DE102009027220A1 - Device for supplying an electric drive for a motor vehicle - Google Patents

Abstract

The invention relates to a device for supplying an electric drive for a motor vehicle with a power network which is connected to the drive and has a fuel cell unit and at least one energy store, wherein the fuel cell unit and the energy store are coupled. According to the invention, the energy grid has a first and a second energy network, the first energy network has a first converter, which is arranged between the fuel cell unit and the drive, the second energy network has a second converter, which is arranged between the energy store and the drive , and the first inverter is decoupled from the second inverter.

Description

The The invention relates to a device for supplying an electrical Drive for a motor vehicle with a power grid, which is connected to the drive and a fuel cell unit and at least one energy store, wherein the fuel cell unit and the energy storage are coupled according to Preamble of claim 1.

State of the art

From the publication DE 102 23 117 A1 It is known that for the electrical supply of an electric drive for a motor vehicle hybrid power supply systems consisting of a fuel cell unit and an energy storage are used. In this case, an energy store is connected via a DC / DC converter in parallel with the active two-terminal of the fuel cell unit, which is responsible for the supply of an electric drive. Other circuit options are that the energy storage is connected directly to the electric drive of the motor vehicle. In this case, the fuel cell unit is connected via a DC / DC converter in parallel with the two-pole of the energy store. Another possibility is to precede each of the fuel cell unit and the energy storage a DC / DC converter, which then connected in parallel serve as an electrical supply to the drive. All illustrated supply concepts require at least one DC / DC converter to perform the desired energy exchange between the fuel cell unit and energy storage. This is because the fuel cell unit and the energy store have different voltage levels in hybridized operation. The disadvantage here is that both energy networks are electrically connected. As a result, the two energy networks can not be constructed and dimensioned independently of each other.

Disclosure of the invention

It The object of the present invention is a simplified one Structure for supplying an electric drive for to allow a motor vehicle, thus reducing costs and at the same time achieve functional advantages of the overall structure.

to Solution to this problem is a device with the features of claim 1, in particular of the characterizing Part. In the dependent claims are preferred Developments executed. The in the claims and in the description mentioned Characteristics essential to the invention individually or in combination be.

According to the invention provided that the energy network has a first and a second energy network, the first power grid has a first inverter, the between the fuel cell unit and the drive is arranged, the second power grid has a second inverter which is between the Energy storage and the drive is arranged, and the first inverter is decoupled from the second inverter.

Especially It is advantageous that an energy transfer from the first Power network to the second power network via the drive, in particular while driving the motor vehicle. In order to can the fuel cell unit and the energy storage be connected separately to the drive. A power DC / DC converter, the normally between the fuel cell unit and the energy storage is required for energy transfer, deleted. The fuel cell unit and the energy storage are direct connected to the drive.

Also is inventively provided that an energy transfer from the first power grid to the second power grid via magnetic alternating field can be done. This is a contactless inductive energy transfer possible. An electric Connection between the first power grid and the second power grid can be omitted. In an extreme energy extraction of a strand of energy, resulting in an undesirable and / or unexpected increase in temperature can lead in this case is advantageously one thermal decoupling exists between the energy networks. It may be due to mechanical contacts between the energy strings be waived. Also, this is a low-maintenance construction given. In addition, the voltage levels of the two energy networks can be chosen independently of each other, what overall greater degrees of freedom in the interpretation of Nets means without any further effort being made got to.

Furthermore, it may be advantageous that the drive has a first and a second winding system, which are arranged on a common stator, wherein the first winding system is coupled to the first inverter and the second winding system to the second inverter. By this arrangement, it is possible to integrate the two separate winding systems in the common electric drive. Thus, the electric machine can act either as a drive or generator and so exchange energy on the separate windings in the common stand. Another advantage of this arrangement is that even with the drive power from the fuel Cell unit can be transmitted to the energy storage via the stator windings. The stator of the drive acts as a transformer. As a possible winding system, a three-phase system can be used, as is typically used in traction drives. Of course, the concept can also be applied to other phase numbers. Likewise, the wiring is in no way limited to a star connection, but can also be used with delta circuits and other phase connections. A solution of a winding system can be considered from a classic grooved stator with a two-layer winding. The two layers are then used for both winding systems. The production cost of such a winding arrangement is the same as in a classic two-layer winding, except that twice as many connections are led to the outside. This described winding arrangement is only one possible embodiment. Alternatively, z. B. four layers are used, the two winding systems are alternately inserted in each case. This increases the magnetic coupling. It is possible to arrange the winding systems in phase, so that numerous components of the motor control can be shared for both inverters. In addition, a common sensor for the rotor angle position detection can be used. At a standstill of the vehicle and accordingly a standstill of the drive, a pure alternating field can be generated. This offers the advantage that the electrical machine generates no torque despite energization. To reduce rotor losses, the angular frequency ω can be chosen low. A particularly high angular frequency ω makes it possible to generate a high proportion of stray flux that does not penetrate the rotor.

Also It is conceivable that the drive has a first stand and a second stand that over coupled to a common rotor, wherein the first stator on the first inverter and the second stator on the second Inverter is arranged. Here are the stator windings slidably arranged so that any covers adjustable between the stator windings and the rotor are. It is also possible that both stator windings have different radii and can be moved into each other. Thus the air gap at the stand with the larger Radius does not get too big, are special flux-leading Components conceivable that minimize the resulting air gap. By This arrangement can be the coupling of the two winding systems in the Art be adjusted as it is for the energy exchange between the fuel cell unit and the energy storage needed is.

It may be advantageous that at least a first electrical component at the fuel cell unit and a second electrical component are arranged on the energy storage. This offers the possibility the electrical supply of consumers with high power requirements to ensure such as B. in a compressor for the cathode air supply of the fuel cell unit needed is. In addition, by using decoupled components with same functionality a redundancy of components of the Overall system to be created to the highest possible To obtain availability. These can then be separated attached to the fuel cell unit and the energy storage become. Likewise it may be possible that the concerned electrical components on a first smaller variant and one split second smaller variant, with the first smaller variant arranged on the fuel cell unit and the second smaller Variant can be arranged on the energy storage. this makes possible it to ensure the energy supply. Furthermore, it is conceivable to additionally mechanically couple the two smaller variants. This could be z. B. be the case with two compressors, the are coupled by a pneumatic impeller.

It is also provided according to the invention that the drive has a first and a second electric machine, in particular that the first machine is separated from the second machine. For this purpose, advantageously, the first and the second electric machine have a common shaft. The first and the second electric machine can act as a motor or generator. Energy can be exchanged via the common wave. Due to the separation of the two electrical machines, it is thus possible that different electrical machines with different performance data are used. Also, the structure of the two electrical machines can be designed differently. Accordingly, the first and second inverters required for the electric machines can also be designed differently and based on different performance data, since these are decoupled from each other. This allows the greatest possible scope for the construction of the device for supplying an electric drive. For a motor vehicle, it is z. B. possible to arrange the first electric machine to the front axle of the motor vehicle and to couple the second electric machine to the rear axle of the motor vehicle. The first electric machine could then be a motor which is supplied with energy via a first converter by a fuel cell unit and thus drives the motor vehicle. The second electric machine could in this case be a generator which supplies the energy store via a second converter with energy during the drive of the motor vehicle. Because the two electric Engine and / or generator can be, it goes without saying that the second electric machine on the rear axle of the vehicle can also act as a motor, which is powered by the energy storage with energy.

advantageously, the first power grid is galvanically isolated from the second one. Thereby It will allow the two energy networks to be independent be designed and designed from each other. This can be done during the planning phase of the device for supplying an electrical Drive cost advantages. In addition, one allows galvanic isolation that in case of electrical failure one energy network the other remains unaffected. Additional security measures such as attachment and assignment of electrical fuses between the two energy networks can be omitted.

Also It is conceivable that an energy transfer from the first Power network to the second energy network via an electric Connection takes place. This creates the opportunity known electrical and electronic coupling methods of the two energy networks. Also a coupling the fuel cell unit and the energy storage over a three-phase system can be made possible. Also the installation of a bidirectional DC / DC converter between the two Energy networks enable energy transfer from the fuel cell unit to the energy storage even when stationary Drive. Electrical components with high power requirements can be used at Energy storage to be connected to an inactive Drive can be powered. It is too possible to make the DC / DC converter unidirectional, so that only transfer energy from the fuel cell unit to the energy storage can be. According to the invention, it is further provided that the periphery for operating a fuel cell system optional supplied by the energy storage and / or the fuel cell unit is. This makes it possible that in any operating condition the device for supplying an electrical drive the periphery is optimally supplied with energy. In addition, possibly failures the energy storage or the fuel cell unit of the other be bridged intact unit.

Further Advantages, features and details of the invention will become apparent the description below, with reference to the drawings several embodiments of the invention in detail are described. It can in the claims and in the description mentioned features individually by itself or in any combination essential to the invention be. Show it:

1 a schematic structure of two energy networks for the energetic supply of a drive,

2 a schematic structure of a winding system,

3 a schematic view of two separate stator with a rotor,

4 a schematic structure for supplying an electric drive with two components to be supplied,

5 a schematic structure of two separate electrical machines,

6 a schematic structure of two electrical machines connected to a shaft,

7 a schematic structure of a supply of an electric drive to be supplied with peripherals and attached DC / DC converter.

In the 1 is a first energy network 20 , with a fuel cell unit 21 and a first inverter 22 shown, the first energy network 20 with a drive 10 connected is. A second energy network 30 with an energy storage 31 and a second inverter 32 is also electric with the drive 10 connected. The first inverter 22 and the second inverter 32 can be on separate winding systems in the electric drive 10 work. This allows energy to be exchanged via the separate windings in a common stand. In addition, the first inverter 22 from the second inverter 32 decoupled.

2 shows a schematic structure of a winding system. A first energy network 20 with a fuel cell unit and a first inverter 22 is with a first winding system 23 coupled. A second energy network 30 with a second inverter 32 and an energy store 31 is with a second winding system 33 coupled. Here is a three-phase system as shown in the drive 10 can be used. Of course, the concept can also be applied to other phase numbers. Likewise, it is in no way limited to the illustrated star connection, but can also be used with delta circuits and other phase connections. The first winding system 23 is from the second winding system 33 galvanically isolated. By decoupling the inverter 22 . 32 , which allow a conversion from DC to AC and vice versa, the structure of the two converters 22 . 32 be different, as these un can be dimensioned depending on each other.

3 shows a schematic structure of a first stator 24 and a second stand 34 passing through a common rotor 40 energetically coupled with each other. The first stand 24 is with the first inverter 22 connected, in turn, with the fuel cell unit 21 which is the first energy network 20 form. The second stand 34 is with the second inverter 32 connected, in turn, with the energy storage 31 is coupled and the second energy network 30 form. The two separate stands 24 . 34 are from the rotor 40 galvanically isolated. There are thus arbitrary overlaps between the individual stands 24 . 34 and the rotor 40 adjustable. It is still possible that both stands 24 . 34 have different radii and can be moved into each other. So that the air gap in the stand with the larger radius is not too big, if he only the rotor 40 and not covered by the other stator, special flux-conducting components are possible, which minimize the resulting air gap.

4 shows a schematic structure of the first power network 20 and the second power network 30 both at the drive 10 are arranged. The first energy network 20 has the fuel cell unit 21 and the first inverter 22 on. This also applies to the second energy network 30 which the energy storage 31 and the second inverter 32 having. A first electrical component 25 is directly at the fuel cell unit 21 arranged. A second electrical component 35 is with the energy storage 31 connected. This allows both electrical components 25 . 35 be supplied independently with electrical energy. Even if the two electrical components 25 . 35 the same function within the device for supplying an electric drive 10 they can be constructed and dimensioned differently. This allows for the individual specific output parameters of the fuel cell unit 21 and / or the energy storage 31 Take into account. In addition, both are electrical components 25 . 35 galvanically isolated from each other, which can lead to a cost reduction compared to electrically bonded components.

The 5 shows a schematic structure of two separate electrical machines 11 . 12 , The first electric machine 11 is about the first inverter 22 with the fuel cell unit 21 connected, which is the first energy network 20 form. The second electric machine 12 is via the second inverter 32 with the energy storage 31 electrically connected, which is the second energy network 30 form. This is the first one 11 from the second electric machine 12 galvanically isolated. Again, the electrical machines can 11 . 12 differently constructed and dimensioned. Thus, the two electric machines 11 . 12 act on different axes of the vehicle. It can be the first 11 and the second electric machine 12 a synchronous machine and / or an asynchronous machine.

The 6 shows a schematic structure of a first electric machine 11 and a second electric machine 12 that have a common wave 13 connected to each other. The energetic feed of the first electric machine 11 via a fuel cell unit 21 that have a first inverter 22 with the first electric machine 11 which is the first energy network 20 form. The energetic supply takes place for the second electric machine 12 via an energy storage 31 that has a second inverter 32 with the second electric machine 12 connected and the second energy network 30 form.

7 shows a schematic structure in which the first power grid 20 with the second energy network 30 through a DC / DC converter 50 connected to each other. At this time, the fuel cell unit becomes 21 via a DC / DC converter 50 with the energy storage 31 electrically connected. The fuel cell unit 21 feeds via the first inverter 22 the first electric machine 11 , The energy storage 31 is via a second inverter 32 with the second electric machine 12 connected. Schematically here is the periphery 60 with the energy storage 31 connected. Of course, connecting the peripherals is as well 60 to the fuel cell unit 21 possible. The periphery 60 can from z. As a compressor, a blower, a pressure regulator, a cooling circuit, a system control, a safety monitoring and / or power electronics exist.

To the 1 to 7 It can be seen that there is a separation of a first converter from a second converter in the power networks for supplying an electric drive.

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 10223117 A1 [0002]

Claims (14)

Device for supplying an electric drive ( 10 ) for a motor vehicle having a power grid connected to the drive ( 10 ) and a fuel cell unit ( 21 ) and at least one energy store ( 31 ), wherein the fuel cell unit ( 21 ) and the energy storage ( 31 ), characterized in that the power grid is a first ( 20 ) and a second energy network ( 30 ), the first energy network ( 20 ) a first inverter ( 22 ), which between the fuel cell unit ( 21 ) and the drive ( 10 ), the second energy network ( 30 ) a second inverter ( 32 ), which between the energy storage ( 31 ) and the drive ( 10 ), and the first inverter ( 22 ) from the second inverter ( 32 ) is decoupled. Apparatus according to claim 1, characterized in that a power transmission from the first energy network ( 20 ) to the second energy network ( 30 ) via the drive ( 10 ) takes place, in particular takes place while driving the motor vehicle. Apparatus according to claim 1, characterized in that a power transmission from the first energy network ( 20 ) to the second energy network ( 30 ) via a magnetic alternating field. Device according to claim 1 or 3, characterized in that the drive ( 10 ) over a first ( 23 ) and a second winding system ( 33 ), which are arranged on a common stator, wherein the first winding system ( 23 ) on the first inverter ( 22 ) and the second winding system ( 33 ) on the second inverter ( 32 ) is coupled. Device according to one of the preceding claims, characterized in that the drive ( 10 ) via a first stator winding ( 24 ) and a second stator winding ( 34 ), which has a common rotor ( 40 ), wherein the first stator winding ( 24 ) on the first inverter ( 22 ) and the second stator winding ( 34 ) on the second inverter ( 32 ) is arranged. Device according to one of the preceding claims, characterized in that at least one first electrical component ( 25 ) on the fuel cell unit ( 21 ) and a second electrical component ( 35 ) on the energy store ( 31 ) is arranged. Device according to one of the preceding claims, characterized in that the drive ( 10 ) a first ( 11 ) and a second electric machine ( 12 ), in particular that the first machine ( 11 ) from the second machine ( 12 ) is disconnected. Device according to claim 6, characterized in that the first ( 11 ) and the second electric machine ( 12 ) about a common wave ( 13 ) feature. Device according to one of the preceding claims, characterized in that the first energy network ( 20 ) from the second ( 30 ) is galvanically isolated. Device according to one of the preceding claims, characterized in that a power transmission from the first energy network ( 20 ) to the second energy network ( 30 ) via an electrical connection. Apparatus according to claim 10, characterized in that the electrical connection via a DC / DC converter ( 50 ) between fuel cell unit ( 21 ) and energy storage ( 31 ) he follows. Apparatus according to claim 11, characterized in that the DC / DC converter ( 50 ) has a uni- or bidirectional orientation. Device according to one of the preceding claims, characterized in that the periphery ( 60 ) for operating a fuel cell system optionally from the energy store ( 31 ) and / or the fuel cell unit ( 21 ) is available. Motor vehicle with a device for supplying an electric drive ( 10 ) according to one of the preceding claims.