Speed regulation system for DC motors with hall generators

• US 3,999,108 A
• Filed: 07/14/1975
• Issued: 12/21/1976
• Est. Priority Date: 08/16/1972
• Status: Expired due to Term

• Current Assignee: Canon Incorporated Taiwan (Canon Inc.), Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Incorporated Taiwan (Canon Inc.), Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tanikoshi, Kinji
• Primary Examiner(s): Dobeck, B.
• Application Number:
  US05/595,419
• Time in Patent Office: 526 Days
• Field of Search: 318/254, 318/138
• US Class Current: 318/400.04
• CPC Class Codes: H02P 6/06 Arrangements for speed regulation of a single motor wherein the motor speed is measured and compared with a given physical value so as to adjust the motor speed

Abstract

A speed regulation system for DC motors of the type comprising a rotor having magnetic poles of opposite polarities, a stator having at least one pair of flux-producing windings positioned in torque producing relation with the rotor, and Hall generators positioned in fixed relation to the stator and angularly spaced apart from each other in magnetic relation to the rotor so as to sense the magnitude of the rotor flux density as a function of the angular position of the rotor. The speed regulation system comprises a circuit for detecting the frequency of the output signals of the Hall generators so as to generate the pulse signals representing the peak values of the output signals, a phase shifter for shifting the phase of the pulse signals, and a wave shaping circuit for generating the signals with a desired waveform in response to the output signal of the phase shifter. In response to the output signals of the wave shaping circuit a drive circuit for supplying the driving current to the stator windings is controlled, whereby the DC motor may be rotated at a constant speed.

Claims

1. A DC motor and control system therefore comprising, in combination:

a. A DC motor comprising

a rotor having magnetic poles of opposite polarities thereon and a non-uniform magnetic flux distribution, and

stator windings positioned in torque-producing relation to said rotor;

b. Hall generators positioned in flux-sensing relation to said magnetic poles so as to detect the instantaneous rotational speed thereof and to generate electrical signals with a frequency representing the instantaneously changing rotational speed of said DC motor;

c. means connected to said Hall generators for detecting the crest or peak values of the output signals of said Hall generators so as to generate pulse signals representing said crest or peak values,

d. means for generating a signal of a waveform corresponding to the magnetic flux distribution of said rotor to retain an axis output of said DC motor constant by compensating for a magnetic flux distribution inherent to the field of said DC motor comprising;

a plurality of waveform generators each adapted to be triggered in response to the pulse signals from said pulse signal generating means to generate the signal with the desired waveform, and switching means for selectively outputting the output signals with various waveforms of said waveform generator, whereby a signal with a desired waveform for compensating for the flux distribution in the DC motor may be developed,

e. motor speed detecting means disposed independently of said Hall generators for generating electrical signals representative of said instantaneous rotational speed of said rotor,

f. amplifier means to which are applied the output signals from said waveform generating means and the output signal of said motor speed detecting means,

said amplifier means being adapted to control the amplification gain of the output signals from the waveform generating means in response to the level of the output signal from said motor speed detecting means, and

g. driving control means connected to both said amplifier means and said stator windings for applying an exciting current to said windings in response to the output of said amplifier means.

2. A DC motor and control system therefor as defined in claim 1 wherein said driving control means comprises phase selecting circuits,

3. said phase selecting circuits being capable of splitting in a predetermined phase interval the output signals of said amplifier means to be supplied to said stator windings, whereby said rotor may be rotated in a predetermined direction so as to provide a uniform shaft output.

4. A DC motor and control system therefor comprising, in combination:

a. a DC motor comprising

a rotor having magnetic poles of opposite polarities thereon and a non-uniform magnetic flux distribution, and

stator windings positioned in torque-producing relation to said rotor;

b. Hall generators positioned in flux-sensing relation to said magnetic poles so as to detect the instantaneous rotational speed thereof and to generate an instantaneously changing rotational speed of said DC motor;

c. pulse signal generating means connected to the output terminals of said Hall generators for detecting the frequency of the Hall voltage output and generating a pulse signal train representing the frequency,

d. means for generating a signal of a waveform corresponding to the magnetic flux distribution of said rotor in response to the pulse signal train from said pulse signal generating means, said waveform generating means including speed control means so that said waveform generating means may have a predetermined frequency used as a reference frequency based upon which said DC motor may be rotated at a constant speed when said waveform generating means is disconnected from said pulse signal generating means,

e. motor speed detecting means including means for detecting the voltages induced across the stator windings which are not supplied with the driving current,

f. Hall generators positioned in flux-sensing relation to said magnetic poles so as to detect the instantaneous rotational speed thereof and to generate electrical signals with a frequency representing the instantaneously changing rotational speed of said DC motor;

g. driving control means connected to both said amplifier means and said stator windings for applying an exciting current to said windings in response to the output of said amplifier means;

h. gate means for detecting the level of the output signal of said motor speed detecting means so as to interrupt the pulse train from said waveform generating means, said gate means interrupting said pulse train when the level of the output signal from said motor speed detecting means reaches a predetermined level which represents a predetermined level which represents a predetermined speed of said DC motor, whereby said waveform generating means functions as a reference signal generating means for generating a reference signal of a predetermined frequency.

5. A DC motor and control system therefor comprising, in combination,

a. a rotor having magnetic poles of opposite polarities thereon and a non-uniform magnetic flux distribution;

b. a stator having flux-producing windings positioned in torque-producing relation to said rotor;

c. Hall generators positioned in fixed relation to said stator and angularly spaced apart from each other and in magnetic relation to said rotor so as to sense the magnitude of the rotor flux density as a function of the angular position of said rotor and to generate electrical signals with a frequency representing the instantaneously changing rotational speed of said DC motor;

d. means for detecting the frequency of the output signals in a digital manner and generating an analog signal representing said frequency,

e. reference signal generating means disposed independently of said Hall generators for generating a reference signal corresponding to a predetermined constant speed of said DC motor;

f. analog comparator means for comparing the analog signal from said detecting means with the reference signal, to generate an output signal representing the difference therebetween,

g. pulse signal train generating means connected to said Hall generators for detecting the output signals thereof and generating a pulse signal train representing the peak values thereof,

h. means connected to said pulse signal train generating means adapted to be triggered thereby for generating a signal of a waveform corresponding to the magnetic flux distribution of said rotor in synchronism with said pulse train,

i. amplifier means to which are applied the output signal from said comparator means and the output signals of said waveform generating means, the amplification gain of said output signals from said waveform generating means being controlled in reponse to the level of said output signal from said comparator means, and

j. driving control means connected to both said amplifier means and said stator windings for applying an exciting current to said windings in response to the output of said amplifier means.

6. A DC motor and control system thereof comprising, in combination:

a. a DC motor comprising a rotor having magnetic poles of opposite polarities thereon and a non-uniform magnetic flux distribution, and stator windings positioned in torque-producing relation to said rotor;

b. Hall generators positioned in flux-sensing relation to said magnetic poles so as to detect an instantaneous rotational speed thereof for generating electrical signals with a frequency representing the instantaneously changing rotational speed of said DC motor;

c. pulse generating means connected to said Hall generators for detecting a predetermined value of the output signals from said Hall generators and generating pulse signals representing said predetermined value;

d. means for generating a signal of a waveform corresponding to the magnetic flux distribution of said rotor to retain an axis output of said DC motor constant by compensating for a magnetic flux distribution inherent to the field of said DC motor in response to the pulse signals from said pulse generating means; and

e. driving control means interconnected between said signal generating means and said stator winding for applying an exciting current to said stator winding in response to the output signals of said signal generating means.