Power supply device for a rail vehicle

Abstract

The invention relates to a 1st power supply arrangement for a rail vehicle. The rail vehicle includes at least one driven car with an intermediate circuit, a brake system and an energy supply system for supplying the brake system with operating energy. In order to improve the framework conditions to ensure reliable electrodynamic braking, the energy supply system contains at least two energy supply units, for the driven car, arranged at the intermediate circuit, for the redundant energy supply to the brake system.

Claims

1. A power supply device for a rail vehicle with at least one driven car and a braking system, comprising: a DC link and an energy supply system for supplying operating energy to the braking system; and an AC train busbar for supplying operating energy to the braking system; said energy supply system including at least two energy supply units for the at least one driven car connected on said DC link for redundant energy supply to the braking system; said at least two energy supply units configured for redundant energy supply to the AC train busbar; and said DC link having at least two segments and each of said at least two energy supply units assigned to a dedicated said segment of said DC link, and said two segments disconnected from one another and used, via said energy supply units for redundant energy supply to said AC train busbar.

2. A power supply device for a rail vehicle with at least one driven car and a braking system, comprising: a DC link and an energy supply system for supplying operating energy to the braking system, said energy supply system including at least two energy supply units for the at least one driven car connected on said DC link for redundant energy supply to the braking system; and two input power converters for the driven car for respectively supplying energy to an entire said DC link and a switching device for connecting said two input power converters to at least one of said energy supply units for supplying energy thereto; wherein said switching device is configured for splitting said DC link into two segments, which are disconnected from one another, are each fed by an input power converter and each have an energy supply unit, and for connecting said two energy supply units to at least one of said two input power converters when said segments are otherwise disconnected.

3. The power supply device according to claim 2, wherein said energy supply unit with a relatively lower power is connected to at least two input power converters and a relatively more powerful said energy supply unit, during regular operation, is configured and conditioned only for supplying energy to an AC train busbar for supplying operating energy to the braking system.

4. A power supply device for a rail vehicle with at least one driven car and a braking system, comprising: a DC link and an energy supply system for supplying operating energy to the braking system, said energy supply system including at least two energy supply units for the at least one driven car connected on said DC link for redundant energy supply to the braking system; a DC train busbar, said energy supply system including at least two energy supply units for redundant energy supply to said DC train busbar; and a DC source configured for feeding said DC train busbar, or each of said energy supply units feeding said DC train busbar having at least two DC storage devices.

5. A power supply device for a rail vehicle with at least one driven car and a braking system, comprising: a DC link and an energy supply system for supplying operating energy to the braking system, said energy supply system including at least two energy supply units for the at least one driven car connected on said DC link for redundant energy supply to the braking system; an AC train busbar having said at least two energy supply units connected thereto by way of a parallel circuit, and a number of AC lines connected to the braking system for supplying operating energy to the braking system, wherein said energy supply units are connected to said AC lines by way of a parallel circuit, and further comprising a switching device for selectively connecting and disconnecting the number of AC lines to or from said AC train busbar; and at least set of limitations selected from the group consisting of a set (1) and a set (2); wherein the set (1) requires that each of said energy supply units is connected to a dedicated input power converter and comprising a further energy supply unit connected to one of said input power converters of one of said energy supply units, and connected to the braking system via a further AC line without any coupling to said AC train busbar by way of a switching device, and wherein said further energy supply unit is configured for redundant energy supply to the braking system; and wherein the set (2) requires that a further energy supply unit is fed from a DC storage device without a DC link and is connected to the braking system via a further AC line, without coupling to said AC train busbar, by way of a switching device, and wherein said further energy supply unit is configured for redundant energy supply to the braking system.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) In the drawings:

(2) FIG. 1 shows a driven and a non-driven car of a rail vehicle comprising a power supply device,

(3) FIG. 2 shows the power supply device shown in FIG. 1 comprising two disconnected DC-link segments,

(4) FIG. 3 shows another embodiment of the power supply device comprising connectable segments of the DC link,

(5) FIG. 4 shows a further embodiment comprising a DC store for feeding an AC train busbar,

(6) FIG. 5 shows a DC train busbar of a train comprising a plurality of non-driven cars, which are fed by two energy supply units,

(7) FIG. 6 shows a DC train busbar, which is fed from each car by an energy supply unit,

(8) FIG. 7 shows the power supply device shown in FIG. 1 comprising separate AC lines and a redundant embodiment of the operating units of the braking system,

(9) FIG. 8 shows a power supply device as in FIG. 7 comprising a further energy supply unit,

(10) FIG. 9 shows a further embodiment comprising a DC source for feeding the third energy supply unit,

(11) FIG. 10 shows a variant of the power supply device in which the operating units of the braking system are supplied exclusively from the AC lines,

(12) FIG. 11 shows an electrical connection of the operating units from FIG. 7 via separate AC feed lines, and

(13) FIG. 12 shows redundant operating unit groups, in each case comprising a dedicated AC feed line.

DESCRIPTION OF THE INVENTION

(14) FIG. 1 shows a schematic illustration of a rail vehicle 2, which has at least one driven car 4 and a plurality of non-driven cars 6, of which, for reasons of clarity, only driven cars 4 and one non-driven car 6 are illustrated. The rail vehicle 2 contains, in the driven car 4, a power supply device 8 for supplying the operating voltage required for operation to the drive motors 10 and the units of the rail vehicle 2.

(15) The power supply device 8 comprises two input power converters 12, which are in the form of controlled converters and are connected to an overhead line of a railroad system via a current collector 14 and possibly a transformer and generate a DC DC-link voltage in a DC link 16 from the system voltage of the overhead line, possibly via a plurality of stages. In general, the DC link 16 does not need to be a voltage DC link, however.

(16) A plurality of motor converters 18, which are in the form of pulse-controlled inverters in the exemplary embodiment here, are electrically connected to the DC link 16. The motor converters 18 convert the DC DC-link voltage into the three-phase AC voltage for the drive motors 10, wherein each of the motor converters 18 supplies in each case one drive motor 10. It is also possible for a motor converter 18 to supply the required operating voltage to a plurality of drive motors 10. The supply of operating voltage to the drive motors 10 is controlled by a control unit 20, which controls the operation of the power supply device 8 and the drive motors 10.

(17) A more detailed illustration of a detail of the power supply device 8 is illustrated in FIG. 2. The power supply device 8 is denoted in FIG. 2 by the reference symbol 8a. In the figures, components parts which are identical per se but have slight differences, for example in terms of dimensions, position and/or function, are denoted by the same reference numeral and different reference letters. If the reference numeral alone is mentioned without a reference letter, reference is being made to the corresponding component parts of all of the exemplary embodiments. The DC link 16 is split into two segments 16a and 16b, which are disconnected from one another and to which energy is supplied in each case by an energy power converter 12. The two segments 16a and 16b of the DC link 16 are operated independently of one another as two independent and separate DC links. Some of the motor converters 18 are connected to each of the segments 16a, 16b, with the result that some operating energy is supplied to some of the drive motors 10 of the driven car 4 from one segment 16a and to the other of the drive motors 10 from the other segment 16b. In addition, an energy supply unit 22a is connected to each of the segments 16a, 16b, via which energy supply unit operating energy is supplied to an AC train busbar 24 with electrical energy for operating units of a braking system 26 of the driven car 4, in particular the electrodynamic brakes. FIG. 2 shows only two units 58a and 58c that are representative for the operating units in a braking system 26, wherein the two units can be assigned together to a braking system 26 or each unit can be assigned individually to a braking system 26.

(18) Operating energy is supplied twofold, i.e. with redundancy, to the AC train busbar 24 via the two energy supply units 22a. The energy supply units 22a each comprise a DC/DC converter, an inverter and a filter. Alternatively, it would be possible for the energy supply unit 22, parallel to the AC train busbar 24, to supply power to the braking system 26, with the result that said braking system is likewise supplied with redundancy by the two energy supply units 22.

(19) If, during operation of the rail vehicle 2, an energy supply unit 22a fails owing to a defect, the AC train busbar 24 is reliably supplied via the other of the two energy supply units 22a. The same applies to the failure of an input power converter 12, owing to which, in the event of a defect, the entire connected segment 16a, 16b is deenergized, and the other of the two segments 16b, 16a in this case remains in operation, however, and can supply sufficient operating energy to the AC train busbar 24 via the remaining energy supply units 22a.

(20) The two energy supply units 22a are designed in terms of their power such that they can jointly provide sufficient energy for operation of all of the operating units. In the event of a failure of an input power converter 12 or an energy supply unit 22a, less power is available in the AC train busbar 24, for example only half the otherwise available power, if the two energy supply units 22a have the same power. As a result, restricted operation of the operating units of the braking system 26 on the AC train busbar 24 may arise. However, it is always ensured that those operating units 26 which are required for the electrodynamic brake have a sufficient supply.

(21) A further example of a power supply device 8b is shown schematically in FIG. 3. The descriptions of the following exemplary embodiments are generally substantially restricted to the differences from the preceding exemplary embodiments in the preceding figures, to which reference is made as regards the features and functions which remain the same. Component parts which remain substantially the same are in principle numbered using the same reference symbols and features which have not been mentioned are incorporated in the following exemplary embodiments without being described again.

(22) In contrast to the exemplary embodiment from FIG. 2, the two segments 16c, 16d of the DC link 16 are connected to one another via a switching means 28, by means of which a plurality of operating modes of the power supply device 8b can be connected. The switching means 28 comprises, for this purpose, in each case one switch on both DC phases of both input power converters 12, with the result that four switching states which are essential to operation are switchable.

(23) If the left-hand input power converter 12 is disconnected from the right-hand energy supply unit 22c, i.e. in each case the upper switch in FIG. 3 of a phase of the switching means 28 is opened and the other one is closed, the two segments 16c, 16d are disconnected from one another, with the result that the state shown in FIG. 2 is produced.

(24) If all of the switches are open, in addition to the disconnection of the segments 16c, 16d, the energy supply unit 22c is also disconnected from the two input power converters 12 and therefore out of operation.

(25) If all of the switches are closed, on the other hand, the two segments 16c, 16d are connected to one another, with the result that all of the motor converters 18 and both energy supply units 22b, 22c are supplied jointly by both input power converters 12.

(26) If the upper switch is closed and the lower switch of each of the two phases is open, the left-hand input power converter 12 not only supplies the segment 16a of the DC link 16, but also the energy supply unit 22c. The remainder of the right-hand segment 16d of the DC link 16 is disconnected from the left-hand input power converter 12 and the segment 16c and is supplied by the right-hand input power converter 12.

(27) The two energy supply units 22b, 22c can be designed to have different powers, wherein the power of the energy supply unit 22b on its own is sufficient to supply the AC train busbar 24 and all of the operating units of the braking system 26 connected thereto in any conventional operating situation. During conventional operation of the rail vehicle 2, therefore, the switching means 28 is open, with the result that all of the switches of the switching means 28 are open. In this operating state, the left-hand input power converter 12 supplies the left-hand DC-link segment 16c, and the right-hand input power converter 12 supplies only the two motor converters 18 on the right-hand side, or the right-hand DC link 16d with the drive motors 10 connected thereto. The right-hand energy supply unit 22c is out of operation. Operating energy is therefore only supplied to the AC voltage train busbar 24 by the more powerful energy supply unit 22b.

(28) If the more powerful energy supply unit 22b fails owing to a defect, the control unit 20 switches the switching means 28 in such a way that the energy supply to the AC train busbar 24 takes place exclusively via the less powerful energy supply unit 22c. This can take place by virtue of the fact that all of the switches are closed and the two DC-link segments 16c, 16d are interconnected. It is likewise possible to close the upper switch and to keep the lower switch open, with the result that the less powerful energy supply unit 22c is also supplied by the left-hand input power converter 12. It is likewise possible for the upper switch to be kept open and for the lower switch to be closed, with the result that the energy supply unit 22c is supplied by the right-hand input power converter 12.

(29) If one of the two input power converters 12 fails, the less powerful energy supply unit 22c can optionally be supplied by the remaining input power converter 12 by virtue of the upper switch being closed and the lower switch being open and the left-hand input power converter 12 supplying the energy supply unit 22c or the upper switch being open and the lower switch being closed, with the result that the right-hand input power converter 12 supplies the energy supply unit 22c. This is particularly advantageous if one of the input power converters 12 and the more powerful energy supply unit 22b fail.

(30) This ensures that operating energy is even reliably supplied to the AC train busbar 24 when at least one input power converter 12 and one energy supply unit 22b, 22c are intact. If the AC train busbar 24 is only supplied by the less powerful energy supply unit 22c, there is possibly insufficient energy for all of the operating units connected to this busbar. However, enough power is present to supply sufficient energy to the operating units of the braking system 26 which are required for electrodynamic emergency braking.

(31) A further exemplary embodiment of a power supply device 8c is illustrated in FIG. 4. In contrast to the previous exemplary embodiments, energy is supplied to one of the energy supply units 22c via a DC source 30a in the form of a battery. This exemplary embodiment has the advantage that operating energy for at least the operating units of the braking system 26 which are required for the electrodynamic braking is supplied to the AC train busbar 24 even when the entire DC link 16 is deenergized, for example because no energy can be called up from the railroad system or both input power converters 12 are defective. The DC source 30a is free of the DC link, i.e. can be used independently of a DC link 16. Instead of the battery, it is also possible for a DC train busbar to be used as DC source 30a. This DC train busbar would need to be operated in the event of failure of the DC link 16 with at least one DC store in another car or attached to a busbar of another driven car.

(32) FIG. 5 shows the rail vehicle 2 comprising two driven cars 4 and a plurality of non-driven cars 6. The rail vehicle 2 has a DC train busbar 32, which extends through the entire rail vehicle 2, i.e. all of the cars 4, 6. Direct current is supplied to the DC train busbar 32, which is passed through the train and is also illustrated in FIG. 1, at the front end of the train and at the rear end of the train by two energy supply units 34a, said DC train busbar supplying operating current to operating units (not illustrated) of the non-driven cars 6. The energy supply units 34a, which are each part of a power supply device 8d, each comprise two controlled converters 36, which each feed energy into the DC train busbar 32 with redundancies. The power of the controlled converters 36 is rated such that operating energy can be supplied to all of the operating units of the non-driven cars 6 if the DC train busbar 32 is supplied by at least two controlled converters 36. In particular, the power of the controlled converters 36 is sufficient to be able to supply the operating units of the non-driven cars 6 which are required for emergency braking even only by means of one controlled converter 36.

(33) In the case of a single train separation, the DC train busbar 32 is ripped into two parts, but these two parts are fed from an energy supply unit 34a in any possible variation of the single train separation. In this way, the braking units of the non-driven cars 6 always remain fully functional even in the case of a single train separation.

(34) For the case where the controlled converters 36 do not receive energy on the input side, for example owing to a technical defect in the rail vehicle 2, all of the energy supply units 34a are equipped with at least two DC stores 30a, by means of which sufficient operating energy can be supplied at least to the braking units of the non-driven cars 6. In this case, each controlled converter 36 is connected to a DC store 30a, with the result that each of the energy supply units 34a has two segments, each having a controlled converter 36 and a DC store 30a.

(35) In the exemplary embodiment shown in FIG. 6, each non-driven car 6 of the rail vehicle 2 is provided with an energy supply unit 34b, wherein the power thereof should be rated such that said energy supply units can in pairs, in particular even on their own, can supply all of the operating units of the respective car 4, 6 which are connected to the DC train busbar 32. A surplus power is advantageous, with the result that operating energy can be supplied to the DC train busbar 32 with multiple redundancy by a plurality of energy supply units 34b.

(36) Owing to the fact that each non-driven car 6 is equipped with an energy supply unit 34b, this energy supply to the operating units is in any case ensured even in the case of a multiple train separation, irrespective of the location or locations of the train separation. In order to have operating energy available for braking units even in the event of a system failure or a DC-link failure, each energy supply unit 34b is equipped with two DC stores 30a, similar to in FIG. 5, which either on their own or jointly make available sufficient power for the units required for the braking.

(37) The controlled converters 36 from the two exemplary embodiments in FIGS. 5 and 6 can be connected on the input side to the AC train busbar 24 of the power supply device 8. It is likewise possible for the DC train busbar 32 to be fed directly from the DC link 16 and for a corresponding power converter to be connected between the DC link 16 and the DC train busbar 32. Said corresponding power converter would then expediently be a buck converter.

(38) The power supply devices 8a, 8b and 8c can each readily be combined with the power supply device 8d or 8e, with the result that a power supply device 8 comprising energy supply units 22 and energy supply units 34 is provided.

(39) A further exemplary embodiment is illustrated schematically in FIG. 7. In contrast to the previous exemplary embodiments, the power supply device 8f has an AC line system 38, which is connected to the operating units 58a-d of the braking system 26 and can have one or more AC lines 38a, 38b. The line system 38 shown in FIG. 7, comprises two AC lines 38a, 38b in a parallel circuit, which each connect one of the two energy supply units 22a to the operating units 58a-d of the braking system 26.

(40) A switching means 42 is provided in each of the two AC lines 38a, 38b. An AC branch line 60 branches off from the AC train busbar 24, which passes through the entire train. Said AC branch line is coupled to the AC line system 38 via a switching means 54. The two energy supply units 22a are connected to the AC train busbar 24 in each case in individually connectable and disconnectable fashion via a switching means 40. The connection of the AC line system 38 to the energy supply units 22a remains uninfluenced by the switching means 40 owing to the structural arrangement. Each individual one of the operating units 58a-d of the braking system 26 has a single AC feed line 44a-d, which is connected via a switching means 56 to the AC line system 38. The operating units 58a-d of the braking system 26 have redundancy, and there are therefore two coolant pumps 58a and 58b and two fans 58c and 58d.

(41) If one of the energy supply units 22a fails owing to a defect, the control unit 20 disconnects the relevant energy supply unit 22a from the operating units 58a-d of the braking system 26. This takes place via the actuation of the switching means 42 in the AC lines 38a and 38b. In this case, the AC line 38a or 38b coupled to the defective energy supply unit 22a is disconnected from the operating units 58a-d. The AC line 38a or 38b of the intact energy supply unit 22a is or remains in this case connected to the operating units 58a-d by the switching means 42. This ensures that the energy supply to the braking system 26 is maintained in the event of failure of one of the two energy supply units 22a. For this purpose, the rated power of the energy supply units 22a illustrated in FIG. 7 is identical to in each case a/2 kVA, i.e. half the main rated power of a kVA, and is rated such that the sufficient operating energy can be supplied to the braking system 26 by only one single energy supply unit 22a, even during normal operation.

(42) If both energy supply units 22a fail, it may be that current is available at least for emergency operation of another railcar via the AC train busbar 24, which passes through the entire train. In order to make use of this, the switching means 54 is closed and the switching means 40 and 42 are opened. By actuating the switching means 40 and 42, the energy supply units 22a are disconnected from the AC train busbar 24 and the AC line 38. By actuation of the switching means 54, a connection is produced between the AC train busbar 24 via the AC branch line 60 and the AC line 38.

(43) A functionally identical arrangement which is alternative in design terms can provide two additional switching means instead of the AC branch line 60 and the switching means 54. These two additional switching means can in each case be arranged between the relevant energy supply unit 22a and the connection of the AC lines 38a and 38b to a connecting line from the relevant energy supply unit 22a to the train busbar 24. If both energy supply units 22a fail, the additional switching means are opened and the switching means 40 is closed, with the result that the feed to the operating units 58a-d of the braking system 26 can take place from the AC train busbar 24 via one or both AC lines 38a and/or 38b.

(44) A defective operating unit 58a-d is disconnected from the AC line 38 by the switching means 56. This prevents the rated potential of the AC train busbar 24 or the AC line 38 being drawn to a much lower potential which is insufficient for supplying the braking system 26.

(45) FIG. 8 shows a further exemplary embodiment of a power supply device 8g. As a variation from the embodiment illustrated in FIG. 7, the power supply device 8g has a further energy supply unit 22d. The energy supply unit 22d is provided in addition to the two energy supply units 22a and is connected to the operating units 58a-d of the braking system 26 via a further AC line 46. Furthermore, a switching means 48 for connecting and disconnecting the connection between the energy supply unit 22d and the operating units 58a-d of the braking system 26 is arranged on the AC line 46.

(46) As in the preceding exemplary embodiments, previously described features are incorporated here as well. Thus, for example, the arrangement of the energy supply units 22a, the AC train busbar 24, the AC lines 38 and the AC branch line 60 is configured in terms of its effect on the supply to the operating units 58a-d of the braking system 26 similarly to the variant embodiment illustrated in FIG. 7. The same applies to the switching means 40, 42 and 54.

(47) Two DC-link segments 16g and 16h are arranged between the input power converters 12 and the energy supply units 22a. The two input phases of the inverter of the energy supply unit 22d are connected to the DC phases of the input power converters 12 via a switching means 28, as a result of which a plurality of operating modes of the power supply device 8g can be selected. The switching means 28 has in each case one switch on each of the two DC phases of the two input power converters 12, with the result that four switching states which are essential to operation can be connected:

(48) If all of the switches of the switching means 28 are closed, the feed to the energy supply unit 22d takes place jointly by both input power converters 12.

(49) If, on the other hand, all of the switches of the switching means 28 are open, the energy supply unit 22d is disconnected from the two input power converters 12 and is out of operation.

(50) If the two upper switches of the switching means 28 are closed and the lower switches are open, the left-hand input power converter 12 feeds the energy supply unit 22d in addition to the segment 16g of the DC link 16.

(51) If the two lower switches of the switching means 28 are closed and the upper switches are open, the right-hand input power converter 12 feeds the energy supply unit 22d in addition to the segment 16h of the DC link 16.

(52) If defects occur in one of the two input power converters 12, the control unit 20 switches the switches of the switching means 28 in such a way that the inputs of the energy supply unit 22d are connected to the positive and negative terminals of the intact input power converter 12 and are disconnected from those of the defective input power converter 12.

(53) If both of the input power converters 12 fail as a result of defects or systematic software faults, all of the energy supply units 22a and 22d are out of operation and the control unit 20 opens the switching means 40, 42, 48 and closes the switching means 54. This ensures that operating energy is supplied to the operating units 58a-d by the AC train busbar 24. The AC train busbar 24 passes through the entire train and is therefore also intended to maintain the energy supply to the operating units 58a-d of the braking system 26 in the event of a defect in the energy supply units 22a and 22d and/or the input power converters 12.

(54) A failure of the AC train busbar 24 can occur in particular in the undesired case of a single or double train separation. The safe energy supply to the operating units 58a-d of the braking system 26 which is required for electrodynamic emergency braking is also ensured in the case of simultaneous failure of the energy supply devices 22a and the AC train busbar 24. This applies if at least one input power converter 12 and the power supply device 22 are in a functional state.

(55) For this purpose, the rated power of the energy supply units 22a illustrated in FIG. 8 is identical to in each case a/2 kVA and is rated such that sufficient operating energy can be supplied to the operating units 58a-d of the braking system 26 by only one single energy supply unit 22a, even during normal operation. The rated power of the energy supply unit 22d can, owing to the structurally provided redundancy of the power supply, can be designed purely for the energy requirement of the operating units 58a-d of the braking system 26 during emergency operation and can thus have a much lower rating, for example a/10 kVA.

(56) A further exemplary embodiment of a power supply device 8h is illustrated schematically in FIG. 9.

(57) The arrangement of the energy supply unit 22a, the AC train busbar 24, the AC lines 38 and the AC branch line 60 is configured similarly to the variant embodiment illustrated in FIG. 7 in terms of its effect on the supply to the braking system 26. The same applies to the switching means 40, 42 and 54.

(58) In addition, a DC source 30a for feeding a further energy supply unit 22c is arranged. The energy supply unit 22c is connected to the operating units 58a-d of the braking system 26, connectably and disconnectably via an AC line 46 and a switching means 48.

(59) The DC source 30a can be used free of a DC link, i.e. at least temporarily independently of the segments 16a and 16b of the DC link 16 which are fed from the input power converters 12. The DC source 30a can be in the form of a battery, for example. In an alternative embodiment, the DC source 30a can be connected to the DC train busbar 32, for example for the purpose of electrical charging or recharging of said DC source.

(60) The exemplary embodiment illustrated in FIG. 9 has the advantage that safe energy supply to the operating units 58a-d is ensured even in the event of a defect in the two input power converters 12 and in the case of simultaneous failure of the AC train busbar 24. The control unit 20, in such a fault case, switches the switching means in such a way that the switching means 48 are closed, the switching means 40, 42 and 52 are open. Operating energy is then supplied to the braking system by the energy supply unit 22c alone. The rated power of the energy supply unit 22c can in this case be selected such that it is sufficient, in the event of a fault, for supplying the braking system 26 and is restricted, for example, to a/10 kVA. The rated power of the energy supply units 22a can be, for example, a/2 kVA, with the result that safe supply to the AC train busbar 24 is ensured.

(61) FIG. 10 shows a further exemplary embodiment of a power supply device 8i comprising three redundant energy supply units 22a and 22d. In this case, the energy supply unit 22a is connected to an input power converter 12, which also feeds a DC link 16i, and is designed for supplying the AC train busbar 24. A switching means 40 is arranged for disconnecting and connecting the power supply unit 22a from or to the AC train busbar 24. A further input power converter 12 is connected to a DC link 16j.

(62) The two further energy supply units 22d are coupled to the operating units 58a-58d of the braking system 26 in order to supply operating energy to said operating units via AC lines 46a and 46b. In this case, each of the energy supply units 22d is connected to a single one of the AC lines 46a and 46b. Each of the AC lines 46a and 46b is also only connected to a single one of the energy supply units 22d. Furthermore, a switching means 48 for connecting and disconnecting the coupling between the energy supply units 22d and the operating units 58a-d of the braking system 26 is arranged on each of the AC lines 46a and 46b.

(63) The two energy supply units 22d are connected to the two input power converters 12 disconnectably and connectably via a switching means 50. In this case, the physical arrangement is such that in each case one of the energy supply units 22d is fed by a single one of the input power converters 12. Each of the input power converters 12 also only feeds a single one of the energy supply units 22d.

(64) By virtue of this type of connection between the input power converters 12 and the energy supply units 22d, three switching states which are essential to operation of the switching means 50 result:

(65) If the two upper switches of the switching means 50 are closed and the lower switches are open, the left-hand input power converter 12 feeds the energy supply unit 22d in addition to the segment 16i of the DC link 16.

(66) If the two lower switches of the switching means 50 are closed and the upper switches are open, the right-hand input power converter 12 feeds the energy supply unit 22d in addition to the segment 16j of the DC link 16. If all of the switches of the switching means 50 are closed, the feed to the two energy supply units 22d is performed jointly by both input power converters 12.

(67) If defects occur in one of the two input power converters 12, the control unit 20 switches the switches of the switching means 50 in such a way that the inputs of the energy supply units 22d are connected to the positive and negative terminals of the intact input power converter 12 and are disconnected from those of the defective input power converter 12. For this purpose, the rated powers of the two energy supply units 22d are each rated for sufficient supply to the operating units 58a-d of the braking system 26 during normal operation and are provided with in each case a/4 kVA, for example. The rated power of the energy supply unit 22a can be, for example, a kVA, with the result that safe supply to the AC train busbar 24 is ensured.

(68) In order to increase the safety of the power supply further still, in an alternative embodiment each of the energy supply units 22d can be connected to each of the input power converters 12.

(69) An illustration of an alternative, redundant power supply of the operating units 58a-d which can also be used in the power supply devices 8 shown in FIGS. 7 to 10 is illustrated in FIG. 11.

(70) Each individual one of the operating units 58a-d is connected to the AC lines 46a and 46b via in each case two AC feed lines 44 and 52. In this case, each of the AC feed lines 44 is connected to one and only one of the AC lines 46a or 46b. Each of the AC feed lines 52 is also connected to one and only one of the AC lines 46a or 46b. Furthermore, the AC feed lines 44 and 52 are connected to in each case one other AC line 46a or 46b.

(71) The independence, freedom from feedback, and redundancy obtained thereby increases the availability of the energy supply in comparison with the connection of the operating units 58a-d via in each case one single AC feed line, which is connected to each of the AC lines, detailed in FIGS. 7 to 10.

(72) Alternatively, the invention can also be developed in that more than the two AC feed lines 44 and 52 are provided per operating unit 58 and more than the two AC lines 46a and 46b are provided for the connection.

(73) FIG. 12 shows a further variant embodiment of the power supply device 8. In this exemplary embodiment, the operating units 58a-d of the braking system 26 are split into two unit groups, i.e. subsets from the totality of all of the operating units 58. Each of the two subsets with the elements 58a and 58d or 58b and 58c is connected to one and only one of the AC lines 46a or 46b. Each of the AC lines 46a and 46b is also only connected to a single one of the unit groups. By virtue of this type of connection, despite the restriction placed on a single AC feed line 44a-d per operating unit 58a-d, there is increased availability of the energy supply. If one of the AC lines 46a or 46b fails owing to a defect, the energy supply to the operating units 58a-d of the braking system 26 can be maintained by the other AC line.