Antispin and antilock methods for an electric traction vehicle

• US 5,289,093 A
• Filed: 10/30/1992
• Issued: 02/22/1994
• Est. Priority Date: 11/08/1989
• Status: Expired due to Term

• Current Assignee: GEC Alsthom SA
• Original Assignee: GEC Alsthom SA
• Inventors: Jobard, Thierry
• Primary Examiner(s): SALATA, ANTHONY J
• Application Number:
  US07/969,517
• Time in Patent Office: 480 Days
• Field of Search: 318/434, 318/52, 318/71, 318/78, 318/139, 318/798-812, 318/432, 361/238, 180/197, 303/93-95, 303/100, 303/102
• US Class Current: 318/434
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 3/10 Indicating wheel slip ; Correction of wheel slip

Abstract

A method of preventing wheel spin or wheel locking on an electric traction vehicle whose traction transmission includes servo controlling of one or more control parameters of the motor(s) of the traction transmission to an input reference value. The method is such that the control parameter(s) obtained at the output from the servo control are permanently limited by ideal values for the control parameter(s), which ideal values are such as to make it possible to obtain an input reference value for the speed of rotation of the motor(s) equal to the real travel speed of the vehicle, referred to as the reference speed, in such a manner as to stabilize the torque transmitted by the motor(s) in the event of wheel spin or wheel locking.

Claims

1. A method of preventing wheel spin or wheel locking on an electric traction vehicle whose traction device includes a servo controller for servo controlling at least one control parameter of at least one motor of said traction device to a predetermined value, the method being characterized in that the at least one control parameter output from said servo controller is permanently limited by an ideal value for said at least one control parameter, such that the predetermined value corresponds to a speed of rotation of said at least one motor equal to a real travel speed of the vehicle, in such a manner as to stabilize the torque transmitted by said at least one motor in the event of wheel spin or wheel locking.

2. A method according to claim 1, characterized in that the at least one control parameter output of said servo controller is permanently limited to the ideal value so that in the event of wheel spin or wheel locking, the torque transmitted by said at least one motor is stabilized to a value corresponding to that which enables transmission at the maximum available adhesion.

3. A method according to claim 1, characterized in that said traction device comprises at least one separate excitation DC motor having armature and field windings, and a chopper and an excitation bridge respectively associated with the armature and field windings, the at least one control parameter being an ON ratio of the chopper below a rated speed of said at least one motor and being an ON ratio of the excitation bridge above the rated speed of said motor, and said ideal value permanently limiting the at least one control parameter output from said servo controller so as to stabilize the torque transmitted by said at least one motor in the event of wheel spin or wheel locking being referred to as a limiting value, the control parameter applied to said at least one motor below the rated speed of said at least one motor being the smaller of a first limiting value and a first output from said servo controller;

and above the definition speed of said at least one motor being the greater or the smaller of a second limiting value and a second output from said servo controller, depending on whether the traction device is operating in traction or in braking.

4. A method according to claim 1, characterized in that said traction device comprises at least one asynchronous motor powered by a voltage inverter, the at least one control parameter being the frequency of the stator feed to said at least one asynchronous motor, said servo controller servo controls a slip frequency of said at least one asynchronous motor, with a measured value of rotation of said at least one asynchronous motor subsequently being added thereto to obtain the frequency of the stator feed, and said ideal value permanently limiting the at least one control parameter output from said servo controller so as to stabilize the torque transmitted by said at least one asynchronous motor in the event of wheel spin or wheel locking being referred to as a limiting value, the control parameter applied to said asynchronous motor is obtained by selecting the smaller of the following two values for a slip value:

a first limiting value and a first value delivered by the servo controller, and in selecting, as the frequency of rotation, the smaller or the greater of a second limiting value and the measured value, depending on whether said traction device is operating in traction or in braking.

5. A method according to claim 1, characterized in that the control parameter output by said servo controller is limited to the ideal value so that in the event of wheel spin or wheel locking, and after a predetermined duration during which the ideal value has been selected for application to said at least one motor instead of the output value form said servo controller, said ideal value is replaced by a value designed to prevent a small amount of wheel spin being maintained due to operation at the available adhesion.

6. A method according to claim 5, characterized in that said value for avoiding a small amount of wheel spin being maintained is constituted by values that permanently limit the at least one control parameter output from said servo controller in such a manner as to stabilize the transmitted torque, in the event of wheel spin or wheel locking, to a value which is lower than the value which the available adhesion is capable of transmitting.

7. A method according to claim 5, characterized in that said value for preventing a small amount of wheel spin being maintained is constituted by outputs of said servo controller to which a reference value is applied that has been reduced to a value corresponding to the value of the torque obtained during said predetermined duration.

8. A method according to claim 1, wherein said method is applied to detect wheel spin or wheel locking in an electric traction vehicle, the method being further characterized in that said detection of wheel spin or wheel locking is obtained by detecting the instant at which said ideal value permanently limiting the control parameter obtained at the output of said servo controller for stabilizing the torque transmitted by said motor in the event of wheel spin or wheel locking, referred to as a limiting value, is selected for application to said at least one motor instead of the output from said servo controller.

9. A method according to claim 2, wherein said method is applied to measure adhesion of an electric traction vehicle, the method being further characterized in that the measurement of adhesion is obtained by comparing a torque reference value with the torque actually obtained, with the available adhesion being greater than or equal to the adhesion enabling the reference torque to be transmitted in the event of equality, or less than that in the vent that the real torque is less than the reference torque, in which case the real torque is representative of the available adhesion.