Traction vehicle adhesion control system without ground speed measurement

A creep rate regulator for an electric motor powered vehicle having a plurality of electric motors each coupled in driving relationship to respective wheels of the vehicle, the regulator comprising:

• means for obtaining a first signal representative of wheel acceleration;
• means for obtaining a second signal representative of vehicle acceleration;
• means for deriving from said first and second signals a third signal representative of wheel creep rate;
• means for comparing said wheel creep rate signal to a signal representative of a desired creep rate to obtain a creep rate error;
• means for converting said creep rate error to a torque command for controlling the electric motors in a manner to minimize said creep rate error.

An adhesion control system for a traction vehicle comprising:

• means for determining a side of operation of the system relative to a peak of the adhesion-creep curve, the side of operation corresponding to the sign of the slope of the adhesion-creep curve, based on a measurement of torque rate and creep rate, wherein the difference between the torque and inertia multiplied by the creep rate provides a measure of tractive effort, and wherein the sign of the rate of change of tractive effort and the sign of the creep rate are used in conjunction to determine the sign of the slope of the adhesion-creep curve;
• means for estimating an actual creep rate comprising a measurement or an estimation of motor or wheel acceleration and locomotive acceleration;
• means for selecting a creep rate set point based on the estimate of the sign of the slope of the adhesion-creep curve;
• and
• means responsive to said creep rate set point for adjusting the operation of the traction vehicle so that the maximum adhesion value is realized wherein the actual creep rate is increased if the creep rate set point is set to the positive value and is decreased if the creep rate set point is set to the negative value.

An adhesion control system for a traction vehicle 10, the adhesion control system comprising:

• a creep rate signal module coupled to receive respective signals representative of vehicle acceleration and vehicle wheel acceleration and to generate a creep rate signal in response to the respective acceleration signals;
• a creep rate set point module coupled to said creep rate signal summing junction and configured to generate a creep rate set point signal in response to said creep rate signal;
• a creep rate error module coupled to said creep rate signal module and said creep rate set point module and configured to generate a creep rate error signal responsive to said respective creep rate signal and said creep rate set point signal;
• and
• an integrator module coupled to said creep rate error module and configured to generate an adhesion torque command in response to said creep rate error signal, said integrator module further being coupled to said a vehicle torque regulator to supply said adhesion torque command thereto.