Method for electrodynamically braking a rail vehicle to a standstill

Abstract

The invention relates to a method for electrodynamically braking a rail vehicle to a standstill, wherein an electric drive system of the rail vehicle comprises a DC link which is connectable to a supply grid via a grid connection, at least one inverter connected to the DC link, at least one drive motor connected to the respective inverter for driving the rail vehicle in a drive mode, a secondary battery connectable to the DC link, and a control device. According to the invention, a braking mode of the drive system is initiated, a current braking torque generated by the at least one drive motor in a generator mode is determined by the control device, the secondary battery is connected to the DC link by the control device depending on the determined current braking torque and an ability to feed the DC link from the supply grid in order to feed the DC link from the secondary battery, and feeding of the at least one drive motor from the DC link is controlled by the control device in order to increase the generated braking torque by means of the inverter.

Description

[0001] 202411851 Late registration version

[0002] 1

[0003] Description

[0004] Method for electrodynamic braking of a rail vehicle to a standstill

[0005] The invention relates to a method for electrodynamically braking a rail vehicle to a standstill, a drive system of a rail vehicle, and a rail vehicle with such a drive system.

[0006] Electric rail vehicles, especially those used in regional and long-distance transport, are increasingly subject to stringent requirements, particularly regarding maximum permissible noise levels during braking and precise positioning at stops. Both of these requirements can be met by using the vehicle's electrodynamic brakes exclusively, as this avoids potential noise from friction brakes and allows for greater accuracy in controlling the braking process compared to friction brakes.

[0007] The electrodynamic brake, with its drive motors operating as generators in the electric drive system of the rail vehicle, has the characteristic that as the motor speed or the speed of the rail vehicle decreases, the generated braking torque drops so significantly that at low speeds it is no longer sufficient to bring the rail vehicle to a standstill. This behavior is typically counteracted by inducing currents in the stator windings of the drive motors below a certain speed, for example, approximately 20 km / h, thereby increasing the braking torque to a desired level. This reversal of the current flow, or this targeted induction of currents to increase the braking torque, is achieved by means of appropriate control of power semiconductor switches in the inverters supplying the drive motors.

[0008] Pulse inverters, with the control typically based on a so-called field-oriented control system.

[0009] The electrical energy required for imprinting is taken from a DC link of the drive system, to which the inverters are connected. The DC link is supplied with electrical energy from a trackside supply network, with which the 202411851 subsequent application version

[0010] 2

[0011] The drive system can be connected via a pantograph. If the power grid is unavailable for energy return from or feed-in to the drive system—for example, because the drive system has been disconnected from the grid by opening a main switch upstream of the pantograph and, if necessary, by lowering the pantograph—the excess electrical energy generated during electrodynamic braking is converted into heat energy via a controlled brake actuator and braking resistors. A lack of grid availability for energy return from or feed-in to the drive system occurs particularly with direct current (DC) power grids, but can also occur with alternating current (AC) power grids.

[0012] Electrodynamic braking to a standstill is not currently possible in the event of such a lack of availability of the power grid, which can occur particularly at short notice, because insufficient energy is available in the DC link to reverse the current flow and induce currents in the stator windings of the drive motors to increase the braking torque. Therefore, recourse to the friction brake is unavoidable, which means that the aforementioned requirements cannot be met.

[0013] The object of the invention is therefore to enable a rail vehicle to be reliably braked electrodynamically to a standstill, even when no power grid is available. This object is achieved by the respective features of the independent claims. Further developments are specified in the dependent claims.

[0014] In the inventive method for electrodynamically braking a rail vehicle to a standstill, wherein an electric drive system of the rail vehicle comprises a DC link which can be connected to a supply network via a mains connection, at least one inverter connected to the DC link, at least one drive motor connected to the respective inverter for driving the rail vehicle in drive mode, a secondary battery connectable to the DC link, and a control unit, a braking operation of the drive system is initiated, the control unit determines a current braking torque generated by the at least one drive motor in generator mode, and the control unit, depending on the determined current braking torque and the availability of power to the DC link from the supply network, the 202411851 subsequent application version

[0015] 3

[0016] The secondary battery is connected to the DC link to supply the DC link from the secondary battery, and the control unit controls the supply of at least one drive motor from the DC link to increase the generated braking torque by means of the inverter.

[0017] The invention takes advantage of the presence of a secondary battery that can be connected to the DC link of the drive system by feeding electrical energy stored in the secondary battery into the DC link when the power supply network is unavailable. This energy can be used to generate currents that are impressed into the stator winding of at least one drive motor by the inverter to increase braking torque, particularly at low speeds, in order to brake the rail vehicle to a standstill using the electrodynamic brake.

[0018] The braking operation of the drive system is initiated, for example, by the control unit upon receiving a braking request from a higher-level control unit of the rail vehicle. This braking request is generated, for instance, by the driver operating a drive / brake lever or by an automated vehicle control system. The braking request may involve, for example, service braking with a predetermined deceleration or negative acceleration, which can be achieved using the electrodynamic brake without the additional use of the rail vehicle's friction brake.

[0019] The braking torque generated by at least one drive motor can be determined by the control unit, for example, by measuring suitable currents and voltages based on the power fed into the inverter by the drive motor or into the DC link by the inverter. Alternatively, the braking torque can be derived from, for example, the current speed or speed change of the drive motor and / or the wheelset of a bogie connected to it via a fixed gear ratio, based on a known dependence on the speed of the drive motor, particularly in the form of characteristic curves. Similarly, based on a known relationship between the speed of the drive motor and the speed of the rail vehicle, particularly in the form of characteristic curves, the braking torque can be derived from, for example, a speed determined independently of the drive system.A change in speed determines the rotational speed and thus the braking torque. 202411851 Subsequent registration version.

[0020] 4

[0021] Especially when the drive system has multiple drive motors, the braking power of the electrodynamic brake, which results from the sum of the respective braking torques of the drive motors, can also be determined from several of the parameters mentioned.

[0022] The aim of determining the generated braking torque is to identify a point in time, a rotational speed and / or a velocity from which or below which the braking torque generated by the drive motors is or will be insufficient, and in this case, or even preventively, to reverse the current or energy flow and, controlled by the control unit, to induce suitable currents in the stator windings of the drive motors in order to increase their respective braking torque and thereby enable electrodynamic braking until the rail vehicle comes to a standstill.

[0023] The dependency of connecting the secondary battery to the DC link on the DC link's availability of power from the mains supply serves to prevent the secondary battery from being connected when the electrical energy required to power the drive motor can be supplied by the mains, as explained in the introduction. This prevents unnecessary discharge of the secondary battery.

[0024] According to a further development of the inventive method, a vehicle electrical system supply is connected to the DC intermediate circuit to supply an electrical vehicle electrical system with electrical energy, the vehicle electrical system supply is connected to electrical consumers via at least one busbar, and the electrical consumers are supplied by the vehicle electrical system supply with electrical energy fed from the DC intermediate circuit.

[0025] Such an on-board power supply, in particular an auxiliary power converter, typically converts the DC link voltage into a DC voltage of, for example, 110 V, and into a three-phase AC voltage of, for example, 400 V at 50 Hz. Further three-phase AC voltages, especially with variable frequency, can also be provided by the on-board power supply. The various voltages are applied to a respective busbar, which, for example, extends continuously over the entire rail vehicle or is divided into several segments. The electrical loads connected to the DC or three-phase busbars include, in particular, auxiliary equipment such as fans, pumps, and control devices that support the function of the drive system, communication systems, and other components.

[0026] 5 and information systems as well as equipment serving passenger comfort, such as air conditioning systems for passenger compartments.

[0027] During braking, the vehicle's electrical system is supplied with electrical energy generated by at least one drive motor or stored in the secondary battery, thus ensuring the supply to the electrical consumer.

[0028] According to a further development based on the above further development, the secondary battery can be directly connected to the DC intermediate circuit, wherein the connection can be established by the control device by means of at least one controllable switch, and the secondary battery is charged with electrical energy via a battery charger, wherein the battery charger is designed as part of the vehicle electrical system or is connected to one of the busbars.

[0029] During drive and braking operation of the drive system, when it is connected to the mains supply and, if necessary, to provide feedback, the at least one controllable switch is open, preventing any current or energy flow between the DC link and the secondary battery. Only when supplying the DC link from the secondary battery is required and connecting it will not overload the secondary battery, is the at least one switch closed by the control unit, thus establishing the connection. Preferably, a switch is arranged in each potential branch of the connection, with the switches being designed as controllable contactors that can be switched under load in both current flow directions.

[0030] The battery charger, used to charge the secondary battery, can be integrated into the vehicle's electrical system or connected as a separate electrical component to a busbar, such as a three-phase busbar. Controlled by the control unit, the battery charger ensures, for example, that the secondary battery maintains a certain minimum charge level when it is not connected to the DC link.

[0031] According to a further embodiment of the inventive method based on the foregoing embodiment, the secondary battery is connected to the DC intermediate circuit via at least one diode, wherein the at least one diode is arranged in such a way as 202411851 Subsequent application version

[0032] 6 is that electrical energy can only be fed into the DC intermediate circuit from the secondary battery.

[0033] Such a diode, or several diodes connected in series, in addition to at least one switch, prevents the secondary battery from being supplied or charged from the DC intermediate circuit, which could potentially lead to an overload or damage to the secondary battery.

[0034] According to an alternative further development of the method according to the invention, the secondary battery is connected to the DC link via a bidirectional DC-DC converter, and the DC-DC converter is controlled by the control unit to charge the secondary battery from the DC link and to discharge the secondary battery into the DC link.

[0035] By means of a DC-DC converter arranged between the secondary battery and the DC link, for example designed as a two-quadrant converter, the control unit can control the charging and discharging of the secondary battery from and into the DC link by appropriately controlling power semiconductor switches of the DC converter. This makes the DC link's ability to be supplied from the secondary battery largely independent of any voltage difference between the DC link and the secondary battery.

[0036] Additionally, at least one switch controllable by the control unit can be arranged in the connection between the secondary battery and the DC-DC converter, or in the connection between the DC-DC converter and the DC link. Opening this switch completely disconnects the secondary battery from the DC link and occurs, controlled by the control unit, for example, when the secondary battery has reached a certain state of charge.

[0037] Preferably, a switch is arranged in each potential branch of the connection, wherein the switches are designed as controllable contactors which can be switched under load in both current flow directions. 202411851 Subsequent filing version

[0038] 7

[0039] According to a further development of the method according to the invention, a brake actuator is connected to the DC intermediate circuit, and the brake actuator is controlled by the control unit to divert electrical energy into at least one braking resistor and / or an instantaneous overvoltage limiter, wherein the diversion takes place depending on whether and / or to what extent the electrical energy generated by the at least one drive motor can be fed back into the supply network, and / or fed into the vehicle electrical system, and / or charged into the secondary battery.

[0040] An instantaneous overvoltage limiter, for example, is designed as an ohmic resistor with a lower power rating compared to a braking resistor, which can be used as an alternative to a braking resistor, especially when operating the rail vehicle in supply networks with a highly available regenerative capability.

[0041] In a further development of the method according to the invention, in preparation for connecting the directly connectable secondary battery to the DC intermediate circuit, the brake actuator is controlled by the control device to adapt a voltage of the DC intermediate circuit to a voltage of the secondary battery, and the secondary battery is connected to the DC intermediate circuit, in particular depending on a voltage difference between the voltage of the DC intermediate circuit and the voltage of the secondary battery.

[0042] By appropriately controlling the brake actuator to derive electrical energy from the DC link, the control device can influence the voltage of the DC link during braking operation of the drive system, for example to lower it to such an extent that the directly connectable secondary battery can be connected to the DC link to supply the DC link.

[0043] If at least one diode is additionally provided between the secondary battery and the DC link, the control unit can close at least one switch, for example, when braking is initiated. As explained above, the at least one diode prevents the secondary battery from being charged from the DC link, even if the voltage of the DC link is higher than the voltage of the secondary battery. (A 202411851 supplementary registration version)

[0044] 8

[0045] The DC link is only supplied with power from the secondary battery, or the secondary battery is discharged via at least one diode, when the voltage of the DC link is lower than the voltage of the secondary battery.

[0046] According to a further development of the inventive method, based in particular on the above further development, the brake actuator is switched off by the control unit during the supply of the DC voltage intermediate circuit from the secondary battery.

[0047] The brake actuator is inactive, in particular, when it is in a switching position in which no electrical energy is diverted from the DC link to the at least one braking resistor or instantaneous overvoltage limiter. This ensures that the electrical energy fed into the DC link from the secondary battery is used exclusively for powering consumers connected to the vehicle's electrical system and increasing the braking torque.

[0048] According to a further development of the inventive method, the ability of the DC voltage intermediate circuit to be supplied from the supply network is determined by the control device depending on information about a connection of a current collector of the network connection with the supply network, and / or a switching state of a main switch of the network connection, and / or a voltage of the supply network, and / or a current flow from the supply network into the drive system.

[0049] The information may already be present in the control unit, for example the switching state of the main switch and the state of the current collector, since these components of the network connection are controlled by the control unit itself, or it may be provided by sensors connected to the control unit, for example voltage and current sensors.

[0050] A drive system according to the invention for a rail vehicle comprises a DC link which can be connected to a supply network via a mains connection, at least one inverter connected to the DC link, at least one drive motor connected to the respective inverter for driving the rail vehicle in drive mode, a secondary battery connectable to the DC link, and a control unit, 202411851 Subsequent application version

[0051] 9 wherein the control device is designed to carry out the method according to the invention.

[0052] According to a further development of the drive system according to the invention, the mains connection comprises a transformer, wherein a primary side of the transformer can be connected to an AC supply network via a main switch and a current collector, and a rectifier connected to a secondary side of the transformer, wherein the rectifier is connected to the DC link, and / or an input filter, which can be connected to a DC supply network via a main switch and a current collector, wherein the input filter is connected to the DC link (DC link).

[0053] In addition to an input filter, the mains connection can, for example, include a DC / DC converter, which converts the voltage of the DC power supply network into a desired voltage of the DC link of the drive system.

[0054] According to a further development of the drive system according to the invention, a capacity of the secondary battery is designed to supply the drive system with electrical energy for a movement of the rail vehicle limited with respect to a drive power and a travel distance and / or to supply electrical consumers connected to an on-board network with electrical energy for a limited period of time.

[0055] The secondary battery is therefore not primarily designed as a traction battery whose stored electrical energy is sufficient to move the rail vehicle on a section of track without a power supply or on a non-electrified section at high traction power. Rather, the secondary battery is primarily intended to ensure that electrical consumers connected to the on-board electrical system, such as air conditioning units for passenger compartments and communication and information equipment, can be supplied even when the drive system is not connected to the power supply or the connected power supply is not carrying any electrical energy. However, due to the secondary battery's connectivity to the DC link, the stored electrical energy can be used additionally or alternatively for propulsion, for example, for limited movement of the rail vehicle in terms of location and speed.Such a limited movement of, for example, a few hundred meters can be used, for example, for a 202411851 subsequent registration version.

[0056] 10

[0057] Emergency driving from a potentially dangerous situation, in a vehicle depot or a car wash, may take place.

[0058] The voltage of the secondary battery is significantly lower, or at least half as low, as the voltage of the DC link during normal operation. Combined with a lower current supplying the DC link compared to the mains supply, the power available from the secondary battery for electrical loads and, if applicable, the drive system, is considerably less than that of the mains supply. The secondary battery typically comprises numerous battery cells, especially lithium-ion cells, connected in series and parallel depending on the desired voltage and capacity. The term "secondary battery" refers to a rechargeable battery or accumulator.

[0059] In addition to the aforementioned electrical components, the drive system according to the invention can comprise further electrical components, as specified above with regard to the method according to the invention. These components can, in particular, include a brake actuator with at least one braking resistor and / or an instantaneous overvoltage limiter, a DC-DC converter, at least one switch, and at least one diode. Furthermore, the DC link of the drive system can be connected to an on-board power supply, which supplies electrical consumers connected to the on-board power supply of the rail vehicle.

[0060] A rail vehicle according to the invention comprises at least one drive system according to the invention and / or at least one drive system designed to carry out the method according to the invention.

[0061] According to a further development of the rail vehicle according to the invention, it is designed as a rail vehicle for regional and / or long-distance transport and in particular for the transport of passengers.

[0062] In particular, the rail vehicle can be designed for a high-speed or maximum-speed range.

[0063] Exemplary embodiments of the invention are described below with reference to drawings. These show: 202411851 Subsequent application version

[0064] 11

[0065] FIG 1 a rail vehicle with a drive system for connection to an AC power supply network,

[0066] FIG 2 shows a drive system according to the invention with a secondary battery, and

[0067] FIG 3 the drive system according to the invention with an alternative connection of the

[0068] Secondary battery connected to the DC link,

[0069] FIG 4 shows the drive system of FIG 2 to illustrate a method for braking operation with the electrodynamic brake and feedback into the supply network,

[0070] FIG 5 shows the drive system of FIG 2 for further explanation of the method in the braking operation of FIG 4 and a supply from the mains supply,

[0071] FIG 6 shows the drive system of FIG 2 to illustrate the method according to the invention during braking operation with the electrodynamic brake in the event of an unavailable power supply network.

[0072] FIG 7 shows the drive system of FIG 2 for further explanation of the method according to the invention in the braking operation of FIG 6 and a supply from the secondary battery,

[0073] FIG 8 shows the drive system of FIG 2 with an added diode in the connection of the secondary battery with the DC link for further explanation of the method according to the invention during the braking operation of FIG 6 and a supply from the secondary battery, and

[0074] FIG 9 shows the drive system of FIG 3 to illustrate the method according to the invention during braking operation with the electrodynamic brake in the absence of a power supply network.

[0075] FIG 1 schematically shows a rail vehicle, which is exemplified as a multiple unit train (DT) for passenger transport in regional or long-distance services. A configuration of the rail vehicle as a railcar or a locomotive is also conceivable, but will not be considered in detail below.

[0076] The exemplary trainset TZ comprises several cars, of which only one end car EW and one intermediate car MW are shown. Cars EW and MW, or rather their passenger compartments (not specifically shown), are connected to each other via gangways in the area of ​​the couplings between the cars EW and MW. The car bodies WK of cars EW and MW are supported by two bogies each on rails of a track (not shown) of a railway network. The outermost bogie of the end car EW is designated as a 202411851 subsequent registration version.

[0077] 12

[0078] The powered bogie TDG is designed in which two wheelsets are driven by a separate drive motor AM, while the inner second bogie of the end car EW and the two bogies of the intermediate car are each designed as an unpowered running bogie LDG. In the area of ​​the car gangway, the car bodies WK of adjacent cars can alternatively be supported on a common bogie, also known as a Jacobs bogie. Likewise, the bogies can alternatively each comprise only one wheelset.

[0079] In addition to the two drive motors AM in the outer bogie TDG, the drive system AS of the trainset TZ comprises a transformer TF, the primary side of which can be connected via a current collector PAN, for example a pantograph, to an overhead line (not shown) of a trackside power supply network in order to supply the drive system AS with single-phase alternating current at a high voltage of, for example, 25 kV at 50 Hz or 15 kV at 16.7 Hz. The transformer TF converts the primary-side high voltage of the power supply network into a lower secondary-side voltage of a DC link ZK of the drive system AS. The secondary side of the transformer TF is connected to a rectifier 4QS, which is preferably designed as a controllable four-quadrant converter.The rectifier 4QS converts the single-phase AC voltage applied to the secondary side of the transformer TF into a DC voltage applied to a DC link capacitor of the DC link ZK. In its configuration as a four-quadrant converter, the rectifier 4QS additionally converts the DC voltage of the DC link ZK into a single-phase AC voltage for feeding back into the power supply network. In principle, the drive system AS can incorporate several rectifiers 4QS or four-quadrant converters, which are connected to the secondary side or a respective secondary winding of the transformer TF, with the rectifiers 4QS feeding a common or individual DC link ZK.

[0080] An inverter PWR is connected to the DC link ZK as an example. The inverter PWR, which is preferably designed as a pulse inverter, converts the DC voltage of the DC link ZK into a three-phase AC voltage of variable amplitude and frequency, which is applied to the stator windings of the two drive motors AM, which are designed as three-phase machines as an example. In principle, the drive system AS can again comprise several inverters PWR or pulse inverters, each of which is connected to the DC link ZK and one or more drive motors AM. The drive motors AM 202411851 Subsequent application version

[0081] 13 can be designed as asynchronous three-phase machines as well as as synchronous machines, in particular permanent magnet synchronous three-phase machines.

[0082] The listed components of the AS drive system of the TZ multiple unit are controlled by a control unit ST, for example, a drive control unit or a combined drive and brake control unit, which is communicatively connected to the components via signal lines or communication interfaces (not shown). The ST control unit is, for example, communicatively connected to a higher-level vehicle control unit (not shown) and receives setpoints for acceleration or braking from it, which the ST control unit then implements by appropriately controlling the various components of the AS drive system.

[0083] FIG 2 schematically shows the drive system AS of the multiple unit TZ of FIG 1 in a more detailed representation as well as with other associated electrical components.

[0084] The DC link ZK of the drive system AS is connected, as explained above, via a rectifier 4QS or four-quadrant converter to the secondary side or a secondary winding of a transformer TF. The primary side or a primary winding of the transformer TF can be connected, on the one hand, via a controllable main switch HS and an adjustable pantograph PAN, to an overhead line (not shown) of the trackside AC power supply network, and on the other hand, via one or more wheelsets, to track or ground potential. A single-phase AC voltage of, for example, 15 kV at 16.7 Hz or 25 kV at 50 Hz is applied to the overhead line.

[0085] The rectifier 4QS, the transformer TF, the main switch HS, and the current collector PAN are components of a network connection NA of the drive system AS, through which the DC link ZK can be connected to the supply network. In the case of a DC supply network, not shown in FIG. 2 or the other figures, the network connection of the drive system AS can, for example, have an input filter instead of the transformer TF and the rectifier 4QS, through which the DC link ZK is connected to a main switch and current collector. Alternatively or additionally, the network connection for a DC supply network can include a DC-DC converter, which converts the voltage of the supply network into a desired voltage of the DC link. Likewise, the network connection of the drive system AS can also include components for a 202411851 subsequent application version.

[0086] 14

[0087] Connection to an alternating current supply network as well as to a direct current supply network, with, for example, each supply network being assigned a specific power consumer.

[0088] By opening the main switch HS and, if necessary, additionally lowering the pantograph PAN, the control unit ST can, particularly under load, control the disconnection of the drive system ASs from the voltage potential of the supply network. Similarly, the control unit ST can, if necessary, control the connection of the drive system AS to the supply network by raising the pantograph PAN and closing the main switch HS.

[0089] The rectifier 4QS converts the single-phase AC voltage of the secondary side of the transformer TF into a DC voltage by means of suitable switching of its power semiconductor switches, controlled by the control unit ST. This DC voltage is applied to an intermediate circuit capacitor, for example, arranged in the DC intermediate circuit ZK. This voltage is subsequently referred to as the intermediate circuit voltage. The intermediate circuit capacitor can be a single capacitor or, alternatively, multiple capacitors, in particular distributed and electrically connected in parallel.

[0090] A controllable bidirectional inverter PWR is connected to the DC link ZK. In drive mode, the inverter converts the DC link voltage into a three-phase AC voltage of variable amplitude and frequency by means of appropriate switching of its power semiconductor switches, controlled by the control unit ST. This AC voltage is applied to the stator windings of the two exemplary drive motors AM to generate the desired drive torque. In braking mode of the drive system AS, or in generator mode of the drive motors AM, the inverter PWR converts the three-phase AC voltage generated by the drive motors AM into a DC voltage. This rectification is achieved, for example, by appropriate switching of the power semiconductor switches of the inverter PWR, controlled by the control unit ST, with the aim of generating a specific braking torque.

[0091] A secondary battery (BAT) is connected to the DC link or can be connected and disconnected at the two voltage potentials via switches (BATS). The switches (BATS), which are controllable by the control unit (ST), are designed as contactors by way of example. (202411851 Subsequent filing version)

[0092] 15 which can be disconnected in both current flow directions under load. This allows the secondary battery BAT to be connected to or disconnected from the DC link ZK depending on the current voltage difference between the battery voltage of the secondary battery BAT and the DC link voltage, in order to prevent overloading, particularly of the battery cells, due to excessive current flow. The secondary battery BAT comprises, for example, a multitude of battery cells, especially lithium-ion-based ones, which are electrically connected in series and parallel according to the desired battery voltage and capacity. The capacity of the secondary battery BAT, or the electrical energy that can be stored in it, is preferably dimensioned such that certain electrical consumers of the rail vehicle can be supplied for a specific period of time when no supply to the drive system AS via a power grid is possible.Due to the connection of the secondary battery (BAT) to the DC link (ZK), the stored electrical energy can also be used, in principle, as a supplement or alternative for the propulsion or movement of the rail vehicle (TZ) by means of the drive motors (AM), but only with limited power and over a limited distance. Such limited movement of the rail vehicle (TZ) without a power supply network can occur, for example, in the area of ​​a depot, a washing facility, or for an emergency run from a potentially dangerous situation.

[0093] The secondary battery BAT is charged by a battery charger LG, which, for example, is powered by a three-phase busbar of the electrical system BN of the rail vehicle TZ. Charging the secondary battery BAT from the DC link ZK is not possible due to the large voltage difference between the DC link voltage and the battery voltage during operation of the drive system.

[0094] The on-board power supply BN, which in particular powers the battery charger LG, is supplied by an on-board power supply HBU or an auxiliary power converter, which is connected to and powered by the DC link ZK. The on-board power supply HBU can also be controlled by the control unit ST and converts the DC link voltage, for example, into a three-phase AC voltage, which is applied to the three-phase busbar, and into a DC voltage, which is applied to a DC busbar. A voltage applied to the three-phase busbar is, for example, 400 V at 50 Hz. In addition to the battery charger LG, other devices connected to the rail vehicle can be powered via the three-phase busbar.

[0095] 16

[0096] The AC loads WV1-WVn, distributed throughout the rail vehicle TZ, such as auxiliary equipment for the drive system AS, air conditioning units for passenger compartments, power outlets, and facilities for passenger catering and entertainment, are supplied with electrical energy from the on-board power supply HBU. The voltage applied to the DC busbar is, for example, 110 V. DC loads GV1-GVn, also distributed throughout the rail vehicle TZ, can also be supplied via the DC busbar. One such DC load is, for example, a battery charger for charging an on-board battery. The on-board battery, which may be redundantly designed, serves to supply certain DC loads, such as control units, emergency lighting for the passenger compartments, and a communication system, when no supply from a mains supply is possible.The AS drive system is disconnected from the power supply network. If the DC busbar is powered by the on-board power supply HBU during normal operation of the drive system, additional DC loads beyond those mentioned can be supplied.

[0097] Furthermore, a brake actuator (BS), controllable by the control unit ST, is connected to the DC link ZK. This serves to dissipate excess electrical energy in the DC link ZK, in particular to prevent an overvoltage of the DC link and the resulting potential damage to electrical and electronic components. The electrical energy is dissipated via a braking resistor (BW) or a bank of several braking resistors, which is switched on and off by the brake actuator (BS) in a pulsed manner. In the braking resistor(s), the electrical energy is converted into thermal energy and released into the ambient atmosphere.Such derivation of electrical energy from the DC link ZK may be necessary, for example, if during electrodynamic braking, particularly at high to medium speeds, the energy generated by the drive motors AM in generator mode cannot be fed back into the power supply network, or not completely, and exceeds the energy required to supply the consumers connected to the vehicle electrical system BN. Furthermore, the DC link voltage can be adjusted by selectively deriving energy from the DC link ZK. For example, in preparation for connecting the secondary battery BAT to the DC link ZK, the DC link voltage can be reduced by closing the BATS switches until it is a predetermined differential voltage below the battery voltage. 202411851 Subsequent registration version.

[0098] 17

[0099] The controllable components of the drive system AS described above, as well as components connected to it, such as the battery charger LG, are each indicated in FIG. 2 and the subsequent figures by a dashed arrow pointing in the direction of the component. Correspondingly, dashed arrows emanate from the control unit ST. These arrows illustrate the transmission of control signals from the control unit ST to the various components via communication links. Such communication links exist, for example, via a wired bus of a communication network of the rail vehicle TZ, to which both the control unit ST and the components are connected, and / or via individual communication lines between the control unit ST and the respective component.

[0100] FIG 3 schematically shows an alternative embodiment of the drive system AS of the multiple unit train TZ of FIG 1 and the other electrical components associated with it.

[0101] Unlike the drive system AS of FIG. 2, the secondary battery BAT in FIG. 3 is not directly connected to the DC link ZK via the controllable switches BATS, but indirectly via a controllable DC-DC converter GSW, which is designed, for example, as a bidirectional DC / DC converter or two-quadrant converter. Depending on whether the secondary battery BAT is to be charged or discharged, the DC link voltage can be adjusted to the battery voltage by the control unit ST by appropriately controlling the power semiconductor switches of the DC-DC converter GSW. This allows a current flow from the DC link ZK towards the secondary battery BAT to charge or discharge it.The battery voltage is adjusted to the intermediate circuit voltage to generate a current flow from the secondary battery (BAT) towards the DC intermediate circuit (ZK) and to discharge the secondary battery (BAT). Adjusting one voltage to the other means that a specific voltage differential is created between the two voltages using the DC-DC converter (GSW), which results in a specific or desired current flow in one direction or the other. 202411851 Subsequent registration version.

[0102] 18

[0103] To protect the secondary battery BAT, controllable switches BATS are also provided, which enable a complete electrical isolation of the secondary battery BAT from the DC intermediate circuit ZK.

[0104] FIGS. 4 to 7 are based on the drive system AS of FIG. 2 of the rail vehicle TZ of FIG. 1. FIGS. 4 and 5 illustrate electrodynamic braking to standstill when the drive system is connected to a power supply network, while FIGS. 6 and 7 illustrate corresponding braking when the power supply network is not available for feeding and regenerating power. Using different switch positions and added block arrows for current and energy flow, the known method shown in FIGS. 4 and 5 is explained below in relation to the method according to the invention.

[0105] FIG 4 shows a state of the drive system AS in which it is in drive mode and connected via the closed main switch HS and the raised pantograph PAN to an overhead line (not shown) of a trackside AC power supply network. The rail vehicle TZ is moving at a desired speed and approaching the next stop on the section of track traversed by the rail vehicle TZ. The control unit ST receives a brake request ba from a higher-level vehicle control system (not shown), for example, initiated by a person controlling the rail vehicle TZ. Upon receiving this brake request ba, the control unit ST initiates braking of the drive system AS. The received brake request ba defines, for example, a specific deceleration to be achieved, which corresponds to a service brake.This specified deceleration or the braking torque required for it can be provided by the electrodynamic brake of the rail vehicle TZ or by the drive motors AM operated as generators.

[0106] The electrical energy generated by the drive motors AM in generator mode is fed into the inverter PWR, as indicated by the block arrow pointing towards the inverter PWR. The inverter PWR, controlled by the control unit ST via its power semiconductor switch, converts the three-phase AC voltage from the drive motors AM into a DC voltage and feeds the converted electrical energy into the DC link ZK. The supplied electrical energy powers the electrical consumers WV1-WVn, GV1-GVn connected to the on-board electrical system BN, including the battery charger LG for charging the 202411851 post-registration version.

[0107] 19

[0108] Secondary battery BAT, as indicated by the block arrows pointing towards the on-board power supply HBU and along the busbars.

[0109] Electrical energy not used to power the on-board electrical system BN or to compensate for losses in the electrical components involved, particularly the drive motors AM and the inverter PWR, is fed into the grid via the mains connection NA. This electrical energy, fed back from the rail vehicle TZ, can be used, for example, to power other rail vehicles traveling on the same section of track.

[0110] As the speed of the rail vehicle TZ decreases over time during braking, and the corresponding rotational speed of the drive motors AM decreases, the braking torque generated by them also decreases. To counteract a reduction in the generated braking torque below the level required for the specified deceleration, particularly at low speeds or low rotational speeds, the energy flow is reversed, for example, after a certain speed is reached. This reverses the operation of the drive system, feeding electrical energy from the supply network into the DC link ZK, as indicated in FIG. 5 by the block arrows pointing towards the transformer TF and the rectifier 4QS of the network connection NA.The electrical energy fed into the DC link ZK from the supply network serves to continuously supply the electrical loads WV1-WVn and GV1-GVn connected to the on-board power supply BN, as well as to induce currents in the stator windings of the drive motors AM via the inverter PWR, thereby generating the desired or required braking torque. The impressed currents are generated by the control unit ST through appropriate control of the power semiconductor switches of the inverter PWR. The currents are adjusted, for example, based on a known field-oriented control system, particularly depending on speed or rotational speed, so that the drive motors AM can generate the desired or required braking torque until the rail vehicle TZ comes to a standstill at the station.

[0111] FIG 6 shows an alternative state of the drive system AS to that of FIG 4 during electrodynamic braking of the rail vehicle TZ. According to the state of FIG 6, the pantograph PAN is raised and connected to the overhead line of the trackside AC power supply network (not shown), but the main switch HS has been closed.

[0112] However, 20 is opened by the control unit ST, so that no energy flow between the supply network and the drive system AS of the rail vehicle TZ is possible.

[0113] The drive system AS is disconnected from the power supply network by controlled opening of the main switch HS, for example, due to an insufficient capacity of the power supply network to receive back electrical energy during the braking operation of the drive system AS, initiated by the control unit ST upon receipt of the braking request ba. Such insufficient capacity may be detected as early as the initiation of the braking operation, or may already be present, leading to the opening of the main switch HS. However, the insufficient capacity may also be detected during the course of the braking operation, for example, after electrical energy generated by the electrodynamic brake has already been fed back into the power supply network, as explained above in relation to FIG. 4.

[0114] As also explained above in FIG. 4, the electrical energy generated by the drive motors AM in generator mode is fed into the inverter PWR, as indicated in FIG. 6 by the block arrow pointing towards the inverter PWR. The inverter PWR converts the energy and feeds it into the DC link ZK. The supplied electrical energy powers the electrical loads WV1-WVn, GV1-GVn connected to the vehicle electrical system BN, including the battery charger LG for charging the secondary battery BAT, as indicated by the block arrows pointing towards the vehicle electrical system HBU and along the busbars.

[0115] The electrical energy not used for powering the vehicle electrical system BN or for compensating for losses in the electrical components involved is routed via the brake actuator BS to the brake resistor BW, as indicated by the block arrow pointing towards the brake resistor BW, and converted into thermal energy there and released into the ambient atmosphere. The brake actuator BS is controlled by the control unit ST such that the desired amount of energy is derived from the DC link ZK by its appropriately timed opening and closing.

[0116] As the speed of the rail vehicle TZ decreases over time during braking, and the corresponding rotational speed of the drive motors AM decreases, so too does the braking torque generated by the [document name] (see 202411851, subsequent registration version).

[0117] 21

[0118] The generator-driven drive motors AM produced electrical energy. At a certain time or at a certain speed, this energy falls below the amount required to supply the electrical consumers WV1-WVn, GV1-GVn connected to the vehicle electrical system BN and to compensate for internal losses of the electrical components involved, in particular the drive motors AM and the inverter PWR. This, possibly aided by a continued discharge of electrical energy from the DC circuit ZK via the brake actuator BS, leads to a discharge of the DC link capacitor and a resulting drop in the DC link voltage.

[0119] When the decreasing DC link voltage approaches or falls below the battery voltage to a certain extent, the secondary battery BAT is connected to the DC link ZK by the control unit ST closing the BATS switches, as shown in FIG. 7. The electrical energy discharged from the secondary battery BAT into the DC link ZK due to the voltage difference is then used to continuously supply the on-board electrical system BN and the electrical loads WV1-WVn, GV1-GVn connected to it, as well as to induce currents in the stator windings of the drive motors AM via the inverter PWR, in order to generate the braking torque required for service braking, preferably until the rail vehicle TZ comes to a standstill. The brake actuator BS is deactivated by the control unit ST during the discharge of the secondary battery BAT.The circuit is opened so that the electrical energy fed into the DC link ZK is not diverted via the braking resistor BW. If necessary, however, the brake actuator BS can be used by the control unit ST to adjust the DC link voltage in order to control the discharge of the secondary battery BAT. The energy flow during the discharge of the secondary battery BAT is shown in FIG. 7 by block arrows pointing from the secondary battery BAT towards the DC link ZK and from the inverter PWR towards the drive motors AM.

[0120] FIG. 8 shows a variant of the drive system AS of FIG. 2 with an added diode DIO in the connection between the secondary battery BAT and the upper connecting branch of the DC link ZK. The schematically depicted diode DIO can comprise several diodes connected in series. The diode DIO is arranged such that it reliably blocks current flow from the DC link ZK to the secondary battery BAT and current flow from the secondary battery BAT to the 202411851 Subsequent Application Version

[0121] 22

[0122] The DC link ZK, i.e., the DC link ZK being supplied from the secondary battery, is permitted. In contrast to the preceding explanation regarding FIG. 8, the BATS switches can already be closed by the control unit ST when the DC link voltage is still above the battery voltage, in particular when braking operation is initiated after receiving a braking request ba. As soon as there is a sufficient voltage difference between the DC link voltage and the battery voltage, or as soon as the DC link voltage falls below the battery voltage, the DC link ZK is supplied from the secondary battery BAT via the closed BATS switches and the diode DIO, as indicated by a block arrow pointing from the secondary battery BAT towards the DC link ZK.The power supply from the secondary battery BAT compensates for a reduction in the power supply from the inverter PWR.

[0123] The method described with respect to FIGS. 6 and 7 can be applied to the drive system AS of FIG. 3, as shown in FIG. 9. The DC-DC converter GSW, arranged between the secondary battery BAT and the DC link ZK, preferably serves during braking to also use the electrical energy fed into the DC link ZK to charge the secondary battery BAT. Controlled by the control unit ST, the DC-DC converter GSW reduces the DC link voltage to a voltage level with a specific voltage difference relative to the battery voltage, thereby initiating a current flow from the DC link ZK towards the secondary battery BAT.The DC-DC converter GSW also allows the secondary battery BAT to be discharged and electrical energy to be fed into the DC link ZK even though the DC link voltage is still higher than the battery voltage. To achieve this, the DC-DC converter GSW raises the battery voltage to a level with a specific voltage difference relative to the DC link voltage, thereby initiating a current flow from the secondary battery BAT towards the DC link ZK. This allows the DC link ZK to be supplied from the secondary battery BAT to raise or stabilize the DC link voltage before it drops to a level, due to the reduced supply from the drive motors AM or the inverter PWR, that could potentially impair the power supply to the electrical loads WV1-WVn and GV1-GVn connected to the vehicle electrical system BN.In particular, the DC intermediate circuit ZK is supplied continuously, whereby an increase in the supply from the secondary battery BAT is a 202411851 subsequent registration version.

[0124] 23

[0125] The reduction in the supply from the inverter PWR compensates for, or compensates for to such an extent that, the electrical consumers WV1-WVn, GV1-GVn connected to the on-board network BN can continue to be supplied and sufficient energy is available to impress currents into the stator windings of the drive motors AM.

[0126] With the sufficient availability of electrical energy in the DC link ZK during braking operation, as explained above in FIGS. 7, 8 and 9, the inverter PWR, controlled by the control unit ST, begins at a suitable time to induce currents in the stator windings of the drive motors AM in order to maintain the braking torque generated by them at the desired or required level until the rail vehicle TZ comes to a standstill at the stop.

[0127] 202411851 Late registration version

[0128] 24

[0129] Reference symbol list

[0130] 4QS - Rectifier

[0131] AM - Drive motor

[0132] AS - Drive system ba - Brake request

[0133] BAT - Secondary battery

[0134] BATS - Switch

[0135] BN - On-board network

[0136] BS - Brake actuator

[0137] BW - Braking resistance

[0138] DIO - Diode

[0139] EW - Endwagen

[0140] GSW - DC / DC converter

[0141] GV1-GVn - DC consumers

[0142] HBU - On-board power supply

[0143] HS - Main switch

[0144] LDG - Running bogie

[0145] LG - Battery charger

[0146] MW - Center car

[0147] NA - Network connection

[0148] PAN - current collector

[0149] PWR - Inverter

[0150] ST - Control unit

[0151] TDG - Drive bogie

[0152] TF - Transformer

[0153] TZ - multiple unit / rail vehicle

[0154] WK - Car body

[0155] WV1-WVn - AC consumers

[0156] DC link

Claims

202411851 Late registration version 25 Patent claims 1. Method for electrodynamically braking a rail vehicle (TZ) to a standstill, comprising an electric drive system (AS) of the rail vehicle (TZ): - a DC link (DC link) which can be connected to a power supply network via a network connection (NA), - at least one inverter (PWR) connected to the DC link (DC link), - at least one drive motor (AM) connected to the respective inverter (PWR) for driving the rail vehicle (TZ) in a drive operation, - a secondary battery (BAT) connectable to the DC intermediate circuit (DC), and - a control device (ST), wherein - a braking operation of the drive system (AS) is initiated, - the control unit (ST) determines a current braking torque generated by at least one drive motor (AM) in generator mode, - depending on the specific current braking torque and the availability of DC link (ZK) from the supply network, the secondary battery (BAT) is connected to the DC link (ZK) by the control unit (ST) to supply the DC link (ZK) from the secondary battery (BAT), and - the control unit (ST) controls the supply of power to at least one drive motor (AM) from the DC link (ZK) to increase the generated braking torque by means of the inverter (PWR).

2. The method of claim 1, wherein - a vehicle electrical system (VES) is connected to the DC link (DC link) to supply an electrical vehicle electrical system (ES) with electrical energy, - the on-board power supply (HBU) is connected to electrical consumers (GV1-GVn, WV1-WVn) via at least one busbar, and - the electrical consumers (GV1-GVn, WV1-WVn) are supplied by the on-board power supply (HBU) with electrical energy supplied from the DC intermediate circuit (ZK).

3. Method according to claim 2, wherein 202411851 Late registration version 26 - the secondary battery (BAT) can be directly connected to the DC intermediate circuit (DC), wherein the connection can be established by the control unit (ST) by means of at least one controllable switch (BATS), and - the secondary battery (BAT) is charged with electrical energy via a battery charger (LG), wherein the battery charger (LG) is designed as part of the vehicle electrical system (BN) or is connected to one of the busbars.

4. Method according to claim 3, wherein the secondary battery (BAT) is connected to the DC intermediate circuit (ZK) via at least one diode (DIO), wherein the at least one diode (DIO) is arranged such that electrical energy can be supplied to the DC intermediate circuit (ZK) exclusively from the secondary battery (BAT).

5. Method according to claim 1 or 2, wherein - the secondary battery (BAT) is connected to the DC link (ZK) via a bidirectional DC-DC converter (GSW), and - the DC / DC converter (DC converter) is controlled by the control unit (ST) to charge the secondary battery (BAT) from the DC / DC circuit (DC) and to discharge the secondary battery (BAT) into the DC / DC circuit (DC).

6. Method according to any one of the preceding claims, wherein - a brake actuator (BS) is connected to the DC intermediate circuit (ZK), and - the brake actuator (BS) is controlled by the control unit (ST) to dissipate electrical energy into at least one braking resistor (BW) and / or an instantaneous overvoltage limiter, the dissipation depending on whether and / or to what extent the electrical energy generated by the at least one drive motor (AM) - can be fed back into the supply network, and / or - can be fed into the vehicle electrical system (VES), and / or - can be charged into the secondary battery (BAT).

7. Method according to claim 3 or 4 and according to claim 6, wherein - in preparation for connecting the secondary battery (BAT) to the DC link (ZK), the brake actuator (BS) is controlled by the control unit (ST) to adapt a voltage of the DC link (ZK) to a voltage of the secondary battery (BAT), and 202411851 Late registration version 27 - the secondary battery (BAT) is connected to the DC intermediate circuit (ZK) depending in particular on a voltage difference between the voltage of the DC intermediate circuit (ZK) and the voltage of the secondary battery (BAT).

8. Method according to claim 6 or 7, wherein the brake actuator (BS) is switched off by the control unit (ST) during the supply of the DC intermediate circuit (ZK) from the secondary battery (BAT).

9. Method according to one of the preceding claims, wherein the supply capability of the DC intermediate circuit (DC) from the supply network is determined by the control unit (CU) depending on information about - a connection of a power consumer (PAN) of the grid connection (NA) with the supply network, and / or - a switching state of a main switch (MS) of the mains connection (MS), and / or - a voltage of the supply network, and / or - a current flow from the supply network into the drive system (AS).

10. Drive system (AS) for a rail vehicle (TZ), comprising: - a DC link (DC link) which can be connected to a power supply network via a network connection (NA), - at least one inverter (PWR) connected to the DC link (DC link), - at least one drive motor (AM) connected to the respective inverter (PWR) for driving the rail vehicle (TZ) in a drive operation, - a secondary battery (BAT) connectable to the DC intermediate circuit (DC), and - a control device (ST), wherein the control device (ST) is configured to carry out the method according to any one of claims 1 to 9.

11. Drive system (AS) according to claim 10, wherein the mains connection (NA) comprises: - a transformer (TF), wherein a primary side of the transformer (TF) can be connected to an AC power supply network via a main switch (HS) and a current collector (PAN), and a rectifier (4QS) connected to a secondary side of the transformer (TF), wherein the rectifier (4QS) is connected to the DC link (ZK), and / or 202411851 Late registration version 28 - an input filter which can be connected to a DC power supply network via a main switch and a current collector, wherein the input filter is connected to the DC intermediate circuit (DC).

12. Drive system (AS) according to claim 10 or 11, wherein a capacity of the secondary battery (BAT) is designed to supply the drive system (AS) with electrical energy for a movement of the rail vehicle (TZ) limited with respect to a drive power and a travel distance and / or to supply electrical consumers (GV1-GVn, WV1-WVn) connected to an on-board network (BN) with electrical energy for a limited period of time.

13. Rail vehicle (TZ), comprising at least one drive system (AS) according to one of claims 10 to 12 and / or configured to carry out the method according to one of claims 1 to 9.

14. Rail vehicle (TZ) according to claim 13, which is designed as a rail vehicle for regional and / or long-distance transport and in particular for the transport of passengers.

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