ENERGY CONVERSION DEVICE FOR AN ELECTRICALLY DRIVEN VEHICLE

Abstract

An energy conversion device for a vehicle is particularly suited for a rail vehicle. The energy conversion device has, in at least one mode, a unit which operates as a generator unit and has at least one synchronous machine, and which has at least one energy discharge unit which is provided for discharging at least a portion of an electrical energy generated by the generator unit, and has at least one resistor unit. The novel energy discharge unit has at least one control unit which is provided to set operating modes from a set of operating modes in which the resistor unit makes available a different resistance value in each case.

Claims

1-15. (canceled)

16. An energy conversion device for a vehicle, the energy conversion device comprising: a unit, operable in at least one mode as a generator unit for generating electrical energy and having at least one synchronous machine; at least one energy diverting unit for diverting at least some of the electrical energy generated by said generator unit; and at least one resistor unit; said energy diverting unit having at least one control unit configured for selecting operating modes from a plurality of operating modes, in each of which said at least one resistor unit provides a different resistance value.

17. The energy conversion device according to claim 16, which comprises a detecting unit for detecting at least one kinematic parameter of the vehicle, and wherein said control unit is configured for selecting operating modes from the plurality of operating modes in dependence on the kinematic parameter detected by said detecting unit.

18. The energy conversion device according to claim 17, wherein the kinematic parameter represents a velocity of the vehicle.

19. The energy conversion device according to claim 18, wherein said control unit is configured for switching over from a first operating mode to a second operating mode, in an event of a transition from a high-speed range to a medium-speed range, for reducing the resistance value.

20. The energy conversion device according to claim 16, which comprises a power supply unit containing said resistor unit and configured to, in a drive mode, supply electrical power to said unit having said at least one synchronous machine.

21. The energy conversion device according to claim 16, which comprises at least one current converter unit connected to provide power between said generator unit and said resistor unit, wherein said resistor unit is connected up to a DC link to be fed from said at least one current converter unit.

22. The energy conversion device according to claim 21, which comprises a control device for controlling said at least one current converter unit such that operation thereof in the operating modes includes a blocking of switching valves of said current converter unit.

23. The energy conversion device according to claim 16, wherein said resistor unit comprises a set of resistance devices and at least one switching device in operative connection with at least one of said resistance devices, and wherein a switchover between the operating modes includes at least one actuation of said switching device.

24. The energy conversion device according to claim 23, wherein said control unit is configured, using said switching device when selecting an operating mode from the plurality of operating modes, to selectively activate or deactivate a parallel circuit of resistance devices of said set.

25. The energy conversion device according to claim 23, wherein said control unit is configured for activating a first and a second resistance device alternately, in at least one operating mode of the plurality of operating modes, by using said switching device.

26. The energy conversion device according to claim 16, configured for incorporation in a rail vehicle.

27. A vehicle, comprising: at least one synchronous machine for driving the vehicle in a traction mode and being operable as a generator unit for generating electrical energy in a braking mode; an energy diverting unit for diverting at least some of the electrical energy generated by said synchronous machine in the braking mode, said energy diverting unit including: at least one resistor unit; and a control unit configured for selecting operating modes from a plurality of operating modes, in each of which said at least one resistor unit provides a different resistance value.

28. The vehicle according to claim 27, being a rail vehicle.

29. The vehicle according to claim 27, being a rail vehicle configured for high-speed operation over at least 300 km/h.

30. The vehicle according to claim 27, being a rail vehicle configured for high-speed operation over 350 km/h.

31. A method of converting electrical energy, the method comprising: generating electrical energy in at least one operating mode of a unit that has at least one synchronous machine and operates as a generator unit; diverting at least some of the electrical energy thus generated via an energy diverting unit, wherein the energy diverting unit has at least one resistor unit; switching over, with a control unit of the energy diverting unit, from a first operating mode, in which the resistor unit provides a first resistance value, to a second operating mode, in which the resistor unit provides a second resistance value different from the first resistance value.

32. The method according to claim 31, which comprises carrying out the method steps in a vehicle.

33. The method according to claim 32, which comprises carrying out the method steps in a rail vehicle.

34. The method according to claim 32, which comprises, in an event of a transition from a high-speed range to a medium-speed range of the vehicle, selecting the second resistance value to be smaller than the first resistance value.

Description

[0036] An exemplary embodiment of the invention will be explained. In the figures:

[0037] FIG. 1 shows a rail vehicle having multiple units in a side view,

[0038] FIG. 2 shows a drive unit of a multiple unit, having a power supply unit,

[0039] FIG. 3 shows the diversion of energy generated on braking to a resistor unit of the power supply unit,

[0040] FIG. 4 shows the braking moment that is generated by the drive unit during energy diversion for a drive axle, as a function of velocity, and

[0041] FIG. 5 shows the braking performance generated during energy diversion for a drive axle.

[0042] FIG. 1 shows an exemplary rail vehicle 10 in a schematic side view. It takes the form of a trainset of cars 12, each of which is equipped for the transport of passengers. For this purpose, the cars 12 have at least one passenger compartment, which is provided for accommodating passengers. At least one of the cars 12 takes the form of a multiple unit that is supported on at least one drive axle 16 that may be driven by a drive unit 14 (see FIG. 2). In the configuration shown here, the rail vehicle 10 has at least four multiple units that are each supported on at least two, in particular four, drive axles 16. The multiple units are supported on the drive axles 16 by two motor bogies 18, wherein in each case two drive axles 16 are mounted on each motor bogie 18. Associated with the drive axles 16 of a motor bogie 18 in each case is a drive unit 14, illustrated in more detail in FIG. 2. This has two permanently excited synchronous machines as the traction motors 20, each of which is connected to a different drive axle 16 for driving. For the purpose of supplying the traction motors 16 of a motor bogie 18 with electrical power, the respective drive unit 14 has a power supply unit 22. This is illustrated in more detail in FIG. 2.

[0043] The rail vehicle 10 takes the form of an electrical vehicle that draws its operating energy from an external power supply 24. For this purpose, it is known to have a current collector 25, which picks up the high voltage provided by the power supply 24. This high voltage may be an alternating voltage and have typical voltage values 15 kV 16 Hz or 25 kV 50 Hz. As an alternative, the high voltage may be a DC voltage and have in particular typical values 1.5 kV or 3 kV. The rail vehicle 10 is in particular provided for operation with an alternating voltage, although it may be suitable for both operation with an alternating voltage and also operation with a DC voltage.

[0044] In an alternating voltage operation, the high voltage provided by the power supply 24 is stepped down by a transformer unit 26. As can be seen in FIG. 2, this may take the form of a classic transformer or a current converter unitin particular a so-called direct converter. The output from the transformer unit 26 shown in FIG. 2 is connected to provide power to the power supply units 22.

[0045] The rail vehicle 10 moreover has a braking device, not shown in more detail, that includes electrically and pneumatically controllable friction brakes.

[0046] FIG. 2 shows a circuit topology of one of the drive units 14. As described above, it has the traction motors 20 of the corresponding motor bogie 18 and the power supply unit 22 associated therewith. The power input to the power supply unit 22 is fed, in an alternating voltage operation, with the output signal from the transformer unit 26. The power supply unit 22 has a first current converter unit 28 on the input side, and this rectifies this output signalin the case of an energy flow carried from the transformer unit 22 toward the traction motors 20, in particular in a traction mode. In the traction mode, the first current converter unit 28 accordingly performs the function of a rectifier. The first current converter unit 28 is in particular formed by an H bridge.

[0047] The power supply unit 22 moreover includes a DC link 30 that, during operation, carries a DC voltage signal. In the traction mode, the DC link 30 is fed with the signal that was rectified by the first current converter unit 28.

[0048] Further, the power supply unit 22 has two current converter units 32.1, 32.2 that are arranged on the motor side and are each associated with one of the traction motors 20. In the traction mode, the current converter units 32.1, 32.2 each perform the function of an inverter, which generates an alternating current from a direct current carried in the DC link 30. In particular, they each take the form of a pulsed-control inverter.

[0049] In a DC voltage mode, the DC voltage signal from the power supply may be fed directly to the DC link 30 or may be transformed using the current converter unit 28, which operates as a voltage reduction unit.

[0050] In the traction mode of the rail vehicle 10, as described above, electrical energy flows from the power supply 24 through the transformer unit 26 and the power supply unit 22that is to say in particular the first current converter unit 28and the DC link 30 and the current converter units 32 to the traction motors 20, which convert some of the electrical energy concerned into kinetic energy.

[0051] In a braking mode of the rail vehicle 10, there is an energy flow in the reverse direction, from the traction motors 20 at least partly through the power supply unit 22 and the transformer unit 26 to the power supply 24. In this braking mode, the traction motors 20 form a generator unit 34 of an energy conversion device 36 that converts the kinetic and where applicable potential energy of the rail vehicle 10 into another form of energy. The generator unit 34 generates electrical energy from this energy in known manner.

[0052] In certain application situations, in which the feeding of energy to the power supply 24 is to be restricted or is not even possible, or in which this feeding is not sufficient to generate a setpoint braking momentas in particular in the case of emergency braking at high speedthe electrical energy generated by the generator unit 34 is diverted away from being fed back to the power supply 24. For this purpose, the energy conversion device 36 has an energy diverting unit 38.

[0053] The energy diverting unit 38 has a resistor unit 40 that is provided for the purpose of establishing a certain resistance value in the flow of electrical energy to be diverted. It has two resistance arrangements R1, R2 that each take the form of an ohmic resistor. Because the resistor unit 40 is utilized in the braking mode of the rail vehicle 10, the resistor unit 40 corresponds to a braking resistor unit. The resistor unit 40 is connected to the current converter units 32.1, 32.3 such that energy generated by the traction motors 20 and carried by them may be fed to the resistance arrangements R1, R2. This is illustrated in the figure by heavy arrows. In the braking mode, the current converter units 32.1, 32.2 are accordingly arranged in the energy flow between the traction motors 20and hence the generator unit 34and the resistor unit 40. In other words, the current converter units 32.1, 32.2 are each connected to the generator unit 38 on one side and the resistor unit 40 on the other for the provision of power. In particular, the resistor unit 40 is connected up to the DC link 30, which is fed by the current converter units 32.1, 32.2 in the braking mode. The resistor unit 40 is connected between the positive busbar and the negative busbar of the DC link 30.

[0054] The energy diverting unit 38 moreover includes a control unit 44 that is provided for selectively setting a first operating mode in which the resistor unit 40 provides a first resistance value, or a second operating mode in which the resistor unit 40 provides a second resistance value.

[0055] For this purpose, the resistor unit 40 has a switching device 46 that may be actuated by the control unit 44 for selecting the first or the second operating mode. This switching device 46 serves to selectively disconnect or connect the first and/or the second resistance arrangement R1, R2 from or to the energy flow generated by the generator unit 34. It has two switching arrangements 48.a, 48.b that are respectively associated with a different resistance arrangement R1 or R2. In particular, the switching arrangements 48.a, 48.b may be actuated independently of one another.

[0056] In the first operating mode of the energy diverting unit 38, the first resistance value is provided in that one of the resistance arrangements R1, R2 is connected to the generator unit 34 such that power is provided. This connection is made by closing the switching arrangement 48.a or 48.b. In the second operating mode, the second resistance value is provided in that both resistance arrangements R1, R2, in particular connected to one another in parallel, are connected to the generator unit 34 such that power is provided. This is done by connecting up the resistance arrangement R2 or R1, by closing the switching arrangement 48.b or 48.a. If the resistance values of the resistance arrangements R1, R2 are identical, by connecting them in parallel it is possible to provide in the second operating mode a resistance value of the resistor unit 40 that is half the resistance value in the first operating mode.

[0057] In the operating modes described above, an alternating electrical current that is generated by a traction motor 20 is carried via the associated current converter unit 32 in a blocking mode of this current converter unit 32. In this blocking mode, the switching valvesin particular power transistors, such as IGBTsof the current converter unit 32 are permanently in a blocked condition, with the result that the electrical current is carried exclusively via freewheeling diodes that are connected in parallel with the switching valves. As illustrated in FIG. 3, the current converter unit 32 thus takes the form of a diode bridge (also called a B6 bridge) that rectifies the electrical current. FIG. 3 illustrates, in an equivalent circuit diagram, the traction motors 20 as the voltage source, having an equivalent resistance and an equivalent inductance. The switching valves are put into the blocking condition by a control device 50 that is illustrated schematically in FIG. 3.

[0058] Switching between the first operating mode and the second operating mode, that is to say in particular connecting up the second resistance arrangement R2 or R1 in parallel with the first resistance arrangement R1 or R2, is performed in dependence on a kinematic parameter K of the rail vehicle 10. In the embodiment shown here, the switching device 46 is controlled on the basis of a parameter that depends on the vehicle velocity V. This parameter K corresponds in particular to a speed of rotation of a wheelset or a component of the drive unit 14 that is coupled to the wheelset for driving. This may be the speed of rotation of a wheel, the shaft of the wheelset, or a gear component or motor shaft coupled thereto for driving. For this purpose, the rail vehicle 10 has a detection unit 52 for detecting the parameter K that has sensors for the speed of rotation (illustrated highly schematically in FIG. 2). The detection unit 52 is in operative connection with the control unit 44, which serves to evaluate detected measurement values. The parameter K may as an alternative or in addition be obtained using further sensor arrangements, such as an inertial sensor or a positioning unit such as a GPS sensor.

[0059] The switching device 46 is actuated by the control unit 44 if it is determined from the monitored parameter K that, during a braking procedure starting from an initial velocity, in particular the maximum permitted velocity, the rail vehicle 10 reaches a pre-selected velocity threshold value GSW.

[0060] This is explained in more detail with reference to FIG. 4. This corresponds to a graph in which the braking moment M for each drive axle 16 is illustrated as a function of the vehicle velocity V. When a braking procedure is initiated above the threshold value GSW=190 km/h, in particular at the maximum permitted velocity of 350 km/h, the switching valves of the current converter units 32 are put in the blocking condition as described above, wherein some of the current generated by the traction motors flows into the resistor unit 40, for example as illustrated in FIG. 3 into the first resistance arrangement R1. The braking moment M in the range between the maximum permitted velocity and the threshold value GSW has an almost constant value. The course of the braking moment M for this resistance value R=R1 in the first operating mode is shown by the curve M.sub.R1. To prevent the braking moment M from falling below this value, when the velocity threshold value GSW is reached the switching device 46 is actuated by the control unit 44. On switching over to the second operating mode, that is to say on connecting up the resistance arrangement R2, the resistor unit 40 has a resistance value R=1/(1/R1+1/R2). The course of the braking moment M for seen from the figure, the braking moment M can be maintained at the previous value during further braking, at least for a certain range of velocities from approximately 100 km/h.

[0061] FIG. 5 shows a graph in which the braking performance L is illustrated as a function of the velocity V. The curve L.sub.R1 corresponds to the course of the braking performance L for the resistance value R=R1 in the first operating mode. On the switchover to the second operating mode described above, it is possible to achieve an increase in the braking performance below the velocity threshold value GSW, following the curve L.sub.R1R2 for the resistance value R=1/(1/R1+1/R2), by comparison with the configuration in which R=R1.

[0062] Moreover, it is advantageous if in the first operating mode, in which only one of the resistance arrangements R1, R2 is active, switchovers between the resistance arrangements R1 and R2 are performed. These switchovers effected by the switching device 46 serve to lessen the thermal load on the resistance arrangements. They are performed periodically or on the basis of the determined load conditions on the resistance arrangements. These may for example be determined by detecting the temperature of the resistance arrangements.

[0063] The description above refers to an embodiment in which the plurality of operating modes comprises two operating modes. In a variant embodiment, it is conceivable for more than two operating modes to be implemented. For this purpose, the resistor unit may have more than two resistance arrangements.