Abstract:
A drive device for a vehicle, in particular a rail vehicle, includes a set of drive units each having at least one electric traction motor and a power generation unit which is provided for generating power for the traction motor, and a set of motor contactor units each being assigned to a traction motor. In order to provide a type of drive device which has a high availability in the event of a failure, has few structural elements and can be produced economically, at least one motor contactor unit includes at least one switching device which is connected between the power generation unit for the associated traction motor and a feed point.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a drive device for a vehicle, in particular a rail vehicle, having a set of drive units which each have at least one electric traction motor and a power generation unit which is provided to generate power for the traction motor, and a set of motor contactor units which are each assigned to a traction motor. 
     In electric drive devices for vehicles, in particular for rail vehicles using conventional asynchronous motor technology, the traction motors and/or the pulse inverters which are necessary to feed the latter are partially connected electrically in parallel in order to make available the necessary drive power with the smallest possible amount of expenditure on components. However, if pulse inverters are connected in parallel with one another, wherein the parallel connection is supplied with electrical energy by a common feed, a defect which relates to a pulse inverter requires the entire parallel connection of pulse inverters to be switched off by means of a central mains contactor which is assigned to the parallel connection. 
     In order to be able to avoid the complete failure of traction, it has already been proposed to provide a plurality of electrically independent feeds, in particular independent intermediate connections, which can be switched on independently of one another. However, this requires additional mains contactors, pre-charging devices and assigned controllers, as a result of which the structural outlay and the costs become higher. This can be limited by supplying a plurality of traction motors from a common pulse inverter. 
     However, a parallel connection of traction motors to a pulse inverter is not possible in certain application cases such as, in particular, in the case of a traction equipment with synchronous motors. In these cases, a separate pulse inverter is provided for each traction motor, wherein each traction motor is respectively assigned a motor contactor unit which when necessary, such as for example when towing, disconnects the traction motor from the assigned pulse inverter. All the pulse inverters are connected in parallel with one another, wherein the parallel connection can be disconnected from the feed by means of a central mains contactor. The availability of the drive equipment with respect to a defect is accordingly particularly low. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention is based on the object of making available a drive device of the generic type with which a high level of availability with respect to a defect can be achieved with low structural outlay and costs. 
     For this purpose it is proposed that at least one motor contactor unit has at least one switching means which is connected between the power generation unit for the assigned traction motor and a feed. As a result, the availability of the rail vehicle can be increased easily and cost-effectively by using a motor contactor unit which is present in a conventional way. This motor contactor unit, which conventionally comprises at least one switching element for disconnecting the assigned traction motor from the respective power generation unit and preferably a control unit for activating the switching element, can be easily retrofitted with an additional switching means which can be controlled by the control unit. 
     If the drive units each have a single traction motor, the dimensioning of the switching means is determined by the power load of the single assigned motor feed line, as a result of which commercially available and cost-effective switching equipment can be used for the switching means. 
     The term “between” relates, in particular, to a power flow for power which is drawn from the feed and fed to the assigned traction motor. With respect to the power flow, the switching means is arranged upstream of the power generation unit and the power flow can be interrupted by the switching means upstream of the power generation unit. 
     A “feed” is to be understood as meaning, in particular, a circuit whose function is to make available a specific electrical voltage. 
     This voltage is preferably a direct voltage, wherein the power generation units are each provided for generating an electrical signal for the assigned traction motor on the basis of the direct voltage which is made available, wherein the properties of the current correspond to a specific electrical power. In particular, the power generation units can be embodied as power converters, preferably as pulse inverters. 
     A plurality of independent feeds can be provided for the set of drive units, said feeds each being embodied as circuits, in particular intermediate circuits, which are independent of one another. 
     The proposed drive device is, however, suitable in particular for an embodiment thereof in which the drive units are connected in parallel with one another and the parallel connection of the drive units is supplied by the feed, since a higher level of availability can be achieved for this topology. The at least one motor contactor unit which is equipped with the at least one switching means can, in the event of a defect in the power generation unit for the traction motor assigned to the motor contactor unit, disconnect this power generation unit from the common feed by means of the switching means of said motor contactor unit, while the further power generation units can continue to be operated. If the parallel arrangement has n drive units, in the case of this defect a loss of at maximum 100/n % of the entire drive power which can be drawn via the feed can occur. 
     A particularly high level of availability can be achieved for arrangements having at least four drive units. 
     The traction motors are preferably embodied as synchronous motors. For the latter the condition applies that a plurality of traction motors cannot be fed by a single power generation unit. In this case there is therefore a need for a high number of power generation units which are preferably connected in parallel with one another and are supplied by a common feed. 
     In one preferred embodiment of the invention, the motor contactor unit has at least one switching element which serves to disconnect the assigned traction motor from the respective power generation unit, and a control unit which is provided for synchronously activating the switching element and the switching means. As a result, particularly simple connection of the switching means to the other, preferably conventional, components of the motor contactor unit can be achieved. When the switching means is opened in order to disconnect the traction motor from the respective power generation unit, this power generation unit can simultaneously be disconnected from the feed. 
     The availability can be increased further if all the motor contactor units each have at least one switching means which is connected between the power generation unit for the assigned traction motor and a feed. If the set of drive units is supplied by a common feed, the set of switching means in this embodiment can advantageously form a feed contactor unit which is designed to disconnect the set of drive units from the common feed by opening all the switching means. In this embodiment, each switching means is preferably assigned a different pre-charging circuit in each case. 
     Alternatively or additionally, the set of drive units can be supplied by a common feed, wherein a feed contactor unit is provided which serves to disconnect the set of drive units from the feed and has a central disconnection element which is connected between the set of drive units and the feed. As a result, a structurally simple connection of the drive device can be achieved. 
     In this context it is proposed that the drive device has a pre-charging circuit which is assigned to the feed contactor unit. A structurally simple embodiment with a central pre-charging circuit for the set of drive units can be obtained with a pre-charging circuit which is assigned to the central disconnection element. 
     In addition it is proposed that the drive device has an inductor unit with inductor elements which are each assigned to a different drive unit and are connected between the respective power generation unit and the feed, as a result of which a structurally simple arrangement for interaction between the power generation unit and the inductor element can be obtained. 
     A particularly low structural outlay can be achieved if all the motor contactor units each have at least one switching means which is connected between the power generation unit for the assigned traction motor and a feed, and the inductor elements are arranged between the feed and the respective switching means. 
    
    
     
       BRIEF DECSRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       Exemplary embodiments of the invention will be explained below with reference to the drawings, in which: 
         FIG. 1 : shows a rail vehicle having drive devices in a schematic side view, 
         FIG. 2 : shows a drive device of the rail vehicle from  FIG. 1  in a detailed view, 
         FIG. 3 : shows an embodiment variant of the drive device from  FIG. 2 , having a common feed contactor and a common pre-charging circuit, and 
         FIG. 4 : shows an embodiment variant of the drive device from  FIG. 3 , having an alternative embodiment of an inductor unit. 
     
    
    
     DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a rail vehicle  10  which is embodied as a trainset, in a schematic side view. In an alternative embodiment, the rail vehicle can be embodied as a locomotive. 
     The rail vehicle  10  is formed by two head units  12 . 1 ,  12 . 3  and at least one center unit  12 . 2  arranged between the latter. The head units  12 . 1  and  12 . 3  each have two motor bogies  14 , with two drive axles  16 .A,  16 .B each. They are also each equipped with a drive device  18  which serves to drive the drive axles  16 .A,  16 .B of the motor bogies  14 . 
     The illustrated sequence of drive axles and idling axles is exemplary, wherein further axle sequences which appear appropriate to a person skilled in the art are conceivable. 
     The drive device  18  of a head unit  12  is illustrated in more detail in a detailed view in  FIG. 2 . Said drive device  18  has a set of four drive units  20 . a  to  20 . d  which each comprise an electric traction motor  22 , which is embodied, in particular, as a synchronous motor, and a power generation unit  24 . The traction motors  22  can each be mechanically coupled to a different drive axle. In the embodiment under consideration, the traction motors  22  can each be mechanically coupled to a drive axle  16 .A or  16 .B of the respective motor bogies  14 . 
     The set of four drive units  20 . a  to  20 . d  draws electrical energy from a common feed  26 , and are connected in parallel with one another. The feed  26  is electrically connected to a traction supply system  28 , formed for example by an overhead line ( FIG. 1 ), while the rail vehicle  10  is operating. Alternatively, the traction supply system  28  can be formed by a power rail in the region of the ground. Furthermore, it is also conceivable that, in an embodiment of the rail vehicle  10  with a diesel-electric drive, the feed  26  is electrically connected to a generator. 
     The feed  26  is formed, in particular, by a DC voltage intermediate circuit which makes available a DC voltage U for the generation of electrical power by the power generation units  24 . When an alternating voltage is made available by the traction supply system  28 , the feed  26  is connected to the traction supply system  28  at least via a rectifier and voltage control device (not shown), such as in particular a transformer. The intermediate connection of a rectifier is also expedient when the feed  26  is connected to a generator onboard the rail vehicle  10 . If a direct voltage is made available by the traction supply system  28 , the intermediate connection of a rectifier can be dispensed with. 
     The power generation units  24  each have switching elements (not illustrated in more detail) which generate, on the basis of the direct voltage U and according to a specific switching strategy, an electrical alternating current for feeding the assigned traction motor  22 , wherein the properties of the current correspond to a desired electrical power. In order to control the power generation units  24 , a drive control unit (not illustrated in more detail) of the drive device  18  is provided. In particular, the power generation units  24  are each embodied as pulse inverters. 
     The drive device  18  also has a set of motor contactor units  30  which are each assigned to a different traction motor  22  and which serve, when necessary, for example when there is a defect in the rail vehicle  10  or in the case of a shunting movement of the rail vehicle  10 , to disconnect the traction motor  22  from the assigned power generation unit  24 . For this purpose, each motor contactor unit  28  has switching elements  32  which are each provided for a different phase of the alternating current, in particular three-phase current, which is generated by the power generation unit  24 . 
     The motor contactor units  30  also each have an additional switching means  34  which is connected between the assigned power generation unit  24  and the feed  26 . The switching means  34  therefore serves, when necessary, to disconnect the power generation unit  24  from the feed  26 . The switching elements  32  and the switching means  34  of a motor contactor unit  30  are activated by means of a control unit  35  of the motor contactor unit  30 . In particular, the motor contactor units  30  are designed in such a way that a disconnection process with the switching elements  32  brings about a disconnection process, in particular a synchronous disconnection process, of the additional switching means  34 . 
     Disconnection of the respective power generation unit  24  from the feed  26  can be carried out by means of the additional switching means  34 . The switching means  34  of the motor contactor units  30  accordingly together form a feed contactor unit  36  which is designed to disconnect the set of drive units  20 . a  to  20 . d  from the feed  26 . The complete set can be disconnected by virtue of the fact that all the switching means  34  are activated. The switching means  34  can be considered to be a disconnection element  37  of the feed contactor unit  36 . 
     Each switching means  34  is assigned a pre-charging circuit  38  with a switching element  40  and a pre-charging resistor R v , wherein the pre-charging circuit  38  is connected between the feed  26  and the respective power generation unit  24 , and in parallel with the switching means  34 . 
     The drive device  18  also comprises an inductor unit  42  with inductor elements  44  which are each assigned to a drive unit  20 . The latter are each connected between the respective power generation unit  24  and the switching means  34  of an assigned motor contactor unit  30 . The inductor elements  44  are formed, in particular, by a common iron core, which preferably corresponds to a transformer core. The inductor unit  42  is embodied, in particular, as a multi-winding inductor. 
       FIG. 3  shows the drive device  18 ′ according to an alternative embodiment. In order to avoid unnecessary repetitions, the following description is limited to the differences between this embodiment variant and the embodiment according to  FIG. 2 . 
     The drive device  18 ′ has a feed contactor unit  36 ′ which serves to disconnect the set of drive units  20  from the feed  26 . Compared to the above embodiment, the feed contactor unit  36 ′ has a disconnection element  37 ′ which is common to the set of drive units  20  and which is connected between this set or the parallel connection of drive units  20  and the feed  26 . As a result, it is possible to dispense, in particular, with a pre-charging circuit  38  for each drive unit  20 . Instead, the feed contactor unit  36 ′ can be assigned one pre-charging circuit  38 ′ for the entire set of drive units  20 , which pre-charging circuit  38 ′ is connected in parallel with the disconnection element  37 ′. The pre-charging circuit  38 ′ has a switching element  40 ′ and an electrical resistor R v . 
       FIG. 4  shows the drive device  18 ″ according to an alternative embodiment to the embodiment form  FIG. 3 . In order to avoid unnecessary repetitions, the following description is limited to the differences between this embodiment variant and the embodiment according to  FIG. 3 . 
     In this embodiment, an inductor unit  42 ″ is provided whose inductor elements  44 ″ are arranged upstream of the respective switching means  34  of the corresponding motor contactor unit  30  and therefore between the switching means  34  and the feed  26 . In this context, the inductor unit  42 ″ is embodied, in particular, as a multi-winding inductor with a common base point.