DE102008022582A1 - Electrical energy on-board supply system for motor vehicle, has controllable electrical coupling device designed such that on-board power supply voltage for one of on-board supply systems is adjustable - Google Patents

Abstract

The system has partial on-board supply systems (TBN1, TBN2) for providing of on-board power supply voltages (Ubn1, Ubn2). Energy storage devices (E1, E2) e.g. on-board power supply battery and double layer capacitor, are coupled with energy converter sources (Q1, Q2) e.g. starter generator, respectively. The partial on-board supply systems are coupled with one another via a controllable electrical coupling device (KE), where the coupling device is designed such that the on-board power supply voltage (Ubn2) for one of the on-board supply systems is adjustable. An independent claim is also included for a method operating an energy on-board supply system for a motor vehicle.

Description

The The invention relates to an electrical power electrical system for a motor vehicle, comprising a first sub-board network and a second, via a controllable coupling device coupled to the first sub-board network second sub-board network.

Such a power cord for a motor vehicle is already in the previously unpublished German patent application with the file number 10 2007 004 279.7 known. This describes a multi-voltage vehicle electrical system with a designed as a low-voltage electrical system sub-board network and designed as a high-voltage electrical system sub-board network, via a controllable switching device a (consumer) board network branch of the low-voltage electrical system off and can be switched on. By disconnecting the disconnectable electrical system branch voltage dips, z. B. during a startup of the engine otherwise could occur in this part of the electrical system, be avoided.

Furthermore, from the DE 10 2005 032 864 A1 a method for finding a power maximum of a photovoltaic generator known, whereby the setting of the maximum generator power is to be realized at an operating point of a generator characteristic.

Of the Invention is based on the object, an energy gate system for to specify a motor vehicle and a method for operating an energy supply network, thereby increasing efficiency in terms of production and deployment of electrical energy is further improved.

According to the invention the task by the totality of the characteristics of the independent Claims solved while in the Subclaims advantageous developments of the invention are indicated. The power cord system according to the invention for a motor vehicle comprises a first sub-board network with a first energy converter source and with a first energy storage device for providing a first vehicle electrical system voltage for Energy supply to a first group of consumers as well second sub-board network with a second energy converter source and with a second energy storage device for providing a second vehicle electrical system voltage for the power supply a second group of consumers. At least one is the two energy converter sources (eg thermoelectric generator (According to the so-called Seebeck effect operating device for production electrical voltage) or photovoltaic element / solar module) in their Power output (strong) operating point dependent (strongly variable Power output), while the other energy converter source (eg generator) in their power output (especially in their Power output prevailing above a predetermined speed of the internal combustion engine) essentially as constant (i.e., in only very narrow predetermined Limits with regard to the output variable) can.

The first subnetwork can be called as low voltage onboard (eg, 14 volts), while the second Part-board network one of the first electrical system voltage different second (in particular one compared to the vehicle electrical system voltage of the first sub-board network higher) vehicle electrical system voltage (eg 24 volts) can deliver. As an energy converter source according to the invention, any technical Device understood that a first form of energy (primary energy) converts into electrical energy and provides. The energy converter source of the first sub-electrical system is advantageous as an electrical machine in Form of a (via the internal combustion engine active or over operating the drive train in regenerative or regenerative braking or regenerative mode) Generators or a starter generator formed. The energy converter source of the second sub-board network is advantageous as a thermoelectric Generator, as a fuel cell, as a solar module or the like educated.

The both sub-networks are via a controllable coupling device, like an advantageously bi-directionally controllable executed DC-DC converter, coupled or coupled together. there the coupling device is designed such that over they are the vehicle electrical system voltage for at least one of the two sub-networks variably adjustable within a predetermined voltage range is (specification of a variable setpoint of the vehicle electrical system voltage).

With Advantage, the coupling device is designed such that the vehicle electrical system voltage of the first sub-board network (eg as low-voltage on-board electrical system with a vehicle electrical system voltage formed by about 14 V) is unchangeable while that of the second sub-board network (hereinafter also referred to as high-voltage on-board electrical system or higher-voltage electrical system referred to with a vehicle electrical system voltage formed by about 24 V) within a predetermined voltage range can be specified variably. In a particularly preferred embodiment the invention, the determination of the setpoint for the variable vehicle electrical system voltage depending on the each present vehicle operating mode. The current vehicle operating mode becomes dependent on predetermined operating parameters determined and depending on this, the vehicle electrical system voltage (Setpoint).

The energy storage device of the first sub-electrical system advantageously comprises a conventional one Vehicle battery, while the energy storage device of the second sub-electrical system consists essentially of (so-called) double-layer or high-performance capacitors.

The inventive method for operating a Energiebordnetzes for a motor vehicle is characterized from that in an energy board network of the type described above in response to predetermined operating parameters currently existing operating mode of the motor vehicle determined and depending on the determined operating mode a setpoint for the second vehicle electrical system voltage is determined and is given. In a further development of the method takes place the determination of the vehicle operating mode and thus the setpoint determination for the vehicle electrical system voltage depending on the continuously determined within a predetermined period of time Rekuperationsanteilen. In the different modes of operation In particular, a distinction is made between highway driving (recuperation share less than / equal to a first limit value), city trip (recuperation share greater than or equal to a second limit) and downhill (Rekuperationsanteil greater than or equal to a third Limit), where the first limit is the smallest and the third Limit value represents the largest value.

One Embodiment of the invention is in the drawing and will be described in more detail below. It demonstrate:

1 : an electrical energy on-board network with two sub-board networks coupled via a controllable coupling device in a first embodiment,

2 FIG. 2: an electrical energy on-board network with two sub-board networks coupled via a coupling device in a second embodiment, FIG.

3 a graph representing the performance characteristics of an energy converter source of one of the two sub-systems, and

4 : A functional diagram to illustrate the operation of the controllable coupling device.

1 shows an electrical power electrical system with two via a controllable coupling device coupled KE sub-board networks TBN1, TBN2 in a first embodiment. In this case, the first sub-electrical system TBN1 comprises a first energy converter source Q1 designed as an electrical generator or starter generator, a first energy storage device E1 designed as a vehicle electrical system battery, and one or more electrical consumers V1. The second sub-board network TBN2 is essentially analogous to the first sub-board network TBN1 and also includes one or more electrical consumers V2, one designed as capacitive (in particular in the form of so-called

Double-layer capacitors) formed second energy storage device E2 and one in their Power output (compared to the first energy converter source Q1) changeable (more variable) second energy converter source Q2. The energy converter source Q2 of the second sub-electrical system TBN2 is with advantage as a thermoelectric generator - ie as one working according to the so-called "Seebeck effect" Device for temperature-dependent energy conversion into electrical energy - trained and over a semiconductor device such as a coupling diode D to the coupling device KE tied up. In this case, the series connection of the second energy converter source Q2 and coupling diode D in parallel to the other on-board network participants how the energy storage device E2 and the consumers V2 switched, wherein the coupling diode D cathode side with the coupling device KE is connected. Advantageous is the TEG with parts of the exhaust system (Exhaust system) thermally coupled - in particular, the TEG on its heat side with parts of the exhaust system and on its cold side with parts of a cooling system (In particular, a cooling system for a drive engine of the motor vehicle).

The coupling device KE is designed such that the vehicle electrical system voltage U _BN2 for the onboard electrical system _{TBN2 is} adjustable with respect to its power variable energy converter source Q2 (or the vehicle electrical system voltage for the electrical system with an energy converter source with operating point-dependent power output). For this purpose, corresponding control components can be implemented in the coupling device KE - alternatively or additionally, however, the coupling device KE can also be connected to a separate control device SE. In the illustrated embodiment, the energy converter source Q2 of the second sub-electrical system TBN2 as a thermoelectric generator (TEG) or as a photovoltaic element and thus as an energy converter source Q2 with strong operating point-dependent (or compared to the first energy converter source Q1 more operating point-dependent) power output formed. Thus, via the coupling element KE, the desired value for the vehicle electrical system voltage U _{BN2 of} the second sub-electrical system TBN2 can be variably (within predetermined limits).

Preferably, the vehicle electrical system voltage U _BN2 (or its desired value) is determined and predetermined in dependence on predetermined operating parameters p _B. In this case, the setpoint specification as a function of individual operating parameters p _B or as a function of, on the basis of the operating parameters p _B ermit switched vehicle operating states (vehicle operating modes). Essentially, in such predetermined operating modes, a distinction is made between city driving, highway driving and downhill driving, wherein the determination of a present operating mode can take place as a function of the recuperation proportions (qualitative and / or quantitative) determined within a predetermined period of time (highway travel: low recuperation shares, city driving average recuperation shares; Downhill: a lot of recuperation shares).

In 2 is shown a particularly preferred embodiment of an electrical power electrical system. While in the embodiment according to 1 the two sub-networks TBN1, TBN2 are quasi completely decoupled from each other by the coupling element KE, the two sub-networks TBN1 ', TBN2' of the power system according to 2 via at least one electrical system branch outside the coupling device KE 'connected to each other. Furthermore, the energy storage device E1 'of the first sub-electrical system TBN1' is also part of the second sub-electrical system TBN2 '. The components of the same mode of action are in the 2 with the same reference numerals as in 1 used and for better distinction, with an additional dash ('). The first sub-board network TBN1 'is analogous to the embodiment in FIG 1 with its potential potential different from ground potential at point P1 on the input side (or on its first part of the electrical system associated connection side) with the coupling element KE ', wherein the second input side terminal of the coupling device KE' analogous to 1 is guided to ground potential. In contrast to the embodiment according to 1 is the first sub-board network TBN1 'with its potential connection at the point P1 in addition to the output-side reference potential terminal (or the reference potential terminal assigned to it on the second sub-electrical system) - 1 is formed by ground potential - the coupling element KE 'connected. In series with the energy storage device E1 'of the first sub-electrical system TBN1', the energy storage device E2 'of the second sub-electrical system TBN2' is connected between the reference potential terminal of the coupling device KE 'and the potential-forming terminal of the coupling device KE' at the point P2. The further on-board network subscribers of the second on-board network TBN2 ', such as the consumers V2' and the second energy converter source Q2 'connected via the coupling diode D', are thus connected in series with the series connection of the first and the ground between the potential of the second sub-electrical system at the point P2 and ground potential second energy storage device E1 ', E2' arranged. The mode of action of the coupling device KE 'is analogous to that with respect to 1 already described mode of action.

3 merely illustrates the characteristic of an energy-conversion source operating point-dependent with respect to its power output. In that, according to the 1 and 2 illustrated and described embodiment, an example designed as a thermoelectric generator or as a solar module energy converter source Q2 is the operating point-dependent source in terms of their power output - at least in comparison with the energy converter source Q1, Q1 'of the first sub-electrical system TBN1, TBN1' - here as an electric generator trained - more work point dependent source. The setpoint _{specification} for the vehicle electrical system voltage U _BN2 , U _BN2 'of the second sub-electrical system TBN2, TBN2' can thus take place in a defined voltage window with the best possible power output, at the same time the requirements of the other board network participants (in particular the on-board network participants of the second sub-electrical system TBN2 / TBN2 ') in can be taken into account.

In 4 is schematically illustrates the operation of the controllable coupling device KE, KE 'illustrated.

To the Operating the power cord network is at least between the modes mechanical recuperation (feeding of electrical energy into the Vehicle electrical system, by the first energy converter source operating as a generator), Discharging (discharging of at least one energy storage device E1, E1 ', E2, E2' for supplying on-board network components), charging from first energy converter source Q1, Q1 '(charging of at least one Energy storage device E1, E1 ', E2, E2' by energy converter source Q1, Q1 ') and charging from second energy converter source Q2, Q2' (charging of at least one energy storage device E2, E2 ', E1, E1' by energy converter source Q2, Q2 ').

In mechanical recuperation operation, electric energy is generated by the regenerative electric machine (energy converter source E1, E1 ') during overrun and / or braking operation of the motor vehicle and thereby the energy storage device E2, E2' of the second sub-electrical system TBN2, TBN2, designed as a double-layer capacitor 'loaded. During the discharging process, the energy storage device E2, E2 'of the second sub-electrical system TBN2, TBN2', which is advantageously designed as a double-layer capacitor, is replaced by a consumer of the vehicle electrical system or via the coupling device KE, KE 'when the vehicle is parked in support of the energy storage device E1, E1 (eg Cyclization vehicle battery) discharged. For charging from the power source Q1, Q1 'of the first sub-board network TBN1, TBN1 'can also be configured as a double-layer capacitor energy storage E2, E2' of the second sub-electrical system TBN2, TBN2 'on the energy converter source Q1, Q1' of the first sub-electrical system TBN1, TBN1 'supplied. Alternatively, the supply of the double-layer capacitor can also take place via the energy converter source Q2, Q2 'of the second sub-electrical system TBN2, TBN2' or via the energy storage device E1, E1 'of the first sub-electrical system TBN1, TBN1'.

During the charging process of the energy storage device E2, E2 'of the second sub-electrical system TBN2, TBN2' from the energy converter source Q2, Q2 'of the second sub-electrical system TBN2, TBN2' charging takes place in dependence on the operating point of the energy converter source Q2 - for example, by the voltage U _DLC , U _DLC 'can be determined over the double-layer capacitor or a size correlated therewith. In a particularly preferred embodiment of the coupling device KE, KE 'the charging process takes place via the energy converter source Q2, Q2' of the second sub-electrical system TBN2, TBN2 'as a function of at least one of the following factors: most favorable voltage for the energy converter source Q2, Q2' with respect to Efficiency of energy conversion, minimum and maximum allowable voltage at least one predetermined load V1, V1 ', V2, V2', maximum amount of energy during a thermal recuperation (by TEG), static and / or dynamic energy reserves (U _{DLC_SR} , U _{DLC_DR} ) at one or more of the energy storage devices E1, E2; E1 ', E2'.

For a capacitive energy storage device such as the double-layer capacitor, the relationship between the amount of energy that can be stored and the voltage across the capacitor is as follows: E = 0.5 × C × U 2 or dE = 0.5 × C × (U1 2 - U2 2 )

The minimum and maximum allowable voltage at the loads is implemented by a voltage limiting function. The maximum storable amount of energy E of the double-layer capacitor (which can be stored, for example, in a recuperation) results from the energy _{content of} the double-layer capacitor set minimum capacitor _voltage U _{DLC_MIN} , the static energy reserve (U _{DLC_SR} ) and any required dynamic energy reserve (U _{DLC_DR} - also as Short-term _reserve ) and the maximum voltage U _{DLC_MAX} actually occurring at the capacitor. The energy content of the double-layer capacitor determined in this way can be converted with the above formula into a voltage to be set on the double-layer capacitor via the coupling device KE, KE '. Furthermore, this voltage U _{DLC_SOLL to be set} (nominal value _{specification} ) is increased by an offset, so that the voltage to be set via the coupling device KE, KE 'is selected such that the energy converter source Q2, Q2' of the second sub-electrical system TBN2, TBN2 'is in as optimal an operating point as possible ( _Operating point or source voltage U _{Q2_MPP} at which the output power of the energy converter source is above a predetermined limit value) is operated. For example, the operation of energy converter source Q2, Q2 'may be performed using a so-called Maximum Power Point (MPP) search (FIG. DE 10 2005 032 864 A1 ) or by replacement values of the energy converter source Q2, Q2 ', such as the air mass flow and / or the temperatures (exhaust gas and / or engine temperature) in a arranged in the exhaust system of an internal combustion engine thermoelectric generator assembly (TEG).

In the 4 is shown to illustrate this mode of operation, as the setpoint determination for the voltage specification via a controllable coupling device KE, KE 'can be done. In this case, via a map in which the z. B. thermoelectric generator designed energy converter source Q2, Q2 'of the second sub-electrical system TBN2, TBN2' model-based is shown, via the coupling device KE, KE 'voltage _setpoint U _{DLC_SOLL to be set} on the double-layer capacitor as a function of, for example, an exhaust air mass flow (dm / dt), an exhaust gas temperature (or a corresponding exhaust gas temperature-dependent temperature difference .DELTA.T from hot to cold side of the TEG) and an actual current value of the TEG are determined.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102007004279 [0002]
• - DE 102005032864 A1 [0003, 0027]

Claims (12)

Electric power on-board network for a motor vehicle, comprising - a first sub-electrical system (TBN1; TBN1 ') for providing a first vehicle electrical system voltage (U _BN1 ; U _BN1 ') comprising a first energy converter source (Q1; Q1 ') and a first energy storage device (E1 E1 '), - a second sub-board network (TBN2; TBN2') for providing a second vehicle electrical system voltage (U _BN2 ; U _BN2 ') comprising a second energy _{converter source} (Q2; Q2') and a second energy storage device (E2; E2 '), and - a controllable electrical coupling device (KE; KE'), via which the two sub-networks (TBN1, TBN2; TBN1 ';TBN2') are coupled together, wherein the coupling device (KE; KE ') is designed such that the vehicle electrical system voltage (UBN2, UBN2 ') can be set for at least one of the two sub-networks (TBN1, TBN2, TBN1', TBN2 '). Electric power supply system according to claim 1, characterized in that the coupling device (KE; KE ') is designed such that in dependence on a currently present operating mode of the motor vehicle - wherein the operating mode was determined from a predetermined selection of at least two different operating modes - the vehicle electrical system voltage ( U _BN1 , U _BN2 , U _BN1 ', U _BN2 ') for one of the two sub-networks (TBN1, TBN2, TBN1 ', TBN2'). Power electrical system according to claim 1 or 2, characterized that at least one energy converter source (Q1, Q2, Q1 ', Q2') as Energy converter source formed with operating point-dependent power output is. Power electrical system according to claim 3, characterized in that the energy converter source (Q1, Q2; Q1 ', Q2') is designed in such a way that the electrical power to be delivered depends on a voltage at the electrical poles of the energy converter source (Q1, Q2; Q1 ', Q2 ') applied voltage (U _BN1, U _BN2; U _BN1', U _BN2 ') is equal to (within a voltage range smaller than / to a first voltage limit U1_Q2) and larger in a second voltage range / equal to a second voltage limit (U2_Q2) is substantially equal to zero , and in one between the two voltage limits (U1_Q2, U2_Q2) voltage range is greater than zero and has a substantially semicircular course. Energy on-board network according to one of the preceding claims, characterized in that the first energy converter source (Q1; Q1 ') is designed as a regenerative electric machine. Energy on-board network according to one of the preceding claims, characterized in that the second energy converter source (Q2; Q2 ') acting in accordance with the Seebeck effect for energy conversion. Energy on-board network according to one of the preceding claims, characterized in that the second energy converter source (Q2; Q2 ') associated energy storage device (E2; E2') capacitive energy storage means includes. Energy on-board network according to one of the preceding claims, characterized in that the energy converter source (Q2; Q2 ') of the second sub-board network (TBN2; TBN2 ') via a coupling diode (D; D ') is connected to the coupling device (KE; KE'). Energy on-board network according to one of the preceding claims, thereby marked that - The controllable coupling device (KE; KE ') designed as a controllable DC voltage converter means is that on its one connection side parallel to the first energy converter source (Q1; Q1 ') and those on its other connection side parallel to the second energy converter source (Q2; Q2 ') is connected, - in which the second energy storage device (E2; E2 ') in series with the first energy storage device (E1; E1 ') and the series circuit first and second energy storage device (E1, E2, E1 ', E2 ') parallel to the second energy converter source (Q2; Q2') and the first energy storage device (E1, E1 ') parallel to the first one Energy converter source (Q1; Q1 ') is connected. Method for operating an energy supply network for a motor vehicle, - wherein the power onboard network via a controllable coupling device (KE; KE ') coupled sub-network (TBN1, TBN2, TBN1', TBN2 ') to provide different electrical system voltages (U _BN1 , U _BN2 , U _BN1 ', U _BN2 '), and - the first sub-electrical system (TBN1, TBN1 ') comprises a generator operating electric machine as an energy converter source (Q1, Q1') for generating the first vehicle electrical system voltage (U _BN1 , U _BN1 ') to be provided second sub-on-board network (TBN2; TBN2 ') comprises a thermoelectric generator operating energy converter source (Q2; Q2') for generating the second onboard electrical system voltage (U _BN2 ; U _BN2 ') to be provided, wherein - depending on predetermined operating parameters (p _B ) a currently present Operating mode of the motor vehicle is determined, - and in dependence on the determined operating mode via the controllable coupling device (KE; KE ') a setpoint for the second vehicle electrical system voltage (U _BN2 , U _BN2 ') is determined and specified. Method according to claim 10, characterized in that that the determination or selection of an operating mode depending on from the recuperation components occurring within a predetermined period of time he follows. Method according to claim 10 or 11, thereby characterized in that when determining an operating mode at least one of the following operating modes detected and in difference is set to another operating mode: - city trip, - Motorway journey, - downhill.