DE102007024567A1 - High-voltage on-board network architecture for a fuel cell vehicle and integrated power electronics for a high-voltage vehicle electrical system architecture - Google Patents

Abstract

High-voltage vehicle electrical system architecture (20) with integrated power electronics (10) for a fuel cell vehicle, in particular a fuel cell hybrid vehicle, with an electric motor (8) combined with a fuel cell unit (1) as at least complementary drive means of the vehicle, with an electrical energy store ( 2) and at least one DC / DC converter (3) as a boost converter and / or buck converter within the electrical system architecture (20), wherein a first DC / DC converter (3) to the electrical energy storage (2) and at least one additional second DC / DC converter (4) is provided on the fuel cell unit (1).

Description

The The present invention relates to a high-voltage vehicle electrical system architecture with integrated power electronics for a fuel cell vehicle, in particular a fuel cell vehicle with an electric motor, with a fuel cell unit and at least one additional Energy storage unit is combined, which in the episode only still referred to as BZ hybrid vehicle. The invention relates as well as integrated power electronics for such High-voltage electrical system architecture.

at Today's wiring systems architectures of motor vehicles that over have a fuel cell / electric motor drive, there is a problem that the electro-electronic requirements are increased to the electrical system. Because of this here at times Increased required high voltages in the controller and control of the various components of hybrid vehicles, for example with fuel cell technology exist with current solutions massive disadvantages with regard to certain operating situations and / or the Variability in the structural design of the elements the network architecture.

For example exist in current systems of on-board network architectures for Fuel cell drives have massive problems in terms of achieving a quick freeze start. Under freeze start you understand problems with regard to the startability of the fuel cell or the fuel cell stack at temperatures below freezing as a result of freezing water, the electrochemical reaction the fuel cell at these low temperatures not through Ice formation may be hampered. It is extreme for the practice important that even with fuel cell hybrid vehicles a safer Start of the vehicle at low temperatures guaranteed is. With today's solutions it is with considerable technical effort among others possible, a so-called Freeze-start at temperatures down to -20 ° C or -25 ° C to allow.

One Another problem of today's wiring systems of such vehicles is it that there are very strong dependencies and possible Influences between the individual components of the vehicle and in particular the drive components and control components among each other. Because of these dependencies and possible influences of the components among each other it is not easy and not without unpredictable problems possible, later changes to the structure architecture and in the form of the components (for Example change in the number of fuel cells of the Stacks or stacks). Therefore, the rest have to electrical / electronic components in each case correspondingly with considerable Effort in the design planning and realization of such vehicles be adjusted. This means that significant limitations in the development opportunity and not negligible additional costs for changes to existing ones Constructions arise.

Of Further, the currently available on-board network architectures Extremely load-dependent for fuel cell-based vehicle drives. This means that all the power electronics of the drives and optionally also other high-voltage components, such as Heater, on a very large input voltage swing, for example in the order of 100V to 500V and very rapid transient load jumps are designed in the electrical system have to. This requires a very elaborate technique, with correspondingly high costs, a comparatively low performance or performance and does not lead most recently also to increased failure rates of the electrical system electronics such vehicles.

About that In addition, the long-term reliability problems in such systems: in a progressive degradation or deterioration of the state of the fuel cell or the fuel cell stack (or stack) At some point a point is reached at which in full load operation of the vehicle, the high-voltage vehicle electrical system voltage a critical value below. In currently known systems, however, the system components are also designed for a certain minimum voltage and thus would be in such a situation no satisfactory operation of the Vehicle more guaranteed. This is therefore currently one critical and major design limitation in the design of network architectures for such Vehicles. Because of these "end-of-life" definitions, that is, critical design constraints, the designers and developers of such Satisfy systems with less efficient architectures.

After all There is also a problem with the known high-voltage vehicle electrical system architectures So far, to the effect that so-called "ripple" voltages can occur on the electrical system. The reason for that lies in an increased repercussion on the electrical system due to unfavorable superposition of the switching operations uncoupled DC / DC converter or the switching operations of Insulated Gate Bipolar Transistors (IGBT Switching) with several individually arranged and switched DC / DC converters (= DC / DC converter).

Around Any disadvantages and errors in operation would be safe to avoid in the known in the art systems and wiring systems architectures so-called EMC shielding (electromagnetic compatibility shielding) for each not belonging to an assembly Converters separately to make each, which in isolated individual transducers (so-called "stand-alone" HV converters) very complex, costly and disadvantageous in terms of weight, volume and manufacturing and realization costs.

In the prior art, various systems for on-board network architectures of fuel cell vehicles are described: In the US Pat. No. 6,496,393 B1 An integrated power supply system is described for use in electric vehicles provided with a fuel cell and an electric motor, wherein an inverter and a DC / DC converter are housed in a common housing.

The US Pat. No. 7,012,822 B2 describes an integrated power conversion system for use in an electrically powered vehicle having an electric motor and an auxiliary power source including an inverter for converting direct current generated by a high voltage power source into an alternating current suitable for driving the electric motor , Essentially, the system disclosed herein is based on the inverter and DC / DC converter sharing one or more common components, such as a high voltage DC bus capacitor.

In contrast, It is the object of the present invention, a high-voltage vehicle electrical system architecture as well as an integrated power electronics suitable for this purpose in particular for use in a fuel cell vehicle to provide, which in the structural design and modification individual components imposed fewer restrictions and which in terms of integratability and compactness is optimized for installation in such vehicles.

The The object of the invention is a high-voltage vehicle electrical system architecture according to the features of claim 1 and after an integrated Power electronics solved according to the features of claim 10. Advantageous aspects and further developments of the invention are the subject matter the respective dependent claims.

The High-voltage on-board network architecture with integrated power electronics for a fuel cell vehicle, which is equipped with an electric motor combined with a fuel cell unit as at least complementary Drive means of the vehicle is equipped, has a battery or a battery unit and at least one DC / DC converter (hereinafter also referred to as a DC / DC converter) within the On-board network architecture. The inventive High-voltage vehicle electrical system architecture is characterized in that a ers ter DC / DC converter on the battery and at least one additional second DC / DC converter to the fuel cell unit or are provided the fuel cell stack. By the additional DC / DC converter to the fuel cell unit according to the Invention are the disadvantages described above in the prior art avoided and solved the problem of the invention: This will result in a second manipulated variable in the system inserted to a controllable high DC link voltage to generate, for example, in the order of magnitude of constant 430 V, and at the same time, the fuel cell unit or the stack to a desired point the Polkurve, for example, during the freeze on about 100 V are kept. Through the targeted decoupling of Components and their dependencies described above, that is, in particular, the fuel cell unit, the High-voltage battery and electric motors, is an optimal and less expensive design of components and components possible according to the invention. Also the problem of a freeze start, which exists in such types of vehicles is, by the invention Vehicle electrical system defused: The warm-up period until the granting of a driving clearance during a cold start can be clear be shortened, because on the one hand, the voltage of the fuel cell stack or unit are kept artificially low for a very long time can, reducing the ratio of heat generation to discharged electric power of the fuel cell unit is further increased. For another is a shortened Warm-up time feasible according to the invention, because a sufficient DC link voltage in the electrical system architecture for Can be made available.

Not last offers the solution of the invention a high degree of freedom with subsequent changes to components, such as the number of fuel cells or Fuel cell stack and the respective possible operating strategies. There are also advantages in terms of electromagnetic compatibility (EMC) given by the invention: this is by an intelligent Clocking the transistors, such as the bipolar transistors with isolated Gate electrode (IGBT transistors), for example via a central processor and common shields for the inventively integrated components in reached a single housing.

Furthermore, a definable and adjustable DC link voltage level is available which makes it possible at any time to respond to future trends or requirements for the vehicle system as a whole and in particular the system of the electrical system architecture. The voltage level in the DC link makes the design of the connected loads more independent of the capacities of fuel cells or high-voltage battery.

There the necessary measures to shield against electromagnetic radiation and to achieve electromagnetic compatibility for the components integrated according to the invention and components in a housing are common, they are easier to realize and are particularly in terms of Weight, volume and cost are further optimized than when for several individual so-called "stand-alone" devices or components to perform. In total by the high-voltage vehicle electrical system architecture according to the invention according to claim 1 for such a vehicle electrical system architecture Advantages with regard to the costs, the packing density and the Efficiencies compared to those known from the prior art Solutions offered.

To An advantageous aspect of the invention is the first DC / DC converter a unidirectional converter, in particular a boost converter or a buck converter. It is known in the art that bidirectional converters in such high-voltage vehicle electrical system architectures to use for hybrid vehicles. At least according to the invention the first DC / DC converter connected to the fuel cell unit is designed as a unidirectional converter.

To Another advantageous aspect of the invention is the additional one second DC / DC converter at the output of the fuel cell unit of Vehicle provided.

To In another advantageous aspect of the invention, the DC / DC converters, that is the first and the second additional DC / DC converter integrated in a common housing. By bringing the two converters in one and the same Housing can be a compact, easy-to-integrate component to be provided. The wiring system architecture according to the invention is thus in terms of packing density and cost as well as in terms Improved the realization in practice. After a further advantageous Aspect in this regard is / are in accordance with the invention the converters also an inverter of the drive motor of the vehicle and possibly other power electronics in one and the same Housing integrated. The individual components can in this way certain functions and components with each other share, such as cooling units or the like. Also, the electromagnetic shielding can for the so common components in a single enclosure and thus inexpensive and easy to manufacture will be realized.

To A further advantageous aspect of the invention is a regulator or a control means (English: Controller) provided with a control strategy, after which the battery downstream DC / DC converter controls a DC link voltage of the network of the vehicle electrical system architecture and the DC / DC converter provided at the output of the fuel cell unit a predetermined point on a pole curve of the fuel cell unit starts or drives. This allows according to the invention, the problems with the freeze start of fuel cell hybrid vehicles to avoid. According to the invention on the one hand a second or additional control value introduced into the system, via which a high and controllable DC link voltage can be generated. At the same time becomes another the fuel cell unit to a desired point the pole curve, for example to about 100 V during the Freeze starts, held.

To In a further advantageous aspect of the invention are all Storage chokes of the DC / DC converter side by side housed in a housing. The storage chokes are in this way in a compact form and space-saving in the common housing with the other power electronics, as the converters and changers accommodated.

To In a further advantageous aspect of the invention, the intermediate circuit side Filter capacities of the vehicle electrical system architecture merged. Also this leads to a further compaction and an improvement in the packaging or in the packing density of the invention Wiring architecture and its spatial constructive Design.

According to claim 5, a power electronics for a high-voltage vehicle electrical system architecture for a fuel cell vehicle is proposed, which is particularly, but not exclusively suitable for a fuel cell vehicle, wherein it is characterized in that a first DC / DC converter to a battery and at least one additional second DC / DC converter are provided on a fuel cell unit of the vehicle. The two transducers are each connected to the corresponding component components either at the output or input, or at both. The additional DC / DC converter on the fuel cell unit provides a further degree of freedom in the regulation and control of the power electronics. About this additional degree of freedom can according to the invention, the conflicting requirements be brought on the one hand a high voltage and on the other hand the highest possible weight-saving and space-saving implementation even in critical operating situations, such as the freeze start of fuel cell hybrid vehicles with each other.

To a further advantageous aspect of the integrated power electronics According to the invention, the DC / DC converters are in a common housing and optionally with other power electronics of the network and / or the vehicle integrated.

Further Advantages and features of the invention are the following description an embodiment with reference to the appended Drawings removable. In the drawing show:

1 a schematic block diagram of an embodiment of a high-voltage vehicle electrical system architecture according to the invention and the driving concept according to the invention;

2 a circuit diagram of an embodiment of a unidirectional DC / DC converter according to the invention here in the form of a boost converter; and

3 a top perspective view of an embodiment of a high-voltage vehicle electrical system architecture according to the invention with the arrangement and integration of the power electronics components in one and the same housing.

In the 1 schematically a block diagram of an embodiment of a high-voltage vehicle electrical system architecture according to the invention and the integrated power electronics according to the invention is shown. The wiring system architecture 20 (gray background in 1 ) is used, for example, for controlling and operating a fuel cell hybrid vehicle, which among other things, an electric motor 8th as a drive motor, a fuel cell unit 1 in the form of a stack of fuel cells and an electrical energy storage 2 for storing energy and for delivering the energy to the engine 8th to drive the vehicle. The integrated power electronics according to the invention 10 the high-voltage wiring system architecture 20 includes, but is not limited to, a first DC / DC converter 3 or DC / DC converter to the electrical energy storage 2 on. In addition, and unlike the prior art, according to the invention is a second DC / DC converter 4 at the output of the fuel cell unit 1 provided, which is realized in this embodiment as a unidirectional DC / DC converter, as shown with the symbol in the block diagram. In addition, there is the wiring system architecture 20 according to the invention from an inverter 6 , before the serving as a drive unit electric motor 8th is switched to convert the DC voltage into an AC voltage required for the motor. According to an advantageous aspect of the invention, the entire power electronics in a common housing 5 integrated, that is, the first converter 3 as well as the second converter 4 together with the inverter and the regulator 7 are in one and the same housing 5 , The regulators 7 or controllers serve to carry out the operation and the control of the individual components with each other.

The regulator 7 can be equipped according to the invention with a control strategy and programmed, after which the electric energy storage 2 downstream DC / DC converter 3 controls a DC link voltage of the network and the output of the fuel cell unit 1 provided DC / DC converter 4 a predetermined point on a pole curve of the fuel cell unit 1 starts or drives. In this way, for example, during a freeze start, a point on the pole curve of about 100 V are approached, with the controller still a relatively high DC link voltage can be generated, for example, at a voltage level of 430 V constant. As a result, an additional manipulated variable in the system and the control of the electrical system architecture 20 introduced according to the invention, which allows independent of the components and their dependencies to meet the requirements in extreme operating situations, especially during a cold start or fuel cells as a freeze start, better meet. The additional manipulated variable through the additional second DC / DC converter offers greater freedom in the design, selection and construction of the individual components and of the overall system.

In the high-voltage wiring system architecture 20 for fuel cell vehicles according to the invention is achieved by the addition of an additional DC / DC converter 4 , preferably at the outlet of the fuel cell unit 1 created the possibility to regulate the DC link voltage to a certain value and at the same time the fuel cell unit 1 to hold on to a certain point of its pole curve. The timing of the integrated transducers 3 . 4 According to the invention is tuned to each other so that so-called "ripple" currents and "ripple" voltages in the high-voltage DC link are minimized as far as possible by choosing a clever switching offset. The example bidirectional DC / DC converter 3 on the electrical energy storage 2 serves to regulate the DC link voltage during the fuel cell unit 1 downstream DC / DC converter 4 the fuel cell unit 1 or holds the fuel cell stack at a certain point of its corresponding Polkurve. The coupling of both parts of the controller 7 or the controller within the integrated power electronics 10 also allows according to the invention much shorter signal delays, as it is the case with conventional vehicles of this type. The conventional vehicles use, for example, CAN bus systems (Controller Area Network). The shortened signal transmission times according to the invention lead to an increase in the dynamics of the entire vehicle electrical system architecture and the integrated power electronics in the interaction of the two DC / DC converters 3 . 4 and the inverter 6 by the engine 8th is switched on.

With this inventively provided second manipulated variable one obtains an additional degree of freedom in the development, design and implementation of on-board network architectures for fuel cell hybrid vehicles. As a result, for example, a more timely release of the ride during freeze start can be offered. Even with older vehicle models and accordingly aged fuel cell unit, which must typically be withdrawn from a certain voltage loss from the market, a sufficient DC link voltage for operation can be achieved for a long time. In addition, the additional control variable according to the invention allows increased freedom of development and adaptation, since certain changes to a component of the electrical system architecture 20 in the present high-voltage vehicle electrical system architecture 20 due to the DC link have less impact on other components, as is the case with conventional such architectures.

In the 2 an embodiment of a DC / DC converter according to the invention is shown in the form of a unidirectional boost converter. The DC / DC converter 4 According to this embodiment, in particular, a storage inductor L _FC . For low power and especially lower speeds of the drive motor 8th (see 1 ), the motor voltage is significantly smaller than the fuel cell unit output voltage. In these cases, there is also the possibility according to the invention of the converter designed as a step-up converter 4 easily switch through. In doing so, the electronic switch provided for charging the storage inductor L _FC remains permanently open (as in FIG 2 shown), so that a voltage transmission of 1: 1 is made in this mode of operation.

• • Ein- und Abschaltverluste der IGBT's
• • Abschaltverluste der Freilaufdioden
• • Hystereseverluste der Eisenkerne in den Speicherdrosseln
• • Ohm'sche Verluste bedingt durch Lade- und Entladeströme der Glättungskondensatoren (C_FC und C_HC)

In this way, in work areas in which the high DC link voltage for driving the vehicle and therefore the electric motor 8th is not necessary, the following losses saved and thus the efficiency of the entire system can be further increased:

• • Switch-on and switch-off losses of the IGBTs
• • Switch-off losses of the freewheeling diodes
• • Hysteresis losses of the iron cores in the storage chokes
• Ohmic losses due to charging and discharging currents of the smoothing capacitors (C _FC and C _HC )

• • Durchlassverluste der Freilaufdioden
• • Ohm'sche Verluste der Speicherdrossel L_FC

This is the serious loss of the converter 4 eliminated in this mode of operation as far as possible. Nevertheless, the following losses occur in the switching operation:

• • Passage losses of the freewheeling diodes
• • Ohmic losses of the storage choke L _FC

In a further embodiment possibility could also be an additional switch 11 be provided, through which the above-described losses of the freewheeling diode and the storage throttle can be avoided.

The 3 Finally, in a perspective plan view shows a constructive realization variant of the inventive solution and the integration concept according to the invention with the lid open. In the common housing 5 On the one hand are the smoothing capacitors 12 for the DC link and on the other hand the inductors 14 (or chokes) provided. Between the inductors 14 and the capacitors 12 are common coolers 13 installed for the power modules. At the rear (in 3 front) end of the housing 5 are each two connections or outputs 15 . 16 on the one hand the connection to the electrical energy storage 2 (Reference 15 ) and, on the other hand, the connection to the fuel cell unit 1 (Reference 16 ). In the inventive integration concept of the essential components and power electronics within a common housing 5 are the chokes (or inductor 14 ) of both DC / DC converters 3 . 4 on one side in the case 5 accommodated. Also, that's for the converters 3 . 4 merged intermediate circuit side smoothing capacitor 12 to recognize in the form of a film capacitor. Further synergy effects are provided by a common cooling via the radiator 13 and a common shielding in terms of electromagnetic compatibility requirements in the form of an internal wall coating in the housing 5 or the like achieved.

In addition to the components shown under certain circumstances, even more power electronics additional auxiliary drives 9 (see 1 ) such as those of Luftmo duls, the hydrogen recirculation blower or the like in the housing 5 integrated according to the invention. In such further integrations of other power electronics components in the field of motor vehicles, one and the same advantages exist and further synergies and advantages in terms of weight, cost and space requirements can be achieved as described above.

The Of course, invention is not limited to this only Example illustrated for purposes of example limited and includes all equivalents and in the scope of protection of the following claims modified embodiments.

1

fuel cell unit (or pile or stack)

2

electrical energy storage

3

first DC / DC converter

4

second (additional) DC / DC converter

5

casing

6

inverter (or inverter)

7

regulator or controller

8th

drive motor (here electric motor)

9

additional Power electronics for auxiliary drives

10

integrated power electronics

11

optional switch

12

capacitor

13

Power electronics components with cooling unit

14

inductor (or throttle)

15

output battery

16

output fuel cell unit

20

High-voltage electrical system architecture

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

• - US 6496393 B1 [0009]
• - US 7012822 B2 [0010]

Claims (11)

High-voltage vehicle electrical system architecture ( 20 ) with integrated power electronics ( 10 ) for a fuel cell vehicle with an electric motor ( 8th ), with a fuel cell unit ( 1 ) and with an electrical energy store ( 2 ) and at least two DC / DC converters ( 3 . 4 ) within the on-board network architecture ( 20 ), characterized in that a first DC / DC converter ( 3 ) to the electrical energy storage ( 2 ) and at least one additional second DC / DC converter ( 4 ) on the fuel cell unit ( 1 ) is provided and both converters feed a DC link. High-voltage vehicle electrical system architecture ( 20 ) according to claim 1, characterized in that the second DC / DC converter (4) is a unidirectional converter, in particular a step-up / step-down converter. High-voltage vehicle electrical system architecture ( 20 ) according to one of the preceding claims, characterized in that the second DC / DC converter ( 4 ) in the fuel cell unit ( 1 ) is integrated. High-voltage vehicle electrical system architecture ( 20 ) according to one of the preceding claims, characterized in that the DC / DC converters ( 3 . 4 ) in a common housing ( 5 ) are integrated. High-voltage vehicle electrical system architecture ( 20 ) according to claim 4, characterized in that in addition to the transducers ( 3 . 4 ) an inverter ( 6 ) of the drive motor ( 8th ) of the vehicle and possibly other power electronics ( 9 ) in one and the same housing ( 5 ) is / are integrated. High-voltage vehicle electrical system architecture ( 20 ) according to one of the preceding claims, characterized in that an electronic unit ( 7 ) is provided, which with the the electrical energy storage ( 2 ) downstream DC / DC converter ( 3 ) the DC link voltage and with the at the output of the fuel cell unit ( 1 ) provided DC / DC converter ( 4 ) the operating point of the fuel cell unit ( 1 ). High-voltage vehicle electrical system architecture ( 20 ) according to one of the preceding claims, characterized in that all storage chokes of the DC / DC converters ( 3 . 4 ) are parallel and electronically wound on the same core. High-voltage vehicle electrical system architecture ( 20 ) according to one of the preceding claims, characterized in that the intermediate-circuit-side filter capacitances of the vehicle electrical system architecture ( 20 ) are merged. High-voltage vehicle electrical system architecture ( 20 ) according to one of the preceding claims, characterized in that for the fuel cell downstream unidirectional DC / DC converter another switch ( 11 ) is provided for bridging. High-voltage vehicle electrical system architecture according to claim 6, characterized characterized in that the switching operations of all involved Power electronics components for reducing voltage / current ripples are matched in the DC bus. High-voltage vehicle electrical system architecture ( 20 ) according to claim 4 or 5, characterized in that the DC / DC converters ( 3 . 4 ) in a common housing ( 5 ) are optionally integrated with other power electronics of the auxiliary drives.