WO1994002335A1

WO1994002335A1 - Method for controlling the drive and/or braking power of a locomotive engine at the wheel traction limit

Info

Publication number: WO1994002335A1
Application number: PCT/EP1993/001603
Authority: WO
Inventors: Karl Hahn
Original assignee: Aeg Schienenfahrzeuge Gmbh
Priority date: 1992-07-22
Filing date: 1993-06-22
Publication date: 1994-02-03
Also published as: HUT66187A; PL171046B1; HU9400826D0; EP0801607A1; RU95105450A; DE4224581C1; CZ61694A3; CZ281629B6; RU2105679C1; PL305014A1

Abstract

The invention concerns a method for controlling the drive and/or braking power of a locomotive engine at the wheel traction limit, the method calling for the transition to the unstable slip region to be detected by virtue of the increase in wheel speed and the drive or braking power reduced to bring the wheels back into the stable slip region and the drive or braking power subsequently reduced again, etc. In the case of a system operating, with an integrator (13), as a pseudo-dead-axle system, the rpm (frot) of a drive axle is used to calculate an rpm difference (Δn) representing the degree of wheel slip. Using a differentiator (22) to calculate the value of dΔn/dt, the transition to the unstable slip region is determined and, on triggering of a limiting-value stage (43), an additional input parameter acting in opposition to the target value with which it is compared is fed to the integrator (13) until the system returns to the stable slip region. In order to avoid losses in tractive power when traction fails suddenly, the invention proposes that, in addition to the reduction in drive or braking power resulting from calculation of the rpm difference (Δn), a further reduction is made which is dependent on the maximum value reached by the first differential function with respect to time (dΔn/dt) of the difference in rpm (Δn).

Description

Method for regulating the drive and / or braking force of the traction motors of a traction vehicle at the adhesion limit of the wheels

The invention relates to a method for regulating the drive and / or

Braking force of the traction motors of a locomotive at the adhesion limit of the wheels, as defined in the preamble of claim 1. Such a method is already known (DE-PS 34 07 309). Through additional measures for a more precise finding of the right time to end the additional input variable at the integrator (DE-PS 38 37 908) and the introduction of

Stimulation impulses to increase the sensitivity to oiled or otherwise smeared rail surfaces (DE-PS 39 02 846) can further improve the known method.

However, there are other operating states to which it is only possible to react unsatisfactorily. These are profiles with a very fast or abruptly breaking frictional connection on the rails. These include the running of the wheel set from a dry rail onto a wet or lubricated area, the maximum adhesion suddenly falling to half or even less, or starting from a standing position or less

Speed on rail surfaces with a very steep drop in the adhesion even with a small amount of slip (water with sand, rust). In these cases, reducing the driving force from the A n course is too slow and undesirably large wheel slips occur, which can only be corrected gradually with a loss of tractive force.

The object of the invention is to exclude or minimize tensile force losses for these special cases.

This object is achieved for a method of the type mentioned at the outset in accordance with the characterizing features of claim 1. Advantageous refinements can be found in the subclaims. The invention is explained in more detail below with reference to the drawing figure.

The figure shows a block diagram for the control of a drive axle with an inverter-powered drive motor. 1 with an inverter is designated, which feeds a three-phase motor 2. The axis speed is e.g. detected by a tachometer machine 3 (or a rotary pulse generator with evaluator). The derived setpoint for the slip frequency f ".. of the motor, which is formed in the drive control, is applied to an input 4. Instead of a real measured vehicle speed, there is a pseudo

Running axle speed, which is compared in a difference generator 6 with the measured axle speed from the tachometer machine 3. The speed difference determined in the difference generator 6 is evaluated in a multiplier 7 with a suitable factor entered at the connection 8 or dependent on the speed and / or tractive force. The value obtained is subtracted from the target value of the engine slip frequency f ".. in a subtraction point 9 and is used as a torque target value. In a summer 10, the sum of the axle speed f and the desired engine slip frequency

Inverter frequency formed as the stator frequency of the traction motor 2.

The setpoint of the expected acceleration or deceleration is supplied to the connection 1 1, derived from the tractive or braking force and the vehicle mass. In locomotives, the trailer load must be taken into account, which can be done with automatic adaptation. This setpoint is in one

Integrator 13, which functions as a pseudo running axis, is integrated at a speed value. The integrator 13 is set so that it integrates faster by a small tolerance range than it corresponds to the true vehicle acceleration, so that the pseudo running axis speed of the actual vehicle speed would slowly run away. The integrator 13 therefore receives an additional feedback via a

Comparator 14, switching points 15 and 16, as well as one-way rectifiers 17, 18 or other arrangements, each of which only allows signals of one polarity, and an adder 12. In comparator 14, the integrator output, i.e. the pseudo running axis speed compared with the speed of a real axis. Positive difference (i.e. the pseudo running axis runs faster) is only in the

Operational state "driving" (15 closed) given to the integrator 13 via one-way rectifier 17 and then controls the pseudo-running axis until this also with the speed of the real axis matches. Negative difference (ie pseudo running axis runs slower) and is given in the "braking ^{" state} (16 closed) to integrator 13 via one-way rectifier 18 and then controls the pseudo running axis upwards until there is agreement with the real axis. As a result, the integrator output is no longer accelerated or decelerated than the vehicle as long as the real axis is rolling. The speed values are the same, and there are no speed differences at the difference generator 6.

If wheel slip occurs in the "driving" state, the axle will ultimately accelerate faster than the vehicle or the integrator. The integrator 13 can now not be taken over the feedback because one-way rectifier 17 does not pass a signal of negative polarity. A speed difference arises at the difference generator 6, as between the driving axle and a real running axle.

When braking, the polarity of the difference is reversed, causing that

Feedback signal is routed via 16, 18. The speed difference signal occurring at the difference generator 6 then controls the torque and thus the traction or braking force of the traction motor, as described with reference numerals 1 to 10.

Now e.g. the pseudo speed of rotation has already reached a value that no longer corresponds to the speed above ground, but to an axis that is already rotating with a slip on the rail, as is necessary to transmit the maximum possible tractive force. During the emergence of this slip, i.e. from the mere rolling of the driving axle, it is already accelerated to a measurably greater extent than the vehicle. Until then, the integrator 13 can still follow the axis speed. A stronger acceleration of the drive axle only begins when the slip of the maximum coefficient of friction is exceeded.

Without further measures, the pseudo running axis integrator 13 would now continue to run freely, the pseudo running axis also gradually becoming faster and faster with respect to the vehicle. The driving axle would also assume ever greater slip and eventually skid.

To prevent this, the control is designed so that the wheelset or

Wheelset group by reducing the driving force of the engine F.. (or braking force when braking) over the adhesion maximum in the stable Hatching area is returned. Here, the elements 19, 20, 21 form a polarity reversal device, which exchanges the polarity of the speed difference signal in braking operation. With 22 a differentiating device is designated, which forms the first time derivative of the speed difference signal d Δ n / dt. With 40 a delay element of the 1st order is designated, which the rise of the output signal from

Differentiation device 22 somewhat flattened. The output of the delay element 40 is also guided via an electronically operated switch 41 with normally closed contact to a limit value stage 43, which outputs a binary signal to an OR gate 44. A feedback leads to a timer 42, which opens the switch 41 after reaching a response delay and after the end of another

Delay time closes this again. This eliminates undesirably long signals in the sense of process monitoring. The output of the OR gate 44 acts on a switch 31 and, via an inverter 45, on the reset input of a 1st timer 46 with a switch-off delay which has been set by the output of the limit value stage 43. The 1st timer 46 abuts a 2nd timer

47, which has a switch-on delay. A second switch 48 is actuated via the second timing element 47, which connects the output of a maximum value selection stage 51 to a Schmitt trigger 52 and triggers it, so that a further signal can reach OR gate 44 via a control switch 53. The maximum value selection stage 51 receives, on the one hand, a direct input signal from the differentiating device 22 and a downstream inverter 49 and, on the other hand, an additionally differentiated input signal via a third differentiator 50. The maximum value selection stage 51 only allows the signal with the larger value of both to pass through. The control switch 53, via which the signal from Schmitt trigger 52 can reach the OR gate 44, is operated by one

Activated trigger stage, which consists essentially of the elements 54, 55, 56, 57, 58, the measured axle speed f and the tensile force F _M derived from the measured engine torque Md.

The axle speed f is differentiated in a second differentiator 54 and as

Axis acceleration a _R , via switch (directly when driving or inverted when braking) fed to a summation point 55, at which the tensile force F _M derived from the electrically measured torque Md. The output at summation point 55 is the calculated tensile force F which the wheel transmits to the rail at the same time. A spin results in one

Force distribution in which only part of the tractive force is still transmitted to the rail and the excess part accelerates the rotating wheel mass. Vice versa If the wheel set is decelerated, the kinetic energy is released again for tractive power transmission and is added to the engine torque. In other words, if you want to determine the real tractive force transferred to the rail, you have to take into account the kinetic energy of the wheelset. This is done by adding F- to the measured engine tensile force at summation point 55. the (also measured)

Wheelset acceleration evaluated with the wheelset mass accordingly, added (negative when driving, positive when braking, as shown in 54, 59, 55).

The tensile force value F determined in this way is differentiated in a first differentiating element 56 and fed via a negation element 57 to a threshold value switch 58 which controls the control switch 53. Only if the 1st differentiator 56 has a negative output, i.e. with decreasing traction. the threshold switch 58 responds. whereby the OR gate 44 receives no further input signal via the b input and - if there is no input signal at the a input at this point in time - no longer outputs an output signal. As a result, the 1st timer 46 is reset via the reset input. It is only switched on again when acceleration or deceleration triggers limit stage 43 and actuates switch 31 via OR gate 44 to influence integrator 13, i.e. a new spin start begins.

If a speed difference appears on the difference generator 6, the wheels have, as described above, exceeded the slip on the rails, which enables the greatest power transmission. They run into the unstable hatching area, i.e. as the slip increases, the adhesive value becomes smaller again. The now increasing torque excess accelerates the compared to

Vehicle mass only small rotating mass of the wheelset with traction motor relatively quickly. The increase in the speed difference is detected by the differentiating device 22 and brings about the delay element 40 (for filtering out short-term disturbances) and the switch 41, the limit value stage 43 to respond. Their output signal actuates the switch 31 via the OR gate 44, as a result of which a signal formed from the expected acceleration value from the terminal 11 and an added constant (addition point 33) and inverted in the inverter 34 via the time stage 32 and the adder 12 at the input of the Integrators 13 takes effect. The time stage 32 allows part of the signal to pass through immediately, the rest to rise to full height with a first-order delay. A

Fall-off delay for the signal does not contain time stage 32, as symbolically indicated. The integrator 13 slows down and starts as soon as that Additional signal exceeds the direct signal to integrate in the opposite direction. The pseudo running axle speed thus becomes lower. As a result, the speed difference at the difference generator 6 initially increases even faster, but at the same time the torque of the traction motor is reduced more with the larger speed difference signal. As a result, the further acceleration of the wheel set ceases, the wheel set begins to "catch ^{" again} , that is to say it runs back into the stable slip area. Since the wheel set speed is again approaching the pseudo running axle speed, the speed difference signal at the difference generator 6 also becomes smaller again. However, the downward control of the integrator 13 via the switch 31 must be maintained until the wheel set has again reached the stable slip range, ie the adhesive value / slip curve has returned via the maximum adhesive value. On the other hand, the system would remain in the unstable area and eventually skid.

This is the purpose of the Schmitt trigger 52, which is sensitive by the inverter 49 to negative dΔ n / dt, that is to say the reduction in the speed difference signal, and likewise outputs its signal to the OR gate 44. After the limit value stage 43 has responded, it takes effect after the second timer 47 and the further switch 38 have expired. Via the third differentiator 50, the Schmitt trigger 52 receives an additional leading signal by means of the maximum value selection stage 51, which means that it can respond even before the limit value stage 43 has dropped back. This avoids a gap in the output signal of the OR gate 44 when the dΔn / dt signal crosses zero. This could also - alternatively - be achieved by an additional drop delay of limit value stage 43 if elements 50 and 51 are omitted. Due to the delay time of the second timer 47, the Schmitt trigger 52 can only respond when the limit value stage 43 has switched on by this minimum time; As a result, short-term disturbances, which are not real spinning approaches, have no further effect here. The fallback time of the 1st timer 46 ensures that the Schmitt trigger 52 can remain effective for an appropriate duration of the negative speed difference signal dΔn / dt when the limit value stage 43 has already switched off again.

The Schmitt trigger 52 thus maintains the additional signal for the integrator 13 until the (negative) dΔn / dt signal goes through zero again.

With the arrangement of the elements 54 to 58, possibly also 59, which always emits a signal from the threshold switch 58 when it is on the rails transmitted tractive force shows a falling tendency, the point in time is determined more precisely by the wheelset beginning to run back into the stable slip area via the maximum adhesion. At precisely this point in time, the signal appears at the threshold switch 58 and switches off a signal still present at the Schmitt trigger 52 by means of the control switch 53, as a result of which the additional signal of the

Integrator 13 of the pseudo-running axis is interrupted and this can accelerate again.

This known arrangement is now, according to the invention - as indicated by a thick line - supplemented by a transmission element 80 and a maximum value memory 81. 80 is a preferably linear transmission link with a dead zone on

Beginning; 81 a maximum value memory with a discharge circuit which allows a stored value to decay back to zero, preferably after an e-function, as soon as and as long as there is no signal at the input which exceeds the instantaneous value. The input of the transmission element 80 is due to the differentiated speed difference dΔn / dt (output of the differentiating device 22) and is connected on the output side to the maximum value memory 81, which with its

Output - on a suitable scale - is connected to subtraction point 9. The

Output is used directly for additional reduction by subtracting from the torque setpoint.

The mode of action is as follows: In the case. a sudden slump in the adhesion due to running wheels on a wet or lubricated spot on the rails or in the event of a steep drop in the adhesion characteristics even at a small one

Slip (e.g. water with sand) instantly causes the wheelset to accelerate rapidly. Δ n grows very quickly and the differentiated value dΔ n / dt immediately becomes much larger than in normal hatching processes. As a result, it crosses the dead zone of the transmission element 80 and the excess part reaches the subtraction point 9 via the maximum value memory 81 and leads to

Reduction of the nominal value of the driving force. Due to the rapidly decreasing torque on the wheels, their further acceleration stops at a small slip and the signal dΔ n / dt disappears again. The maximum value memory 81 still maintains its signal with its decay time constant. If this is chosen appropriately, the reduction in the driving force over time disappears approximately to the extent that it is replaced by the normal process which starts at the same time in the known arrangement by reduction the pseudo-run speed in the integrator 13, where the Δ n necessary for the required reduction is produced in the difference former 6. The drive suddenly accepted the new, reduced torque and is now being continued from the known arrangement as before. The part according to the invention then no longer intervenes, because in normal wheel slip processes the dead zone of the transmission member 80 is not exceeded by the dΔn / dt values.

Claims

Patent claims

1.Procedure for regulating the drive and / or braking force of the traction motors of a traction vehicle at the adhesion limit of the wheels, in which the transition to the unstable slip range is determined on the basis of the increasing wheel acceleration (deceleration), the wheelset or the wheelset group then by reducing the The drive or braking force is returned to the stable slip range beyond the adhesion maximum and then the drive or braking force is increased again, etc., for an arrangement working with an integrator (13) as a pseudo running axis, in each of which the speed difference (Δn ) between the output variable of the integrator (13) and the axle speed (f) of an assigned drive axle serves as a measure of the wheel slip and is evaluated to reduce the drive or braking torque and in each case by means of a differentiating device

(22) the first time derivative of the speed difference (dn / dt) detects the transition to the unstable slip range based on the onset of stronger acceleration and, when a limit value step (43) is triggered, the integrator (13) receives an additional setpoint for the acceleration or The input counteracting deceleration until the return is applied to the stable slip range, characterized in that, in addition to the reduction in the drive or braking force caused by the evaluation of the speed difference (Δn), a further reduction takes effect, which is dependent on the maximum height of the first time derivative (dΔn / dt) of the speed difference (n) is dependent.

2. The method according to claim 1, characterized in that the portion of the first time derivative (dΔn / dt) exceeding a threshold value is held in a maximum value memory (81) and is returned to zero with a decay function as soon as and as long as the time Course of the first time derivative (dn / dt) falls below the maximum and the respective value of the decay function.

3. The method according to claim 2, characterized in that the decay function

-t / T is an exponential function f = U * e as when a capacitor is discharged.