US3854079A - Speed control for d. c. motors - Google Patents

Speed control for d. c. motors Download PDF

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Publication number
US3854079A
US3854079A US00305507A US30550772A US3854079A US 3854079 A US3854079 A US 3854079A US 00305507 A US00305507 A US 00305507A US 30550772 A US30550772 A US 30550772A US 3854079 A US3854079 A US 3854079A
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United States
Prior art keywords
capacitor
transistor
speed control
motor
speed
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Expired - Lifetime
Application number
US00305507A
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English (en)
Inventor
R Brown
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CAV Ltd
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CAV Ltd
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Publication date
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
    • A61G5/00—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs
    • A61G5/04—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs motor-driven
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
    • H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current
    • H02P7/18—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power
    • H02P7/24—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices
    • H02P7/28—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices
    • H02P7/285—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only
    • H02P7/29—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only using pulse modulation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
    • A61G2203/00—General characteristics of devices
    • A61G2203/10—General characteristics of devices characterised by specific control means, e.g. for adjustment or steering
    • A61G2203/14—Joysticks

Definitions

  • a control circuit for a DC motor comprises an oscillator having a variable mark space ratio and including a pair of transistors, means for adjusting the mark space ratio of the oscillator a third transistor for connection in series with the motor and a source of supply, the conduction of said third transistor being controlled by the oscillator whereby said mearis can act to vary the current flowing in the motor.
  • a speed control in accordance with the invention comprises in combination, first and second transistors connected together to form a square wave oscillator, means for adjusting the markspace ratio of the oscillator and a third transistor for connection in series with the motor and a source of supply, the conduction of said third transistor being controlled by said oscillator; whereby said means can actto vary the current flowing in the motor.
  • FIG. 1 is a circuit diagram of the speed control together with the motor, a
  • FIG. 2 illustrates a portion of acontrol device in which the 'speed control is' utilised
  • a FIG. 3 shows a modification of the circuit of FIG. 1.
  • terminals and 11 for connection respectively to the positive and negative terminals of a source of d.c. supply 12.
  • a p-n-p transistor T1 having-its emitter connected to the positive terminal 10 and its collector connected to the negative terminal 11 by way of a resistor R1.
  • the collector of transistor T1 is connected to the base terminal of a further p-n-p transistor T2 the emitter of which is connected to the positive terminal. 10 by way of a resistor R2.
  • the base The collector of transistor T2 is connected to the negative terminal 11 byway of resistors R3 and R4 in series and the junction of these two resistors is connected-to the base of an n-p-n transistor T3.
  • the emitter of this transistor is connected to the negative terminal 11 by way of a resistor R5 and the collector of transistor T3 is connected to the anode of adiode D3 the cathode of which is connected to the positive terminal 10.
  • the motor 13 which may be of the permanent magnet type or a wound field type.
  • the emitter of transistor T3 is connected to the base terminals of n-p-n transistors T4 and T5. The emitters of these'two transistors are connected 2 to the negative terminal 11 whilst the collectors-thereof are connected to the collector of transistor T3;
  • transistor T1 is rendered conductive and this has the effect of raising the base voltage of transistor T2 so that the latter is rendered nonconductive.
  • transistor T1 will begin to turn off and this will reduce the base voltage .of transistor T2 which thereby starts to conduct and raises the base potential of transistor T3. This also conducts and at the same time causes conduction of transistors T4 and T5 so that current flows in the motor.
  • Capacitor C1 discharges through the collector emitter path of transistor T2 at a rate dependent upon the resistance offered by the left hand portion of the resistance element of the potentiometer, and when the capacitor has discharged transistor T1 again starts to conduct and switches transistor T2 off-so that in turn tran' sistors T3, T4 and T5 are turned off.
  • the rate of charge of the capacitor is determined largely by the resistance offered by the right hand portion of the resistance element of the potentiometer and the rate of discharge of the capacitor is determined largely by the resistance of the left hand portion of the potentiometer.
  • Diode D2 is provided to ensure that the charging current for the capacitor flows only through the right hand portion of the resistance element of potentiometer POTl and diode Dlis provided to protect trans'istorTl against reverse base emitter voltage when transistor T2 is switched on. I
  • control circuit One application for such a control circuit is to control the speed of one of the motors of a pair of motors for a wheel chair or the like, it being appreciated that a similar circuit is provided to control the other motor.
  • the two motors are coupled to wheels on opposite sides of the wheel chair respectively and a special form of control is provided which couples the potentiometers and at the sametime provides for switching of the motor input terminals to achieve reverse rotation thereof.
  • the potentiometer POTl as shown in FIG. 1 is moditied for this purpose as shown in FIG. 3 and as will be seen from this Figure the resistance element of the potentiometer POT2 is provided with a centre tapping which is connected to the anode of diode D2, the opposite ends of the resistance element are connected together and to the cathode-ofdiode D1.
  • the capacitor When the slider of the potentiometer is'in the middle position as shown, the capacitor will charge slowly and be discharged quickly so that the mean value of the current flowing in the associated motor will be so small as to cause no rotation of the motor.
  • the mean value of current increases as the slider is moved away in either direction from the mid position.
  • the potentiometers are indi-, cated at 14 and they are operatively coupled toan opposed pair of pinions 15 of a differential gear which includes a pinion l6 meshing with the pinions 15.
  • the pinion l6. is coupled to a control lever 17 and this is movable angularlyabout theaxis of rotation of the cont'r'ol members of the potentiometers l4 and also about an axis normal to the aforesaid axes.
  • the pinions 15 are coupled to cams 18 which control the operation of switches 19.
  • the switches 19 are included in the connections to the motors and are provided for reversing the polarities of the supply terminals to achieve reversal of the motors. Also associated with the cams are spring loaded cam followers 20 which bias the cams and also the lever 17 to the central position as shown in the drawings.
  • a speed control apparatus for a D. C. motor comprising, in combinatioma D. C. motor whose speed is desired tov be controlled, and means for'controlling the speed of said D. C. motor, said speed control means comprising:
  • Oscillator means comprising first and second transistors and a capacitor for producing a square wave oscillating signal
  • a third transistor connected in series with said D. C. motor and a source of supply, means connecting said second transistor to said third transistor such that conduction of said second transistor effects conduction of said third transistor; said oscillator meansi'ncluding: 1
  • First circuit means including the base emitter path of said first transistor and an adjustable resistance element for charging said capacitor, said first circuit means being connected across said source of supply for charging said capacitor immediately upon the activation of said supply, said first transistor being rendered conductive during charging of said capacitor and being rendered non-conductive when said capacitor is charged;
  • Second circuit means including the collector emitter path of said second transistor and an adjustable resistance element for discharging said capacitor
  • mark-space ratio of said oscillator means is controlled by varying said adjustable resistance elements.
  • a speed control as claimed in claim 1 in which said resistance elements are connected in series and form the resistance element of a potentiometer.
  • a speed control as claimed in claim 2 in which one plate of said capacitor is connected to the slider of the potentiometer.
  • a speed' control as claimed in claim 3 including switch means operable to reverse the flow of current through the motor thereby to achieve reversal of the motor.
  • a speed control as claimed in claim 4 in which the opposite ends of the potentiometer are connected together and a fixed tapping from the centre of the resistance element connects the resistance element to the discharge circuit of the capacitor.
  • a speed controller for a pair of d.c. motors comprising a pair of speed controls as claimed inclaim 5 associated with the motors respectively, a differential gear including a first gear pinion and a pair of oppositely disposed pinion in mesh therewith, means interconnecting said pair of pinions with the potentiometers respectively and an operating lever coupled to said first pinion and movable about the axis of said first pinion to achieve opposite movement of the sliders of the po tentiometers and about the common axis of the pair of pinion to achieve movement of the sliders in the same direction.
  • a speed controller as claimed in claim 6 including cam means coupled to said pair of pinions respectively said cam means operating said switches whereby upon angular movement of the lever about the axis of said first pinion from an intermediate position the motors will operate in opposite directions, the speedof operation increasing as the lever is moved further from the intermediate position.
  • a speed control as claimed in claim 5 in which the discharge circuit of the capacitor includes a diode acting to prevent charging current flowing to the capacitor from circuit components associated with the discharge path of the capacitor.
  • a speed control asclaimed in claim 2 in which the discharge circuit of the capacitor includes a diode acting to prevent charging current flowing to the capacitor from circuit components associated with the discharge path of the capacitor.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Control Of Direct Current Motors (AREA)
  • Continuous-Control Power Sources That Use Transistors (AREA)
  • Control Of Multiple Motors (AREA)
US00305507A 1971-11-10 1972-11-10 Speed control for d. c. motors Expired - Lifetime US3854079A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5220271A GB1413476A (en) 1971-11-10 1971-11-10 Speed control for dc motors

Publications (1)

Publication Number Publication Date
US3854079A true US3854079A (en) 1974-12-10

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ID=10463018

Family Applications (1)

Application Number Title Priority Date Filing Date
US00305507A Expired - Lifetime US3854079A (en) 1971-11-10 1972-11-10 Speed control for d. c. motors

Country Status (9)

Country Link
US (1) US3854079A (it)
JP (1) JPS529806B2 (it)
CA (1) CA990782A (it)
DE (1) DE2255015C3 (it)
ES (2) ES408658A1 (it)
FR (1) FR2160163A5 (it)
GB (1) GB1413476A (it)
IT (1) IT973432B (it)
ZA (1) ZA727726B (it)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4233549A (en) * 1978-12-08 1980-11-11 Baxter Travenol Laboratories, Inc. Speed and torque control for fractional horsepower motors
US4325011A (en) * 1980-01-31 1982-04-13 Peterson Donovan F Pulse width modulation control circuit
US5526460A (en) * 1994-04-25 1996-06-11 Black & Decker Inc. Impact wrench having speed control circuit
US20030102835A1 (en) * 2001-12-01 2003-06-05 Morris Castro Power control device
US11050368B2 (en) * 2019-01-25 2021-06-29 Shenzhen H&T Intelligent Control Co., Ltd. Apparatus for controlling rotation speed of motor, motor and food processing equipment

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2617883A1 (de) * 1976-04-23 1977-11-10 Bosch Gmbh Robert Impulssteuerschaltung fuer elektrische verbraucher
EP0076039A1 (en) * 1981-08-31 1983-04-06 Capax Electrische Apparatenfabriek B.V. Speed control for power tools having a DC motor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3617845A (en) * 1970-04-27 1971-11-02 Applied Motors Inc Energy-conserving control circuit using power transistors
US3624474A (en) * 1967-03-24 1971-11-30 Philips Corp Series motor on-off speed control circuit having means for generating a complementary field current
US3716767A (en) * 1970-12-26 1973-02-13 Hitachi Ltd Control device for electric automobiles including accelerator position and current feedback

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1341960A (fr) * 1961-12-29 1963-11-02 Philips Nv Multivibrateur astable
GB1196244A (en) * 1966-07-26 1970-06-24 Cableform Ltd Improvements relating to Electrically Propelled Invalid Carriages

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3624474A (en) * 1967-03-24 1971-11-30 Philips Corp Series motor on-off speed control circuit having means for generating a complementary field current
US3617845A (en) * 1970-04-27 1971-11-02 Applied Motors Inc Energy-conserving control circuit using power transistors
US3716767A (en) * 1970-12-26 1973-02-13 Hitachi Ltd Control device for electric automobiles including accelerator position and current feedback

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4233549A (en) * 1978-12-08 1980-11-11 Baxter Travenol Laboratories, Inc. Speed and torque control for fractional horsepower motors
US4325011A (en) * 1980-01-31 1982-04-13 Peterson Donovan F Pulse width modulation control circuit
US5526460A (en) * 1994-04-25 1996-06-11 Black & Decker Inc. Impact wrench having speed control circuit
US20030102835A1 (en) * 2001-12-01 2003-06-05 Morris Castro Power control device
US6911796B2 (en) 2001-12-01 2005-06-28 Westland Helicopters Ltd Power control device
US11050368B2 (en) * 2019-01-25 2021-06-29 Shenzhen H&T Intelligent Control Co., Ltd. Apparatus for controlling rotation speed of motor, motor and food processing equipment

Also Published As

Publication number Publication date
FR2160163A5 (it) 1973-06-22
IT973432B (it) 1974-06-10
JPS4858330A (it) 1973-08-16
DE2255015A1 (de) 1973-05-17
ES408658A1 (es) 1976-03-01
DE2255015B2 (de) 1979-01-25
ES435937A1 (es) 1976-12-16
DE2255015C3 (de) 1979-09-13
GB1413476A (en) 1975-11-12
ZA727726B (en) 1973-06-27
JPS529806B2 (it) 1977-03-18
CA990782A (en) 1976-06-08

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