DE10312082B4 - Multi-circuit energy on-board network for a motor vehicle - Google Patents

Abstract

Multi-circuit power electrical system for a motor vehicle, having at least two sub-board networks, which are electrically connected via at least one connecting element, wherein the first sub-board network is connected to a first sub-electrical system associated first energy storage and in which the second sub-board network is connected to at least one input capacitor having a consumer and in a rest state of the vehicle is separated from a second energy storage device associated with the second sub-electrical system via a battery disconnector (7), and measures are provided for pre-charging the at least one input capacitor, wherein by means of a software-based power management system (12) via the connecting element ( 5) from the first part of the electrical system (1) energy in the second sub-electrical system (2) can be fed, so that the at least one input capacitor (8) before a request for the power supply of the input capacitor (8) having n Verbraucher (10, 10 ') is pre-chargeable, wherein the power management system, the connecting element (5) controls such that the pre-charging of the at least one input capacitor (8) is released in response to a detected by the power management system sensor signal, which opening at least one vehicle door or indicates a release of a vehicle door in a resting state of the vehicle, and wherein a closing of the battery disconnect switch by actuation of an ignition lock of the vehicle is triggered.

Description

The invention relates to a multi-circuit power supply system for a motor vehicle, having at least two sub-board networks, which are electrically connected via at least one connecting element, wherein the first sub-board network is connected to a first sub-electrical system associated first energy storage and wherein the second sub-electrical system with at least one input capacitor is connected in a resting state of the vehicle from a second sub-electrical system associated second energy storage via a battery disconnect switch, and are provided in the measures for pre-charging the at least one input capacitor.

The increasing demands on safety and comfort increase as well as consumption and emission reduction lead to an increasing electrification of components in motor vehicles. In particular, for the realization of technical innovations such as hybrid drive or drive-by-wire systems in future vehicles conventional conventional systems are no longer sufficient for the provision of the required power. In particular, for the supply of high-current, or high-power consumers, such as crankshaft starter generators (KSG), air conditioning units, windscreen heaters, window regulator motors, an electrical system with a 36 V energy storage (battery) is now favored at a charging voltage of 42V. On the other hand, many conventional electrical consumers, such as incandescent lamps, displays, instrument clusters, control units, designed for the conventional 12 V / 14 V electrical system and not or only with great effort to a 42 V electrical system customizable. Therefore, multi-voltage vehicle electrical systems have been proposed, for example, a two-voltage vehicle electrical system with a 42V high voltage circuit and a 14V low voltage circuit. Such two-voltage systems are, for example, from DE 101 19 985 A1 . DE 100 28 748 A1 . DE 100 42 524 A1 and the DE 102 08 981 A1 , known.

The voltage circuits, or sub-electrical systems are usually connected to a DC-DC converter. In this case, the high voltage circuit is obligatorily disconnected from the 36 V battery by a battery disconnect switch (BTS) in an idle state of the vehicle and is closed when the vehicle is started up in order to supply the power to the consumers of the 42 V high voltage circuit.

Furthermore, it is known that in consumers with a pulse-width modulated control, PWM short, (thereby instead of a continuous current application current or voltage pulses abandoned and changed by a variation of the pulse widths and / or the duration between pulses the integral on the supplied power) or with a high frequency clocking, the current edges at its input are sputtered through coil / capacitor filter circuits (L / C combinations) to meet the electromagnetic compatibility (EMC) specifications. The capacities of such filter circuits interconnected as DC buses in the vehicle electrical system are in the range of several 10 mF for normal consumers in the mF range and for high current consumers such as a KSG. If these components are switched by a relay when the battery disconnect switch is closed, very high peak currents flow. The peak currents can exceed orders of magnitude of the rated current consumption of the consumer by orders of magnitude. The relay used must therefore be designed so that the peak current can be reliably switched over the service life, ie. H. it must be considerably oversized compared to the rated current requirement.

To avoid this costly oversizing, it is known to provide discharge of the main relay Vorladeschaltungen with additional load relay that pre-charge the capacitors, or capacitors, with a defined current at startup, and then close the main relay with the power supply. This can be realized either by an individual precharging of the individual components via a Vorladezweig per component connected to the electrical system or by a central summation of all high-current components via a relay-connected parallel branch to the battery disconnector of the electrical system.

A disadvantage of the individual precharge affects that a duplicated costly component complexity arises because an additional load relay / switching element for the connection and disconnection of the charging current per component is required. Depending on the type of circuit of the precharge branches, a reduced filter function of the filter circuits can also be set.

A disadvantage of the central pre-charging has the effect that, in the event of component failures, the reliability and availability of the entire vehicle electrical system is called into question, and thus the operational reliability of the electrical system can be impaired.

Furthermore, in case of failure of the circuit breaker, the precharge circuit must be designed so that it is not thermally overloaded when operating the load. This leads to a considerable effort in the design of each resistor and each switching element. The effort is particularly high when high capacities (small charging resistance to reduce the charging time) and High current consumers (small load resistance) are located in the electrical system.

Finally, pre-charging the capacitances typically takes a period of 10-100 ms. These times can have a noticeably delaying effect on a starting process of the vehicle in which the 42 V subnetwork is requested, but then first the subpoena must be performed before the sub-board network is available.

The document DE 198 53 451 A1 describes a method for activating and / or deactivating a preferably installed in a motor vehicle network component network with a plurality of network components that can communicate with each other via a common bus or a bus network system. In this case, a detection device is provided in an access area which is connected to a first network component which generates a detection signal which indicates the access / departure of a user and thus a probably forthcoming commissioning / de-commissioning requirement of the network components. After receiving the detection signal by the first network component, the state of the first network component is changed from the deactivated state to the activated state or vice versa, and a message is sent from the activated first network component to at least one further network component via the common bus for notifying the state change.

The document DE 30 09 369 A1 describes a device for performing start preparations on motor vehicles, with a switching element, with which the power supply of a consumer can be switched, wherein the switching element is controlled by a receiver downstream amplifier, the receiver is housed in the vehicle interior and accessible only after opening the vehicle, and wherein a portable transmitter is provided with its own power supply, on whose emitted signals the receiver responds 2.

The document US 2003/0 029 654 A1 discloses a power supply apparatus for a vehicle in which an inverter circuit inputs a voltage from a first battery unit through switches. A smoothing capacitor is provided in parallel between the first battery unit and the inverter circuit. A DC / DC converter is provided between the smoothing capacitor and a second battery unit to convert electrical energy stored in the first battery unit or the smoothing capacitor to power the second battery unit and electrical energy stored in the second battery unit to convert to the supply of the smoothing capacitor. An electronic control unit controls the DC / DC converter before starting the power supply to the inverter circuit so that the switches are closed after the smoothing capacitor is charged to a voltage within a predetermined allowable voltage range from the voltage of the first battery unit.

The document US 5,541,494 A discloses an engine control system for an electric vehicle having means for detecting and preventing an abnormal drop in an input or output voltage of a DC power circuit.

The document DE 199 26 206 A1 discloses a vehicle electrical system configuration system for automatically configuring vehicle electrical systems that include at least partially hardware components connected to a data bus network and software components implemented in at least a portion thereof for performing associated functionalities.

Object of the present invention is to improve the known multi-circuit vehicle electrical system so that they allow pre-charging of capacity with little effort on components and costs, without start delay and compliance with a high level of reliability.

The object is achieved by the features of claim 1, wherein a power management system controls the connecting element such that the precharge of the at least one input capacitor is released in response to a detected by the power management system sensor signal which opening at least one vehicle door or unlocking a vehicle door in indicates a resting state of the vehicle, and wherein a closing of the battery disconnect switch is triggered by actuation of an ignition switch of the vehicle.

The connector (eg, a DC / DC DC / DC converter) may be fed from the first sub-board network (eg, a conventional 12V circuit with a 14V charge), while the second sub-board system (eg, a 36V circuit with a 42V Charging voltage) in the idle state of the vehicle is compulsory disconnected from the 36 V battery by the battery disconnect switch. This makes it possible, with the connecting element, a pre-charge of the capacity of the second sub-electrical system, already on leaving the idle state of the vehicle, ie the so-called "waking up" of the electrical system, for example, when opening a vehicle door, with a constant current up to the voltage level make the battery. If now the battery disconnector, for example via the ignition lock (Kl. 87-element), is closed, there is only a marginal equalizing current. The second sub-board network and thus the entire vehicle electrical system is ready for use immediately after connecting the battery. As a result, a start delay is avoided and short start-up or start times are feasible. In addition, there are no fundamental restrictions with regard to the capacitive load of the vehicle electrical system.

Instead of precharge circuits, the power management system is introduced. This advantageously has a control unit with a microcomputer, in which software can be stored, and via which the precharge processes can be regulated. The fact that the capacities of the electrical system can be precharged with the help of the power management system, there are no costs for additional components (relays, semiconductors, additional cables, plugs) for Vorladeschaltungen. Consequently, no effort must be made in the event of failure of one or more of these components. This continues to save costs. With the elimination of additional components and a weight savings in the switching devices of the electrical system is connected. In addition, the availability of the vehicle electrical system and the filter effect of the input filter circuits of consumers, in particular of PWM - consumers, not be adversely affected.

Preferred embodiments of the multicircuit energy electrical system according to the invention are described in subclaims 2 to 6.

The invention can be used particularly advantageously for the supply of high current consumers. Crankshaft starter generators with their high input capacities can be operated particularly effectively via the vehicle electrical system according to the invention. Likewise, electromagnetic or variable valve train devices (EVT, VVT) are particularly suitable.

In particular, 14 V / 42 V two-voltage systems are suitable, but also suitable are dual-circuit 14 V single-voltage systems in which one sub-board network is designed as a stabilized circuit for normal-current consumers and the other sub-board network is designed as a dynamic circuit for high-current consumers.

In principle, all multi-circuit on-board network topologies are conceivable which are connected by a suitable connecting element and in which at least one branch can be completely separated from the associated primary energy store (battery) of this branch.

The known method for pre-charging of capacities in multi-circuit electrical systems have the disadvantage that they delay the starting process of the vehicle and can affect the reliability of the electrical system unfavorable.

Another object of the present invention is therefore to improve the known methods so that they ensure a delay-free and reliable availability of the electrical system.

This object is achieved by a method for pre-charging of capacities of a multi-circuit power lane system of a motor vehicle, with at least two sub-board networks, which are electrically connected via at least one connecting element, in which the first sub-board network is connected to a first sub-electrical system associated first energy storage and in which the second sub-board network is connected to at least one consumer having an input capacitor and is disconnected in a resting state of the vehicle from a second sub-electrical system associated second energy storage via a battery disconnect switch, wherein the at least one input capacitor when leaving the idle state of the vehicle by means of a software-based power management system before a Requirement of the power supply of the input capacitor having consumer is precharged.

Due to the fact that the input capacitors or input capacitances already on leaving the rest state of the vehicle, d. H. When the on-board network is woken up, the entire vehicle electrical system is immediately available when it is requested (for example, by actuating a terminal 15 element). The power management also guarantees the availability and operational safety of the electrical system.

Preferred embodiments of this method can be seen in that the power management system controls the connecting element in such a way that the precharge of the at least one input capacitor is released as a function of a sensor signal detected by the power management system, where appropriate the sensor signal is a first opening of at least one vehicle door in a respective idle state indicates the vehicle and optionally the at least one input capacitor is at least approximately precharged to the nominal voltage level of the input capacitor having the sub-electrical system.

It is particularly advantageous to start the pre-charging process when opening a vehicle door of the vehicle at rest. Since the pre-charge after a short time (less than a second) is completed, stands at Starting the vehicle (during the boarding process, the capacities are already pre-charged), the entire electrical system immediately available and there are no start delays. In principle, however, other suitable start signals (for example, unlocking a door) are conceivable.

It is also particularly effective to make the precharge up to the rated voltage level of the corresponding battery. As a result, only low currents flow when the power supply is closed. The switching elements are spared and can be designed cost-saving.

Further details of the invention will become apparent from the following detailed description and the accompanying drawings in which a preferred embodiment of the invention is for example illustrated and an accompanying drawing for explaining the prior art.

Show it

1 : A circuit diagram of a two-circuit electrical system with a power management system and

2 : A circuit diagram of the dual-circuit vehicle electrical system with two variants of a precharge circuit according to the prior art.

A multi-circuit wiring system consists essentially of two via a connecting element 5 connected sub-networks 1 . 2 as well as from a power management system 12 ,

The two sub-networks 1 . 2 form a dual-circuit two-voltage electrical system 13 , The first sub-board network 1 is in a conventional manner permanently to a trained as a 12 V battery first energy storage 3 connected. The second subnetwork 2 is via a battery disconnect switch 7 to a second energy storage device designed as a 36 V battery 4 connectable, so that a first voltage level to ground at a rated voltage of +12 V and a second voltage level to ground at a rated voltage of +36 V. The energy of the electrical system 13 is through a second sub-board network 2 associated alternator 6 generated, which is driven by a vehicle engine. The generator 6 provides the charging voltage for the batteries 3 . 4 , The charging voltage in the first sub-board network 1 is 14 V, in the second sub-board network 2 it is 42 V, so that a 14 V / 42 V electrical system is formed. The connecting element 5 for the mutual transfer of energy between the sub-board networks 1 . 2 is in the two-voltage electrical system 13 . 13 ' as a DC-DC converter (DC / DC converter) is formed.

About the 14 V circle 1 are conventional (stable) consumers 11 (For example, a vehicle lighting) supplied. These can be permanently available (for example, a parking light) or can be connected via corresponding known controls (for example, a driving light). High current consumers and dynamic consumers, in particular dynamic high current consumers 10 . 10 ' , For example, a crankshaft starter generator, are assigned to the 42 V circuit. The consumers 10 . 10 ' are operated with a pulse width modulation, ie with voltage or current pulses. These consumers 10 . 10 ' is preceded by a filter circuit, which is composed of a capacitor-coil combination. Thus, the current edges of the pulses are attenuated, or smoothed to ensure compliance with the EMC specifications, or bring about. For the sake of simplicity, the filter circuits are only capacitors or input capacitors 8th represented; The longitudinal inductances are omitted for clarity. For the operating principle this is irrelevant. The consumers 10 . 10 ' can over switch 9 (Relays) are switched on or off (without switch 9 ) supplied in continuous plus operation.

To relieve the switching elements or relays 7 . 9 are measures to pre-charge the capacitors 8th intended.

This is the state of the art in a circle of tension 2 ' in a vehicle electrical system 13 ' realized by means of precharge circuits. In 2 are two variants 20 . 21 located. The precharge circuits 20 . 21 each have an additional load relay / switching element 23 as well as a resistor 22 on. In the precharge circuit 20 becomes the capacitor 8th initially precharged with a defined current, and only then the main relay 9 with the power supply of the consumer 10 closed. In the precharge circuit 21 becomes the load relay 23 with the resistance 22 bridged. The internal resistance of the switch 23 is then in series with the capacitor 8th , In the precharge circuit 20 can increase the lead impedance increased by the circuit (= ohmic resistance, = capacitive resistance, = inductive resistance) unfavorable in the Vorladeschaltung 21 the filter function of the filter circuit can unfavorably decrease. During a boot process, the capacitors must first 8th be preloaded for a period, only then may the switching elements 9 , respectively. 7 otherwise they would be overloaded with inadmissible peak currents. The boot process will be delayed accordingly until the consumers 10 . 10 ' finally can be turned on. In addition, the precharge circuits have 20 . 21 the disadvantages already explained in the introductory description.

In contrast, in the vehicle electrical system according to the invention 13 the precharge circuits 20 . 21 not mandatory. Instead, it's a power management system 12 provided as it is in 1 is shown. In a resting state, ie when the vehicle is turned off, the battery disconnect switch 7 open, leaving the 42 V circle 2 from the 36 V battery 4 is separated. The circle of tension 2 but then with the DC-DC converter 5 from the permanently supplied voltage circuit 1 supplied. This will now be done by driving the converter 5 by means of the power management system 12 realized. Will the battery disconnect switch 7 closed, are the capacitors 8th already pre-charged and there is only a small compensation current flows. That's why the switches can 7 . 9 are no longer overloaded, hence the precharge circuits 20 . 21 superfluous.

A method for pre-charging the capacities of a multi-circuit power-train network of a motor vehicle is based essentially on one or more capacitors 8th a sub-board network 2 of the vehicle using a software-based power management system 12 before requesting a power supply to the capacitor 8th having a consumer 10 is summoned.

The method is used with the above-described electrical system according to the invention 13 carried out. When leaving the vehicle's resting state, where the sub-board network 2 from the battery 4 is disconnected, the capacitors 8th down to the voltage level of the battery 4 summoned. A start signal to initiate the precharge receives the power management system 12 advantageous when opening a vehicle door. After boarding the driver, the pre-charging process is already completed. The driver now operates the ignition of the vehicle and thereby closes the battery switch 7 , is the 42 V side of the electrical system 13 immediately after connecting the 36 V battery 4 Ready for operation without waiting time, which means that a very short start-up time / starting time can be achieved in the multi-circuit electrical system with high-current consumers or dynamic consumers.

LIST OF REFERENCE NUMBERS

1

Part-board network

2, 2 '

Part-board network

3

energy storage

4

energy storage

5

connecting element

6

generator

7

Battery disconnect switch

8th

input capacitor

9

relay

10, 10 '

consumer

11

consumer

12

Power Management System

13, 13 '

Two-voltage electrical system

20

precharge circuit

21

precharge circuit

22

resistance

23

relay

Claims (6)

Multi-circuit power electrical system for a motor vehicle, having at least two sub-electrical networks, which are electrically connected via at least one connecting element, wherein the first sub-electrical system is connected to a first sub-electrical system associated first energy storage and in which the second sub-electrical system is connected to at least one input capacitor having a consumer and in a state of rest of the vehicle from a second energy store associated with the second sub-electrical system via a battery disconnector ( 7 ) and in which measures are provided for precharging the at least one input capacitor, wherein by means of a software-based power management system ( 12 ) via the connecting element ( 5 ) from the first sub-board network ( 1 ) Energy in the second sub-board network ( 2 ) is input, so that the at least one input capacitor ( 8th ) before a request for the power supply of the input capacitor ( 8th ) ( 10 . 10 ' ) is chargeable, wherein the power management system, the connecting element ( 5 ) such that the precharging of the at least one input capacitor ( 8th ) is released in response to a detected by the power management system sensor signal indicating an opening of at least one vehicle door or a release of a vehicle door in a resting state of the vehicle, and wherein a closing of the battery disconnect switch is actuated by actuation of an ignition switch of the vehicle. Multi-circuit power electrical system according to claim 1, characterized in that at least one with an input capacitor ( 8th consumer ( 10 . 10 ' ) is a high current consumer. Multi-circuit power electrical system according to claim 1 or 2, characterized in that the sub-network ( 1 . 2 ) a dual-circuit two-voltage electrical system ( 13 ), in which the first sub-board network ( 1 ) as a low-voltage circuit and the second sub-board network ( 2 ) is formed as a high-voltage circuit, and wherein the connecting element ( 5 ) is designed as a DC-DC converter. Multi-circuit power electrical system according to claim 3, characterized in that the low-voltage circuit ( 1 ) from an energy store ( 3 ) With a 12 V nominal voltage and a 14 V charging voltage can be fed, and that the higher voltage circuit ( 2 ) from an energy store ( 4 ) with a 36 V nominal voltage and a 42 V charging voltage can be fed. Multi-circuit power electrical system according to one of claims 1 to 2, characterized in that the sub-network ( 1 . 2 ) form a dual-circuit single-voltage on-board electrical system in which both sub-networks ( 1 . 2 ) have a same rated voltage and a same charging voltage, and wherein the connecting element ( 5 ) is designed as a DC-DC converter. Multi-circuit power electrical system according to claim 5, characterized in that the rated voltage of the two-circuit voltage on-board electrical system is 12 V and the charging voltage of the two-circuit Einspannungsbordnetzes 14 V.

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