Nippon Densan Corporation

Kouhei Yonemura

Isao Kaneda

Akihiro Okubo

A driving control circuit of a sensorless motor having a stator and a rotor, used for a magnetic disk device, comprising a high-frequency stepping oscillator, stepping oscillator, a timer, a stepping timing generating circuit, a current switching logic, an output driver, and a counter electromotive force detecting circuit, wherein three-phase driving coils are connected to an output driver. For starting, a high frequency stepping step a holding step where current flow conditions are held without switching currents to the driving coils, are executed; then, currents to the driving coils are inverted to obtain a reversed excited condition; and, after performing a stepping step for starting the motor is controlled at a steady rotating speed by detecting counter electromotive forces.

Method of and circuit for starting sensorless motor

A driving control circuit of a motor having a sensorless stator and a rotor, used for a magnetic disk device, comprising a high-frequency stepping oscillator, stepping oscillator, a timer, a stepping timing generating circuit, a current switching logic, an output driver, and a counter electromotive force detecting circuit, wherein three-phase driving coils are connected to an output driver. For starting, a holding step where current flow conditions are held without switching currents to the driving coils, are executed; then, currents to the driving coils are inverted to obtain a reversed excited condition, and, after performing a stepping step for starting, the motor is controlled at a steady rotating speed by detecting counter electromotive forces.

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Youkaichi, Japan

Kouhei Yonemura