Spindle Motor Commutation Phase Re-initialization for Disk Drive Stability
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Solution Overview
Problem
Prior art disk drives experience acoustic noise, torque/speed jitter, and disk vibration due to current transients in spindle motor windings when driving signals are disabled for BEMF zero-crossing detection, affecting commutation control and head positioning accuracy.
Innovation Solution
The control circuitry initializes and periodically re-initializes the phase of the commutation controller using timing data from servo sectors, switching from BEMF signal to timing data for commutation sequence driving once synchronization is established, and adjusts the commutation sequence to compensate for cumulative phase errors, thereby minimizing disruptions and maintaining stable spindle motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If driving signals are disabled during BEMF zero-crossing detection, then measurement precision of commutation timing is improved, but acoustic noise and torque/speed jitter increase due to current transients in windings
Solution Approach 1:
The patent introduces an intermediary approach by using timing data from servo sectors on the disk as a mediator to drive the commutation sequence, replacing direct BEMF signal dependency. This allows commutation control to continue without disabling driving signals, thereby avoiding current transients while maintaining synchronization through the intermediary timing data from servo sector zero-crossings
Solution Approach 2:
The system performs preliminary synchronization by detecting zero-crossings of BEMF voltage to establish initial timing reference, then uses this reference to periodically re-initialize the phase of the commutation controller. This preliminary action ensures accurate timing establishment before transitioning to servo sector-based commutation driving, preventing cumulative phase errors without requiring repeated disabling of driving signals
2Measurement precision
If BEMF zero-crossing detection is used for commutation control, then commutation timing accuracy is improved, but driving signals must be disabled causing current transients and operational disturbances
Solution Approach 1:
The patent uses timing data from servo sectors as an intermediary to maintain commutation control without disabling driving signals. The servo sector zero-crossings provide a reliable timing reference that allows continuous operation of the spindle motor while achieving accurate commutation synchronization, thus improving reliability without sacrificing timing precision
Solution Approach 2:
The system implements feedback by periodically re-initializing the phase of the commutation controller using timing data from servo sectors. This feedback mechanism corrects cumulative phase errors and maintains synchronization accuracy over time, ensuring both commutation timing precision and operational reliability through continuous correction rather than repeated disabling of driving signals
3Measurement precision
If commutation sequence is driven by BEMF signal, then timing synchronization is improved, but cumulative phase errors occur requiring periodic re-initialization
Solution Approach 1:
The patent implements a feedback mechanism where the phase of the commutation controller is periodically re-initialized using timing data from servo sectors. This feedback loop detects and corrects cumulative phase errors by referencing the accurate timing information from servo sector zero-crossings, thereby maintaining both timing synchronization and phase stability over extended operation periods
Solution Approach 2:
The system employs periodic action by re-initializing the commutation phase at regular intervals based on servo sector passages. This periodic re-initialization prevents cumulative phase errors from degrading synchronization accuracy, maintaining stable commutation control through repeated correction cycles without disrupting continuous motor operation
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 reduces acoustic noise, torque/speed jitter, and disk vibration by ensuring continuous and accurate commutation sequencing, enhancing the operational stability and precision of the disk drive.
Implementation Method 1
A commutation controller applies a driving signal to the windings of the spindle motor using a particular commutation sequence in order to generate a rotating magnetic field that causes the spindle motor to rotate
Implementation Method 2
measuring a zero-crossing frequency of a back electromotive force (BEMF) voltage generated by the windings of the spindle motor
Implementation Method 3
a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk
Data Source
AI summary
A data storage device is disclosed comprising a disk comprising timing data, a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings, and a head actuated over the disk. A phase of a commutation controller is initialized based on the timing data on the disk, and a commutation sequence of the commutation controller is driven based on the timing data on the disk, wherein the commutation controller is configured to commutate the windings based on the commutation sequence. The phase of the commutation controller is re-initialized based on the timing data on the disk, thereby compensating for a cumulative phase error when driving the commutation sequence based on the timing data on the disk.