Motor Drive Synchronous Rectification for HDD Head Safety
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Solution Overview
Problem
Conventional motor drive devices experience energy loss during power supply interruptions due to inefficient regenerative voltage generation and rectification processes, particularly in hard disk drives where the power supply to the voice coil motor needs to be maintained until the magnetic head is retracted.
Innovation Solution
A motor drive device with a power supply line, ground line, and a first motor driver that generates a rectified voltage from phase voltages during idling by synchronously rectifying phase voltages using comparators and control units, optimizing switching control to minimize energy loss by efficiently managing regenerative current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If regenerative voltage is generated from phase voltages during motor idling to maintain power supply during interruptions, then power supply continuity is improved, but energy loss increases due to inefficient rectification processes
Solution Approach 1:
The patent converts the harmful energy loss during rectification into a beneficial process by using synchronous rectification controlled by comparator outputs. The rectification process is optimized by selectively activating switching elements based on voltage comparisons, thereby converting what would be wasted energy into useful regenerative power during motor idling
Solution Approach 2:
The patent changes the operational parameters of the rectification process by dynamically controlling switching elements based on real-time voltage comparisons. The control unit adjusts the rectification parameters (which switching elements are activated) based on the instantaneous phase voltages, optimizing the energy conversion efficiency while maintaining power supply continuity
2Reliability
If power supply voltage is applied to voice coil motor during power interruption for magnetic head evacuation, then safety is improved, but energy consumption increases
Solution Approach 1:
The system uses the kinetic energy already present in the rotating spindle motor to generate the electrical power needed for voice coil motor operation during power interruptions. The spindle motor serves itself by providing regenerative power through its idling phase voltages, eliminating the need for external power supply while ensuring magnetic head evacuation safety
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 reduces energy loss by optimizing synchronous rectification operations, allowing for efficient regenerative current flow and maintaining power supply integrity during power outages, thus preventing collisions between the magnetic head and platter.
Implementation Method 1
the first motor driver is structured so as to rectify the phase voltages of the different phases synchronously in accordance with results of comparison among the phase voltages of the difference phases, the rectified voltage, and the ground voltage when generating the rectified voltage
Implementation Method 2
a power supply line to which a power supply voltage is applied; a ground line to which a ground voltage is applied
Data Source
AI summary
A motor drive device has: a power supply line to which a power supply voltage is applied; a ground line to which a ground voltage is applied; and a first motor driver that, when the power supply voltage is normal, rotates an N-phase first motor (where N is an integer of 2 or more) by using the supply voltage and, when the power supply voltage is abnormal, generates a rectified voltage from phase voltages of different phases appearing while the first motor is idling to regenerate the rectified voltage to the power supply line. The first motor driver, when generating the rectified voltage, synchronously rectifies the phase voltages of the different phases according to the results of their comparison with the rectified voltage and the ground voltage. The first motor driver is structured so as to rectify the phase voltages of the different phases synchronously in accordance with results of comparison between the phase voltages of the difference phases, the rectified voltage, and the ground voltage.