Electricity: motive power systems – Reciprocating or oscillating motor – Energizing winding circuit control
Patent
1978-01-12
1979-01-16
Rubinson, Gene Z.
Electricity: motive power systems
Reciprocating or oscillating motor
Energizing winding circuit control
318721, 318254, 318722, H02K 2900
Patent
active
041351207
ABSTRACT:
A drive circuit for a brushless motor of the type having a rotor magnet and energizable stator windings. The drive circuit includes position sensors for sensing the rotary position of the rotor magnet and for generating varying position signals corresponding to the sensed rotary position. A plurality of amplifier stages is coupled to the position sensors, the amplifier stages being responsive to the position signals to produce drive currents which are supplied to the stator windings. In one embodiment, each amplifier stage includes a voltage amplifier having a linear gain characteristic for amplifying the position signal applied thereto, a current amplifier connected in cascade with the voltage amplifier and responsive to the amplified position signal to produce a drive current, and a feedback circuit interconnected between the output of the current amplifier and the input to the voltage amplifier, the feedback circuit including a resistor and a capacitor connected in parallel and operative as a low pass filter circuit to prevent harmonics of the drive current frequency from being transmitted to the stator winding, thereby preventing notching in the drive current.
In another embodiment, the drive circuit also includes a speed sensor for sensing the speed of the motor and for generating a signal whose frequency varies in accordance with the motor speed, a converter coupled to the speed sensor for converting the frequency of the generated signal to a voltage, a circuit for applying the converted voltage to the position sensors so as to modify the position signals in accordance with the sensed motor speed, and a circuit for supplying an offset voltage to the last-mentioned circuit such that if the speed of the motor exceeds a predetermined amount, the offset voltage exceeds the converted voltage whereby the resultant voltage which is applied to the position sensors causes a modification in the drive currents supplied to the stator windings, to produce an opposite torque in the motor. In this embodiment, excess motor speeds are rapidly corrected.
REFERENCES:
patent: 3383574 (1968-05-01), Manteuffel
patent: 3930190 (1975-12-01), Liska
patent: 3940670 (1976-02-01), Tanikoshi
patent: 3999108 (1976-12-01), Tanikoshi
patent: 4070606 (1978-01-01), Morozumi et al.
Hoshimi Susumu
Sato Toshio
Eslinger Lewis H.
Rubinson Gene Z.
Sinderbrand Alvin
Sony Corporation
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