US3602787A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Speed-control system for induction motor
Assignee: ELEKTRONIK REGELAUTOMATIK GmbH
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Filing: 1970-04-20
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Granted: 1971-08-31
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Expires: 1990-04-20
Abstract
Abstract A tachogenerator driven by the shaft of a squirrel cage motor generates an oscillation, of a magnitude and frequency proportional to the shaft velocity, from which a unipolar ripple voltage is derived for charging a storage condenser at a rate decreasing with slip speed. A synchronizing stage for each phase winding of the motor is unblocked in the rhythm of the supply voltage to produce, during each half-cycle, a trigger pulse for a respective thyristor of a pair of oppositely poled thyristors connected in series with the corresponding phase winding of the motor''s stator; the timing of this trigger pulse, and therefore the interval of conductivity of the thyristor, is controlled by the charge of the storage condenser. The charging circuit of this condenser includes a transistor amplifier with a differentiating feedback connection intermittently blocking this amplifier during an ''''on'''' period, determined by the difference between the ripple voltage and an adjustable reference voltage, whereby the amplifier oscillates at a frequency many times higher than the supply frequency and the condenser is progressively charged to an extent depending upon the duration of that period.
Inventors
- 👤 Ernst Tuchen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:38
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/02; H02P27/026
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
178 words
A speed-control system for an induction motor having at least one stator winding and a rotor, comprising: a source of alternating driving voltage for said stator winding; electronic gate means in series with said winding; an alternating-current generator coupled with said rotor for producing an oscillation of a magnitude and frequency varying with rotor speed; raw-rectification means for converting said oscillation into a unipolar ripple voltage; amplifier means provided with conduction-promoting biasing means and connected to said raw-rectification means for receiving said ripple voltage and for being rendered nonconductive during peaks of said ripple voltage exceeding a predetermined threshold; storage means connected to be charged by said ampliFier means during periods of conductivity thereof and to an extent depending upon the duration of said periods; a normally blocked synchronizing circuit connected to said source for periodic unblocking during successive cycles; and timing means jointly controlled by said synchronizing circuit and by said storage means for generating a signal to open said electronic gate means during each cycle for an interval depending on the charge of said storage means.
Claim 2
Dependent Claim
178 words
A speed-control system for an induction motor having at least one stator winding and a rotor, comprising: a source of alternating driving voltage for said stator winding; electronic gate means in series with said winding; an alternating-current generator coupled with said rotor for producing an oscillation of a magnitude and frequency varying with rotor speed; raw-rectification means for converting said oscillation into a unipolar ripple voltage; amplifier means provided with conduction-promoting biasing means and connected to said raw-rectification means for receiving said ripple voltage and for being rendered nonconductive during peaks of said ripple voltage exceeding a predetermined threshold; storage means connected to be charged by said ampliFier means during periods of conductivity thereof and to an extent depending upon the duration of said periods; a normally blocked synchronizing circuit connected to said source for periodic unblocking during successive cycles; and timing means jointly controlled by said synchronizing circuit and by said storage means for generating a signal to open said electronic gate means during each cycle for an interval depending on the charge of said storage means.
Claim 3
Dependent Claim
22 words
A system as defined in claim 1 wherein said biasing means includes a source of adjustable reference voltage for varying said threshold.
Claim 4
Dependent Claim
40 words
A system as defined in claim 1 wherein said amplifier means is provided with a reactive feedback circuit for periodically interrupting the charging path of said storage means at a cadence substantially greater than the frequency of said driving voltage.
Claim 5
Dependent Claim
23 words
A system as defined in claim 3 wherein said cadence is on the order of 100 times the frequency of said driving voltage.
Claim 6
Dependent Claim
26 words
A system as defined in claim 3 wherein said amplifier means comprises a plurality of cascaded transistor stages, said feedback circuit including a resistive-capacitive differentiation network.
Claim 7
Dependent Claim
37 words
A system as defined in claim 1 wherein said electronic gate means comprises triggerable semiconductor means and said timing means comprises a trigger circuit for said semiconductor means connected to said storage means through said synchronizing circuit.
Claim 8
Dependent Claim
43 words
A system as defined in claim 6 wherein said storage means comprises a first capacitor and said trigger circuit includes a second capacitor connected to receive the charge of said first capacitor by way of said synchronizing circuit in the unblocked condition thereof.
Claim 9
Dependent Claim
25 words
A system as defined in claim 7 wherein said trigger circuit further includes a unijunction transistor with an input circuit connected across said second capacitor.
Claim 10
Dependent Claim
29 words
A system as defined in claim 8 wherein said second capacitor is further provided with an ancillary charging path controlled by said synchronizing circuit independently of said storage means.
Claim 11
Dependent Claim
76 words
A system as defined in claim 1 wherein said stator has three phase windings each provided with electronic valve means individual thereto, said synchronizing circuit and said timing means having each three sections respectively connected to said electronic valve means, said alternating-current generator having an operating frequency equal to at least three times the frequency of said driving voltage upon said rotor approaching synchronous speed, said storage means comprising a condenser common to all said sections.
Claim 12
Dependent Claim
30 words
A system as defined in claim 1 wherein said amplifier means is provided with an energizing circuit including a time-constant network for delaying an initial buildup of operating voltage therefor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-30 | 1975-03-01 | 1975-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-30 | 1979-03-01 | 1979-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-30 | 1983-03-01 | 1983-08-31 | $7700.00 | Window Closed / Lapsed |