Patent US3611081A successfully refreshed from Google Patents.
US3611081A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Counter emf commutated self-starting brushless d.c. motor
Assignee: Unisys Corp
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Filing: 1970-04-06
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Granted: 1971-10-05
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Expires: 1990-04-06
Abstract
Abstract The stator windings of a brushless DC motor are energized through individual silicon controlled rectifiers arranged in a ring counter circuit which is triggered from a pulse source. When the motor is to be started, an AND gate forces the first pulse to trigger a specific silicon controlled rectifier. The AND gate then permits subsequent pulses to be steered to various silicon controlled rectifiers in the desired sequence. The pulse source is synchronized through an OR gate coupled to receive signals from each stator winding. When a given silicon controlled rectifier is turned off, the corresponding stator winding is deenergized. The motion of the rotor, however, induces a counter EMF in the deenergized winding. This counter EMF is applied through the OR gate to synchronize the pulse source.
Inventors
- 👤 Tritus F Watson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:42
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/14; H02P6/16; H02P6/18; H02P6/182
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
280 words
A commutating circuit for a brushless DC motor of the type including permanently magnetized rotor rotatable between a plurality of stator windings energized from a DC source, said commutating circuit comprising a pulse source for producing CLOCK pulses at a given repetition rate, said pulse source including a relaxation oscillator having a charging capacitor arranged to accumulate charge at a given rate and a voltage responsive discharge means coupled to discharge said capacitor when the accumulated charge thereon reaches a given value, switching means for energizing individual stator windings in a desired sequence in response to pulses from said pulse source, said switching means including an individual switching stage corresponding to each stator winding, each of said switching stages being connected to the corresponding stator winding at an individual stator winding junction point, OR gating means coupled to respond to voltages at each of said junction points, said OR gating means further being arranged to produce an output signal whenever the voltage level at any of said junction points rises above the voltage level of said DC source, whereby said gating means provides an output signal in response to a counter EMF induced in said stator winding by the motion of said rotor, synchronizing means for increasing the charging rate of said capacitor in response to an output signal from said OR gating means, additional gating means responsive to the voltages at all of said junction points for providing a START pulse in response to a CLOCK pulse when the voltage at each of said junction points is substantially at the level of said DC source, and means to actuate a specified switching stage in response to a START pulse.
Claim 2
Dependent Claim
280 words
A commutating circuit for a brushless DC motor of the type including permanently magnetized rotor rotatable between a plurality of stator windings energized from a DC source, said commutating circuit comprising a pulse source for producing CLOCK pulses at a given repetition rate, said pulse source including a relaxation oscillator having a charging capacitor arranged to accumulate charge at a given rate and a voltage responsive discharge means coupled to discharge said capacitor when the accumulated charge thereon reaches a given value, switching means for energizing individual stator windings in a desired sequence in response to pulses from said pulse source, said switching means including an individual switching stage corresponding to each stator winding, each of said switching stages being connected to the corresponding stator winding at an individual stator winding junction point, OR gating means coupled to respond to voltages at each of said junction points, said OR gating means further being arranged to produce an output signal whenever the voltage level at any of said junction points rises above the voltage level of said DC source, whereby said gating means provides an output signal in response to a counter EMF induced in said stator winding by the motion of said rotor, synchronizing means for increasing the charging rate of said capacitor in response to an output signal from said OR gating means, additional gating means responsive to the voltages at all of said junction points for providing a START pulse in response to a CLOCK pulse when the voltage at each of said junction points is substantially at the level of said DC source, and means to actuate a specified switching stage in response to a START pulse.
Claim 3
Dependent Claim
107 words
The circuit of claim 1 wherein said additional gating means is an AND gate, said AND gate including a group of diodes each cOnnected to separate ones of said junction points, each of the diodes in said group being arranged to be back biased when the corresponding junction point is at a high voltage level and to be forward biased when the corresponding junction point is at a low voltage level, said AND gate further including a diode connected to be back biased by a CLOCK pulse, said AND gate further including output means for providing a START pulse when all of said diodes become back biased.
Claim 4
Dependent Claim
242 words
A commutating circuit for a brushless DC motor of the type including a permanently magnetized rotor and a plurality of stator windings energized from a DC source and arranged to cause rotation of said rotor, said commutating circuit comprising a ring countercircuit including a switching stage corresponding to each of said stator windings, individual stator winding junction points connecting each stator winding to the corresponding switching stage in the ring countercircuit, a source of clock pulses coupled to each stage in said ring countercircuit, said source being constructed to produce pulses at a nominal repetition rate, fist gating means responsive to the instantaneous voltage level of all stator winding junction points and to the presence of a CLOCK pulse, means in said first gating means for producing a START pulse when said gating means detects a high voltage level at each of said stator winding points in the presence of a CLOCK pulse, means for triggering a specific stage in said ring counter circuit in response to a START pulse, second gating means responsive to the voltage level of each of said stator winding junction points, said second gating means being constructed to produce a specific output signal whenever the voltage level at each of said stator winding junction points rises above the level of said DC source, and means to accelerate the pulse repetition rate of said pulse source in response to a specified output signal from said second gating means.
Claim 5
Dependent Claim
242 words
A commutating circuit for a brushless DC motor of the type including a permanently magnetized rotor and a plurality of stator windings energized from a DC source and arranged to cause rotation of said rotor, said commutating circuit comprising a ring countercircuit including a switching stage corresponding to each of said stator windings, individual stator winding junction points connecting each stator winding to the corresponding switching stage in the ring countercircuit, a source of clock pulses coupled to each stage in said ring countercircuit, said source being constructed to produce pulses at a nominal repetition rate, fist gating means responsive to the instantaneous voltage level of all stator winding junction points and to the presence of a CLOCK pulse, means in said first gating means for producing a START pulse when said gating means detects a high voltage level at each of said stator winding points in the presence of a CLOCK pulse, means for triggering a specific stage in said ring counter circuit in response to a START pulse, second gating means responsive to the voltage level of each of said stator winding junction points, said second gating means being constructed to produce a specific output signal whenever the voltage level at each of said stator winding junction points rises above the level of said DC source, and means to accelerate the pulse repetition rate of said pulse source in response to a specified output signal from said second gating means.
Claim 6
Dependent Claim
180 words
A commutating circuit for a brushless DC motor of the type including a permanently magnetized rotor rotatable between a plurality of stator windings energized from a DC source, said commutating circuit comprising a pulse source for producing CLOCK pulses at a given repetition rate, switching means for energizing individual stator windings in a desired sequence in response to pulses from said pulse source, gating means responsive to counter EMFs induced in said stator windings by the motion of said rotor, said gating means being constructed to provide an output signal when the counter EMF induced in any stator winding exceeds a predetermined value, synchronizing means for accelerating the pulse repetition rate of said pulse source in response to a signal from said gating means, additional gating means responsive to the voltages at all of said junction points for providing a START pulse in response to a CLOCK pulse when the voltage at each of said junction points is substantially at the level of said DC source, and means to actuate a specified switching stage in response to a START pulse.
Claim 7
Dependent Claim
180 words
A commutating circuit for a brushless DC motor of the type including a permanently magnetized rotor rotatable between a plurality of stator windings energized from a DC source, said commutating circuit comprising a pulse source for producing CLOCK pulses at a given repetition rate, switching means for energizing individual stator windings in a desired sequence in response to pulses from said pulse source, gating means responsive to counter EMFs induced in said stator windings by the motion of said rotor, said gating means being constructed to provide an output signal when the counter EMF induced in any stator winding exceeds a predetermined value, synchronizing means for accelerating the pulse repetition rate of said pulse source in response to a signal from said gating means, additional gating means responsive to the voltages at all of said junction points for providing a START pulse in response to a CLOCK pulse when the voltage at each of said junction points is substantially at the level of said DC source, and means to actuate a specified switching stage in response to a START pulse.
References Cited (Backward Citations)
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 |