Disk Drive Power Failure Management via Motor-Generated Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional disk drives face challenges in ensuring data integrity during power failures, as they struggle to complete pending write commands and safely shut down without losing user data, particularly in systems that cache data in volatile semiconductor memory.
Innovation Solution
The disk drive charges a capacitor to a high voltage using host supply voltage and, during a power failure, switches to using motor supply voltage to maintain the capacitor voltage above a safe level, allowing the control circuitry to continue operating and complete write operations by converting residual kinetic energy from the spindle motor into a generator for the motor supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a high voltage capacitor is used to generate backup power during power failure, then cost effectiveness is improved, but the duration the capacitor can maintain safe voltage level deteriorates
Solution Approach 1:
The patent implements continuous charging of the capacitor by switching between host supply voltage (during normal operation) and motor supply voltage (during power failure). This continuous action ensures the capacitor maintains safe voltage levels for an extended period, resolving the contradiction between using a single capacitor for cost effectiveness and maintaining adequate backup power duration.
2Use of energy by moving object
If host supply voltage is used to charge the capacitor, then charging efficiency is improved, but during power failure the capacitor voltage decays below safe level faster
Solution Approach 1:
The patent enables the spindle motor to serve dual purposes: acting as a motor during normal operation and as a generator during power failure to produce charging voltage. This self-service mechanism allows the system to maintain capacitor voltage without external power sources, improving reliability during power failures while maintaining charging efficiency through the motor's kinetic energy conversion.
3Adaptability or versatility
If the spindle motor is converted to generator for motor supply voltage, then power autonomy during power failure is improved, but system complexity increases
Solution Approach 1:
The patent makes the spindle motor universal by enabling it to function both as a motor during normal operation and as a generator during power failure. This multi-functionality achieves power autonomy without adding separate backup power systems, thereby improving adaptability while minimizing the increase in system 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 that the disk drive can safely shut down and complete write operations during a power failure by maintaining the capacitor voltage above a safe level for a longer period, reducing data loss and operational complexity.
Implementation Method 1
a capacitor charged to a capacitor voltage higher than the host supply voltage
Implementation Method 2
converting residual kinetic energy from the spindle motor into a generator for the motor supply voltage
Data Source
AI summary
A disk drive is disclosed comprising a disk, a spindle motor operable to rotate the disk, a head actuated over the disk, an interface operable to receive a host supply voltage, and a capacitor. The host supply voltage is used to charge the capacitor to a capacitor voltage higher than the host supply voltage. During a power failure, the host supply voltage stops charging the capacitor, and a motor supply voltage is generated from the spindle motor. The capacitor voltage is used to operate control circuitry, and when the capacitor voltage decays below the motor supply voltage, the motor supply voltage charges the capacitor.