Method and apparatus for analysis of polyphase electrical motor systems
First Claim
1. A method of determining at least one operating parameter for determining the operating condition of a polyphase electrical motor system comprising the steps of:
- (a) sensing the instantaneous current signal as a function of time for more than one electrical phase of the motor;
(b) sensing the instantaneous voltage signal as a function of time for more than one electrical phase of the motor;
(c) amplitude demodulating the sensed current signals and the sensed voltage signals to provide an amplitude demodulated current signal as a function of time and an amplitude demodulated voltage signal as a function of time for more than one electrical phase;
(d) phase demodulating the sensed current signals and the sensed voltage signals to provide a phase demodulated current signal as a function of time and a phase demodulated voltage signal as a function of time for more than one electrical phase; and
(e) utilizing the amplitude demodulated current and voltage signals and the phase demodulated current and voltage signals to determine at least one electrical motor operating parameter as a function of time from the group consisting of;
total real power, real power per phase, total reactive power, reactive power per phase, total apparent power, apparent power per phase, overall power factor, power factor per phase, electrical impedance per phase, and electrical balance.
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Abstract
A method for determining at least one operating parameter to determine the operating condition of a polyphase electric motor system comprises sensing the instantaneous current signal and the instantaneous voltage signal as a function of time for more than one electrical phase of the motor. The sensed current signals and the sensed voltage signals are both amplitude demodulated and phase demodulated to provide amplitude demodulated current and voltage signals as a function of time and phase demodulated current and voltage signals as a function of time. The resulting amplitude and phase demodulated signals are used to determine one or more of the following electrical parameters as a function of time: total real power, real power per phase, total reactive power, reactive power per phase, total apparent power, apparent power per phase, overall power factor, power factor per phase, electrical impedance per phase, and electrical balance.
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Citations
25 Claims
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1. A method of determining at least one operating parameter for determining the operating condition of a polyphase electrical motor system comprising the steps of:
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(a) sensing the instantaneous current signal as a function of time for more than one electrical phase of the motor; (b) sensing the instantaneous voltage signal as a function of time for more than one electrical phase of the motor; (c) amplitude demodulating the sensed current signals and the sensed voltage signals to provide an amplitude demodulated current signal as a function of time and an amplitude demodulated voltage signal as a function of time for more than one electrical phase; (d) phase demodulating the sensed current signals and the sensed voltage signals to provide a phase demodulated current signal as a function of time and a phase demodulated voltage signal as a function of time for more than one electrical phase; and (e) utilizing the amplitude demodulated current and voltage signals and the phase demodulated current and voltage signals to determine at least one electrical motor operating parameter as a function of time from the group consisting of;
total real power, real power per phase, total reactive power, reactive power per phase, total apparent power, apparent power per phase, overall power factor, power factor per phase, electrical impedance per phase, and electrical balance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of determining at least one operating parameter for detecting the operating condition of a polyphase electrical motor system comprising the steps of:
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(a) sensing the instantaneous current signal as a function of time for more than one electrical phase of the motor; (b) sensing the instantaneous voltage signal as a function of time for more than one electrical phase of the motor; (c) amplitude demodulating the sensed current signals and the sensed voltage signals to provide an amplitude demodulated current signal as a function of time and an amplitude demodulated voltage signal as a function of time for more than one electrical phase; and (d) utilizing the amplitude demodulated current and voltage signals to determine at least one electrical motor operating parameter as a function of time from the group consisting of;
total apparent power, apparent power per phase, and electrical balance.
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22. A method of determining the power factor per phase for detecting the operating condition of a polyphase electrical motor system comprising the steps of:
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(a) sensing the instantaneous current signal as a function of time for more than one electrical phase of the motor; (b) sensing the instantaneous voltage signal as a function of time for more than one electrical phase of the motor; (c) phase demodulating the sensed current signals and the sensed voltage signals to provide a phase demodulated current signal as a function of time and a phase demodulated voltage signal as a function of time for more than one electrical phase; and (d) utilizing the amplitude demodulated current and voltage signals and the phase demodulated current and voltage signals to determine the power factor per phase as a function of time.
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23. A system for determining the operating condition of a polyphase electrical motor system using at least one operating parameter of the motor, the system comprising:
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a first sensor for sensing an instantaneous current signal supplied to the motor as a function of time for more than one electrical phase of the motor; a second sensor for sensing an instantaneous voltage signal supplied to the motor as a function of time for more than one electrical phase of the motor; means for amplitude demodulating the sensed current signals and the sensed voltage signals to provide an amplitude demodulated current signal as a function of time and an amplitude demodulated voltage signal as a function of time for the more than one electrical phases of the motor; means for phase demodulating the sensed current signals and the sensed voltage signals to provide a phase demodulated current signal as a function of time and a phase demodulated voltage signal as a function of time for the more than one electrical phases of the motor; and means for calculating at least one electrical motor operating parameter as a function of time utilizing the amplitude demodulated current and voltage signals and the phase demodulated current and voltage signals, wherein the at least one electrical motor operating parameter is from the group consisting of;
total real power, real power per phase, total reactive power, reactive power per phase, total apparent power, apparent power per phase, overall power factor, power factor per phase, electrical impedance per phase, and electrical balance.
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24. An apparatus for determining at least one operating parameter for detecting the operating condition of a polyphase electrical motor system, the apparatus comprising:
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a first sensor for sensing an instantaneous current signal supplied to the motor as a function of time for more than one electrical phase of the motor; a second sensor for sensing an instantaneous voltage signal supplied to the motor as a function of time for more than one electrical phase of the motor; means for amplitude demodulating the sensed current signals and the sensed voltage signals to provide an amplitude demodulated current signal as a function of time and an amplitude demodulated voltage signal as a function of time for the more than one electrical phase of the motor; and means for calculating at least one electrical motor operating parameter as a function of time utilizing the amplitude demodulated current and voltage signals, wherein the at least one electrical motor operating parameter is from the group consisting of;
total apparent power, apparent power per phase, and electrical balance.
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25. An apparatus for determining the power factor per phase for detecting the operating condition of a polyphase electrical motor system, the apparatus comprising:
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a first sensor for sensing an instantaneous current signal supplied to the motor as a function of time for more than one electrical phase of the motor; a second sensor for sensing an instantaneous voltage signal supplied to the motor as a function of time for more than one electrical phase of the motor; means for phase demodulating the sensed current signals and the sensed voltage signals to provide a phase demodulated current signal as a function of time and a phase demodulated voltage signal as a function of time for the more than one electrical phase of the motor; and means for calculating the power factor per phase as a function of time utilizing the phase demodulated current and voltage signals.
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Specification