US3809979A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Motor brake circuit
Assignee: Rhewum GmbH
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Filing: 1972-12-11
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Granted: 1974-05-07
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Expires: 1992-12-11
Abstract
Abstract In a direct current brake circuit for braking a three-phase, short-circuit rotor motor, a thyristor and diode are connected between the motor and its three phase supply, via controllable switches, overvoltage protection components are connected to the thyristor and the diode, and protective circuitry is connected to cause the thyristor and diode to be connected to the motor stator and to the motor supply, and the braking voltage to be applied to the motor stator, under no load conditions.
Inventors
- 👤 K Zarth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:07
CPC Classifications
H; H02; H02P; H02P3/00; H02P3/06; H02P3/18; H02P3/24
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
146 words
In a direct current brake circuit for a three-phase current short-circuit rotor motor, which circuit brakes the motor by applying a pulsating d.c. voltage to the stator of the motor while the three-phase current supply to the motor is switched off, the improvement wherein said circuit includes: means for deriving a pulsating d.c. voltage from an a.c. voltage; and switch means selectively connecting said deriving means between the motor stator and the three-phase current supply for the motor for supplying such pulsating voltage to the motor; said deriving means comprising a diode and a controllable thyristor connected to said diode and connectable by said switch means in series between one phase of the three phase supply and the motor stator, and a protective circuit connected to each of said diode and thyristor, said protective circuit constituting means for protecting said diode and thyristor against excess voltages.
Claim 2
Dependent Claim
146 words
In a direct current brake circuit for a three-phase current short-circuit rotor motor, which circuit brakes the motor by applying a pulsating d.c. voltage to the stator of the motor while the three-phase current supply to the motor is switched off, the improvement wherein said circuit includes: means for deriving a pulsating d.c. voltage from an a.c. voltage; and switch means selectively connecting said deriving means between the motor stator and the three-phase current supply for the motor for supplying such pulsating voltage to the motor; said deriving means comprising a diode and a controllable thyristor connected to said diode and connectable by said switch means in series between one phase of the three phase supply and the motor stator, and a protective circuit connected to each of said diode and thyristor, said protective circuit constituting means for protecting said diode and thyristor against excess voltages.
Claim 3
Dependent Claim
72 words
A circuit as defined in claim 1 further comprising timer means which switch on before conduction through said thyristor commences and which switch off ofter conduction through said thyristor terminates and connected to said switch means for establishing a load-free connection of the direct braking voltage to the stator of the motor, and of said deriving means to the three-phase current supply, and for connecting said deriving means to the motor stator.
Claim 4
Dependent Claim
27 words
A circuit as defined in claim 2 further comprising a selectively variable timer switch connected for controlling the duration of the direct current supply to the motor.
Claim 5
Dependent Claim
68 words
A circuit as defined in claim 3 further including an electronic control for influencing said deriving means and comprising: supply means containing a transformer arranged to be connected to the three-phase current supply and rectifier bridge connected to the output of said transformer; and a thyristor setting member containing a pulse generator composed of a unijunction transistor and a potentiometer connected between said supply means and said thyristor.
Claim 6
Dependent Claim
138 words
A circuit as defined in claim 4 further comprising an electronic switch-on delay member connected to said thyristor setting member, said electronic switch-on delay member having a constant switch-on delay period and including a transistor, a capacitor, three ohmic resistors, and means interconnecting them; a first electronic switch-off delay member having an adjustable delay period and connected to be influenced by said switch-on delay member and to act on saiD thyristor setting member; and a second electronic switch-off delay member connected to interrupt the connection between said deriving means and at least one of the three-phase current supply and the motor stator, said second electronic switch-off delay member being set to act before said thyristor setting member when the braking process is being initiated and to act after said thyristor setting member when the braking process is completed.
Claim 7
Dependent Claim
29 words
A circuit as defined in claim 1 wherein said protective circuit comprises two series RC circuits each connected in parallel with a respective one of said diode and thyristor.
References Cited (Backward Citations)
US3514682A
Cited
US3708734A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-06 | 1977-11-05 | 1978-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-06 | 1981-11-05 | 1982-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-06 | 1985-11-05 | 1986-05-07 | $7700.00 | Window Closed / Lapsed |