WO1991004607A1 - D.c. motor control system - Google Patents

D.c. motor control system Download PDF

Info

Publication number
WO1991004607A1
WO1991004607A1 PCT/GB1990/001429 GB9001429W WO9104607A1 WO 1991004607 A1 WO1991004607 A1 WO 1991004607A1 GB 9001429 W GB9001429 W GB 9001429W WO 9104607 A1 WO9104607 A1 WO 9104607A1
Authority
WO
WIPO (PCT)
Prior art keywords
motor
control system
driven element
signal
producing
Prior art date
Application number
PCT/GB1990/001429
Other languages
French (fr)
Inventor
Richard Alan Stanley Forrest
Original Assignee
Britax Weathershields Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Britax Weathershields Limited filed Critical Britax Weathershields Limited
Publication of WO1991004607A1 publication Critical patent/WO1991004607A1/en

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E05—LOCKS; KEYS; WINDOW OR DOOR FITTINGS; SAFES
    • E05F—DEVICES FOR MOVING WINGS INTO OPEN OR CLOSED POSITION; CHECKS FOR WINGS; WING FITTINGS NOT OTHERWISE PROVIDED FOR, CONCERNED WITH THE FUNCTIONING OF THE WING
    • E05F15/00—Power-operated mechanisms for wings
    • E05F15/40—Safety devices, e.g. detection of obstructions or end positions
    • E05F15/41—Detection by monitoring transmitted force or torque; Safety couplings with activation dependent upon torque or force, e.g. slip couplings
    • 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
    • H02P7/03—Arrangements for regulating or controlling the speed or torque of electric DC motors for controlling the direction of rotation of DC motors
    • E—FIXED CONSTRUCTIONS
    • E05—LOCKS; KEYS; WINDOW OR DOOR FITTINGS; SAFES
    • E05Y—INDEXING SCHEME RELATING TO HINGES OR OTHER SUSPENSION DEVICES FOR DOORS, WINDOWS OR WINGS AND DEVICES FOR MOVING WINGS INTO OPEN OR CLOSED POSITION, CHECKS FOR WINGS AND WING FITTINGS NOT OTHERWISE PROVIDED FOR, CONCERNED WITH THE FUNCTIONING OF THE WING
    • E05Y2900/00—Application of doors, windows, wings or fittings thereof
    • E05Y2900/50—Application of doors, windows, wings or fittings thereof for vehicles
    • E05Y2900/53—Application of doors, windows, wings or fittings thereof for vehicles characterised by the type of wing
    • E05Y2900/55—Windows
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
    • H02H7/0851—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load for motors actuating a movable member between two end positions, e.g. detecting an end position or obstruction by overload signal
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • H02H7/093—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against increase beyond, or decrease below, a predetermined level of rotational speed

Definitions

  • This invention relates a control system for a d.c. commutated motor which is arranged to move a driven element along a predetermined path, the control system including means for deriving a control signal by producing an electrical signal proportional to the electric current in the motor. It has particular but not exclusive application to sensing the position of a member such as a movable panel for an opening roof of a motor vehicle.
  • US-A-4585981 A system of this type, applied to an opening roof of a motor vehicle, is disclosed in US-A-4585981. Detection of an increase in the current consumed by the motor above a threshold level is used to provide an indication that the panel has hit an obstruction. For detecting the position of the panel, reference is made to US Patent Application 530714 (US-A-4556835) , in which a potentiometer is coupled to the panel to provide a signal indication its position.
  • a control system of the type described above comprises filter means for ' isolating an alternating component of said electrical signal proportional to the electrical current through the motor, and amplifier means for producing a signal having a pulse waveform of frequency equal to the frequency of said a.c. component.
  • the a.c. component of the current in a d.c. commutated motor arises from a number of sources such as power drop-out during commutation, back e. .f. and mutual inductance. However, all these sources depend on the asymmetry of the rotor and consequently remain in phase with one another.
  • Figure 1 is a circuit diagram of an embodiment of the invention suitable for use with an opening roof for a vehicle; and Figures 2 to 5 are waveform diagrams illustrating the variation of voltage with time at four different points in the circuit shown in Figure 1.
  • a d.c. commutated electric motor 10 is arranged to drive a driven element 11, such as a closure panel for a vehicle opening roof.
  • the motor 10 is connected, via the two poles 12 and 14 of a two-pole three-position reversing switch, in series with a resistor 16 to a battery 18.
  • the switch 12, 14 is an electronic device controlled by a microprocessor 20 (shown schematically) .
  • the resistor 16 is a low value, high power resistor, chosen so as to be capable of carrying the stalled-rotor current of the motor 10 while causing negligible reduction to the voltage applied to the motor 10 from the battery 18.
  • a typical example of the voltage across the resistor 16 when the motor 10 is running is shown in Figure 2. It should be understood that the amplitude of the a.c. component is greatly exaggerated in relation to the d.c. voltage. The a.c. component may in practice amount to as little as lmV.
  • the operational amplifier 24 is connected in cascade with a second operational amplifier 26. Their inputs are also connected to a network of four equal resistors 28, 30, 32 and 34 but their feedback is left open in order to obtain saturation at all input signal levels.
  • Negative parts of the signal shown in Figure 3 will drop to the lowest saturation level and positive parts will be raised to the highest saturation level, as can be seen from the output signal from the operational amplifier 26 shown in Figure 4.
  • the output of the operational amplifier 26 is connected via a second capacitor 36 and a further resistor
  • the microprocessor 20 has a motor control unit 44 which controls the settings of the switch 12, 14 and which receives an input from a manual control 46 indicating the desired position of the driven element.
  • the input pulse train shown in Figure 5 is applied both to a reversible position counter 48 and to a calculator 46.
  • the position counter 48 stores a value recording the number of pulses received, the value being incremented or decremented depending on the direction of rotation of the motor 10, as indicated by the motor control unit 44.
  • the calculator 50 determines an instantaneous value for the speed of the motor 10 from the input pulse rate.
  • a comparator 52 compares this value with a pre-programmed memory map of speeds at different panel positions (held in a store 54).
  • the control unit 44 to stop the motor 10.
  • the comparator 52 detects a predicted large variation in the speed profile (e.g. when the panel reaches either of its end positions so that the pulse rate goes down to zero), it sends a signal to the position counter 48 to reset the count, thereby correcting any errors in the indicated position which may have accumulated over a period of time.
  • microprocessor has been described as consisting of special-purpose component units, in practice it is preferable to use a suitably programmed general- purpose computer.

Abstract

A control system for a d.c. commutated motor (10) is arranged to move a driven element (11) along a predetermined path. The control system includes means (16) for deriving a control signal by producing an electrical signal proportional to the electric current in the motor. A filter (22) isolates an alternating component of said electrical signal proportional to the electrical current through the motor, and an amplifier (24, 26) produces a control signal having a pulse waveform of frequency equal to the frequency of said a.c. component. The control signal is applied to a computer (20) which controls the power supply to the motor (10).

Description

D.C. MOTOR CONTROL SYSTEM
FIELD OF THE INVENTION
This invention relates a control system for a d.c. commutated motor which is arranged to move a driven element along a predetermined path, the control system including means for deriving a control signal by producing an electrical signal proportional to the electric current in the motor. It has particular but not exclusive application to sensing the position of a member such as a movable panel for an opening roof of a motor vehicle.
RELATED ART
A system of this type, applied to an opening roof of a motor vehicle, is disclosed in US-A-4585981. Detection of an increase in the current consumed by the motor above a threshold level is used to provide an indication that the panel has hit an obstruction. For detecting the position of the panel, reference is made to US Patent Application 530714 (US-A-4556835) , in which a potentiometer is coupled to the panel to provide a signal indication its position.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a control system of the type described above having means for detecting the position of a driven element which does not require the use of optical or electromechanical transducers other than the driving motor itself.
According to the invention, a control system of the type described above comprises filter means for' isolating an alternating component of said electrical signal proportional to the electrical current through the motor, and amplifier means for producing a signal having a pulse waveform of frequency equal to the frequency of said a.c. component.
The a.c. component of the current in a d.c. commutated motor arises from a number of sources such as power drop-out during commutation, back e. .f. and mutual inductance. However, all these sources depend on the asymmetry of the rotor and consequently remain in phase with one another.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a circuit diagram of an embodiment of the invention suitable for use with an opening roof for a vehicle; and Figures 2 to 5 are waveform diagrams illustrating the variation of voltage with time at four different points in the circuit shown in Figure 1.
DETAILED DESCRIPTION
Referring to Figure 1, a d.c. commutated electric motor 10 is arranged to drive a driven element 11, such as a closure panel for a vehicle opening roof. The motor 10 is connected, via the two poles 12 and 14 of a two-pole three-position reversing switch, in series with a resistor 16 to a battery 18. The switch 12, 14 is an electronic device controlled by a microprocessor 20 (shown schematically) .
The resistor 16 is a low value, high power resistor, chosen so as to be capable of carrying the stalled-rotor current of the motor 10 while causing negligible reduction to the voltage applied to the motor 10 from the battery 18. A typical example of the voltage across the resistor 16 when the motor 10 is running is shown in Figure 2. It should be understood that the amplitude of the a.c. component is greatly exaggerated in relation to the d.c. voltage. The a.c. component may in practice amount to as little as lmV.
The .a.c. component of the voltage across the resistor 16 is applied via a capacitor 22 (which acts as a filter blocking the d.c. component) to one input of an operational amplifier 24. Figure 3 shows the voltage signal at this input corresponding to the voltage signal in Figure 2.
The operational amplifier 24 is connected in cascade with a second operational amplifier 26. Their inputs are also connected to a network of four equal resistors 28, 30, 32 and 34 but their feedback is left open in order to obtain saturation at all input signal levels.
Negative parts of the signal shown in Figure 3 will drop to the lowest saturation level and positive parts will be raised to the highest saturation level, as can be seen from the output signal from the operational amplifier 26 shown in Figure 4. The output of the operational amplifier 26 is connected via a second capacitor 36 and a further resistor
38 to the base of a transistor 40 which produces an output signal across further resistor 42 which is TTL compatible
(as shown in Figure 5) and which is applied to the microprocessor 20.
The microprocessor 20 has a motor control unit 44 which controls the settings of the switch 12, 14 and which receives an input from a manual control 46 indicating the desired position of the driven element. In the microprocessor 20, the input pulse train shown in Figure 5 is applied both to a reversible position counter 48 and to a calculator 46. The position counter 48 stores a value recording the number of pulses received, the value being incremented or decremented depending on the direction of rotation of the motor 10, as indicated by the motor control unit 44. The calculator 50 determines an instantaneous value for the speed of the motor 10 from the input pulse rate. A comparator 52 compares this value with a pre-programmed memory map of speeds at different panel positions (held in a store 54). Any large deviation from this indicates an obstruction, causing the control unit 44 to stop the motor 10. In addition, when the comparator 52 detects a predicted large variation in the speed profile (e.g. when the panel reaches either of its end positions so that the pulse rate goes down to zero), it sends a signal to the position counter 48 to reset the count, thereby correcting any errors in the indicated position which may have accumulated over a period of time.
Although the microprocessor has been described as consisting of special-purpose component units, in practice it is preferable to use a suitably programmed general- purpose computer.

Claims

1. A control system for a d.c. commutated motor (10) which is arranged to move a driven element (11) along a predetermined path, the control system including means (16) for deriving a control signal by producing an electrical signal proportional to the electric current in the motor, characterised by filter means (22) for isolating an alternating component of said electrical signal proportional to the electrical current through the motor, and amplifier means (24, 26) for producing a signal having a pulse waveform of frequency equal to the frequency of said a.c. component.
2. A control system according to claim 1, f rther comprising computer means (20) within which the control signal is applied both to counter means (48) for maintaining a count of received pulses indicating the position of the driven element and to calculator means (50)" for producing a signal indicating the actual speed of the driven element, the computer means further comprising storage means (54) for storing the expected speed of the driven element at each of its positions on said predetermined path, comparator means (52) responsive to the calculator means (50) and to the storage means (54) for detecting deviation of the actual speed from the expected speed and motor control means (44) for stopping the motor- (10) when the comparator means (52) indicates that the driven element (11) has encountered an obstruction.
3. A control system according to claim 1, wherein the comparator means (52) is arranged to send a reset signal to the counter means (48) when the driven element (11) reaches an end of its predetermined path.
PCT/GB1990/001429 1989-09-16 1990-09-17 D.c. motor control system WO1991004607A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8921025.6 1989-09-16
GB898921025A GB8921025D0 (en) 1989-09-16 1989-09-16 Motor position sensor

Publications (1)

Publication Number Publication Date
WO1991004607A1 true WO1991004607A1 (en) 1991-04-04

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1990/001429 WO1991004607A1 (en) 1989-09-16 1990-09-17 D.c. motor control system

Country Status (2)

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GB (1) GB8921025D0 (en)
WO (1) WO1991004607A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995002268A1 (en) * 1993-07-08 1995-01-19 Doduco Gmbh + Co. Dr. Eugen Dürrwächter Process for controlling the d.c. motor used for moving a window in a motor vehicle
EP1679777A1 (en) * 2005-01-05 2006-07-12 Behr-Hella Thermocontrol GmbH Device for indicating an obstruction of a DC commutated motor based on the ripple of the field current

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2518630A1 (en) * 1981-12-23 1983-06-24 Yoshida Kogyo Kk APPARATUS FOR CONTROLLING THE OPERATION OF AN AUTOMATIC DOOR WITH MINIMUM ERROR IN THE DETECTED POSITION OF THIS DOOR
EP0100852A1 (en) * 1982-07-16 1984-02-22 Robert Bosch Gmbh Circuit arrangement for rising and lowering a motor-operated antenna
EP0275238A2 (en) * 1987-01-15 1988-07-20 CAVIS CAVETTI ISOLATI S.p.A. Circuit arrangement for controlling the electric motors used for raising and lowering glasses in motor vehicles and the like

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2518630A1 (en) * 1981-12-23 1983-06-24 Yoshida Kogyo Kk APPARATUS FOR CONTROLLING THE OPERATION OF AN AUTOMATIC DOOR WITH MINIMUM ERROR IN THE DETECTED POSITION OF THIS DOOR
EP0100852A1 (en) * 1982-07-16 1984-02-22 Robert Bosch Gmbh Circuit arrangement for rising and lowering a motor-operated antenna
EP0275238A2 (en) * 1987-01-15 1988-07-20 CAVIS CAVETTI ISOLATI S.p.A. Circuit arrangement for controlling the electric motors used for raising and lowering glasses in motor vehicles and the like

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995002268A1 (en) * 1993-07-08 1995-01-19 Doduco Gmbh + Co. Dr. Eugen Dürrwächter Process for controlling the d.c. motor used for moving a window in a motor vehicle
EP1679777A1 (en) * 2005-01-05 2006-07-12 Behr-Hella Thermocontrol GmbH Device for indicating an obstruction of a DC commutated motor based on the ripple of the field current

Also Published As

Publication number Publication date
GB8921025D0 (en) 1989-11-01

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