Braking method, braking circuit and speed control apparatus for a DC motor
First Claim
1. A method of braking a pulse-driven DC motor which comprises:
- charging a capacitor connected to a winding of said DC motor having a counter electromotive force generated in said winding of said DC motor after a driving pulse is fed to said winding, said capacitor being charged with a reverse polarity with respect to said driving pulse, andapplying plugging to said DC motor by feeding said counter electromotive force charged in said capacitor to said winding during an absence of said driving pulse.
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Abstract
A braking method for DC motor of the present invention is applied to a pulse-driven DC motor. A counter electromotive force of reverse polarity to driving pulses which is generated by induction at the winding of the DC motor is charged in a capacitor. The charged counter electromotive force is fed to the winding of the DC motor during the time that the driving pulses are not fed to the motor, so that plugging is applied to the DC motor. Thus, an external power source for plugging is not necessary, and power consumption is reduced and the construction of the braking circuit becomes very simple. Also, the driving period and the plugging period have a complementary relationship therebetween, thereby enabling the accurate controlling of the rotational speed of the DC motor with a very simple circuit.
26 Citations
7 Claims
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1. A method of braking a pulse-driven DC motor which comprises:
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charging a capacitor connected to a winding of said DC motor having a counter electromotive force generated in said winding of said DC motor after a driving pulse is fed to said winding, said capacitor being charged with a reverse polarity with respect to said driving pulse, and applying plugging to said DC motor by feeding said counter electromotive force charged in said capacitor to said winding during an absence of said driving pulse. - View Dependent Claims (2)
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3. A braking circuit for a pulse-driven DC motor comprising:
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a capacitor connected to a winding of said DC motor; a diode interposed between said capacitor and said winding so as to charge said capacitor with a counter electromotive force generated in said winding after the feeding of a driving pulse to said winding; and a switching element interposed between said capacitor and said winding so as to feed said counter electromotive force charged in said capacitor to said winding; wherein said capacitor discharges its electrical charge and said discharged electrical charge is fed to said winding with a reverse polarity with respect to said driving pulse by switching on said switching element in the absence of said driving pulse so that plugging is applied to said DC motor. - View Dependent Claims (4)
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5. A speed control apparatus for a pulse-driven DC motor comprising:
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a rotational speed detecting device for detecting the rotational speed of said DC motor; a circuit for generating a driving pulse whose duty ratio corresponds to a difference between a speed setting signal for said DC motor and a detected speed signal from said speed detecting device; a capacitor connected to a winding of said DC motor; a diode interposed between said capacitor and said winding so as to charge said capacitor with a counter electromotive force generated in said winding after the feeding of a driving pulse to said winding; a switching element interposed between said capacitor and said winding so as to feed said counter electromotive force charged in said capacitor to said winding; and a switching element control circuit for switching on said switching element at a proper time. - View Dependent Claims (6, 7)
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Specification