Patent US3924166A successfully refreshed from Google Patents.
US3924166A
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US
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Speed control system for low speed brushless d-c motors
Assignee: Papst Licensing GmbH and Co KG
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Filing: 1973-10-01
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Granted: 1975-12-02
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Expires: 1993-10-01
Abstract
Abstract The voltages induced in the motor windings of a permanent magnet d-c motor, preferably an axial air gap motor are sensed, halfwave rectified and added in an adder circuit which is connected so that at least a portion of the instantaneous rectified voltages as added, and used as a speed control signal for a speed regulator. The adder circuit may be adjusted in such a way that control signals of double the frequency of modulation with respect to the induced voltages derived from the motor windings at the then instantaneous motor speed are obtained, so that such low speeds as, for example, 33-1/3 rpm, for direct drive of phonograph turntables can be accurately controlled, especially if a motor having a higher number of poles, e.g. 8 poles, is used.
Inventors
- 👤 Benno Doemen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:40
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/06
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
311 words
Brushless d-c motor (M) and speed control combination system in which the motor (M) has a permanent magnet rotor (R) and stator armature windings (10-13), comprising controlled commutating switches (18-21) connected in a supply circuit to respective armature windings of the motor; diodes (31-34) having one terminal each coupled to respective armature windings (10-13) and deriving sensed undulating d-c signals representative of voltages (FIGS. 2: u10, u11, u12, u13) induced in the stator armature windings (10-13) upon passage of the permanent magnetic rotor (R) past said windings during the interval when said armature windings carry no current due to blocking of supply power to respective windings by respective ones of said switches; the other terminals of the diodes (31-34) being connected to a common junction (41), said common junction having applied thereto a d-c voltage having an amplitude which is dependent on motor speed and a superimposed first a-c voltage (ue) of nonsinusoidal wave shape, the frequency of which is likewise dependent on motor speed; a first adder circuit (35-38; 47) connected to said diodes (3134) and adding at least a portion of each of the instantaneous values of the sensed undulating d-c signal to thus obtain a second a-c voltage of non-sinusoidal wave shape, and of a phase which is opposite that of said first a-c voltage; a second adder circuit (42) connected to said common junction (41) and having said second voltage connected thereto to superimpose or instantaneously, algebraically add said first and second voltages so that superimposed, or algebraically added output voltages will appear as an output signal (uD) at the output (43) thereof; and a speed control circuit (24, 25; 44) connected to said output (43), controlled by the superimposed added first and second a-c voltages forming the output signal (uD) thereat, and having its control output connected to control energization of the controlled commutation switches (18-21).
Claim 2
Dependent Claim
311 words
Brushless d-c motor (M) and speed control combination system in which the motor (M) has a permanent magnet rotor (R) and stator armature windings (10-13), comprising controlled commutating switches (18-21) connected in a supply circuit to respective armature windings of the motor; diodes (31-34) having one terminal each coupled to respective armature windings (10-13) and deriving sensed undulating d-c signals representative of voltages (FIGS. 2: u10, u11, u12, u13) induced in the stator armature windings (10-13) upon passage of the permanent magnetic rotor (R) past said windings during the interval when said armature windings carry no current due to blocking of supply power to respective windings by respective ones of said switches; the other terminals of the diodes (31-34) being connected to a common junction (41), said common junction having applied thereto a d-c voltage having an amplitude which is dependent on motor speed and a superimposed first a-c voltage (ue) of nonsinusoidal wave shape, the frequency of which is likewise dependent on motor speed; a first adder circuit (35-38; 47) connected to said diodes (3134) and adding at least a portion of each of the instantaneous values of the sensed undulating d-c signal to thus obtain a second a-c voltage of non-sinusoidal wave shape, and of a phase which is opposite that of said first a-c voltage; a second adder circuit (42) connected to said common junction (41) and having said second voltage connected thereto to superimpose or instantaneously, algebraically add said first and second voltages so that superimposed, or algebraically added output voltages will appear as an output signal (uD) at the output (43) thereof; and a speed control circuit (24, 25; 44) connected to said output (43), controlled by the superimposed added first and second a-c voltages forming the output signal (uD) thereat, and having its control output connected to control energization of the controlled commutation switches (18-21).
Claim 3
Dependent Claim
47 words
System according to claim 1 wherein the second adder (42) adding the out-of-phase first and second a-c voltages is adjusted to modify the voltages to be added to obtain a resultant output signal (uD), at said double frequency of modulation, having waves of approximately equal amplitude excursions.
Claim 4
Dependent Claim
71 words
System according to claim 1 wherein the means rectifying said voltages comprises a group of diodes (31-34) connected as polyphase half-wave rectifiers; and the first adder circuit includes a group of resistors (35-38), one resistor each respectively connected in series with each diode (31-34), all said series diode-resistor circuits having their free terminals connected at the common junction (41); the second adder circuit (42) being connected to said common junction (41).
Claim 5
Dependent Claim
30 words
System according to claim 3 wherein the second adder circuit comprises an additional adding resistor (42) connected in series between the speed control circuit (44) and the common junction (41).
Claim 6
Dependent Claim
44 words
System according to claim 4, wherein the relative resistance values of the respective reistors (35-38) of the group, and of the additional adding resistor (42) are selected to produce an added a-c voltage output (uD) having twice the frequency of the first a-c voltage.
Claim 7
Dependent Claim
30 words
System according to claim 5, wherein the relative resistance values are selected to provide an added resultant output signal at said double-frequency modulation having waves of approximately equal amplitude excursions.
Claim 8
Dependent Claim
26 words
System according to claim 4 wherein at least some of the resistors (35-38; 42) are adjustable to provide for weighting the respective voltages upon addition thereof.
Claim 9
Dependent Claim
37 words
System according to claim 3 wherein said speed control circuit comprises a control amplifier (44) having a feedback circuit (50) including a damping or filtering circuit and interconnecting the output and input (43) of the control amplifier.
Claim 10
Dependent Claim
14 words
System according to claim 8 wherein said control amplifier is an operational amplifier (44).
Claim 11
Dependent Claim
61 words
System according to claim 3 wherein the adder circuits include a source (47) of substantially constant current (47); the speed control circuit comprises an operational amplifier; said source (47) and the common junction (41) are connected to one terminal (43) of the operational amplifier; and a reference command source (46) connected to the other input terminal (45) of the operational amplifier.
Claim 12
Dependent Claim
134 words
System according to claim 10 wherein the second adder circuit comprises an additional adder resistor (42) connected between said common junction (41) and said one input terminal (43) of the operational amplifier (44) so that current from said source (47) of substantially constant current will flow through said additional resistor (42) and through the resistors (35-38) of said group of resistors, dividing into said resistors in accordance with the then instantaneously induced voltages in the armature windings, the voltage being applied to said one terminal (43) of the operational amplifier (44) being the sum of the voltages induced in said windings and of a signal representative of the individual instantaneous voltage induced in any one winding as modified by multiplication factors introduced by the respective relative values of resistance of each of said resistors.
Claim 13
Dependent Claim
37 words
System according to claim 1 wherein the second adder circuit comprises an adder resistor (42) and a source (47) of substantially constant current supplying said resistor (42), the resistor being further connected to the common junction (41).
Claim 14
Dependent Claim
25 words
System according to claim 10 wherein the source of substantially constant current comprises a resistor (47) connected to a stabilized voltage power supply (16, 17).
Claim 15
Dependent Claim
152 words
A system according to claim 1 wherein the first adder circuit comprises a group of adder resistors (35-38), each resistor of the group being connected to a respective one of the motor armature windings (10-13) through the respective diode (31-34) with one terminal thereof and each having a resistance value high with respect to that of the respective diode (31-34), the other terminal of said resistors (35-38) being connected in common to a common junction (41); and wherein the second adder circuit comprises a common adder resistor (42) connected to said common junction (41) of the resistors (35-38); and a constant current source (47) is provided common to the resistors of both said adder circuits connected to the other terminal of said common adder resistor (42) to add the undulating d-c signal from the second a-c voltage, and to add the first a-c voltage thereto and thus form said output signal (uD).
Claim 16
Dependent Claim
36 words
System according to claim 1 wherein the motor is a multipole phonograph turntable motor; in combination with a phonograph turntable, the rotor (R) of the motor (M) being directly coupled (C) to the phonograph turntable (T).
Claim 17
Dependent Claim
132 words
System according to claim 2 wherein the motor is a multipole phonograph turntable motor; in combination with a phonograph turntable (T), the rotor (R) of the motor (M) being directly coupled (C) to the phonograph turntable (T); wherein the first adder circuit comprises a group of adder resistors (35-38), each resistor of the group being connected through the respective diode (31-34) to a respective one of the motor armature windings (10-13) with one terminal thereof, the other terminal of said resistors (35-38) being connected to the common junction (41); the second adder circuit comprises a common adder resistor (42) connected to said common junction (41) of the resistors (35-38); and wherein the speed control circuit comprises an amplifier circuit means (44) connected to the other terminal of said common adder resistor (42).
Claim 18
Dependent Claim
33 words
A system according to claim 16 wherein the relative resistance relationship of the group of resistors (35-38) and the resistance value of said adder resistor (42) is adjustable to vary the motor speed.
Claim 19
Dependent Claim
44 words
System according to claim 16 wherein the resistance value of any of the resistors (35-38) of said group is large with respect to the internal resistance of the respectve diode (31-34) connected to the respective armature winding (10-13) to provide the rectified induced voltages.
Claim 20
Dependent Claim
58 words
System according to claim 18 wherein said turntable motor is an eight-pole motor; and the resistance of any of the resistors (35-38) of the group is in the order of about 400 ohms, and the resistance of said common adder resistor (42) is about twice that of the resistance of any of said resistors (35-38) of the group.
Claim 21
Dependent Claim
36 words
System according to claim 4 wherein the resistance value of each of said common connected resistors (35-38) of the group is high with respect to that of the internal resistance of the respectively connected diode (31-34).
Claim 22
Dependent Claim
34 words
System according to claim 20 wherein the resistance value of said additional adding resistor (42) is approximately twice that of the resistance value of any one of said adder resistors (35-38) of the group.
References Cited (Backward Citations)
US3504252A
Cited
US3488566A
Cited
US3584280A
Cited
US3648137A
Cited
US3651368A
Cited
US3611081A
Cited
US3757185A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-01 | 1979-06-02 | 1979-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-01 | 1983-06-02 | 1983-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-01 | 1987-06-02 | 1987-12-02 | $7700.00 | Window Closed / Lapsed |