Controlling torsional shaft oscillation
First Claim
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1. A system for minimizing torsional oscillation of a shaft, said system comprising:
- a converter for providing a drive signal in response to receiving power wherein the converter has a separately excited field and the drive signal is a function of the excitation of the separately excited field;
a motor for providing torque to the shaft in response to the drive signal provided by the converter;
a sensor for sensing a torsional strain of the shaft;
a regulator for producing a compensation signal as a function of the torsional strain of the shaft; and
an excitation circuit responsive to the sensor for regulating the separately excited field to vary the drive signal as a function of the compensation signal such that torsional strain of the shaft is attenuated.
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Abstract
Torsional oscillation of a shaft in a swing drive system of an excavator is minimized by monitoring torsional strain of the shaft. An electric motor provides torque to the shaft in response to a drive signal provided by a converter. A compensation circuit produces a compensation signal as a function of torsional strain of the shaft. A field excitation circuit or regulator powers a converter as a function of the compensation signal such that a counter torque is provided to the shaft and torsional oscillation of the shaft is reduced.
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Citations
24 Claims
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1. A system for minimizing torsional oscillation of a shaft, said system comprising:
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a converter for providing a drive signal in response to receiving power wherein the converter has a separately excited field and the drive signal is a function of the excitation of the separately excited field; a motor for providing torque to the shaft in response to the drive signal provided by the converter; a sensor for sensing a torsional strain of the shaft; a regulator for producing a compensation signal as a function of the torsional strain of the shaft; and an excitation circuit responsive to the sensor for regulating the separately excited field to vary the drive signal as a function of the compensation signal such that torsional strain of the shaft is attenuated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of minimizing torsional oscillation of a shaft, said method comprising:
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generating a drive signal in a converter in response to receiving power at the converter wherein the converter has a separately excited field and the drive signal is a function of the excitation of the separately excited field; providing torque from a motor to the shaft in response to the drive signal driving the motor; sensing a torsional strain of the shaft; producing a compensation signal as a function of the sensed torsional strain; and providing power to the separately excited field of the converter as a function of the compensation signal to vary the drive signal as a function of the compensation signal such that the torsional strain of the shaft is attenuated. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of modifying an excavator swing drive system comprising:
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connecting an armature of a converter of the swing drive system to exactly one drive motor; connecting a forward field winding and a reverse field winding of the converter in parallel to form a single separately excited field; monitoring a torsional strain of a shaft driven by the exactly one drive motor; and regulating the separately excited field of the converter as a function of the monitored torsional strain such that torsional oscillation of the shaft is attenuated. - View Dependent Claims (21, 22, 23, 24)
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Specification