US3593077A — Electrical circuit for pulse fed inductive load

Claim 1

Independent Claim 222 words

A hoist motor system for an elevator comprising a direct current hoist motor; an armature for said motor; a shunt field for said motor; means for energizing said shunt field; a direct current generator; an armature for said generator connected to said motor armature; a shunt field for said generator; means for generating a signal proportional to the speed of said motor; means for generating a speed command signal; means for combining said speed signal and said command signal to produce an error signal; a source of alternating current having two terminals; a pair of controlled rectifiers having like electrodes connected to the opposite terminals of said source, the electrodes of said rectifiers opposite said like electrodes being connected to a common point; a control electrode for each rectifier; means to periodically apply signals to said control electrodes of a magnitude and phase to initiate conduction in said rectifiers; means to control the magnitude of said signals to said control electrodes according to said error signal; said rectifiers passing current to the shunt field of said generator as unidirectional pulses of opposite polarity; a capacitance connected across said generator field to enable said pulses to build up the direct current flux in said generator; and an inductance connected in series with said capacitance to limit the pulsating current drawn through said rectifiers.

Claim 2

Dependent Claim 222 words

A hoist motor system for an elevator comprising a direct current hoist motor; an armature for said motor; a shunt field for said motor; means for energizing said shunt field; a direct current generator; an armature for said generator connected to said motor armature; a shunt field for said generator; means for generating a signal proportional to the speed of said motor; means for generating a speed command signal; means for combining said speed signal and said command signal to produce an error signal; a source of alternating current having two terminals; a pair of controlled rectifiers having like electrodes connected to the opposite terminals of said source, the electrodes of said rectifiers opposite said like electrodes being connected to a common point; a control electrode for each rectifier; means to periodically apply signals to said control electrodes of a magnitude and phase to initiate conduction in said rectifiers; means to control the magnitude of said signals to said control electrodes according to said error signal; said rectifiers passing current to the shunt field of said generator as unidirectional pulses of opposite polarity; a capacitance connected across said generator field to enable said pulses to build up the direct current flux in said generator; and an inductance connected in series with said capacitance to limit the pulsating current drawn through said rectifiers.

Claim 3

Dependent Claim 105 words

In combination a controlled source of electrical pulses, a first terminal for said source repetitively issuing pulses of a first polarity of a controlled magnitude, a second terminal for said source repetitively issuing pulses of said first polarity of a controlled magnitude, an inductive load for said source, means connecting said first and second terminals across said inductive load, a capacitance of a magnitude to supply the current required of said load during the intervals of nonconduction of pulses from the terminal issuing the pulses of greatest magnitude connected across said inductive load, and current limiting means in series with said capacitance across said load.

Claim 4

Dependent Claim 105 words

In combination a controlled source of electrical pulses, a first terminal for said source repetitively issuing pulses of a first polarity of a controlled magnitude, a second terminal for said source repetitively issuing pulses of said first polarity of a controlled magnitude, an inductive load for said source, means connecting said first and second terminals across said inductive load, a capacitance of a magnitude to supply the current required of said load during the intervals of nonconduction of pulses from the terminal issuing the pulses of greatest magnitude connected across said inductive load, and current limiting means in series with said capacitance across said load.

Claim 5

Dependent Claim 25 words

A combination according to claim 2 wherein said inductive load of about 6 henrys and said capacitance is of the order of 1, 500 microfarads.

Claim 6

Dependent Claim 14 words

A combination according to claim 2 wherein said current limiting means is an inductance.

Claim 7

Dependent Claim 34 words

A combination according to claim 6 wherein said inductance has an inductive reactance at the frequency of application of said pulsations from said source of more than twice the capacitive reactance of said capacitance.

Claim 8

Dependent Claim 93 words

A combination according to claim 2 wherein said source comprises first and second controlled rectifiers each having a main anode and a main cathode-electrode, said first and second terminals are like main electrodes of said first and second controlled rectifiers respectively, said load is a shunt field of a dynamoelectric generator, and said current limiting means is an inductive reactance more than twice the capacitive reactance of said capacitance at the frequency of application of pulses from said source, and said combination includes a resistance across said capacitance and said current limiting means.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1974-07-12	1975-01-11	1975-07-13	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1978-07-12	1979-01-11	1979-07-13	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1982-07-12	1983-01-11	1983-07-13	$7700.00	Window Closed / Lapsed

Electrical circuit for pulse fed inductive load

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