Method for controlling an electrodynamic brake apparatus of a rail vehicle

Abstract

The invention relates to a method for controlling an electrodynamic brake apparatus of a rail vehicle, wherein the electrodynamic brake apparatus of the rail vehicle comprises, as parts of a drive system of the rail vehicle: at least one electric drive motor; a converter that is electrically connected to said motor and comprises a plurality of power semiconductor switches; and a control device that controls the plurality of power semiconductor switches. The method according to the invention is characterised in that the power semiconductor switches of the converter are controlled according to a first control algorithm of the control device during emergency braking in order to generate a target braking torque, the first control algorithm including functions both of driving and of braking of the drive system; during the braking process, an actual braking toque generated by the electrodynamic brake apparatus is determined and compared with the target braking torque; and on the basis of the comparison, the power semiconductor switches of the converter are controlled by means of a second control algorithm of the control device, the second control algorithm including exclusively functions of braking.

Description

[0001] Description

[0002] Method for controlling an electrodynamic braking device of a rail vehicle

[0003] The invention relates to a method for controlling an electrodynamic braking device of a rail vehicle, a drive system of a rail vehicle with such an electrodynamic braking device and a rail vehicle.

[0004] Electrically powered rail vehicles, particularly for local, regional and long-distance traffic, are preferably braked during braking by means of electrodynamic braking devices, since these can be operated with virtually no wear compared to friction brakes, and there is also the option of feeding electrical energy generated during braking into the electrical supply network, for example an overhead line or a so-called third rail, which provides the electrical energy required for the drive.

[0005] However, the use of the electrodynamic braking device is still limited to service braking. During rapid braking, also known as emergency braking or hazard braking, additional friction braking devices are used to initiate a braking process with maximum braking torque for the safety of passengers in the rail vehicle and third parties outside the rail vehicle. The use of friction braking devices, compared to the electrodynamic braking devices otherwise used, is based on the previously higher reliability of the friction braking devices.However, the disadvantage is that it is necessary to equip rail vehicles with both electrodynamic braking devices and friction braking devices, which enable safe emergency braking from the maximum speed of the rail vehicle, which leads to a high level of technical complexity, additional weight and, in particular, high costs for production and operation, particularly in the case of high-speed trains.

[0006] For some time now, efforts have been made to increase the reliability of electrodynamic braking systems on rail vehicles to such an extent that they can be approved for emergency braking by the relevant authorities or organizations, providing proof of sufficiently high reliability. Such approval would have the advantage of enabling friction braking systems to be implemented with less technical effort and thus less weight due to the significantly lower braking torque required. Such friction brakes could be limited, in particular, to the function of stopping brakes, which act at low speeds and when the vehicle is stationary.

[0007] From German published patent application DE 10 2012 203 132 A1, for example, it is already known to provide two brake control units in order to increase the reliability of an electrodynamic braking device. In a first braking mode, a first brake control unit controls a power supply unit to provide a braking effect, and a braking effect monitoring unit switches, depending on a braking effect parameter, by means of a switching unit to a second braking mode in which a second brake control unit controls the power supply unit to provide a braking effect. By providing two brake control units between which it is possible to switch, redundancy is created which increases the reliability. The brake control units can differ, in particular in the sense of diverse redundancy, with regard to their structural and / or algorithmic design.The disadvantage of providing a second brake control unit and a switching unit is that it not only increases the number of units but also requires additional proof of a sufficiently high level of reliability of these additional units.

[0008] The object of the invention is therefore to provide a method and an electrodynamic braking device that ensure sufficiently high reliability of the electrodynamic braking device, particularly during emergency braking. This object is achieved by the respective features of the independent patent claims. Further developments are specified in the respective dependent patent claims.

[0009] A first aspect of the invention relates to a method for controlling an electrodynamic braking device of a rail vehicle, wherein the electrodynamic braking device of the rail vehicle comprises at least one electric drive motor, a power converter electrically connected thereto with a plurality of power semiconductor switches, and a control device controlling the plurality of power semiconductor switches as parts of a drive system of the rail vehicle.The method according to the invention is characterized in that during rapid braking to generate a target braking torque the power semiconductor switches of the power converter are controlled according to a first control algorithm of the control device, wherein the first control algorithm comprises functions of both driving and braking the drive system, during the braking process an actual braking torque generated by the electrodynamic braking device is determined and compared with the target braking torque, and depending on the comparison the power semiconductor switches of the power converter are controlled by means of a second control algorithm of the control device, wherein the second control algorithm exclusively comprises functions of braking.

[0010] According to the invention, the reliability of the electrodynamic braking device of a rail vehicle is advantageously increased in that a different, second control algorithm, which has a lower complexity and a smaller range of functions, serves as a fallback level for controlling the power semiconductor switches of the power converter. For such a reduced control algorithm, it is easier to demonstrate sufficiently high reliability. Advantageously compared to the solution described in the introduction according to the published application DE 10 2012 203 132 A1, no redundant or even diverse-redundant control device is required, whereby the complexity of the braking device and the costs are advantageously reduced compared to this known solution.

[0011] The lower complexity and the smaller range of functions of the second control algorithm is achieved according to the invention in that it only uses functions which are related to the generation of a braking torque or with the generation of a maximum braking torque when emergency braking is requested. For example, the second control algorithm does not use any active pointers of a pulse width modulation, by means of which the drive motor designed as a three-phase machine is controlled. This has the effect that, for example, feeding back into the supply network, generating a small braking torque, as is particularly advantageous at low speeds, quickly varying the braking torque, as is particularly advantageous for wheel slide protection, and generating a drive torque is not possible.

[0012] The second control algorithm serves merely as a fallback level for the electrodynamic braking device in the rare error case that the required actual braking torque cannot be generated by the first control algorithm during emergency braking. Conversely, this means that the full range of functions of the first control algorithm can usually be used to advantage even when emergency braking is requested. These functions enable, for example, a highly dynamic response to the braking torque generated, which in particular enables wheel slide protection and braking down to low speeds, and feedback into the supply network, provided the drive system is connected to it and the system can absorb the generated electrical energy.

[0013] The actual braking torque generated by the electrodynamic braking device during braking corresponds to the braking force that can be transmitted by the drive motor to a wheelset that is mechanically connected to it, usually via a single- or multi-stage gearbox and a clutch. A wheelset comprises a wheelset axle and two wheels rigidly connected to it, which are supported on rails. The actual braking torque is determined, for example, by the higher-level control device, which also compares the determined actual braking torque with the target braking torque. The actual braking torque actually generated or that can be generated is determined, for example, based on the power at the connection terminals of the drive motor.Alternatively or additionally, the actual braking torque can also be determined, for example, based on a negative acceleration, which can be derived from the observation of a change in the speed of the rail vehicle, which is detected, for example, by means of one or more speed sensors on the motor and / or wheelset shafts, or from signals from one or more acceleration sensors. Furthermore, the actual braking torque can also be determined based on a torque acting on a torque arm of the drive motor. Preferably, redundant or diversely redundant information is taken into account when determining the actual braking torque in order to ensure sufficiently high failure safety in this regard too.

[0014] The target braking torque, based on whose value the control device activates the power semiconductor switches of the power converter using the first control algorithm, is specified to the control device, for example, by a higher-level control device connected to it via signaling. When emergency braking is requested, this target braking torque initially corresponds to a maximum braking torque that can be provided by the electrodynamic braking device. The request for emergency braking can be made, for example, by the person driving the vehicle, either manually or automatically.

[0015] According to a first development of the method according to the invention, the second control algorithm has a smaller range of functions with regard to the braking function than the first control algorithm.

[0016] According to a further development of the method according to the invention, in the step of comparing, the determined actual braking torque is compared with a threshold value dependent on the desired braking torque and, if the actual braking torque falls below the threshold value, the power semiconductor switches of the power converter are controlled by means of the second control algorithm.

[0017] A threshold value suitable for comparison by the higher-level control device corresponds, for example, to the target braking torque; alternatively, however, it can also be below the target braking value and have a predetermined relative, in particular percentage, or predetermined absolute distance from it. By means of a threshold value defined lower than the target braking torque, it can advantageously be ensured that even slight deviations between the determined actual braking torque and the target braking torque do not trigger activation of the second control algorithm with a reduced range of functions.

[0018] According to a further development of the method according to the invention, the power semiconductor switches of the power converter are controlled by means of the second control algorithm of the control device until the emergency braking is completed.

[0019] A second aspect of the invention relates to an electric drive system of a rail vehicle, wherein the drive system has at least one electrodynamic braking device, which comprises at least one electric drive motor, a power converter electrically connected thereto with a plurality of power semiconductor switches, and a control device controlling the plurality of power semiconductor switches. The electric drive system is characterized in that the electrodynamic braking device is designed to carry out the method according to the first aspect of the invention.

[0020] According to a first development of the drive system according to the invention, the at least one drive motor is designed as a permanently excited three-phase synchronous motor.

[0021] According to a further development of the drive system according to the invention, the at least one power converter is designed as a pulse inverter.

[0022] According to a further development of the drive system according to the invention, the electrodynamic braking device further comprises a further control device which is higher-level than the control device, wherein the further control device is designed in particular to specify the desired braking torque to the control device and / or to compare the determined actual braking torque with the desired braking torque. Finally, a third aspect of the invention relates to a rail vehicle, wherein the rail vehicle is characterized in that it has at least one electrodynamic braking device designed to carry out the method according to the first aspect of the invention or at least one drive system according to the second aspect of the invention.

[0023] According to a further development of the rail vehicle according to the invention, this is designed as a high-speed multiple unit.

[0024] The invention is explained below using exemplary embodiments. In the following:

[0025] FIG 1 a rail vehicle with an electric drive system for operation on an AC supply network,

[0026] FIG 2 a rail vehicle with an electric drive system for operation on a direct current supply network,

[0027] FIG 3 shows the drive system of the rail vehicle of FIG 1 with devices of the electrodynamic braking device according to the invention, and

[0028] FIG 4 is a flow diagram of the method according to the invention.

[0029] For reasons of clarity, the same reference symbols are used in the figures for components that are identical or have the same or almost identical functions.

[0030] FIG 1 shows a schematic side view of a rail vehicle TZ. The rail vehicle TZ is designed, for example, as a multiple unit for passenger transport with a plurality of carriages, whereby only an end car EW and a middle car MW coupled to it are shown. Both cars have a car body WK, which is moved via bogies in the form of a motor bogie TDG with drive motors AM or TDG arranged therein.

[0031] LDG bogies without traction motors are supported on rails not shown. The TZ rail vehicle moves on the rails in the directions FR specified by these.

[0032] The end car EW schematically shows components of an electric drive system AS of a rail vehicle TZ operated on an AC power supply network. These components are usually arranged in special areas within the car body WK, in the underfloor area, in the roof area, or distributed across several cars of the rail vehicle TZ. Other components of the drive system AS, in particular the auxiliary systems required for the operation of the components, are also provided, although they are not specifically shown in FIG. 1.

[0033] The drive train AS can be electrically connected to an overhead line of the AC supply network (not shown) via a pantograph PAN, which is arranged, for example, in the roof area of ​​the end car EW. The overhead line carries, for example, a single-phase alternating current. The alternating current is fed to a network-side primary winding of a drive transformer ATR, in which the network-side voltage level of, for example, 15 kV, 16.7 Hz or 25 kV, 50 Hz is transformed to a lower voltage level. A secondary winding of the drive transformer ATR is connected to a network-side converter 4QS, for example a four-quadrant converter, which rectifies the alternating current.

[0034] The line-side converter 4QS feeds a DC intermediate circuit ZK, which in turn feeds a load-side converter PWR, for example a pulse-controlled inverter. One or more intermediate circuit capacitors are arranged in the DC intermediate circuit ZK and serve as electrical energy storage devices, in particular to smooth the DC voltage. The load-side converter PWR generates a three-phase AC voltage of variable frequency and amplitude from the DC voltage of the DC intermediate circuit ZK, which voltage is used to feed the stator windings of, for example, two drive motors TM arranged in the motor bogie TDG of the end car EW. The function of the line-side 4QS ​​and the load-side converter PWR in particular is controlled by a control unit ICU, although alternatively individual control units can be provided for the converters.

[0035] FIG 2 shows a schematic diagram of a rail vehicle TZ corresponding to the rail vehicle TZ in FIG 1 with an alternative drive system AS. In this example, the pantograph PAN can be connected to an overhead line (again not shown) of a direct current supply network. Particularly in local transport, instead of an overhead line, a conductor rail is often run parallel to the track, to which the drive train AS can be connected via one or more side current collectors, which are arranged, for example, in the area of ​​the car body ends or the bogies. The direct current from the supply network is fed to the direct voltage intermediate circuit ZK of the drive system AS via an input filter or mains filter NF. The mains filter NF comprises, for example, a filter inductance in the form of a choke and a capacitor, whereby the capacitor can also additionally fulfil the function of an intermediate circuit capacitor ZK of the drive train AS.

[0036] FIG. 3 schematically shows the exemplary drive system AS of the rail vehicle TZ of FIG. 1, although not all of the system components described above are shown again. For example, only one secondary winding of the drive transformer ATR, which is fed by an AC power supply network, and only one drive motor AM are shown.

[0037] In the drive system AS, the secondary winding of the drive transformer ATR is connected to the line-side power converter 4QS. The line-side power converter 4QS is designed as a four-quadrant divider which converts the alternating voltage provided on the input side by the drive transformer ATR into a direct voltage and makes it available on the output side. The conversion takes place by controlling power semiconductor switches or power transistors, whereby the power semiconductor switches are made, for example, of silicon or a semiconductor with a larger band gap than silicon, in particular silicon carbide (SiC), gallium nitride (GaN) or diamond. Two power transistors are electrically connected in series in a switching branch, the middle connection point of which is connected to a respective input of the line-side power converter 4QS.The outer connection points of the switching branches are connected to a respective output of the mains-side converter 4QS.

[0038] The line-side converter 4QS feeds a DC intermediate circuit ZK via the outputs, which in turn is connected to inputs of the load-side converter PWR. In the DC intermediate circuit ZK, for example, an intermediate circuit capacitor CZK is arranged, to which an intermediate circuit voltage UZK is applied. As an alternative to the one intermediate circuit capacitor CZK shown, several intermediate circuit capacitors CZK can also be electrically connected in parallel to provide a desired capacitance. In the DC intermediate circuit ZK, a braking resistor BST is also arranged parallel to the intermediate circuit capacitor CZK, which braking resistor BST, for example, comprises a series circuit of a controllable switch and a resistor R.The load-side power converter PWR is designed, for example, as a pulse-controlled inverter which converts the direct voltage applied at the input side into an alternating voltage of variable voltage and frequency and makes it available at the outputs. The conversion takes place by means of a control device ICU controlling the power semiconductor switches or power transistors, whereby the power semiconductor switches are in turn made, for example, from silicon or a semiconductor with a larger band gap than silicon, in particular silicon carbide (SiC), gallium nitride (GaN) or diamond. In contrast to the mains-side power converter 4QS, the load-side power converter PWR has three or four phases for the example three phases of the stator winding SW of the drive motor AM.an integer multiple of three parallel switching branches, each with two series-connected power semiconductor switches, to which a so-called freewheeling diode is connected antiparallel.

[0039] The drive motor AM fed by the load-side converter PWR is designed as a separately excited three-phase asynchronous machine or preferably as a permanent magnet excited three-phase synchronous machine.

[0040] The control unit ICU controls the six power semiconductor switches of the load-side power converter PWR, given as examples, according to a control algorithm ral, with signals from this control being represented by six vertical dashed arrows emanating from the control unit ICU. The control unit ICU is signaled by a higher-level control unit MCU, which controls, for example, several or all of the control units ICU of the drive system AS of the rail vehicle TZ, in particular specifications relating to a drive torque or braking torque, which the control unit implements by means of a control algorithm, taking further information into account if necessary. FIG 3 specifically considers the case of initiation of emergency braking of the rail vehicle TZ.The higher-level control unit MCU receives an emergency braking request sba, the signal for which was triggered, for example, by the person driving the rail vehicle TZ or automatically by a safety system of the rail vehicle TZ. In response to receiving the emergency braking request sba and depending on further information, in particular a current speed and a current weight of the rail vehicle TZ, the higher-level control unit MCU defines a target braking torque sbm with which a maximum braking effect is to be achieved by the electrodynamic braking device EBV. The higher-level control unit MCU signals this target braking torque sbm to the control unit ICU, which uses a first control algorithm ral to generate control commands for controlling the power semiconductor switches of the load-side power converter PWR.

[0041] An actual braking torque ibm achieved by the electrodynamic braking device EBV as a result of this control is determined by the higher-level control unit MCU based on various signals or information supplied to it. Such signals or information include or represent, for example, currents in the phases of the stator winding SW of the drive motor AM, which are determined, for example, by means of ammeters A arranged in or on the motor cables.Alternatively or additionally, signals or information taken into account by the higher-level control unit MCU can include or represent an intermediate circuit voltage UZK, which is determined, for example, by means of a voltmeter V arranged in the DC voltage intermediate circuit ZK parallel to the intermediate circuit capacitor ZK, a speed D of the drive motor AM, which is determined, for example, by means of a speed sensor on the motor shaft of the drive motor AM, a speed or speed curve determined by a central unit of the rail vehicle TZ, or an acceleration of the rail vehicle TZ measured by means of one or more acceleration sensors.

[0042] The higher-level control unit MCU compares the determined actual braking torque ibm with the defined target braking torque sbm. If this comparison shows that the actual braking torque ibm is lower than the target braking torque sbm, whereby a threshold value dependent on the target braking torque sbm is used for the comparison, for example, the higher-level control unit MCU signals the control unit ICU to select a second control algorithm ra2, by means of which control commands for controlling the power semiconductor switches of the power converter PWR are to be generated. This second control algorithm ra2, which, like the first control algorithm ral, is stored in the control unit ICU, has a smaller range of functions than the first control algorithm ral.

[0043] The components, devices and method steps described above can be implemented in the same way in a drive system AS corresponding to that of the rail vehicle TZ in FIG. 2, wherein this drive system AS according to the above description does not have a mains-side converter and transformer, but is electrically connected to a direct current supply network via a mains filter NF.

[0044] FIG. 4 schematically shows a flow diagram of the method according to the invention based on the electrodynamic braking device EBV of FIG. 3, wherein only steps for requesting emergency braking are considered. Furthermore, in the initial situation of the flow diagram, the control unit ICU uses the first control algorithm ral, which includes functions for both driving and electrodynamic braking of the drive system AS.

[0045] In a first step S1, the higher-level control unit MCU receives an emergency braking request sba. Based on this received request sba, the higher-level control unit MCU defines a target braking torque sbm in a subsequent second step S2 and signals this to the control unit ICU.

[0046] Subsequently, in a third step S3, the higher-level control unit MCU determines an actual braking torque ibm achieved by the electrodynamic braking device EBV, taking into account signaled or supplied information for this purpose. In a subsequent fourth step S4, the higher-level control unit MCU compares the determined actual braking torque ibm with the defined target braking torque sbm or with a threshold value derived therefrom. If this comparison shows that the actual braking torque ibm is less than the target braking torque or falls short of the target braking torque sbm by a certain relative or absolute amount (branch “yes”), the higher-level control unit MCU signals to the control unit ICU in a fifth step S5 the selection of the second control algorithm ra2, which has a reduced range of functions compared to the first control algorithm ral initially used.However, if the determined actual braking torque ibm corresponds to the target braking torque or is not below a threshold value (branch "no"), the higher-level control unit MCU continues to monitor or determine the current actual braking torque ibm.

[0047] Based on the signaling of the selection ara received from the higher-level control unit MCU, the control unit ICU uses the second control algorithm ra2 for controlling the power semiconductor switches of the power converter PWR in a subsequent sixth step S 6 .

Claims

Patent claims 1. Method for controlling an electrodynamic braking device (EBD) of a rail vehicle (TZ), wherein the electrodynamic braking device (EBD) of the rail vehicle (TZ) comprises at least one electric drive motor (AM), a power converter (PWR) electrically connected thereto with a plurality of power semiconductor switches, and a control unit (ICU) controlling the plurality of power semiconductor switches as parts of a drive system (AS) of the rail vehicle (TZ), characterized in that - during emergency braking to generate a target braking torque (sbm), the power semiconductor switches of the converter (PWR) are controlled according to a first control algorithm (ral) of the control unit (ICU), wherein the first control algorithm (ral) includes functions of both driving and braking the drive system (AS), - during the braking process, an actual braking torque (ibm) generated by the electrodynamic braking device (EBD) is determined and compared with the target braking torque (sbm), and - depending on the comparison, the power semiconductor switches of the power converter (PWR) are controlled by means of a second control algorithm (ra2) of the control unit (ICU), whereby the second control algorithm (ra2) includes only braking functions.

2. Method according to claim 1, characterized in that the second control algorithm (ra2) has a smaller range of functions with respect to the braking function compared to the first control algorithm (ral).

3. Method according to claim 1 or 2, characterized in that In the comparison step, the determined actual braking torque (ibm) is compared with a threshold value dependent on the target braking torque (sbm), and if the actual braking torque (ibm) falls below the threshold value, the power semiconductor switches of the converter (PWR) are controlled by means of the second control algorithm (ra2).

4. Method according to one of the preceding claims, characterized in that the power semiconductor switches of the power converter (PWR) are controlled by means of the second control algorithm (ra2) of the control unit (ICU) until the emergency braking is completed.

5. Electric drive system (AS) of a rail vehicle (TZ) , wherein the drive system (AS) comprises at least one electrodynamic braking device (EBD) comprising at least one electric drive motor (AM) , a power converter (PWR) electrically connected thereto with a plurality of power semiconductor switches, and a control unit (ICU) controlling the plurality of power semiconductor switches, characterized in that the electrodynamic braking device (EBD) is configured to carry out the method according to one of claims 1 to 4 .

6. Drive system (AS) according to claim 5, characterized in that the at least one drive motor (AM) is designed as a permanent magnet three-phase synchronous motor.

7. Drive system (AS) according to claim 5 or 6, characterized in that the at least one power converter (PWR) is designed as a pulse inverter.

8. Drive system (AS) according to one of claims 5 to 7, characterized in that The electrodynamic braking device (EBD) further comprises a higher-level control unit (MCU) superior to the control unit (ICU), wherein the higher-level control unit (MCU) is in particular designed to specify the target braking torque (sbm) to the control unit (ICU) and / or to perform the comparison of the determined actual braking torque (ibm) with the target braking torque (sbm).

9. Rail vehicle (TZ) , characterized in that it has at least one electrodynamic braking device (EBD) designed for carrying out a method according to one of claims 1 to 4 or at least one drive system (AS) according to one of claims 5 to 8.

10. Rail vehicle (TZ) according to claim 9, characterized in that it is designed as a high-speed multiple unit train.

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