US3783360A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric motor speed control systems
Assignee: Dunlop Ltd
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Filing: 1972-05-23
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Granted: 1974-01-01
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Expires: 1992-05-23
Abstract
Abstract A control system, for maintaining an electric motor at a required speed of rotation irrespective of the externally applied load, in which a command input provides a voltage proportional to the desired speed and direction of rotation of the motor and a switching circuit supplies current to the motor as a series of current pulses of constant frequency. The switching circuit is arranged to vary the duration of the pulses of current applied to the motor in response to input signals received from the command input and two negative feed back loops, one feed back loop being arranged to feed back a voltage dependent on the actual velocity of the motor and the other on the acceleration of the motor, of which the following is a Specification.
Inventors
- 👤 J Bundy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:26
CPC Classifications
H; H02; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/29; H02P7/03; H02P7/05; H02P7/2913; H02P7/292; H02P7/293
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
205 words
A control system for maintaining an electric motor at a required speed of rotation comprising a command input means arranged to provide a voltage proportional to the desired speed and direction of rotation of the motor, an integrator arranged to receive the command input voltage as a signal input, a switching circuit arranged to receive the output of the integrator and to supply current to the motor as a series of current pulses of constant frequency, means to generate a voltage dependent on the actual speed of rotation of the motor, a first negative feed back loop arranged to feed back the motor velocity dependent voltage as a further signal input to the integrator, a second negative feed back loop arranged to differentiate the motor velocity dependent voltage so as to provide an acceleration dependent signal and to feed the acceleration dependent signal as an input to the switching circuit, the switching circuit being arranged to vary the duration of the pulses of current applied to the motor in response to the switching circuit inputs from the integrator and second feed back loop so as to tend to maintain the motor speed substantially constant at the required value irrespective of any externally applied motor load.
Claim 2
Dependent Claim
205 words
A control system for maintaining an electric motor at a required speed of rotation comprising a command input means arranged to provide a voltage proportional to the desired speed and direction of rotation of the motor, an integrator arranged to receive the command input voltage as a signal input, a switching circuit arranged to receive the output of the integrator and to supply current to the motor as a series of current pulses of constant frequency, means to generate a voltage dependent on the actual speed of rotation of the motor, a first negative feed back loop arranged to feed back the motor velocity dependent voltage as a further signal input to the integrator, a second negative feed back loop arranged to differentiate the motor velocity dependent voltage so as to provide an acceleration dependent signal and to feed the acceleration dependent signal as an input to the switching circuit, the switching circuit being arranged to vary the duration of the pulses of current applied to the motor in response to the switching circuit inputs from the integrator and second feed back loop so as to tend to maintain the motor speed substantially constant at the required value irrespective of any externally applied motor load.
Claim 3
Dependent Claim
94 words
A control system according to claim 1 wherein power is supplied to the motor through a two arm power bridge circuit, one arm of the power bridge circuit controlling the current supplied to the motor in the forward direction of rotation and the other arm controlling the current supplied to the motor in the reverse direction of rotation, the switching circuit being arranged to switch the power through the appropriate arm of the bridge and to vary the duration of the constant frequency current pulses supplied to the motor via the power bridge circuit.
Claim 4
Dependent Claim
163 words
A control system according to claim 2 wherein the switching circuit comprises a ramp generator arranged to produce a constant frequency saw-toothed wave form, a phase splitter arranged to produce two saw-toothed wave outputs 180 degrees out of phase with one another and two pulse width modulators in the form of differential amplifiers, one pulse width modulator being arranged to receive one of the phase splitter outputs as a positive input and the other pulse width modulator being arranged to receive the other phase splitter output as a positive input, both pulsE width modulators being arranged to receive, as a combined negative input, the signals from the integrator and the second negative feed back loop, the output of one modulator being arranged to control the supply of power to the motor through one arm of the power bridge circuit and the output of the other modulator being arranged to control the supply of power through the other arm of the power bridge circuit.
Claim 5
Dependent Claim
76 words
A control system according to claim 3 wherein one pulse width modulator is arranged to switch on the power to the motor via one arm of the power bridge circuit when the modulators positive input exceeds its negative input and the other pulse width modulator is arranged to switch on the power to the motor via the other arm of the power bridge circuit when the negative input of the other modulator exceeds its positive input.
Claim 6
Dependent Claim
116 words
A control system according to claim 4 wherein the output of one pulse width modulator is connected to the base of a N-P-N transistor which controls the supply of power to one arm of the power bridge circuit and is arranged to render the N-P-N transistor conductive when the negative input of the pulse width modulator exceeds its positive input and the output of the other pulse width mpdulator is connected to the base of a P-N-P transistor which controls the supply of power to the other arm of the power bridge circuit and is arranged to render the P-N-P transistor conductive when the positive input of the other pulse width modulator exceeds its negative input.
Claim 7
Dependent Claim
74 words
A control system according to claim 1 wherein a split series electric motor is employed; the field or armature winding of the motor comprising a single coil split into two portions, the switching circuit being arranged to supply current to one portion of the field or armature winding to drive the motor in the forward direction of rotation and to allow a portion of the winding to drive the motor in the reverse direction.
Claim 8
Dependent Claim
174 words
A control system according to claim 6 wherein the switching circuit comprises a ramp generator arranged to produce a constant frequency saw-toothed wave form and two pulse width modulators in the form of differential amplifiers, one pulse width modulator being arranged to receive the ramp generator output as a positive capacitance-coupled input and the signals from the integrator and second negative feed back loop as a combined negative input, the other pulse width modulator being arranged to receive the ramp generator output as a negative capacitance-coupled input and the signals from the integrator and second negative feed back loop as a combined positive input, the positive ramp generator input to the one modulator being biased to a higher voltage level than the negative ramp generator input to the other modulator, the output of one modulator being arranged to control the supply of current to one portion of the field or armature winding and the output of the other modulator being arranged to control the supply of current to the other portion of the winding.
Claim 9
Dependent Claim
66 words
A control system according to claim 7 wherein the outputs of both modulators are respectively connected to the base contacts of two separate N-P-N transistors, each respective N-P-N transistor being arranged to be conductive, thereby supplying current to the associated oppositely wound coil, or portion of the field or armature winding of the motor, whenever the negative input to that particular modulator exceeds its positive input.
Claim 10
Dependent Claim
67 words
A control system according to claim 1 wherein a split series motor is employed, the field or armature winding of the motor comprising two oppositely wound coils, the switching circuit being arranged to supply current to one of the oppositely wound coils to drive the motor in the forward direction of rotation and to the other oppositely wound coil to drive the motor in the reverse direction.
Claim 11
Dependent Claim
171 words
A control system according to claim 9 wherein the switching circuit comprises a ramp generator arranged to produce a constant frequency saw-toothed wave foRm and two pulse width modulators in the form of differential amplifiers, one pulse width modulator being arranged to receive the ramp generator output as a positive capacitance-coupled input and the signals from the integrator and second negative feed back loop as a combined negative input, the other pulse width modulator being arranged to receive the ramp generator output as a negative capacitance-coupled input and the signals from the integrator and second negative feed back loop as a combined positive input, the positive ramp generator input to the one modulator being biased to a higher voltage level than the negative ramp generator input to the other modulator, the output of one modulator being arranged to control the supply of current to one of the oppositely wound coils and the output of the other modulator being arranged to control the supply of current to the other oppositely wound coil.
Claim 12
Dependent Claim
66 words
A control system according to claim 10 wherein the outputs of both modulators are respectively connected to the base contacts of two separate N-P-N transistors, each respective N-P-N transistor being arranged to be conductive, thereby supplying current to the associated oppositely wound coil, or portion of the field or armature winding of the motor, whenever the negative input to that particular modulator exceeds its positive input.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |