Spindle Motor Closed Loop Park Mode During Spin Down
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Solution Overview
Problem
Existing data storage devices experience discontinuities and acoustic noise due to current limit events and frequent mode switching during spindle motor spin down, leading to unreliable operation and increased host reverse current.
Innovation Solution
Implementing a closed loop extended park mode that controls the braking duty cycle of the spindle motor to maintain current within a selected limit, using feedback loops and proportional-integral controllers to adjust the braking percentage and prevent current limit events, thereby reducing spin down time and acoustic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional spin down operation is used, then spin down time is reduced, but current limit events and acoustic noise increase
Solution Approach 1:
The patent implements a feedback control mechanism that continuously monitors the current discharged from the spindle motor during spin down and dynamically adjusts the braking duty cycle to maintain current within a selected limit. This closed-loop control prevents current limit events that cause acoustic noise while optimizing spin down time.
Solution Approach 2:
The braking duty cycle is dynamically adjusted during spin down operation based on real-time current measurements. The system transitions from static braking control to dynamic control, modifying the braking percentage continuously to prevent current limit events and reduce acoustic noise.
2Speed
If conventional spin down operation is used, then spin down speed is increased, but current limit events occur frequently
Solution Approach 1:
A feedback control mechanism continuously monitors the current discharged from the spindle motor and dynamically adjusts the braking duty cycle to maintain current within a selected limit, preventing current limit events while maintaining optimal spin down speed.
3Loss of time
If braking duty cycle is increased to reduce spin down time, then spin down time decreases, but current discharged exceeds motor current limit
Solution Approach 1:
The system uses feedback control to monitor discharged current and dynamically adjust the braking duty cycle, ensuring that spin down time is minimized while the current discharged from the spindle motor does not exceed the motor current limit.
Solution Approach 2:
The braking duty cycle parameter is dynamically changed during spin down operation based on real-time current measurements. The system adjusts the braking percentage to maintain current within acceptable limits while optimizing spin down performance.
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
The solution significantly reduces current limit events, minimizes acoustic noise, and decreases host reverse current, enhancing the reliability and efficiency of the data storage device by maintaining a stable current flow and optimizing spin down time.
Implementation Method 1
the back EMF of the spindle motor causes a current to be generated that may flow through the voice coil motor and switches of a VCM
Data Source
AI summary
A data storage device has a closed loop extended park mode during spin down operation. A data storage device comprises a spindle motor configured to rotate one or more disks, and one or more processing devices. The one or more processing devices are configured to determine a value of current that is discharged from the spindle motor over time during a spin down of the spindle motor, and control a braking duty cycle for braking the spindle motor during the spin down such that the value of current discharged from the spindle motor over time does not exceed a selected current limit.