Electricity: motive power systems – Positional servo systems – With particular motor control system responsive to the...
Patent
1992-08-21
1994-01-11
Shoop, Jr., William
Electricity: motive power systems
Positional servo systems
With particular motor control system responsive to the...
318696, G05B 1940
Patent
active
052784819
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the control of stepping motors, and in particular provides a control circuit for a stepping motor, and a stepping motor controller.
It is known that to obtain optimum torque from a stepping motor over a range of speeds, its switching angle has to be varied. However, many earlier control schemes have enabled variation of the switching angle over one step only.
The present invention seeks to provide a control circuit and a controller for a stepping motor which is more convenient than those available previously, and which enables the switching angle of a stepping motor to be varied substantially without limit so that complete control of the stepping motor is available.
According to a first aspect of the present invention there is provided a control circuit for a stepping motor comprising drive means having a plurality of switching positions in each of which the drive means is arranged to supply current to selected windings of a stepping motor in selected directions, and means arranged to change the switching positions in sequence, said control circuit further comprising sensor means for providing information relating to the speed and position of the motor, and control means arranged to receive the speed and position information and to generate in response thereto change excitation signals for application to said drive means to change the switching positions, the control means also being arranged to produce direction signals for application to said control means to determine the direction in which the sequence of switching positions is changed.
The invention also extends to a control circuit for a stepping motor comprising drive means having a plurality of switching positions in each of which the drive means is arranged to supply current to selected windings of a stepping motor in selected directions, and means arranged to change the switching positions in sequence, said control circuit further comprising sensor means for providing information relating to the speed and position of the motor, and control means arranged to receive the speed and position information and to generate in response thereto control signals for said drive means, wherein said control means further comprises inhibiting means arranged selectively to inhibit the application of control signals to said drive means.
According to a further aspect of the invention there is provided a control circuit for a stepping motor comprising drive means having a plurality of switching positions in each of which the drive means is arranged to supply current to selected windings of a stepping motor in selected directions, and means arranged to change the switching positions in sequence, said control circuit further comprising sensor means for providing information relating to the speed and position of the motor, and control means arranged to receive the speed and position information and to generate in response thereto control signals for said drive means, wherein said control means further comprises step complete signal generating means arranged to generate a step complete signal upon receipt of information from said sensor means indicating the motor has moved a predetermined number of steps, and synchronising means receiving said step complete signals and arranged to enable generation of said control signals upon receipt of a step complete signal.
Preferably, the control signals generated by said control means comprise change excitation signals for application to said drive means to change the switching positions, and direction signals for application to said drive means to determine the direction in which the sequence of switching positions is changed.
The provision of both change excitation signals and direction signals offers maximum flexibility, because it enables, for example, speedy reversal of the torque of a stepping motor by causing the drive means to step backwardly through the switching sequence.
In an embodiment, said sensor means is arranged to be coupled to the motor and is arranged to generate a train of puls
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Transactions of the Institute of Measurement and Control, vol. 6, No. 6, Dec. 1984, Dorking GB, pp. 282-286; Acarnley: "Minimising point-to-point positioning times using closed-loop stepping-motor control".
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British Technological Group Ltd.
Masih Karen
Shoop, Jr. William
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