Abstract: According to one embodiment, an inverter device configured to be capable of switching an on or off state of each of a plurality of switching elements, on the basis of a control command signal, and operable as a single-phase inverter, includes: a pulse width modulator configured to set a voltage value at a time when one of the switching elements is set to the on state to a first voltage, and set a voltage value at a time when the other three of the switching elements are set to the on state to a second voltage larger than the first voltage, in operation as the single-phase inverter; and a detection unit configured to detect the control command signal in operation as the single-phase inverter.

Abstract: According to an embodiment, an inspection apparatus inspects an inverter circuit including three pairs of arms. The apparatus includes a current controller and a control signal generator. The current controller generates a control output for controlling a current to be output by the inverter circuit. The control output enables the current to approach a target value of the current. The control signal generator generates a first control signal for controlling ON/OFF of a first arm as one of the three pairs of arms based on the control output, a second control signal for fixing a second arm paired with the first arm, in an OFF-state, and a third control signal for fixing at least part of arms other than the first arm and the second arm in an ON-state.

Abstract: According to one embodiment, a correction device is used for an apparatus including a coil and a conductor in a vicinity of the coil. The correction device corrects an influence of a magnetic field generated by the conductor when a current flows through the coil. The correction device includes a first measuring device, a second measuring device, and a control device. The first measuring device measures a first signal of the coil. The second measuring device measures a second signal of the coil, which is different from the first signal. The control device estimates the influence acting on the coil, based on a difference between the first signal filtered by a first filter and the second signal filtered by a second filter. Furthermore, the control device controls a command signal for flowing the current to the coil, based on an estimation result of the influence.

Abstract: According to an embodiment, an inspection apparatus inspects an inverter circuit including three pairs of arms. The apparatus includes a current controller and a control signal generator. The current controller generates a control output for controlling a current to be output by the inverter circuit. The control output enables the current to approach a target value of the current. The control signal generator generates a first control signal for controlling ON/OFF of a first arm as one of the three pairs of arms based on the control output, a second control signal for fixing a second arm paired with the first arm, in an OFF-state, and a third control signal for fixing at least part of arms other than the first arm and the second arm in an ON-state.

Abstract: According to one embodiment, an inverter device configured to be capable of switching an on or off state of each of a plurality of switching elements, on the basis of a control command signal, and operable as a single-phase inverter, includes: a pulse width modulator configured to set a voltage value at a time when one of the switching elements is set to the on state to a first voltage, and set a voltage value at a time when the other three of the switching elements are set to the on state to a second voltage larger than the first voltage, in operation as the single-phase inverter; and a detection unit configured to detect the control command signal in operation as the single-phase inverter.

Abstract: According to one embodiment, a servo write control apparatus is for a disk apparatus including a read element and a write element located in an outer side of a disk from the read element. The servo write control apparatus detects a plurality of first burst signals recorded in a circumferential direction of the disk by the read element. The servo write control apparatus calculates an offset in a radial direction when the write element writes a second burst signal, based on amplitude values of at least two of the first burst signals used for positioning the read element. The servo write control apparatus adjusts a write position of the second burst signal based on the offset.

Abstract: An evaluation apparatus of an embodiment for evaluating an inverter circuit for an electric motor includes a three-phase-to-two-phase converter, a current controller, gate signals generator, and a storage. The three-phase-to-two-phase converter converts primary three-phase currents i1u, i1v, and i1w of the electric motor connected to the inverter circuit into a d-axis current i1d and a q-axis current i1q. The current controller generates d-axis and q-axis voltage command values v1d* and v1q* for adjusting the q-axis current i1q to a command value i1q* being substantially zero and the d-axis current i1d to a command value i1d* with feedback control of the electric motor through the inverter circuit. The gate signals generator generates gate signals gs based on the command values v1d* and v1q* and applies the gate signals gs to the inverter circuit. The storage stores the command value v1d*.

Abstract: According to one embodiment, a correction device is used for an apparatus including a coil and a conductor in a vicinity of the coil. The correction device corrects an influence of a magnetic field generated by the conductor when a current flows through the coil. The correction device includes a first measuring device, a second measuring device, and a control device. The first measuring device measures a first signal of the coil. The second measuring device measures a second signal of the coil, which is different from the first signal. The control device estimates the influence acting on the coil, based on a difference between the first signal filtered by a first filter and the second signal filtered by a second filter. Furthermore, the control device controls a command signal for flowing the current to the coil, based on an estimation result of the influence.

Abstract: According to one embodiment, a control apparatus identifies a load characteristic of a circuit by an impulse response. In the control apparatus, a controller provides a control signal. A first generator generates first gate signals based on the control signal. A second generator generates second gate signals to identify the load characteristic of the circuit. A switching part switches connection to one of the first generator and the second generator. A bridge circuit connected to the switching part includes a plurality of switching elements. When the switching part is connected to the first generator, the switching elements are operated based on the first gate signals, and the bridge circuit outputs a first signal. When the switching part is connected to the second generator, the switching elements are operated based on the second gate signals, and the bridge circuit outputs an impulse second signal different from the first signal.

Abstract: According to one embodiment, a servo write control apparatus is for a disk apparatus including a read element and a write element located in an outer side of a disk from the read element. The servo write control apparatus detects a plurality of first burst signals recorded in a circumferential direction of the disk by the read element. The servo write control apparatus calculates an offset in a radial direction when the write element writes a second burst signal, based on amplitude values of at least two of the first burst signals used for positioning the read element. The servo write control apparatus adjusts a write position of the second burst signal based on the offset.

Abstract: According to one embodiment, a hard disk drive includes a head, a voice coil motor, a driving circuit, an identification unit, a storage unit, and an estimation unit. The head is configured to perform write/read of information to a storage medium. The voice coil motor is configured to move the head. The driving circuit is configured to drive the voice coil motor, based on a command signal. The identification unit is configured to identify at least one parameter of a discrete-time model. The discrete-time model represents a transfer function from the command signal to a voltage drop quantity by an inductance of a coil of the voice coil motor. The storage unit is configured to store the parameter. The estimation unit is configured to estimate a back electromotive force of the coil, based on the discrete-time model including the parameter.

Abstract: A magnetic disk device includes a head, a coil, a drive circuit, a detector, a first calculation unit, a generation unit, a first estimation unit, and a control unit. The detector detects an inter-terminal voltage across the coil. The first calculation unit calculates a back electromotive force across the coil by the use of the inter-terminal voltage. The generation unit generates a target velocity as a reference value of a velocity of the head. The first estimation unit estimates a first velocity of the head and an error of the first velocity by the use of the back electromotive force. The first estimation unit estimates a second velocity for decreasing the error. The control unit calculates a control instruction to bring the second velocity close to the target velocity.

Abstract: A ramp-unloading seek control device includes a voice coil motor, a detector, an instruction-current detector, a head-speed computing unit, and an identification structure. The identification structure estimates an error between a true resistance value and an estimated resistance value of the voice coil motor. The identification structure can minimize an estimated error defined as a difference between an estimated value ?(k) of the head speed and the head speed y(k), and employs {circumflex over (b)}1 to calibrate the estimated error. {circumflex over (b)}1 is determined by minimizing the estimated error. ?(k) and y(k) are defined by the equation (A): ?(k)=?â1y(k?1)+{circumflex over (b)}0u(k?1)+{circumflex over (b)}1u(k?2)??(A). y(k?1) denotes a head speed computed by the head-speed computing unit at the last sampling time. k denotes the present sampling time. u(k?1) and u(k?2) denote instruction currents at the last sampling time and the last but one sampling time, respectively.

Abstract: According to one embodiment, an estimation method comprises measuring and creating. The measuring is configured to measure a head velocity and a terminal voltage of a coil of a voice coil motor at least two times before unload in a control system eliminating an influence caused by a transient response of inductance of the voice coil motor. The calculating is configured to a calculate torque constant and a coil resistance based on command voltages and at least two measured head velocities and terminal voltages of the coil.

Abstract: A magnetic disk device includes a head, a coil motor, a drive circuit, a voltage detector, a head position calculation unit, a velocity calculation unit, a counter electromotive voltage calculation unit, a coil resistance estimation unit, and a control unit. The head position calculation unit calculates a position of the head for each sampling cycle on the basis of servo information. The velocity calculation unit calculates a velocity of the head for each sampling cycle. The counter electromotive voltage calculation unit calculates a counter electromotive voltage of the coil for each sampling cycle. The coil resistance estimation unit successively estimates a coil resistance value of the coil. The control unit calculates a drive instruction for controlling the velocity and outputs the drive instruction to the drive circuit. In addition, the counter electromotive voltage calculation unit subtracts a voltage drop from the inter-terminal voltage to calculate the counter electromotive voltage.

Abstract: According to one embodiment, a hard disk drive includes a head, a voice coil motor, a driving circuit, an identification unit, a storage unit, and an estimation unit. The head is configured to perform write/read of information to a storage medium. The voice coil motor is configured to move the head. The driving circuit is configured to drive the voice coil motor, based on a command signal. The identification unit is configured to identify at least one parameter of a discrete-time model. The discrete-time model represents a transfer function from the command signal to a voltage drop quantity by an inductance of a coil of the voice coil motor. The storage unit is configured to store the parameter. The estimation unit is configured to estimate a back electromotive force of the coil, based on the discrete-time model including the parameter.

Abstract: According to one embodiment, an estimation method comprises measuring and creating. The measuring is configured to measure a head velocity and a terminal voltage of a coil of a voice coil motor at least two times before unload in a control system eliminating an influence caused by a transient response of inductance of the voice coil motor. The calculating is configured to a calculate torque constant and a coil resistance based on command voltages and at least two measured head velocities and terminal voltages of the coil.