HK1134591B - Traction drive of a rail vehicle for driving and generative braking with load correction - Google Patents

Description

Traction drive system for a rail vehicle for driving and electric braking with load compensation

Technical Field

The invention relates to a traction drive system for the drive and the generative braking (regenerative braking) of rail vehicles or rail trains, and to a device for load compensation when the rail vehicle or rail train is braked galvanically by means of the traction drive system.

Background

The invention proceeds from the prior art as follows:

● traction drive system for the drive and generator braking (regenerative braking) of rail vehicles or rail trains, wherein at least one axle of the rail vehicle or rail train is equipped with at least one permanently excited synchronous motor and a traction converter, and the traction converter has at least one motor-side pulse converter, which is connected at its terminals to a changeover switch in such a way that the permanently excited synchronous motor can switch on the pulse converter for driving or the load line forming the load for generator braking, and

●, for load compensation when electrically braking a rail vehicle or a rail vehicle train comprising an air damping device with at least one air spring bellows by means of a traction drive train.

The aim in rail vehicle installations is ultimately to use more efficient and lighter drive devices. As a standard drive, asynchronous motors powered by frequency converters are used. However, such devices have little potential for improvement in terms of weight reduction and increased torque density, and in most applications in rail vehicles require a gearbox. Therefore, there is currently increasing effort to develop and employ a permanent magnet excited synchronous machine as a vehicle drive device. This type of device, due to its high torque density, makes it possible to achieve direct drive and, in particular, to considerably reduce the weight of the drive train by eliminating the gearbox.

Because of its permanent excitation, a permanently excited synchronous machine has some special features compared with asynchronous machine technology. For example, it can be operated in addition to a frequency converter-regulated generator when the electric machine is rotating, with purely passive components to achieve a braking action. The braking action produced by a permanently excited synchronous machine by connecting a braking resistor is known from DE 10160612a1 of the same type.

When the rotating permanent-magnet excited synchronous machine is connected to the brake resistor, a torque or force characteristic curve, which is also referred to as an inherent brake characteristic curve, is obtained as a function of the rotational speed of the synchronous machine and thus also of the change in vehicle speed. The characteristic curve has a maximum in the variation with respect to the rotational speed/speed.

When a power generation braking operation of a permanent magnet excited synchronous motor is applied, it is desirable to control a braking force or a braking torque according to a load.

Disclosure of Invention

The object of the present invention is therefore to improve a traction drive of the type mentioned at the outset in such a way that a load adaptation of the braking force can be achieved in a simple and economical manner. A corresponding device for load compensation should also be provided.

To this end, the invention provides a traction drive system for the drive and generator braking of rail vehicles or rail trains, wherein at least one axle of the rail vehicle or rail train is equipped with at least one permanently excited synchronous motor and a traction converter, and the traction converter has at least one motor-side pulse converter, which is connected to a changeover switch at its connection terminals in such a way that the permanently excited synchronous motor can switch on the pulse converter for driving or the load line forming the load for generator braking, wherein the load line switching on the permanently excited synchronous motor for generator braking is designed and/or controlled in such a way that the characteristic value of the load line can be varied depending on the load of the rail vehicle or rail train; the load line has a resistance and also an inductance and/or a capacitance, characterized in that: an actuator is provided which includes a switching device which switches the inductance and/or capacitance on or off the resistance depending on the load.

The invention also provides a device for load compensation during the regenerative braking of a rail vehicle or a rail train by means of the traction drive system, which rail vehicle or rail train comprises an air damping device with at least one air spring bellows, characterized in that: the actuator is formed by a pneumatic actuator which is directly controlled by the pressure in the at least one pneumatic spring chamber and, depending on this pressure, switches the inductance and/or capacitance on or off the resistance or steplessly adjusts the inductance and/or capacitance depending on the load.

The invention has the advantages that:

the basic inventive concept of the present invention is that the load circuit, which switches on the permanently excited synchronous motor for generating braking, is designed and controlled in such a way that the characteristic value of the load circuit can be varied depending on the load of the rail vehicle or rail train.

This is based on the knowledge that by changing the load path, the braking characteristic curve of a permanently excited synchronous motor can be changed with regard to the position and height (magnitude) of the maximum braking torque. For example, as the brake resistance value decreases, the maximum brake torque value moves in the direction of a smaller rotational speed, but the maximum brake torque value does not change in magnitude. Conversely, as the brake resistance increases, the maximum brake torque moves in the direction of a greater rotational speed. By means of the parallel connection of the capacitor and the brake resistor, the maximum value of the brake torque can be increased. And connecting an inductor in series with the brake resistor reduces the maximum braking torque. The intrinsic braking characteristic can therefore be adapted to the respective requirements caused by the load change by means of a corresponding connection of the load elements. This usually means that: at higher loads, the braking force or torque is greater, while at lower loads, a lesser braking force or torque is required.

This load-dependent change of the load path can be achieved without complicated regulating devices and can be designed economically as simple control devices.

The device for load compensation during the regenerative braking of rail vehicles or rail trains by means of a traction drive train generally comprises the following components:

1. a load measuring means for generating a load signal related to the load,

2. a transmission or control mechanism for processing the load signal and for controlling an adjusting signal for at least one actuator,

3. an actuator for switching or adjusting the load elements (resistance, capacitance and inductance) of the load circuit in response to a load signal.

The load measuring mechanism may include mechanical, pneumatic and electrical mechanisms:

● mechanical means such as linkages associated with elastic deformation. The load signal or measurement consists of the elastic deformation stroke or angle.

● pneumatic mechanisms such as a force or pressure dependent equalization valve or simply an air spring pressure within an air spring housing of a rail car air cushioning device. The load signal or measurement value is formed by a pressure.

● an electrical mechanism such as a potentiometer which relies on elastic deformation. The load signal or measurement consists of resistance, current or voltage, capacitance, inductance or field strength.

The type of transmission or control means is preferably dependent on the type of load measuring means and can be constructed in the following manner:

● are mechanically connected, such as by links, levers,

● are pneumatically actuated, e.g. by pneumatic lines, pressure multipliers, pneumatic amplification valves, or

● are electrically powered, such as by electrical leads, amplifiers.

The actuator for switching or adjusting the load element may

● contain, for the purpose of the stepped switching or switching-on of passive load elements, corresponding switching elements, such as mechanically or pneumatically actuated switching contacts, electromechanical contactors, electrical/electronic switches, for example thyristors or transistors,

● for continuously or steplessly changing the value of the passive load elements (resistance, inductance, capacitance) contain corresponding adjusting elements which cause a change in the characteristic value of the inductive magnetic circuit, for example by changing the air gap of the coil core by means of a movement of the coil core, or by changing the resistance value by means of sliding contacts.

A particularly simple and economical design is to use only the pressure prevailing in the air spring bellows of the air suspension of a rail vehicle or a rail train as a load signal in the load measuring range and to use it as an actuating signal directly into the pneumatic pressure switch for the stepped switching or switching on of the load element or into a pneumatic actuator for the continuous or stepless adaptation of the value of the passive load element. In the second case, the pneumatic actuator adjusts, for example, one or more coil cores of the inductor.

In order to implement this embodiment, the load line has, for example, a resistor, an inductor and/or a capacitor, which can be switched on and off with respect to the resistor by the actuator. Alternatively, adjustable or controllable resistances, inductances or capacitances, which are adjusted by the actuator as a function of the load, can also be considered.

According to a preferred embodiment, the load circuit has a resistor and an inductance connected in series with the resistor, wherein the transmission or control device controls the at least one actuator as a function of the load in such a way that the inductance decreases with increasing load and increases with decreasing load.

According to the above rule, an increase in the inductance (including from zero) in series with the braking resistor results in a decrease in the maximum braking torque, whereas a decrease in the inductance results in an increase in the maximum braking torque.

Accordingly, this improved structure of the present invention is suggested from two opposite aspects: for lightly loaded or unloaded rail vehicles, braking takes place with a lower braking torque than the theoretically available high maximum braking torque, and the braking torque is only increased by reducing the inductance if the rail vehicle or rail train is loaded. For this way, it is desirable, on the one hand, to decelerate the rail vehicle constantly, irrespective of the load state. Considering the relation F ═ m × a, this means: as the load decreases, the braking force F must be reduced without the deceleration acceleration a changing, which is achieved by increasing the inductance. On the other hand, even if a higher deceleration is tolerated in the unloaded state of the rail vehicle than in the normal unloaded state of the rail vehicle, the adhesion forces which are present between the wheels and the rail and which are reduced by moisture or dirt on the rail and the normal forces which are reduced thereby are generally not allowed to transmit considerable braking forces to the rail without causing a more severe slip which is not an optimum slip. For braking calculations, therefore, the specialist literature is always using conditions with a difference in friction coefficient of 0.10 to 0.12, at most 0.15, for safety reasons. It is therefore valuable to have a rule that braking is performed with a lower braking torque than the potential braking torque when the vehicle is lightly loaded or unloaded, and with the maximum possible braking torque only when the vehicle is loaded.

The inductor particularly preferably comprises a magnetic coil, wherein the pneumatically actuated actuator can change its magnetic circuit, for example, by adjusting the position of its coil core, in order to adjust the inductor as a function of the load.

Alternatively, the pneumatic actuator can be formed by a pressure switch controlled by the pressure in the at least one pneumatic spring bellows, and the inductance or capacitance can be switched on or off as a function of the load relative to the resistance.

According to a further development, the generator brake based on the permanently excited synchronous motor forms a safety or emergency brake, which is provided as a safety stage under the service brake. In order to implement safety or emergency braking, the generator brake can interact with a safety circuit of the rail vehicle or rail train in such a way that, after a limit value has been exceeded or fallen below, the load line is switched by a permanently excited synchronous motor variable along the safety circuit. In this way, a very simple and economical load compensation of the safety or emergency braking can be achieved by means of the invention.

Drawings

Embodiments of the invention are illustrated in the drawings and will be explained in detail in the following description. In the drawings, there is shown:

FIG. 1 is a schematic illustration of a traction drive system for an AC electric vehicle;

fig. 2 is a general block diagram of a device for load compensation during regenerative braking of a rail vehicle or a rail train, which is equipped with a traction drive according to fig. 1;

fig. 3 is a schematic illustration of a preferred embodiment of a device for load compensation during power braking of a rail vehicle or a rail train;

fig. 4 is a schematic illustration of a further embodiment of a device for load compensation during power braking of a rail vehicle or a rail train.

Detailed Description

Fig. 1 shows a traction drive 1 for an AC electric vehicle (also referred to as an AC rail vehicle) in detail, wherein 2 denotes a traction transformer, 4 denotes a traction converter, 6 denotes a permanently excited synchronous motor, and 8 denotes a braking device. The traction transformer 2 has a primary winding 10 and a plurality of secondary windings 12, only one of which 12 is shown. The traction converter 4 has a four-quadrant controller 14, a snubber circuit 16, a capacitive accumulator 18, an overvoltage protection device 20 and a machine-side pulse converter 22. The four-quadrant controller 14 is connected on the ac voltage side to the secondary winding 12 of the traction transformer 2 and on the dc voltage side to a parallel circuit. The dc voltage-side input connections of the absorption circuit 16, the capacitive battery 18, the overvoltage protection means 20 and the machine-side pulse current transformer 22 are connected in parallel with the two dc voltage-side connections 24 and 26 of this supply line. At the output, a machine-side pulse current transformer 22 can be connected to the terminals of the permanently excited synchronous motor 6.

The braking device 8 is composed of a braking resistor 28 and a changeover switch 30 in each phase of the permanently excited synchronous motor 6. The braking resistors 28 are connected, for example, in a star circuit and each have, for example, a constant resistance value. Alternatively, a delta connection is also contemplated. The changeover switch 30 is connected to the output of the machine-side pulse current transformer 22 and to the input of the permanently excited synchronous motor 6 in such a way that the input of the permanently excited synchronous motor 6 can be connected to the braking resistor 28 on the one hand and to the output of the machine-side pulse current transformer 22 on the other hand.

These changeover switches 30, which are also referred to as failsafe switches, can be operated electrically or mechanically or pneumatically. As soon as the changeover switches 30 have reached the "braking" operating position (i.e. the connection of the connection terminals of the permanently excited synchronous motor 6 to the output of the machine-side pulse current transformer 22) from the "drive" operating position (i.e. the connection terminals of the permanently excited synchronous motor 6 to the star-connected braking resistor 28), the permanently excited synchronous motor 6 generates a braking torque which changes according to the behavior of the braking characteristic as the speed of the rail vehicle decreases. Neither the motor-side pulse current transformer 22 nor any regulating device is required for generating this braking torque.

Such a traction drive is described in detail in DE 10160612a1 mentioned at the outset. And thus, a description thereof will not be repeated here.

Preferably, the generator brake based on the permanently excited synchronous motor forms a safety or emergency brake, which is provided as a safety stage under the service brake. For safety or emergency braking, the generator brake device 8 interacts with a safety circuit of the rail vehicle or rail train in such a way that, after a limit value has been exceeded or fallen below, the load line is switched by a permanently excited synchronous motor 6 which is varied along the safety circuit.

In contrast to the known traction drive according to fig. 1, in the present invention, a device 34 for load compensation during the regenerative braking of a rail vehicle or rail train is provided, which according to fig. 2 generally comprises the following components:

1. a load measuring mechanism 36 for generating a load signal related to the load,

2. a transmission or control means 38 for processing the load signal and an adjustment signal for controlling the at least one actuator,

3. an actuator 40 for switching or adjusting the load elements 42 (resistance, capacitance and inductance) of the load line 32 in response to a load signal.

The device 34 for load compensation during power braking is preferably used in a rail vehicle or a rail train comprising an air damping device 44 with at least one air spring bellows 46. Such an air damping device 44 is schematically shown in fig. 3. Here, a wheel 50, for example a bogie 52 of a rail vehicle, which is mounted on an axle 48, is supported elastically relative to a vehicle body 54 by means of an air spring bellows 46. This air spring housing 46 should be one example of many air spring housings of the air cushioning device 44.

A load-dependent pressure p is present in the air spring chamber 46. In the load measuring range, the pressure p prevailing in the air spring bellows 46 is used as a load signal and is fed directly via the pneumatic line 56 as an actuating signal to a pneumatic pressure switch 58, in particular having two switching positions, which serves as an actuator for the stepped switching or switching on of the load element 42 of the load line 32. The pneumatic line 56 does not change the tank pressure p as a load and regulation signal, apart from the unavoidable pressure losses due to friction inside the line 56, so this line 56 is the transmission device 38 in the sense of the present invention.

According to the embodiment of fig. 1, the load line 32 has a resistor 28 and additionally, for example, one or more inductors 60 connected in series with the resistor 28, wherein the pressure switch 58 can be controlled as a function of the tank pressure p in such a way that the inductance decreases with increasing load and increases with decreasing load. To this end, pressure switch 58 switches inductor 60 on resistor 28 as the load decreases and switches off as the load increases. It is also conceivable to use a pressure switch 58 with more than two switching steps, which switches on and off several inductors 60 in series with the resistor 28 in a multistage manner as a function of the load in order to adjust the braking torque in a stepwise manner as a function of the load.

For this purpose, the inductors 60 are each bridged by a shunt 62 connected in parallel. When there are a plurality of inductors 60, there are a corresponding number of jumper legs 62. When the crossover branch 62 is open, current flows through the inductor 60, which is bridged when the switching branch 60 is closed, so that only the resistor 28 or a small number of inductors 60 act in the load path 32. Furthermore, load line 32 with an on-off capacitor arranged in parallel with resistor 28, instead of or in addition to inductor 60, is also conceivable.

Here, an increase in the inductance in the load line 32, for example from zero, by switching on the inductance 60, results in a reduction in the maximum braking torque, whereas a reduction in the inductance results in an increase in the maximum braking torque. Thus, when the rail vehicle is lightly loaded or unloaded, braking is carried out with a smaller braking torque than the theoretically available maximum value of the large braking torque, which corresponds to the first switching position of the pressure switch 58, in which the jumper path 62 is open, so that current flows through the effective inductance 60.

When the rail vehicle or rail train is on load, this corresponds to the second switching position of the pressure switch 58 shown in fig. 3, in which the bridging branch 62 is closed and the inductance 60 is bridged, and current flows through the bridging branch 62, increasing the maximum braking torque that can be achieved as a result of the inductance reduction. The inductance in the load line 32 is therefore equal to zero in this case, but if a plurality of such inductances 60 are connected in series with the associated resistors 28, the inductance can also be reduced in stages by switching off a single inductance 60.

According to a further embodiment shown in fig. 4, the tank pressure p prevailing in the air spring tank 46 is also used as a load signal for load measurement and is supplied directly to the pneumatic actuator 64 as an adjustment signal via the pneumatic line 56, in order to steplessly adjust an inductance 66, which is likewise arranged in series with the resistor 28, as a function of the load. In order to be able to adjust the inductances 66 in a stepless manner, they are, for example, formed as magnetic coils and have a multi-part coil core, wherein a part of the coil core can be moved by the pneumatic actuator 64 relative to a stationary part of the coil core in such a way that the clear width of the air gap between the two parts of the coil core is changed, and thus the inductance. The pneumatic actuator 64 thereby steplessly adjusts the inductance of the load line 32 in accordance with the load.

The invention is not limited to ac circuit-powered vehicle traction drives, but can also be used in vehicle traction drives with permanently excited synchronous motors powered by a dc network, as described for example in DE 10160612a 1.

List of reference numerals

1 traction drive 34 device for load compensation

2 traction transformer 36 load measuring mechanism

4-traction converter 38 transmission or control mechanism

6 synchronous motor 40 actuator

8 brake 42 load element

10 primary winding 44 air damping device

12 secondary winding 46 air spring box

14 four-quadrant regulator 48 axle

16 absorption circuit 50 wheel

18 capacitive battery 52 truck

20 overvoltage protector 54 carriage

22 pulse current transformer 56 pneumatic pipeline

24-joint 58 pressure switch

26-joint 60 inductor

28 brake resistor 62 is connected across the branch

30 change-over switch 64 pneumatic actuator

32 load line 66 inductance

Claims (10)

1. A traction drive system (1) for the drive and generative braking of rail vehicles or rail trains, wherein at least one axle of the rail vehicle or rail train is provided with at least one permanently excited synchronous motor (6) and a traction converter (4), furthermore, the traction converter (4) has at least one machine-side pulse converter (22), the permanently excited synchronous motor (6) is connected to its connection terminals in such a way that it is connected to a changeover switch (30), namely, the permanent magnet excited synchronous motor (6) is driven by connecting a pulse converter (22) or by connecting a load line (32) constituting a load to generate power and brake, wherein the load circuit (32) for switching on the permanent-magnet synchronous motor (6) for generating braking is designed and/or controlled, enabling the characteristic value of the load line (32) to be changed as a function of the load of the rail vehicle or rail train; the load line (32) has a resistance (28) and also an inductance (60; 66) and/or a capacitance, characterized in that: an actuator (40; 58; 64) is provided which comprises a switching device (58, 62) which switches the inductance (60) and/or the capacitance on/off the resistance (28) depending on the load.

2. The traction drive system as defined in claim 1, wherein: the resistance, inductance or capacitance is changed in steps or steplessly.

3. The traction drive system as defined in claim 1, wherein: the load line (32) has an inductance (60; 66) which is connected in series with the resistor (28), wherein a transmission or control device (38, 56) controls the actuator (58; 64) as a function of the load in such a way that the actuator reduces the inductance of the load line (32) with increasing load and increases it with decreasing load.

4. A traction drive system as defined in claim 3, wherein: the switching device (58, 62) has an element for crossing the inductance (60).

5. The traction drive system as defined in claim 4, wherein: the inductor (66) comprises a magnetic coil, and the actuator (64) steplessly adjusts the inductor (66) by varying the magnetic circuit in response to a load.

6. Traction drive system according to one of claims 1 to 5, characterized in that: the generator brake based on the permanently excited synchronous motor (6) forms a safety or emergency brake, which is provided as a safety stage under the service brake.

7. Device (34) for load compensation during the regenerative braking of a rail vehicle or a rail train comprising an air damping device (44) with at least one air spring bellows (46) by means of a traction drive system (1) according to one of claims 1 to 6, characterized in that: the actuator (40; 58; 64) is formed by a pneumatic actuator (58; 64) which is directly controlled by the pressure (p) in the at least one air spring chamber (46) and, depending on this pressure (p), switches the inductance (60; 66) and/or the capacitance into or out of the resistance (28) depending on the load or steplessly adjusts the inductance (60; 66) and/or the capacitance.

8. The apparatus for load compensation as defined in claim 7, wherein: the pneumatic actuator is formed by a pressure switch (58) which is controlled by the pressure (p) in the at least one air spring chamber (46).

9. The apparatus for load compensation as defined in claim 8, wherein: the pneumatic actuator (64) steplessly adjusts the magnetic path of the inductor (66) in response to the load.

10. The apparatus for load compensation as defined in claim 9, wherein: the pneumatic actuator (64) steplessly adjusts the size of the air gap between the coil core portions of the inductor (66) coil core in response to load.