 700 700 700 Applied power [W] 600 600 560 800 900 600 Difference between applied and nominal power: [W] 40 40 0 100 200 -100 ΔP-LT: [W] 280 Required power reduction per LPD: [W] 29,47368 29,47368 0 73,68421 147,3684 0 Power limits for LPDs [W] 570,5263 570,5263 560 726,3158 752,6316 600 Performance limits for LPDs [%] 95,09% 95,09% 100,00% 90,79% 83,63% 100,00%

[0048] LPDs 1, 2, 4, and 5 have a higher applied power than their nominal power. The applied power of LPD 6, on the other hand, is lower than its nominal power. Accordingly, a positive amount ΔP-LT = 280W arises, by which the LPDs must be limited in total. To do this, the LPDs must be prioritized among themselves and their respective contribution to reducing the applied power in the system must be determined. The following prioritization mechanism is proposed. The greater the difference between the applied and nominal power of an LPD, the more severely this LPD is limited. With this prioritization mechanism, the following order for the limitation of LPDs results for the example given: LPD5 → LPD4 → LPD2, LPD1. LPD5 is limited the most because it has the greatest difference to its nominal power. LPD3 and LPD6 are not limited because they are not operated above their nominal power.

[0049] Alternatively, a fixed prioritization based on the connected loads for the respective LPDs is conceivable. For example, LPDs 1 and 2 can be limited to their maximum first, before LPDs 3, 4, 5, and 6 are limited.

[0050] It should also be mentioned that only QM consumers are downgraded; safety-relevant consumers that are currently required are not downgraded.

[0051] Fig. Figure 5 shows the composition of Power ShortTerm, on the left side 300 for an example without battery and on the right side 302 for an example at extreme temperatures.

[0052] The individual blocks are: Ppeak-DCDC (available) 310, Pnenn-DCDC (available) 312, Power ShortTerm 314, Power LongTerm 316, P-SRC Reserve 318, P-SRC Actual 320, P-QM Actual 322, ΔP-LT 324 P-Battery (available) 326. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2020 213 357 A1

[0006]

Claims

[1] Method for operating an on-board network (10) comprising at least one energy source, at least one power distributor (14, 20, 22) and at least one consumer (24, 25, 26, 28, 30, 32), wherein each consumer (24, 25, 26, 28, 30, 32) is assigned to one of the at least one power distributors (14, 20, 22) for supply, in the method, an on-board network power balance is created which takes into account the power provided by the at least one energy source and the consumption of the at least one consumer (24, 25, 26, 28, 30, 32), and depending on the on-board power balance created, power limits (120, 122, 124) are defined for the at least one power distributor (14, 20, 22). [2] Method according to claim 1, in which at least one higher-level central power distributor (CPD) (14) and at least one lower-level local power distributor (LPD) (20, 22) are used as power distributors (14, 20, 22), each local power distributor (20, 22) being assigned to at least one of the at least one central power distributors (14) for supply. [3] Method according to claim 1 or 2, in which at least one safety-relevant consumer (14, 26, 30) and at least one non-safety-relevant consumer (25, 28, 32) are supplied in the on-board network (10). [4] Method according to claim 3, wherein the definition of the power limits (120, 122, 124) takes into account the extent to which the non-safety-relevant consumers (25, 28, 32) are limited in order to ensure the supply for safety-relevant consumers (24, 26, 30). [5] Method according to one of claims 1 to 4, in which, if necessary, at least one consumer (24, 25, 26, 28, 30, 32) is degraded. [6] On-board network for a vehicle, wherein the on-board network (10) comprises at least one power distributor (14, 20, 22) and at least one consumer (24, 25, 26, 28, 30, 32) and is designed to carry out a method according to one of claims 1 to 5. [7] On-board power system according to claim 6, which has as power distributors (14, 20, 22) at least one higher-level central power distributor (CPD) (14) and at least one lower-level local power distributor (LPD) (20, 22). [8] On-board power system according to claim 6 or 7, in which at least one safety-relevant consumer (14, 26, 30) and at least one non-safety-relevant consumer (25, 28, 32) are provided. [9] On-board electrical system according to one of claims 6 to 8, in which a battery (18) and / or a DC-DC converter (16) is / are provided as at least one energy source. [10] On-board network according to one of claims 6 to 9, in which at least one output of the at least one power distributor (14, 20, 22) uses a MOSFET switch and / or an eFuse.

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