Western Digital Technologies, Inc.

Seagate Technology Incorporated

Nanyang Technological University

Shuyu Cao

Guoxiao Guo

Jie Yu

KianKeong Ooi

MingZhong Ding

KeXiu Liu

Jie Wan

Jern Khang Tan

Anshuman Tripathi

Wei Xi

Jianghong Ding

Hui Li

Qing Wei Jia

Abishek Sethupandi

Qingwei Jia

Brihadeeswara Sriram Vaisambhayana

Xiaotian Xu

Fengjiao Cui

Hossein Dehghani Tafti

YiLei Wu

Zhou Yong

This invention relates to a method of controlling a Solid State Transformer (SST). The method comprises dividing a dual active bridge (DAB) power reference on a Low Voltage (LV) side Direct Current (DC) link voltage to obtain a total DAB reference current; dividing the total DAB current reference by N number of DAB modules to obtain a reference current for each DAB module; in response to SST being in a normal power regulation, determining a deviation of a capacitor voltage at the HV side of each of a k DAB modules with reference from an average voltage from the HV DC bus; determining a current adjustment signal for each of the k DAB modules based on the total DAB reference current and a corresponding deviation of the capacitor voltage of each of the k DAB modules; adding a saturated current adjustment signal together with the reference current for each of the k DAB modules to obtain a total current reference for each of the k DAB modules; and subtracting a sum of the total current reference of each of the k DAB modules from the total DAB reference current to determine a total current reference for an NDAB module.

Dual voltage and current loop linearization control and voltage balancing control for solid state transformer

An apparatus includes: a disk; a spindle motor configured to rotate the disk; and control circuitry with a spindle motor control loop, coupled to the spindle motor, the control circuitry configured to: inject a bandwidth test frequency into the spindle motor control loop, measure an open loop gain of the spindle motor control loop, calculate, using coordinate transformations, an estimated loop bandwidth of the spindle motor control loop based at least on one iteration of the bandwidth test frequency injection and the open loop gain measurement, and generate optimum loop parameters of the spindle motor control loop.

Electronic system with a method of motor spindle bandwidth estimation and calibration thereof

A disk drive is disclosed comprising a disk comprising a plurality of servo tracks defined by servo sectors recorded around the circumference of the disk at a servo sampling frequency, and a servo control system operable to actuate a head over the disk by generating a control signal applied to an actuator. A first sinusoid is injected into the servo control system and a first DC component (dc1) is measured in the control signal. A second sinusoid is injected into the servo control system and a second DC component (dc2) is measured in the control signal, wherein the second sinusoid comprises a phase offset from the first sinusoid. A resonance mode of the servo control system is measured based on dc1 and dc2.

Disk drive measuring a resonance mode by injecting sinusoids into a servo control system

A disk drive is disclosed comprising a servo control system configured to control an actuator for actuating a head over a disk. Servo sectors are sampled at a servo sample frequency fto generate a position error signal PES(k) that is filtered with a compensator to generate a first control signal u(k). A first discrete-time sinusoid comprising a sinusoid frequency of f+&#x394;f is added to the first control signal u(k) to generate a second control signal u(k). The second control signal u(k) is applied to the actuator, and a frequency response of the actuator is determined at the frequency |&#x394;f|. The frequency response of the actuator is determined at the frequency f+&#x394;f based at least in part on the frequency response of the actuator at the frequency |&#x394;f| and a measured signal of the servo control system when applying the second control signal u(k) to the actuator.

Disk drive determining frequency response of actuator near servo sample frequency

A disk drive is disclosed comprising a head and a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors. The disk drive further comprises control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors. The disk is rotated at a first speed and the servo sectors are read at a first servo sample frequency to generate first servo samples. The disk is rotated at a second speed different from the first speed and the servo sectors are read at a second servo sample frequency to generate second servo samples. The second servo samples are processed to measure a frequency response of the servo control system proximate the first servo sample frequency.

Disk drive adjusting rotation speed of disk to compensate for blind area when measuring frequency response of servo control system

A shock detection circuit housed in an electronic device includes an output shock signal that is indicative of vibration amplitude. To compensate for vibrations that are experienced by the electronic device, the output shock signal is analyzed. The analysis of the output shock signal allows a vibration frequency of the output shock signal to be identified and used in vibration compensation.

Vibration compensation based on identification of vibration frequency

A terminal voltage of an actuator motor is measured while the actuator motor is in a high impedance state. An internal voltage of the actuator motor is measured, and a back-EMF voltage of the actuator motor is estimated in response to the terminal voltage of the actuator motor and the internal voltage of the actuator motor. A drive current supplied to the actuator motor is controlled in response to the estimated back-EMF.

Discontinuous mode back EMF measurement

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Singapore, Singapore

Shuyu Cao