Wheelspeed estimation system and method
First Claim
1. A method of estimating the speed of a vehicle propelled by a DC traction motor having an armature coil and a field coil and being mechanically coupled to at least one wheel on the vehicle so as to rotate said wheel and propel the vehicle, said method including monitoring electrical operating parameters of the DC traction motor without use of a speed sensor, said method comprising:
- measuring the current in the armature coil and the current in the field coil of the DC traction motor;
measuring a voltage applied to the DC traction motor; and
determining a rotational speed of the DC traction motor as a function of the measured currents and voltage.
2 Assignments
0 Petitions
Accused Products
Abstract
A system and method for estimating the wheel speed of a vehicle propelled by DC motors mechanically coupled to at least one wheel on the vehicle so as to rotate said one or more wheel. At least one current detector is configured to measure armature and field current in each of the DC motors and produce a signal proportional to said currents and a voltage detector is configured to measure voltage applied to each of the DC motors and produce a signal proportional to said voltage. A processor is configured to determine a rotational speed as a function of the measured currents and voltages and configured to apply a correction factor to the determined rotational speed to obtain a corrected rotational speed.
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Citations
26 Claims
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1. A method of estimating the speed of a vehicle propelled by a DC traction motor having an armature coil and a field coil and being mechanically coupled to at least one wheel on the vehicle so as to rotate said wheel and propel the vehicle, said method including monitoring electrical operating parameters of the DC traction motor without use of a speed sensor, said method comprising:
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measuring the current in the armature coil and the current in the field coil of the DC traction motor;
measuring a voltage applied to the DC traction motor; and
determining a rotational speed of the DC traction motor as a function of the measured currents and voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for estimating the speed of a vehicle propelled by a DC traction motor having an armature coil and a field coil and being mechanically coupled to at least one wheel on the vehicle so as to rotate said one or more wheel and propel the vehicle, said method including monitoring electrical operating parameters of the traction motor without use of a speed sensor, said system comprising:
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at least one electric current detector configured to measure current in an armature coil of the DC traction motor and produce a signal indicative of said currents;
at least one electric current detector configured to measure current in a field coil in the DC traction motor and produce a signal indicative of said current;
a voltage detector configured to measure voltage applied to the DC traction motor and produce a signal proportional to said voltage; and
a processor receiving signals indicative of said current and voltage for determining a rotational speed of the motor as a function of the motor currents and voltages. - View Dependent Claims (15, 16, 17, 18, 23, 24, 25, 26)
a motoring speed estimator module configured to determine a motor rotational speed using the current and voltage signals when the vehicle is operating in a motoring mode.
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16. A system for estimating the speed of a vehicle propelled by the DC traction motor in accordance with claim 15, wherein said processor further comprises a locked axle detection module.
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17. A system for estimating the speed of a vehicle propelled by the DC traction motors in accordance with claim 16 wherein the speed correction module is configured to use an integration process using an Euler approximation.
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18. A system for estimating the speed of a vehicle propelled by the DC traction motors in accordance with claim 14 wherein the vehicle is a locomotive.
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23. A system for estimating the speed of a vehicle as set forth in claim 14 further comprising a processor configured to apply a correction factor to the determined rotational speed to obtain a corrected rotational speed.
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24. A system for estimating the speed of a vehicle as set forth in claim 14 further comprising a braking speed estimator module configured to determine a motor rotational speed using the current and voltage signals when the vehicle is operating in a braking mode.
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25. A system for estimating the speed of a vehicle as set forth in claim 15 further comprising a speed correction module configured to receive said signal indicative of the motoring mode motor rotational spped and at least one reference signal, said speed correction module configured to apply a correction factor to said rotational speed signal and translate said rotational speed signal to a linear speed signal.
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26. A system for estimating the speed of a vehicle as set forth in claim 24 further comprising a speed correction module configured to receive said signal indicative of the braking mode motor rotational speed and at least one reference signal, said speed correction module configured to apply a correction factor to said rotational speed signal and translate said rotational speed signal to a linear speed signal.
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19. A method of detecting the occurrence of a locked axle condition in a vehicle propelled by multiple DC traction motors each having an armature coil and a field coil by monitoring electrical operating parameters of the traction motor, without use of a speed sensor, said method comprising:
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measuring current in the armature coil for each of a plurality of DC traction motors connected to a plurality of axles;
determining a minimum armature current from the measured currents;
determining a maximum armature current from the measured currents; and
comparing the minimum armature current to the maximum armature current to identify the occurrence of a locked axle condition. - View Dependent Claims (21, 22)
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20. A method of detecting the occurrence of a locked axle condition in a vehicle propelled by multiple DC traction motors in accordance with claim 20 further comprising determining if the locomotive is operating in a motoring mode or a braking mode, and adding a value to the minimum armature current proportional to an Emf value for the traction motor multiplied by the rotational speed of the traction motor and divided by a resistance value for the traction motor when the vehicle is operating in the motoring mode.
Specification