Thermal protection for locomotive main traction alternators
First Claim
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1. A thermal overload protection control method for a locomotive having an alternator, the method comprising the steps of:
- (a) providing a sensor temperature;
(b) sensing ambient inlet air temperature to the alternator;
(c) calculating a traction motor current limit to generate a calculated traction motor current limit value, including the steps of,i. dividing a difference between the stator winding sensor temperature and the alternator ambient air temperature by a calibration factor to generate a first value,ii. summing the first value and the alternator ambient air temperature to generate a second value,iii. multiplying the second value and a constant related to a time rate of load reduction to generate a third value, andiv. substracting the third value from a constant related to a maximum permissible winding temperature to generate a fourth value which is indicative of the calculated traction motor current limit value; and
(d) controlling thermal overload in response to the calculated traction motor current limit value.
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Abstract
In a thermal overload protection system three system variables are sensed and provide the inputs required for a calculation conducted in real time at one second intervals. The system variables include ambient inlet air temperature to the alternator, alternator stator winding embedded sensor temperature, and traction motor armature current. A traction motor current limit is calculated using the inlet air temperature and the sensor temperature. The thermal overload is then controlled in response to the traction motor current.
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Citations
13 Claims
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1. A thermal overload protection control method for a locomotive having an alternator, the method comprising the steps of:
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(a) providing a sensor temperature; (b) sensing ambient inlet air temperature to the alternator; (c) calculating a traction motor current limit to generate a calculated traction motor current limit value, including the steps of, i. dividing a difference between the stator winding sensor temperature and the alternator ambient air temperature by a calibration factor to generate a first value, ii. summing the first value and the alternator ambient air temperature to generate a second value, iii. multiplying the second value and a constant related to a time rate of load reduction to generate a third value, and iv. substracting the third value from a constant related to a maximum permissible winding temperature to generate a fourth value which is indicative of the calculated traction motor current limit value; and (d) controlling thermal overload in response to the calculated traction motor current limit value. - View Dependent Claims (2, 3, 4)
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5. A thermal overload protection system for a locomotive having an alternator comprising:
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(a) means for providing a sensor temperature; (b) means for sensing ambient inlet air temperature to the alternator; (c) means for calculating a traction motor current limit to generate a calculated traction motor current limit value, including, i. means for dividing a difference between the sensor temperature and the alternator ambient air temperature by a calibration factor to generate a first value, ii. means for summing the first value and the alternator ambient air temperature to generate a second value, iii. means for multiplying the second value and a constant related to a time rate of load reduction to generate a third value, and iv. means for subtracting the third value from a constant related to a maximum permissible winding temperature to generate a fourth value which is indicative of the calculated traction motor current limit value; and (d) means for controlling thermal overload in response to the calculated traction motor current limit value. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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Specification