Spindle Motor Power Generation During Drive Failure
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Solution Overview
Problem
Prior art disk drives face challenges in optimizing power generation from the spindle motor during a power failure, particularly when transitioning from normal operation to a power generator, which can result in the supply voltage falling below critical thresholds, potentially interrupting data write operations.
Innovation Solution
The control circuitry configures the spindle motor into a power generator by reducing and then incrementally increasing the amplitude of the driving voltage applied to the windings, and in some embodiments, reversing the polarity of the driving voltage, to maximize power generation and prevent the supply voltage from dropping below preamp fault thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the spindle motor is transitioned into a power generator during a power failure, then power generation capability is improved, but the supply voltage may drop below critical thresholds
Solution Approach 1:
The system detects power failure conditions before they occur and proactively transitions the spindle motor into generator mode in advance. The control circuitry monitors power supply status and initiates the mode transition sequence, including reversing polarity and adjusting driving voltage amplitude, before the power failure fully impacts the system. This preliminary action ensures the motor is ready to generate power immediately when needed, while maintaining voltage stability through controlled transition.
Solution Approach 2:
The system dynamically adjusts the driving voltage amplitude applied to the spindle motor windings during the transition from motor mode to generator mode. The control circuitry varies the voltage amplitude based on the detected power failure condition, optimizing the transition process to maximize power generation while preventing supply voltage from dropping below critical thresholds. This dynamic adjustment resolves the contradiction between power generation capability and voltage stability.
2Power
If the amplitude of driving voltage is reduced and then incrementally increased, then power generation is optimized, but the transition process complexity increases
Solution Approach 1:
The system employs periodic action by reversing the polarity of the driving voltage applied to the spindle motor windings during the transition to generator mode. This polarity reversal, combined with incremental amplitude adjustments, creates a controlled periodic transition sequence that optimizes power generation. The periodic nature of the voltage adjustment simplifies the control logic while achieving optimal power generation, resolving the contradiction between power optimization and transition complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures sufficient power is generated during a power failure to complete write operations and maintain the supply voltage above critical thresholds, preventing interruptions and optimizing power generation at the onset of a power failure.
Implementation Method 1
measuring a zero-crossing frequency of a back electromotive force (BEMF) voltage generated by the windings of the spindle motor
Implementation Method 2
The control circuitry configures the spindle motor into a power generator by reducing and then incrementally increasing the amplitude of the driving voltage applied to the windings
Data Source
AI summary
A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings. The windings of the spindle motor are commutated based on a commutation sequence while applying a driving voltage to each winding, wherein the driving voltage comprises an operating polarity during normal operation. When a supply voltage falls below a threshold while the spindle motor is rotating the disk, the spindle motor is configured into a power generator by at least reversing the polarity of the driving voltage for an interval and then reversing the polarity of the driving voltage back to the operating polarity.