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US3611087A Expired / Lapsed US ⏱️ 0.0 years remaining

Frequency-controlled ac drive

Assignee: Individual
•
Filing: 1970-05-12
•
Granted: 1971-10-05
•
Expires: 1990-05-12
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Abstract

Abstract As is well known, a six-phase thyristor circuit of a so-called cycloconverter provided with 36 thyristors allows an output frequency at the order of 15 to 20 c.p.s. to be produced with the network frequency being equal to 60 c.p.s. A frequency-controlled AC drive of the invention is based on the use of modulation apparatus of nonreversible magnetic amplifiers with an output of second harmonics and diodes, which simultaneously perform functions of demodulators and internal feedback tubes. Thyristors are employed for varying the direction of current in the windings of the motors. For a three-phase motor provided with six-phase magnetic amplifiers, there are required in total 6 thyristors and 36 noncontrolled diodes. Thus an output frequency is obtained ranging from 0 to 90 percent of the network frequency. Hence, at a frequency of 60 c.p.s. it is possible to achieve a gradual variation in frequency from 0 to 50-55 c.p.s. Efficiency of the modulators based on double magnetic amplifiers attains even with low powers a value of the order of 80 percent. Even with low frequencies and voltages, the output voltage will approximate a sinusoidal one. The present invention may be used at increased network frequencies of the order of 400 to 500 c.p.s. for driving induction and synchronous alternating current motors of an increased rotation speed.

Inventors

  • 👤 Isaak Maximovich Shtein

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-25 22:00
CPC Classifications
H; H02; H02M; H02M5/00; H02M5/02; H02M5/04; H02M5/22; H02M5/25; H02M5/27

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 117 words
In a frequency-controlled AC drive having an electric motor with multiple phases, and an auxiliary source for supplying variable frequency; magnetic amplifiers in each phase of the electric motor and operating in the mode of frequency modulation effected by the variable frequency supplied by said auxiliary source of frequency; said magnetic amplifiers being of a nonreversible type having double-frequency outputs, each output including secondary windings in said magnetic amplifiers and demodulator diodes, the phases of said motor including semiwindings, said outputs of each magnetic amplifier being connected with two semiwindings of one of the phases of said electric motor so as to form a bridge circuit including diagonals, and noncontact switches operating in turn in said diagonals.
Claim 2
Dependent Claim 117 words
In a frequency-controlled AC drive having an electric motor with multiple phases, and an auxiliary source for supplying variable frequency; magnetic amplifiers in each phase of the electric motor and operating in the mode of frequency modulation effected by the variable frequency supplied by said auxiliary source of frequency; said magnetic amplifiers being of a nonreversible type having double-frequency outputs, each output including secondary windings in said magnetic amplifiers and demodulator diodes, the phases of said motor including semiwindings, said outputs of each magnetic amplifier being connected with two semiwindings of one of the phases of said electric motor so as to form a bridge circuit including diagonals, and noncontact switches operating in turn in said diagonals.
Claim 3
Dependent Claim 40 words
A frequency-controlled AC drive according to claim 1, wherein the magnetic amplifiers include inputs and the motor is a two-phase motor, including an antiparallel connection of the inputs of the said magnetic amplifiers for individual phases to aid auxiliary source.
Claim 4
Dependent Claim 39 words
A frequency-controlled AC drive according to claim 1, wherein the magnetic amplifiers include inputs and the motor is a two-phase motor, including an antiseries connection of the inputs of said magnetic amplifiers for individual phases to said auxiliary source.
Claim 5
Dependent Claim 76 words
A frequency-controlled AC drive according to claim 1, including a midpoint circuit connection of said demodulator diodes whereby there results a positive internal current feedback for each magnetic amplifier during the positive half-cycle of the controlling AC voltage and a negative feedback during the negative half-cycle and, after demodulation, the frequency and voltage phase shift at the amplifier output is twice as low as the frequency and voltage phase shift at the input of said amplifier.
Claim 6
Dependent Claim 39 words
A frequency-controlled AC drive according to claim 3, wherein the magnetic amplifiers include inputs and the motor is a two-phase motor, including an antiparallel connection of the inputs of said magnetic amplifiers for individual phases to the auxiliary source.
Claim 7
Dependent Claim 39 words
A frequency-controlled AC drive according to claim 3, wherein the magnetic amplifiers include inputs and the motor is a two-phase motor, including an antiseries connection of the inputs of said magnetic amplifiers for individual phases to the auxiliary source.
Claim 8
Dependent Claim 13 words
A frequency-controlled AC drive according to claim 1, wherein the switches are thyristors.
Claim 9
Dependent Claim 15 words
A frequency-controlled AC drive according to claim 1, wherein the auxiliary source is a generator.

References Cited (Backward Citations)

US3127547A Cited
US3209226A Cited
US3364414A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1974-10-04 1975-04-05 1975-10-05 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1978-10-04 1979-04-05 1979-10-05 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1982-10-04 1983-04-05 1983-10-05 $7700.00 Window Closed / Lapsed

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