Electricity: motive power systems – Open-loop stepping motor control systems
Patent
1981-09-21
1983-11-15
Truhe, J. V.
Electricity: motive power systems
Open-loop stepping motor control systems
318685, 318254, 368156, G05B 1940
Patent
active
044158459
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an electric motor control device of the type comprising a magnetic rotor and at least two separate magnetic stator circuits, each coupled with at least one electric coil and disposed in such manner as to form between them an electric angle of 2K.pi..+-..pi./2 (k=0, 1, 2). A known device of the type with which the invention is concerned comprises a source of electric energy, a pulse generator circuit controlled by a clock signal source for supplying rotor driving pulses to at least one of the coils of one of the magnetic stator circuits, and comprises an integrator circuit arranged for receiving the signals induced by the rotor in at least one of the coils of another of the said magnetic stator circuits for determining the duration of a driving pulse of the rotor.
In this known control device, one of the magnetic stator circuits is reserved during operation of the motor for the function of detecting the flux induced by the rotor and thus it does not contribute to the drive proper. This device is in addition designed for operating with continuous rotation in a given direction of movement.
The present invention has for its object to provide a control device permitting a motor of the aforementioned type to be caused to operate in two-phase manner and step-by-step in one or other direction of movement, while permitting a servo control of the position of the rotor and an automatic regulation of the duration of the driving pulses. The invention is more particularly concerned with providing a simple and efficient device which can be used particularly in the clock and watch-making field.
To this end, the device according to the invention is characterised in that it comprises a logic control circuit connected, by its inputs, firstly to the source of clock signals and secondly to the output of the integrator circuit and, by its outputs, to the control inputs of a commutating circuit, the commutating circuit being connected to the electric energy source, to the different coils and to the input of the integrator circuit, the logic control circuit and the commutating circuit being arranged so as to be able to connect the coupled coils with each of the said magnetic stator circuits to the electric energy source or to the input of the said integrator circuit in such manner that the motor operates in two-phase manner and step by step under the effect of driving pulses supplied alternately to the coils associated with one and the other phase, at least one of the coils associated with the phase not supplied by a driving pulse being connected, at least temporarily, to the integrator circuit.
According to a preferred embodiment, the control device comprises a level detector associated with the integrator circuit, the logic circuit being arranged for interrupting a driving pulse and/or for triggering a new driving pulse as a function of the presence of an output signal from one of the level detectors and from the instant of the appearance of this signal with respect to the clock signals, and also for resetting the integrator to zero at the commencement and at the end of each provided integration period.
On the other hand, the logic circuit may be arranged for temporarily short-circuiting at least one coil, so as to damp the moving rotor in the vicinity of the position of equilibrium and/or to tend to hold it in this position by such a circuit.
The control device according to the invention not only makes possible a reduction in the energy consumption of the motor by limiting the duration of the electric driving pulses to the value necessary for a given load of the motor and by permitting the locking torque of the motor necessary for the stepwise operation to be reduced by construction, while assuring an improved functioning which is practically insensitive to external disturbances.
In effect, with the present control device, the position of the rotor is controlled by means of a servo-control loop comprising a detector of the flux induced by the rotor, an integrator of this flux associated with a
REFERENCES:
patent: 4136308 (1979-01-01), King
patent: 4242623 (1980-12-01), Oudet et al.
patent: 4250435 (1981-02-01), Alley et al.
Bergmann Saul M.
Portescap
Truhe J. V.
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