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US 5,675,230 AGranted
Method and apparatus for dynamic low voltage spindle motor operation
AssigneeSeagate Technology LLC
InventorJohn C. G. Dunfield
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AssigneeSeagate Technology LLC
InventorJohn C. G. Dunfield
Estimating the term…
Dynamic operation of a brushless N-phase DC motor results in a high torque constant (Kt) line-to-line phase configuration during spindle motor power-up, and in a lower effective Kt configuration once normal run speed operation is attained. When the spindle motor is rotating below a predetermined run speed, drive transistors coupled to the motor phases cause at least two phases to be series-coupled between the source of operating voltage and ground. This ensures a large initial torque because the Kt contribution of each series-coupled phase is combined vectorially. Once run speed is achieved, effective Kt is lowered by causing the drive transistors to energize but a single phase, reconfiguring the spindle motor for line-to-neutral operation. So doing reduces the effective back electromagnetic force, permitting sufficient run current from a given magnitude operating voltage source. The present invention permits designing the spindle motor Kt for line-to-neutral normal run speed conditions, while ensuring a large start-up Kt by starting the motor line-to-line.
A method for dynamic operation of a brushless N-phase DC motor, where N.gtoreq.3, wherein a first end of each phase is coupled to a source of operating voltage or ground by an associated drive switch, and each second end of each said phase is coupled via a mode switch to said source of operating voltage, comprising the following steps:
A system for dynamic operation of a brushless N-phase DC motor, where N.gtoreq.3, one end of each said phase is coupled between a source of operating voltage and an associated drive switch comprising:
In a magnetic disc drive storage system including one or more magnetic storage discs rotate by a brushless N-phase DC motor, where N.gtoreq.3, a method for dynamic operation of said motor wherein a first end of each phase is coupled to a source of operating voltage or ground by an associated drive switch, and each second end of each said phase is coupled via a mode switch to said source of operating voltage, comprising the following steps:
A system for dynamic operation of a brushless N-phase DC motor where N.gtoreq.3, comprising means for determining rotational speed of said motor during motor startup by examining back emf of said motor, and for comparing said rotational speed to a run velocity of said motor electronic switch drive means coupled to said motor for coupling at least two of said N-phases to a source of operating voltage in a line-to-line configuration when said motor has rotational speed less than a predetermined run velocity, and for configuring said motor to connect less than two phases to said source in a line-to-neutral mode when said motor has a rotational speed equal to a predetermined run velocity.
Dependencies are inferred from the claim text.