Start up circuit for continuous sine-wave commutated brushless motors

• US 5,491,391 A
• Filed: 09/16/1993
• Issued: 02/13/1996
• Est. Priority Date: 09/16/1993
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Nguyen, Du V., Teichman, Gary A., Bahr, Allen A.
• Primary Examiner(s): Cabeca, John W.
• Application Number:
  US08/122,113
• Time in Patent Office: 880 Days
• Field of Search: 318/603, 318/640, 318/594, 318/627, 318/685, 318/254, 318/138, 318/439, 318/39, 318/45, 318/50, 318/54, 318/65, 318/66, 318/55, 318/77, 318/102, 318/103, 324/144, 324/150, 324/143, 324/166, 324/163
• US Class Current: 318/39
• CPC Class Codes: G11B 15/46 Controlling, regulating, or indicating speed dependent on position of tape in reserve, loop G11B15/56, G11B15/58
• CPC Class Codes: G11B 15/67 by extracting end of record carrier from container or spool
• CPC Class Codes: H02P 6/22 in a selected direction of rotation

Abstract

Automatic start up of a continuous sine-wave commutated, brushless, direct current motor in a predetermined direction is done by applying a ramped armature current to the direct current motor to generate an armature field. The resulting armature field is rotated independent of angular position of the shaft. Upon rotation of the motor shaft beginning, the direction of rotation of the shaft is determined. Responsive to rotation of the shaft in an undesired direction, the direction of rotation of the armature field is reversed. A base angle of rotation of a shaft in the direct current motor is determined from an index mark as it rotates by an index mark detector. Responsive to detection of the index mark, rotation of the armature field and the angular position of the shaft are synchronized.

Claims

1. A tape drive mechanism, comprising:

means for setting phase angle counters for a shaft for a takeup motor and for a shaft for a supply motor to predetermined values;

means for locking out the supply motor;

means for incrementing the phase angle counter for the takeup motor;

means for generating a ramp scaler for the takeup motor;

means responsive to the phase angle counter for the takeup motor and ramp scaler for the takeup motor for generating a plurality of phase differentiated armature currents;

means for detecting a direction of rotation of the takeup motor;

means responsive to the takeup motor rotating in an undesired direction for reversing the direction of the armature currents;

means responsive to encountering an index mark defining take up motor rotation position for setting the phase angle counter to a predetermined base phase value and locking out the takeup motor while enabling the supply motor;

means for incrementing the phase angle counter for the supply motor;

means for generating a ramp scaler for the supply motor;

means responsive to the phase angle counter for the supply motor and ramp scaler for the supply motor for generating a plurality of phase differentiated armature currents for the supply motor;

means for detecting a direction of rotation of the supply motor;

means responsive to the supply motor rotating in an undesired direction for reversing direction of the armature currents; and

means responsive to encountering an index mark for the supply motor for setting the phase angle counter for the supply motor to a predetermined base phase value and enabling the takeup motor.