DE102013020677A1 - Drive system for a motor vehicle, in particular an electric or hybrid vehicle - Google Patents

Abstract

The invention relates to a drive system (1) for a motor vehicle, in particular for an electric or hybrid vehicle, having a battery system (2) with a first and a second battery string (3a, 3b), which has a first voltage tap (4a) and a second With a setting unit (5, 5 ') for setting the second electrical output voltage (V2), - with a generator connected to the first voltage tap (4a) generator motor (6), by means of which in a generator Operation, an electrical generator output voltage (VGA) can be generated, - with at least one auxiliary unit (7) connected to the second voltage tap (4b), - with a control unit cooperating with the setting unit (5) and the generator motor (6). Control unit (8), which controls the setting unit (5; 5 ') and the generator motor (6) in such a way, by the first electrical voltage tap (4a) flowing electric current (I1) and / or the electrical current (I2) flowing through the second electrical voltage tap (4b) is determined according to a predetermined control strategy.

Description

The invention relates to a drive system for a motor vehicle, in particular an electric or hybrid vehicle, as well as an electric or hybrid vehicle with such a drive system.

To supply various vehicle components of modern electric or hybrid vehicles - hereinafter referred to simply as electric vehicle for simplicity - with electrical energy drive systems are used with battery systems that can provide at least two different electrical output voltages, so that the higher of the two output voltages for operating the the vehicle driving electric motor is available, whereas the lower of the two output voltages for powering one or more accessories of the electric vehicle can be used. Such an accessory may be, for example, an air conditioning compressor, a power steering pump, a servo brake system, or the like. The preceding list is not exhaustive; rather, the term "ancillary unit" expressly includes other components of the electric vehicle to be supplied with electrical energy.

Against this background, the DE 10 2009 057 919 A1 an electrical system for a motor vehicle with at least two electrical voltage levels and with at least one electrical load for each of the two voltage levels and electrical energy with at least two. The electrical system further comprises a first generator which generates a first electrical voltage whose amplitude essentially determines an electrical potential of a first voltage level. Accordingly, a second electrical generator generates a second electrical voltage, the amplitude of which substantially defines the electrical potential difference between the first voltage level and a second voltage level whose electrical potential is greater than that of the first voltage level.

The DE 101 02 243 A1 describes a device for generating and distributing electrical energy in a motor vehicle. The device has at least one electric drive motor, which is connected via a converter to a fuel cell unit. The fuel cell unit is connected to at least a first, a second and a third electrical voltage network, wherein each electrical voltage network is associated with at least one electrical load and / or at least one energy store. The first electrical voltage network is formed by a fuel cell voltage network and connected via a first bidirectional DC-DC converter to the second electrical voltage network. By means of this DC-DC converter, the first electrical voltage network is electrically isolated from the second electrical voltage network.

Finally, it is still the DE 103 14 360 A1 mentions that discloses a power supply for a motor vehicle, in which at least two voltage circuits with different voltage levels are connected to supply a voltage on-board network and / or for an electric vehicle drive. For energy supply at least one energy source is provided, this energy source is an energy converter, which is designed as a fuel cell stack of series-connected fuel cell elements. The fuel cell stack has a multiple voltage tap, over which the voltage levels provided for respective voltage levels can be tapped, and over which the voltage circuits associated consumers can be supplied with electrical energy.

However, proves to be problematic in such drive systems that their design with two or even more electrical voltage levels requires a very high design effort.

It is therefore an object of the invention to provide a two electrical output voltages providing drive system for an electric or hybrid vehicle, which - compared to conventional drive systems - significantly reduced design complexity is to be realized and which is designed for a long service life. It is a further object of the invention to provide a motor vehicle with such a drive system.

The above objects are achieved by the subject matter of the independent claims. Preferred embodiments are subject of the dependent claims.

The basic idea of the invention is therefore to provide a drive system with a battery system which provides a first electrical output voltage and a second, smaller electrical output voltage compared to the first electrical output voltage. The first electrical output voltage is used to supply power to a generator motor, which is able to drive a vehicle during engine operation, whereas in a generator operating mode it generates an electrical generator output voltage which can be fed into the battery cells of the battery system for charging.

In contrast, the second electrical output voltage serves to supply energy to a or several ancillaries such as a coolant pump of the electric vehicle. The voltage value of the second electrical output voltage required for the supply of the ancillary units can be varied with the aid of an adjusting unit, which can be designed approximately in the form of an adjustable voltage converter. The control of this adjustment is carried out according to the invention by means of a cooperating with the setting and the generator motor control unit: This controls the setting and the generator motor via a bus system, such as a LIN or CAN bus, such that the followed by the first electrical voltage tap first electrical current flowing and / or flowing through the second electrical voltage tap second electric current of a predetermined control strategy. By means of such a control can be considered in particular the electrical voltage generated by the generator motor. Such a control strategy may be defined in such a way - and stored in the control / regulating unit as executable program code, for example - that the lifetime of the individual battery cells of the battery system - referred to below as battery units - is maximized. For this purpose, said control strategy can be based, for example, on the idea of providing an amount of substantially identical electrical current flow through the individual battery unit, so that all battery cells are subjected to the same aging process.

In the control of the setting and the generator motor this is of course the interconnection configuration of the individual battery units, in particular with regard to their electrical interconnection in parallel or in series to consider each other.

According to a preferred embodiment, the battery system may be constructed symmetrically with respect to its two battery strings, d. H. the first battery string has a first plurality of rechargeable first battery units connected electrically in parallel with one another and the second battery string has a second plurality of rechargeable second battery units connected in parallel to one another, the first plurality being equal to the second one, corresponding to said symmetrical structure Plural is. In the battery system, a current sensor which is in communication connection with the control / regulation unit is furthermore provided, by means of which the electrical current flowing through the second voltage tap can be determined and transmitted to the control / regulation unit. To implement the above-proposed, as long as possible life of the battery units promotional control strategy, the control of the setting and the generator motor by adjusting the electrical generator output voltage and the second electrical output voltage is such that a current flowing through the second voltage tap in the electric current Essentially regulated to a zero value. Such zero-value regulation according to the invention ensures that an electric current flowing through the second battery string always flows through the first battery string - and vice versa - so that the battery units are always discharged simultaneously in the case of battery strings - and also recharged - and thus age the same age.

By means of the control strategy provided by the control unit according to the invention, therefore, a uniform loading of the two battery strands is effected, which thus leads to a substantially identical and also maximum service life of the battery strands of the battery system. In particular, it is avoided in this way that due to a different aging of one of the two battery strings must be replaced in time before the other battery string or that the entire battery system must be replaced, although only one of the two battery strings has reached its maximum life.

According to a variant alternative to the aforementioned embodiment, the first battery string may comprise a first battery unit and the second battery string may comprise at least two battery units connected in parallel to one another. Such a construction of the two battery strings proves to be asymmetric, in contrast to the above-described symmetrical structure. Even with such an asymmetrical variant, a current sensor which is in communication connection with the control / regulation unit is provided in the battery system by means of which an electrical current flowing through the second voltage tap can be determined and transmitted to the control / regulation unit. Furthermore, in the battery system, an additional current sensor in communication with the control / regulation unit can be provided, by means of which an electrical current flowing through the first voltage tap can also be determined and transmitted to the control / regulation unit.

In order to realize the aforementioned control strategy in an asymmetrical battery system, the control of the adjustment unit and the generator motor is performed via the control unit by adjusting the electric generator output voltage and the second electrical output voltage such that the electric current flowing through the first battery unit is substantially equal to an electric current flowing through one of the at least two second battery units. By such rules of the electrical currents in the battery system ensures that regardless of whether the battery system is to supply electrical energy via the first or second voltage tap, substantially the same electrical current flows through all the battery units of the battery system.

According to an advantageous development of the above-described asymmetric construction of the battery system, the control / regulating unit is designed such that by adjusting the electrical generator output voltage and the converted electrical output voltage by the control unit flowing through the first and second voltage tap first and second electric current I ₁ , I ₂ is controlled in each case such that between the first and the second electric current substantially the following relationship is satisfied: I ₂ = I ₁ (N ₂ - 1), where N _{2 is} the number of second battery units. In this way, it is ensured that essentially the same electrical current flows through all the battery units of the battery system, so that they age substantially equally fast.

In an embodiment that is particularly easy to implement, the setting unit may comprise a voltage conversion unit having an input and an output terminal which converts an input electrical voltage applied to the input terminal into an adjustable converted output electrical voltage at the output terminal which is smaller than that electrical input voltage. The input terminal of such a voltage conversion unit is electrically connected to the first voltage tap of the battery system, the output terminal, however, with its second voltage tap. Said voltage conversion unit can therefore be used to convert the first electrical output voltage provided at the first voltage tap and to provide it at the second voltage tap. By means of the control unit, the degree of reduction caused by the voltage conversion unit to achieve the desired control strategy can be adjusted without the value of the second electrical output voltage being changed thereby. In other words, the voltage conversion unit makes it possible to realize a predetermined control strategy, without this resulting in an undesirable variation of the value of the second electrical output voltage. Rather, said second electrical output voltage is kept constant by a corresponding control of the voltage conversion unit, which is absolutely necessary for supplying the at least one adjoining unit connected thereto with electrical energy.

However, an embodiment in which the above-presented voltage conversion unit is part of the battery system proves to be particularly advantageous. Such a structure proves to be particularly compact and can thus be particularly easily implemented in the vehicle using the drive system.

Alternatively, it is also conceivable to arrange the voltage conversion unit outside the battery system. Associated with particularly low production costs is an embodiment in which the voltage conversion unit is designed as a DC-DC converter.

As an alternative to the above-proposed use of a voltage conversion unit, in particular in the form of a DC-DC converter, there is also the use of so-called "balancers" which are typically already integrated in conventional multi-cell battery systems and which are also known to the person skilled in the art as "compensation regulators". are common. By means of such balancer modules can be individually discharged battery units of the two battery strings, specifically, so as to ensure a uniform state of charge of all battery units. It is also possible to carry cargo over these resistances during the charging process. Likewise, active balancers are conceivable to shift the charge of individual battery units with each other.

In the drive system proposed here, a separate balancer module can be provided for each of the two battery strings, which are then both controlled by the control / regulation unit. By deliberately discharging individual or all of the battery units, the electrical voltage provided by the battery units at the second voltage tap can be manipulated analogously to the above-discussed variant using a DC-DC converter to realize a particular control strategy.

In an advantageous development, it is advisable to equip the drive system with a bus system, in particular with a CAN or LIN bus system, by means of which the control and regulation unit can communicate with at least the setting unit and the generator motor in order to control these two components ,

The invention further relates to an electric or hybrid vehicle having a drive system with one or more of the aforementioned features.

Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

In each case show schematically:

1 a first example of a drive system according to the invention,

2 a variant of the example of 1 with an asymmetrical design of the battery system used,

3 a second example of a drive system according to the invention.

1 illustrates an inventive drive system 1 in a schematic diagram. This includes a battery system 2 with a first battery string 3a and one to the first battery string 3a electrically connected in series second battery string 3b ,

The battery system 2 is with respect to its two battery strings 3a . 3b symmetrically constructed, ie the first battery string 3a has a first plurality of electrically connectable first battery units connected in parallel with each other 9a and the second battery string 3b a second plurality of chargeable second battery units connected in parallel with each other electrically 9b wherein, according to said symmetrical structure, the first plurality is equal to the second plurality.

The battery system 2 has a first voltage tap 4a for outputting a first electrical output voltage V ₁ and a second voltage tap 4b for outputting a second electrical output voltage V ₂ . At the first voltage tap 4a is a generator engine 6 connected to the motor vehicle, by means of which in a generator operation, an electrical generator output voltage V _{GA is} generated. To the second voltage tap 4b is an accessory 7 , in the form of a heating element or a coolant pump, connected.

The drive system 1 also has an adjustment unit 5 for adjusting the second electrical output voltage V ₂ . The adjustment unit 5 includes a voltage conversion unit 11 For example, in the form of a known in the art in the field of electrical engineering as a DC-DC converter voltage converter. This has an input and an output connection 12 . 13 which one at the input terminal 12 applied electrical input voltage in an adjustable / variable and at the output terminal 13 converted converted electrical output voltage that is smaller than the electrical input voltage. The input connection 12 such a voltage conversion unit 11 is electrical with the first voltage tap 4a of the battery system 2 connected, the output terminal 13 with its second voltage tap 4b ,

Said voltage conversion unit 11 is now used to the first voltage tap 4a provided to convert first electrical output voltage V ₁ in a smaller voltage and this at the second voltage tap 4b provide. By means of the control unit 8th can be the implementation of the desired control strategy according to the invention by the voltage conversion unit 11 to adjust to achieve reduction in electrical voltage, so that the second electrical output voltage V ₂ regardless of the generator motor 6 generated generator output voltage can be adjusted.

In the presentation of the 1 is the voltage conversion unit 11 Part of the battery system 2 , Such a structure proves to be particularly compact and can thus be particularly easily implemented in the vehicle using the drive system. Alternatively, it is also conceivable, the voltage conversion unit 11 ' as part of the adjustment unit 5 ' outside the battery system 2 to arrange what is in 1 is shown by way of example in dashed lines. (Please in the picture 1 the point 13 ' move to the left side of the box)

The adjustment unit 5 and the generator engine 6 in the example scenario the 1 now by a control unit 8th triggered such that by the first electrical voltage tap 4a flowing first electric current I ₁ and by the second electrical voltage tap 4b flowing second electric current I ₂ according to one of the control unit 8th predetermined regulatory strategy. In the battery system 2 is this one with the control unit 8th in communication connection current sensor 10b provided by means of which by the second voltage tap 4b flowing electrical current and determines the control unit 8th is transmitted. To realize the above discussed, as long as possible life of the battery units 9a . 9b Promotional control strategy carried out the control of the adjustment 5 and the generator motor 6 via the control unit 8th by adjusting the generator electrical output voltage V _GA and the second output electrical voltage V ₂ such that the current through the second voltage tap 4b flowing electrical current I ₂ is controlled substantially to a zero value. By setting this to a zero value, it ensures that one through the second battery string 3b flowing electric current always through the first battery string 3a flows and vice versa, so that the parallel connected battery units 9a . 9b the first and second battery string 3a . 3b Always be discharged at the same time and recharged - and thus age the same age. By means of the control unit 8th provided control strategy is thus a uniform load on the two battery strings 3a . 3b achieved.

In a variant of the example of 1 can the first battery string 3a with a first battery unit 9a and the second battery string 3b with at least two electrically connected in parallel with each other second battery units 9b be equipped. Such a scenario is simplified in 2 shown, which refers to the electrical wiring of the battery units 9a . 9b the two battery strings 3a . 3b limited. The number of first battery units 9a is therefore different from that of the second battery units 9b , The structure of the two battery strings 3a . 3b is in contrast to the example of 1 thus asymmetrical. Even with such, asymmetrical variant is in the battery system 2 the one with the control unit 8th in communication connection and in 1 already shown current sensor 10b available.

Of the 1 can also be seen that for the asymmetric structure of the battery strings 3a . 3b in the battery system 2 one with the control unit 8th also in communication connection, additional current sensor 10a is provided, by means of which also a through the first voltage tap 4a flowing electrical current I ₁ determined and to the control unit 8th can be transmitted. To implement a control strategy according to the invention in the asymmetrically constructed battery system 2 the control of the adjustment takes place 6 and the generator motor 5 via the control unit 8th now by adjusting the electric generator output voltage V _GA and the second electrical output voltage V ₂ such that one through each a first battery unit 9a flowing first electrical current in each case substantially equal to one through one of the at least two second battery units 9b flowing electric current is. The current regulation takes place in such a way that essentially the following relationship is fulfilled between the first and the second electrical current I ₁ , I ₂ : I ₂ = I ₁ (N ₂ - 1), where N ₂ = (multiplicity 9b ) / (Mehrzahligkeit 9a ).

This will ensure that through all the battery units 9a . 9b of the asymmetrical battery system 2 essentially the same electrical current flows, so that they age substantially equally fast.

3 shows an alternative variant of the example of 1 in which, as an alternative to the above proposed use of a voltage conversion unit 11 the balancer modules typically already integrated in multi-cell battery systems 14 - as part of the adjustment unit 5 Be used to set the second output voltage V ₂ . By means of the balancer modules 14 can be individual battery units 9a . 9b the two battery strings 4a . 4b about resistances - these are in 3 symbolically through the with 15 indicated arrows - specifically unloaded, thus a uniform state of charge of all battery units 9a . 9b sure.

In the example of 3 is for each of the two battery strings 3a . 3b a separate balancer module 14 provided, both from the control unit 8th be controlled. By targeted discharging of individual or all battery units 9a . 9b becomes that of said battery units 9a . 9b at the second voltage tap 4b provided second electrical output voltage V ₂ in an analogous manner to the above discussed, using a DC-DC converter variant manipulated to realize the desired control strategy.

The drive system 1 according to the 1 to 3 is with a bus system 16 , For example, equipped with a CAN or LIN bus system, by means of which the control and regulation unit 8th with the adjustment unit 5 . 5 ' and the generator engine 8th communicated.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009057919 A1 [0003]
• DE 10102243 A1 [0004]
• DE 10314360 A1 [0005]

Claims (10)

Drive system ( 1 ) for a motor vehicle, in particular for an electric or hybrid vehicle, - with a battery system ( 2 ) with a first battery string ( 3a ) and one to the first battery string ( 3a ) electrically connected in series second battery string ( 3b ), which has a first voltage tap ( 4a ) for outputting a first electrical output voltage (V ₁ ) and a second voltage tap ( 4b ) for outputting a second electrical output voltage (V ₂ ), - with a setting unit ( 5 ; 5 ' ) for setting the second electrical output voltage (V ₂ ), - with a to the first voltage tap ( 4a ) connected generator motor ( 6 ), by means of which in a generator operation, an electrical generator output voltage (V _GA ) can be generated, - with at least one of the second voltage tap ( 4b ) connected accessory ( 7 ), - with one with the setting unit ( 5 ) and the generator engine ( 6 ) cooperating control unit ( 8th ), which the adjustment unit ( 5 ; 5 ' ) and the generator engine ( 6 ) is controlled such that by the first electrical voltage tap ( 4a ) flowing first electrical current (I ₁ ) and / or by the second electrical voltage tap ( 4b ) flowing second electrical current (I ₂ ) according to one of the control unit ( 8th ) predetermined regulatory strategy are set. Drive system according to claim 1, characterized in that - the first battery string ( 3a ) a first plurality of electrically connected in parallel with each other rechargeable first battery units ( 9a ), - the second battery string ( 3b ) a second plurality of electrically connected in parallel with each other chargeable second battery units ( 9b ), - the first plurality is equal to the second plurality, - in the battery system ( 2 ) with the control unit ( 8th ) in communication connection current sensor ( 10b ) is provided, by means of which by the second voltage tap ( 4b ) flowing second electrical current (I ₂ ) determinable and to the control unit ( 8th ) can be transmitted, - the control of the setting unit ( 5 ; 5 ' ) and the generator engine ( 6 ) by the control unit ( 8th ) by adjusting the electrical generator output voltage (V _GA ) and the second electrical output voltage (V ₂ ) such that the voltage applied by the second voltage tap (V _GA ) 4b ) flowing second electrical current (I ₂ ) is controlled substantially to a zero value. Drive system according to claim 1, characterized in that - the first battery string ( 3a ) a, first battery unit ( 9a ) and the second battery string ( 3b ) at least two electrically parallel to each other connected second battery units ( 9b ), - in the battery system ( 2 ) with the control unit ( 8th ) in communication connection current sensor ( 10b ) is provided, by means of which by the second voltage tap ( 4b ) flowing second electrical current (I ₂ ) determinable and to the control unit ( 8th ), - in the battery system ( 2 ) with the control unit ( 8th ) in communication connected additional current sensor ( 10a ) is provided, by means of which a by the first voltage tap ( 4a ) flowing electrical current (I ₁ ) determinable and to the control / regulation unit ( 8th ) can be transmitted, - the control of the setting unit ( 5 ; 5 ' ) and the generator engine ( 8th ) by the control unit ( 8th ) by adjusting the electrical generator output voltage (V _GA ) and the second electrical output voltage (V ₂ ) such that the voltage applied by the first battery unit ( 9a ) flowing electrical current in each case substantially equal to one through one of the at least two second battery units ( 9b ) is flowing electrical current. A drive system according to claim 3, characterized in that the first and second voltage taps ( 4a . 4b ) flowing first or second electric current (I ₁ , I ₂ ) is controlled such that between the first and second electrical current (I ₁ , I ₂ ) substantially the following relationship is satisfied: I ₂ = I ₁ (N ₂ - 1), where N _{2 is} the number of second battery units ( 9b ). Drive system according to one of claims 1 to 4, characterized in that - the setting unit ( 5 ; 5 ' ) a voltage conversion unit ( 11 ; 11 ' ) with an input and an output terminal ( 12 . 13 ), which one at the input terminal ( 12 ) applied electrical input voltage in an adjustable and at the output terminal ( 13 ) converted converted electrical output voltage which is smaller than the electrical input voltage, wherein the input terminal ( 12 ) electrically connected to the first voltage tap ( 4a ) and the output terminal ( 13 ) electrically connected to the second voltage tap ( 4b ) connected is. Drive system according to claim 5, characterized in that - the voltage conversion unit ( 11 ) Part of the battery system ( 2 ), or that - the voltage conversion unit ( 11 ' ) outside the battery system ( 2 ) is arranged. Drive system according to claim 5 or 6, characterized in that the voltage conversion unit ( 11 ; 11 ' ) is a DC-DC converter. Drive system according to one of claims 1 to 4, characterized in that the adjusting unit ( 5 ) one in the battery system ( 2 ) comprises compensating controller provided. Drive system according to one of the preceding claims, characterized in that the control unit ( 8th ) by means of a bus system ( 16 ), in particular by means of a CAN bus system, with the setting unit ( 5 ; 5 ' ) and the generator engine ( 6 ) is in communication connection. Electric or hybrid vehicle with at least one drive system ( 1 ) according to any one of the preceding claims.

Images