Spindle Motor Mode Switching Synchronization
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Solution Overview
Problem
Spindle motors in hard disk drives face synchronization issues when switching modes, leading to inconsistencies in spindle interrupts, as the actual motor location may differ from the intended location specified by control circuitry or firmware.
Innovation Solution
A data storage device with a spindle motor configured to operate in multiple modes, where a reference point is selected for spindle motor interrupt service routines, and a delay time is determined based on the number of magnetic pole-pairs and mechanical revolution period, allowing the spindle motor to switch modes synchronously by using a timer or BEMF window counting to maintain consistent interrupt locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the spindle motor switches modes based on control circuitry instructions, then the motor can adapt to different task requirements (high frequency electrical mode vs low frequency mechanical mode), but the actual motor location may differ from the intended interrupt location, causing synchronization issues
Solution Approach 1:
The patent applies preliminary action by calculating and storing the delay time in advance based on the number of magnetic pole-pairs and mechanical revolution period. When a mode switch is needed, the system retrieves the pre-calculated delay time and applies it to ensure the interrupt occurs at the correct location, eliminating the need for real-time calculation and ensuring synchronization consistency.
Solution Approach 2:
The patent introduces a delay time as an intermediary parameter that mediates between the control circuitry's mode switching instruction and the actual motor position. This delay time acts as a buffer that compensates for the discrepancy between intended and actual interrupt locations, ensuring that the spindle interrupt occurs at the consistent reference point regardless of mode changes.
2Ease of operation
If the spindle interrupt location is referenced to zero cross location, then the interrupt timing can be simplified, but the motor may move with respect to the intended switch location, creating inconsistency
Solution Approach 1:
The system performs preliminary calculation of the delay time based on known motor parameters (number of magnetic pole-pairs and mechanical revolution period) before the mode switch occurs. This pre-calculated delay is stored and applied to maintain consistent interrupt location, combining the simplicity of zero-cross referencing with the precision needed for consistent interrupt timing.
Solution Approach 2:
The patent replaces direct mechanical position sensing with a calculated time delay approach. Instead of mechanically tracking the motor position to determine interrupt timing, the system uses electrical parameters (pole-pairs count, revolution period) to calculate the appropriate delay, substituting mechanical complexity with electrical calculation simplicity while maintaining precision.
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
Ensures consistent spindle motor location for interrupts during mode switches, improving synchronization and reducing errors in spindle motor operation across different modes.
Implementation Method 1
determining a target number of back electromotive force (BEMF) windows for each spindle interrupt
Data Source
AI summary
Various illustrative aspects are directed to a data storage device comprising one or more disks; a spindle motor for rotating the one or more disks, wherein the spindle motor comprises a plurality of magnetic pole-pairs, and wherein the spindle motor is configured to operate in a plurality of modes, including at least a first mode and a second mode; and one or more processing devices configured to select a reference point for spindle motor interrupt service routines (ISRs), determine a delay time, wherein the delay time is based at least in part on a number of magnetic pole-pairs and a mechanical revolution period of the spindle motor, start a timer at a first ISR, and when the timer is equal to the delay time, switch operation of the spindle motor from the first mode to the second mode.