Spindle Motor BEMF Voltage Regulation During Power Failure
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Solution Overview
Problem
Existing data storage devices face challenges in efficiently managing power failures during disk operations, as conventional methods can lead to over-voltage conditions damaging control circuitry and inefficient energy utilization.
Innovation Solution
The implementation of a control circuitry system that utilizes a periodic signal to short the spindle motor windings, adjusting the signal's amplitude and duty cycle based on the power voltage to generate a power voltage, which is then used to power the voice coil motor and control circuitry, allowing for safe unloading of the head during a power failure while optimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power management methods are used during power failure, then the system can operate with simple control circuitry, but over-voltage conditions occur that damage control circuitry and result in inefficient energy utilization
Solution Approach 1:
The spindle motor's residual kinetic energy is converted into electrical energy through electromagnetic induction to self-power the control circuitry during power failure. The system uses its own residual energy to protect itself, eliminating the need for external backup power sources or complex power management circuits.
Solution Approach 2:
The patent converts the harmful effect of residual kinetic energy in the spindle motor (which would normally dissipate as heat through friction and braking) into a beneficial electrical power source. By using electromagnetic induction during the motor's natural deceleration, the system generates usable electricity from what would otherwise be wasted energy.
2Productivity
If the spindle motor is braked immediately during power failure, then the head can be quickly unloaded, but significant energy is wasted through friction and heat
Solution Approach 1:
Instead of continuous braking, the system employs periodic commutation of the spindle motor windings during power failure. This periodic action maintains controlled rotation while converting kinetic energy to electrical energy, allowing the head to be unloaded at appropriate intervals without continuous energy dissipation.
Solution Approach 2:
The system dynamically adjusts the commutation timing and duration based on the real-time voltage generated by the spinning spindle motor. As the motor slows down, the commutation parameters are adjusted to maintain optimal power generation until the voltage drops below the threshold needed to operate the control circuitry.
3Loss of energy
If the spindle motor is allowed to coast to stop during power failure, then energy is conserved, but the head remains vulnerable to damage from uncontrolled stopping
Solution Approach 1:
The control circuitry continuously monitors the voltage generated by the spinning spindle motor and uses this feedback to determine when to activate periodic commutation for head protection. The system only engages braking/commutation when the generated voltage is sufficient, minimizing energy use while ensuring protection when needed.
Solution Approach 2:
The control circuitry acts as an intermediary between the spinning spindle motor and the head actuator. It uses the electrical energy from the motor to power itself and the VCM, coordinating the unloading process to protect the head without requiring external power sources.
4Reliability
If external backup power sources are used during power failure, then reliable operation can be maintained, but the device complexity and cost increase significantly
Solution Approach 1:
The spindle motor serves multiple functions: it rotates the disk during normal operation, generates electrical power during power failure through electromagnetic induction, and provides controlled braking through commutation. This multi-functionality eliminates the need for separate backup power sources, batteries, or complex power management hardware.
Solution Approach 2:
The system uses its own residual kinetic energy in the spindle motor to power the control circuitry and head unloading operations during power failure. No external backup power sources, batteries, or capacitors are needed—the system protects itself using its own residual energy.
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 solution effectively prevents over-voltage damage and optimizes energy utilization from residual kinetic energy, ensuring safe and efficient completion of operations during power failures in data storage devices.
Implementation Method 1
a periodic signal is used to short the windings of the spinning spindle motor to generate a power voltage from a back electromotive force (BEMF) voltage of the spinning spindle motor
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. During a power failure the head is unloaded by generating a periodic signal, shorting the windings of the spindle motor based on the periodic signal in order to generate a power voltage, and adjusting the periodic signal based on an amplitude of the power voltage.