Method for controlling a drive-off process of a railway vehicle

Abstract

A method controls a drive-off process of an electrically driven vehicle, the electric motor of which is fed via a converter. A holding torque necessary to prevent the vehicle from rolling back is determined. By using sensors for determining carriage masses and sensors for determining route inclinations, the holding torque can be precisely determined. In order to achieve a drive-off process of the electrically driven vehicle that is gentle on the electric motor and as long as a determined rotational motor speed is less than a specified limit rotational speed, a traction torque is limited by a control unit of the vehicle to a limit torque dependent on the holding torque, and the traction torque is increased beyond the limit torque by the control unit only once the rotational motor speed is greater than the limit rotational speed.

1 - 15 . (canceled) 
     
     
         16 . A method for controlling a drive-off process of an electrically driven vehicle, with which a holding torque necessary for preventing the electrically driven vehicle from rolling back is determined, which comprises the steps of:
 limiting a traction torque via a control unit of the electrically driven vehicle to a torque limit dependent on the holding torque if a determined motor revolution rate is less than a predetermined first revolution rate limit; and   raising the traction torque above the torque limit by the control unit if the determined motor revolution rate exceeds the predetermined first revolution rate limit.   
     
     
         17 . The method according to  claim 16 , wherein the torque limit is less than a maximum of 1.3 times the holding torque and 0.3 times a maximum traction value that can be set by the control unit. 
     
     
         18 . The method according to  claim 16 , wherein the torque limit exceeds the maximum of 1.2 times the holding torque and 0.2 times the maximum traction value that can be set by the control unit. 
     
     
         19 . The method according to  claim 16 , which further comprises increasing the traction torque linearly in relation to the determined motor revolution rate by the control unit until a predetermined second revolution rate limit is reached once the determined motor revolution rate is greater than the predetermined first revolution rate limit. 
     
     
         20 . The method according to  claim 16 , which further comprises setting the predetermined first revolution rate limit via the control unit depending on the holding torque. 
     
     
         21 . The method according to  claim 19 , wherein a ratio of the predetermined second revolution rate limit to the predetermined first revolution rate limit equals a ratio of a maximum of a traction value that can be set by the control unit to the torque limit. 
     
     
         22 . The method according to  claim 16 , which further comprises:
 determining for each carriage of the electrically driven vehicle a respective carriage mass and a carriage gradient parameter dependent on a track gradient angle;   calculating a carriage holding torque from the respective carriage mass and the carriage gradient parameter; and   calculating the holding torque of the electrically driven vehicle by summing all determined carriage holding torques.   
     
     
         23 . The method according to  claim 16 , wherein a brake is released by the control unit for driving off and a rise of the traction torque takes place in dependence on a reducing brake torque. 
     
     
         24 . The method according to  claim 16 , wherein a brake is released by the control unit for driving off before the traction torque is increased by the control unit starting from zero. 
     
     
         25 . The method according to  claim 16 , wherein a brake is released by the control unit for driving off and the traction torque is controlled by the control unit so that the traction torque first reaches the torque limit when a brake torque reaches zero. 
     
     
         26 . The method according to  claim 16 , which further comprises increasing the traction torque via the control unit so that a sum of the traction torque and a brake torque remains constant. 
     
     
         27 . The method according to  claim 16 , which further comprises:
 precalculating a first point in time at which a brake torque will have fallen to zero; and   calculating a preceding second point in time from the first point in time, so that, rising at a maximum allowed rate from zero at the preceding second point in time, the traction torque reaches the torque limit at the first point in time.   
     
     
         28 . The method according to  claim 16 , wherein if the determined motor revolution rate falls below the predetermined first revolution rate limit the traction torque is held by the control unit at the torque limit while the determined motor revolution rate is less than the predetermined first revolution rate limit, and the traction torque is increased by the control unit to above the torque limit once the determined motor revolution rate exceeds the predetermined first revolution rate limit. 
     
     
         29 . The method according to  claim 16 , wherein the traction torque is a negative traction torque for electrical braking. 
     
     
         30 . The method according to  claim 16 , which further comprises increasing the traction torque via the control unit so that a sum of the traction torque and a brake torque is equal to the torque limit. 
     
     
         31 . A control system for an electrically driven vehicle having at least one electric motor and a converter for supplying the electric motor, the control system comprising:
 a control unit for controlling the converter, said control unit configured to determine a holding torque that is necessary to prevent rolling back of the electrically driven vehicle, said control unit further configured to control the converter so that a determined motor revolution rate is less than a predetermined first revolution rate limit, and a traction torque of the vehicle is limited to a torque limit that is dependent on the holding torque and the traction torque is only then raised above the torque limit if the determined motor revolution rate is greater than the predetermined first revolution rate limit.