Spindle Motor Position Detection Using Mutual Inductance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing disk drives face challenges in accurately estimating the angular position of the spindle motor during spin-up, leading to insufficient resolution and performance, particularly at low speeds where zero crossings in mutual inductance voltages occur too infrequently.
Innovation Solution
Applying opposite polarity driving voltages to pairs of windings connected in series and combining mutual inductance voltages to generate a mutual inductance signal, allowing for estimation of the angular position with increased resolution from sixty to thirty electrical degrees, thereby improving spin-up performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mutual inductance sensing is used for spindle motor position detection, then the system structure remains simple, but the angular position estimation resolution is insufficient (only 60 electrical degrees)
Solution Approach 1:
The patent segments the winding control into multiple phases with opposite polarity driving voltages applied to different winding pairs. By dividing the measurement into sequential steps with different polarity combinations, the system achieves higher resolution position detection (30 electrical degrees) without requiring a completely complex new sensing architecture
Solution Approach 2:
The patent employs periodic alternation of driving voltage polarities across different winding pairs in a systematic sequence. This periodic action generates multiple mutual inductance voltage measurements at different angular positions, enabling the estimation resolution to be doubled from 60 to 30 electrical degrees through repeated cyclic measurements
2Measurement precision
If zero crossings in mutual inductance voltages are used for position estimation, then the measurement method remains simple, but the resolution is insufficient at low speeds where zero crossings occur too infrequently
Solution Approach 1:
The patent changes the measurement parameters by applying opposite polarity driving voltages to different winding pairs in a systematic sequence. This parameter variation creates additional measurable events (mutual crossings) that occur more frequently than traditional zero crossings, especially at low spindle motor speeds, thereby improving position estimation resolution independent of rotation speed
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 enhances the resolution of angular position estimation, improving the spindle motor's spin-up performance and enabling more precise control, which is critical for efficient disk rotation and data storage operations.
Implementation Method 1
measuring a first mutual inductance voltage across a third winding used to generate a mutual inductance signal for estimating an angular position of the 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. A first driving voltage is applied across a first and second windings of the spindle motor connected in series while measuring a first mutual inductance voltage across a third winding, wherein the first driving voltage comprises a first amplitude and a first polarity. A second driving voltage is applied across the first and second winding connected in series while measuring a second mutual inductance voltage across the third winding, wherein the second driving voltage comprises the first amplitude and a second polarity opposite the first polarity. The first measured mutual inductance voltage and the second measured mutual inductance voltage are combined to generate a first mutual inductance signal, and an angular position of the spindle motor is estimated based on the first mutual inductance signal.