Variable reluctance stepper motor drive and method of operation as a DC brushless motor

A drive for a magnetic storage disc comprising:

• a rotary variable reluctance motor of the stepper type comprising a rotor, a stator having a plurality of pole positions and windings carried by said stator at said pole positions;
• a read/write head for reading or writing data on the disc;
• means for coupling the rotor to a magnetic storage disc;
• means located substantially at the radial outer extremity of said rotor for directly sensing the position of the rotor;
• tachometer means coupled to said sensing means for generating a signal representing the rotational speed of said rotor;
• a supply voltage;
• a sequence control means coupled to said speed control means including means for sequentially supplying said voltage to said winding means for sequential energization thereof;
• and
• speed control means coupled to said tachometer means for controlling said sequential energization in response to the speed of the motor so as to maintain the speed of the motor substantially constant.

A drive for a magnetic storage disc comprising:

• a rotary variable reluctance motor of the stepper type comprising a rotor, a stator having a plurality of pole positions and windings associated with said stator at said pole positions;
• a read/write head for reading or writing data on the disc;
• means for coupling the rotor to a magnetic storage disc;
• means for sensing the position of the rotor;
• tachometer means coupled to said sensing means for generating a signal representing the rotational speed of said rotor;
• a supply voltage;
• a sequence control means coupled to said speed control means including means for sequentially supplying said voltage to said winding means for sequential energization thereof;
• speed control means coupled to said tachometer means for controlling said sequential energization in response to the speed of the motor so as to maintain the speed of the motor substantially constant;
• and
• start-up means coupled to said tachometer means and said motor drive means for continuously applying an input signal to said motor drive means to change the phase relationship between the mechanical motor position and the electrical energization of the motor until a predetermined speed is reached.

A drive for a magnetic storage disc comprising:

• a rotary variable reluctance motor of the stepper type comprising a rotor, a stator having a plurality of pole positions and windings associated with said stator at said pole positions;
• a read/write head for reading or writing data on the disc;
• means for coupling the rotor to a magnetic storage disc;
• means for sensing the position of the rotor;
• p1 tachometer means coupled to said sensing means for generating a signal representing the rotational speed of said rotor;
• speed control means including a supply voltage means coupled to said tachometer means for producing a supply voltage varying in response to the speed of the motor;
• a sequence control means coupled to said speed control means including means for sequentially supplying said supply voltage to said winding means for sequential energization thereof;
• and
• start-up means coupled to said tachometer means and said sequence control circuit for applying an input signal to said sequence control circuit to change the phase relationship between the mechanism motor position and the electrical energization of the motor until a predetermined speed is reached, said start up means comprising an oscillator.

A drive for a magnetic storage disc comprising:

• a rotary variable reluctance motor of the stepper type comprising a rotor, a stator having a plurality of pole positions and windings associated with said stator at said pole positions;
• a read/write head for reading or writing data on the disc;
• means for coupling the rotor to a magnetic storage disc;
• means for sensing the position of the rotor;
• tachometer means coupled to said sensing means for generating a signal representing the rotational speed of said rotor;
• speed control means including a supply voltage means coupled to said tachometer means for producing a supply voltage varying in response to the speed of the motor;
• a sequence control means coupled to said speed control means including means for sequentially supplying said supply voltage to said winding means for sequential energization thereof;
• start-up means coupled to said tachometer means and said sequence control circuit for applying an input signal to said sequence control circuit to change the phase relationship between the mechanical motor position and the electrical energization of the motor until a predetermined speed is reached;
• and
• said tachometer means including means for interrupting the application of said input signal when a predetermined rotor speed is exceeded and reinitiating the application of said input signal when the rotor speed drops below said predetermined speed.

A drive for a magnetic storage disc comprising:

• a rotary variable reluctance motor of the stepper type comprising a rotor, a stator having a plurality of pole positions and windings associated with said stator at said pole positions;
• a read/write head for reading or writing data on the disc;
• means for coupling the rotor to a magnetic storage disc;
• means for sensing the position of the rotor;
• tachometer means coupled to said sensing means for generating a signal representing the rotational speed of said rotor;
• a supply voltage;
• a sequence control means coupled to said speed control means including means for sequentially supplying said voltage to said winding means for sequential energization thereof;
• speed control means coupled to said tachometer means for controlling said sequential enerigization in respons to the speed of the motor so as to maintain the speed of the motor substantially constant;
• and
• start-up means coupled to said tachometer means and said motor drive means for applying an input signal to said motor drive means to change the phase relationship between the mechanical motor position and the electrical energization of the motor until a predetermined speed is reached, said start-up means also applying said input signal to said motor drive means when the motor speed falls below said predetermined speed.