US4874993A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sensorless brushless motor
Assignee: Sony Corp
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Filing: 1988-09-30
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Granted: 1989-10-17
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Expires: 2008-09-30
Abstract
Abstract In a brushless motor of the kind not employing a sensor for detecting rotor position, a rotational reference position of the rotor is detected based on an induction voltage in a stator excitation coil, and an energization switching point of the stator excitation coil is determined to occur a delayed time from the reference position. The time delay is increased or decreased in response to the rotational speed of the motor, so that energization switching of the excitation coils is performed at the optimum position in accordance with corresponding changes in the rotational speed of the motor. Signal masking is performed so that noise generated by the excitation coil switching does not interfere with the detection of the rotor reference position.
Inventors
- 👤 Masato Tanaka
- 👤 Toshiya Kan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:13
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/04; H02P6/14; H02P6/16; H02P6/18; H02P6/182; H02P6/08; H02P6/085; H02P6/12; H02P6/15; H02P6/20; H02P6/21
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
163 words
A sensorless brushless motor comprising: a rotor having a magnet; an excitation coil; a switching circuit for performing energization switching of said excitation coil; a reference position detector for detecting a reference position of rotor rotation based on a voltage induced in said excitation coil by said magnet; a delay circuit for producing a delay clock signal having clock pulses delayed by a predetermined amount from the reference position detected by said reference position detector; a delay pulse signal forming circuit for forming a delay pulse signal based on the delay clock signal from said delay circuit; a switching signal generator for generating an energization switching signal based on the delay pulse signal and supplying the switching signal to said switching circuit; and a control circuit for detecting a rotational speed of said rotor for controlling the amount of delay in said delay circuit, and adjusting the energization switching position to said excitation coil in accordance with the rotational speed of said rotor.
Claim 2
Dependent Claim
163 words
A sensorless brushless motor comprising: a rotor having a magnet; an excitation coil; a switching circuit for performing energization switching of said excitation coil; a reference position detector for detecting a reference position of rotor rotation based on a voltage induced in said excitation coil by said magnet; a delay circuit for producing a delay clock signal having clock pulses delayed by a predetermined amount from the reference position detected by said reference position detector; a delay pulse signal forming circuit for forming a delay pulse signal based on the delay clock signal from said delay circuit; a switching signal generator for generating an energization switching signal based on the delay pulse signal and supplying the switching signal to said switching circuit; and a control circuit for detecting a rotational speed of said rotor for controlling the amount of delay in said delay circuit, and adjusting the energization switching position to said excitation coil in accordance with the rotational speed of said rotor.
Claim 3
Dependent Claim
15 words
A motor according to claim 1, wherein said switching circuit comprises a plurality of transistors.
Claim 4
Dependent Claim
15 words
A motor according to claim 1, wherein said reference position detector comprises a zero-cross comparator.
Claim 5
Dependent Claim
24 words
A motor according to claim 1, wherein said delay circuit comprises a counter with said delay clock signal produced at a selected output thereof.
Claim 6
Dependent Claim
16 words
A motor according to claim 1, wherein said delay pulse signal forming circuit comprises a flip-flop.
Claim 7
Dependent Claim
13 words
A motor according to claim 1, wherein said control circuit comprises a microprocessor.
Claim 8
Dependent Claim
22 words
A motor according to claim 1, wherein said excitation coil and said switching circuit form a polyphase unidirectional energization of said motor.
Claim 9
Dependent Claim
22 words
A motor according to claim 1, wherein said excitation coil and said switching circuit form a polyphase bidirectional energization of said motor.
Claim 10
Dependent Claim
150 words
A sensorless brushless motor comprising: a rotor; an excitation coil; a switching circuit for performing energization switching of the excitation coil; a reference position detector for detecting a reference position of rotor rotation based on a voltage induced in said excitation coil by said rotor; a delay circuit for producing a delay clock signal having pulses delayed by a predetermined amount from the reference position detected by said reference position detector; a delay pulse signal forming circuit for producing a delay pulse signal based on the delay clock signal from said delay circuit; a switching signal generator for generating an energization switching signal fed to said switching circuit in response to the delay pulse signal; and a masking circuit for forming a noise masking signal based on at least the delay clock signal for suppressing noise pulses in a detection output of said reference position detector at the reference position.
Claim 11
Dependent Claim
150 words
A sensorless brushless motor comprising: a rotor; an excitation coil; a switching circuit for performing energization switching of the excitation coil; a reference position detector for detecting a reference position of rotor rotation based on a voltage induced in said excitation coil by said rotor; a delay circuit for producing a delay clock signal having pulses delayed by a predetermined amount from the reference position detected by said reference position detector; a delay pulse signal forming circuit for producing a delay pulse signal based on the delay clock signal from said delay circuit; a switching signal generator for generating an energization switching signal fed to said switching circuit in response to the delay pulse signal; and a masking circuit for forming a noise masking signal based on at least the delay clock signal for suppressing noise pulses in a detection output of said reference position detector at the reference position.
Claim 12
Dependent Claim
47 words
A motor according to claim 9, wherein said masking circuit forms the noise masking signal with predetermined masking width based on the delay clock signal and the detection output of the reference position immediately after the detection of the reference position and generation of the switching signal.
Claim 13
Dependent Claim
49 words
A motor according to claim 9, further comprising a masking gate circuit receiving a detected reference position from said reference position detector and said noise masking signal, and producing a pulse signal from which the noise pulses are removed and being fed to said delay pulse signal forming circuit.
Claim 14
Dependent Claim
34 words
A motor according to claim 11, further comprising leading and trailing edge detectors for producing edge pulses fed to said masking gate circuit based on the detected reference position from said reference position detector.
Claim 15
Dependent Claim
48 words
A motor according to claim 9, further comprising a control circuit for detecting a rotational speed of said rotor for controlling a delay amount of said delay circuit and adjusting an energization switching position of said excitation coil in accordance with the detected rotational speed of said rotor.
Claim 16
Dependent Claim
13 words
A motor according to claim 13, wherein said control circuit comprises a microcomputer.
Claim 17
Dependent Claim
24 words
A motor according to claim 9, wherein said switching circuit comprises a plurality of transistors connected in a bridge network to said excitation coil.
Claim 18
Dependent Claim
15 words
A motor according to claim 9, wherein said reference position detector comprises a zero-cross comparator.
Claim 19
Dependent Claim
26 words
A motor according to claim 9, wherein said delay circuit comprises a delay counter with said delay clock signal being produced at a selected output thereof.
Claim 20
Dependent Claim
16 words
A motor according to claim 9, wherein said delay pulse signal forming circuit comprises a flip-flop.
Claim 21
Dependent Claim
14 words
A motor according to claim 9, wherein said masking circuit comprises a masking counter.
Claim 22
Dependent Claim
25 words
A motor according to claim 10, further comprising a control circuit for varying the masking width in accordance with a rotational speed of said motor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-16 | 1993-04-17 | 1993-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-16 | 1997-04-17 | 1997-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-16 | 2001-04-17 | 2001-10-17 | $7700.00 | Window Closed / Lapsed |