Nippon Densan Corporation

Nidec Corporation

Sgs-thomson Microelectronics S.r.l.

Nippon Ltd.

Nippon Densen Corporation

Isao Kaneda

Kouhei Yonemura

Kohei Yonemura

Akihiro Okubo

Hisashi Yamamoto

Masanobu Chuta

Carlo C De Martiis

Sandro Cerato

Shiming Tang

Tetsuya Tsuji

Hiromasa Fujii

A brushless motor comprising a stator core having a plurality of tooth portions disposed peripherally at intervals, coils wound in a required manner on a plurality of tooth portions, an annular rotor magnet disposed in opposition to the stator core and having N poles and S poles alternately disposed, and a position detecting sensor for detecting the rotating angular position of the rotor magnet. The stator core is formed by laminating an anisotropic steel sheet in which the easily magnetizable axis of the crystal is in a specific direction.

Brushless motor

A method of starting a sensorless motor comprising a stator provided with three-phase stator coils to which an exciting current is supplied, and a rotor provided with a rotor magnet for obtaining a rotating torque by the electromagnetic interaction of the stator wherein a first stepping step and a second stepping step for starting the rotor at the time of starting the motor are carried out. In the early period of the second stepping step, a reverse exciting operation is carried out in which an exciting current is switched off from positive to negative or from negative to positive without including a cessation period in two-phase coils out of the three-phase stator coils.

Method of starting a sensorless motor

A starting method for starting a multiphase DC motor having a stator provided with stator coils, a rotor provided with a rotor magnet and detector for detecting revolutions of the rotor, has stepping process and acceleration process. In the stepping process, a plurality of stepping steps is performed. The accelerating process is performed after the stepping process is completed. The plurality of the stepping steps include counter-exciting operation. Each of the plurality of stepping steps is provided by a rotation detection step. The stepping process is completed and the accelerating process is performed when a rotation detector detects that the revolutions of the rotor exceeds a predetermined value.

Multiphase DC motor and starting method thereof

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 method of starting a motor comprising a first starting step of supplying an exciting current to armature coils, a first holding step for holding the exciting current after the first starting step, a second starting step of supplying an exciting current to the armature coils after the first holding step, a second holding step of holding this exciting current after the second starting step, and a third starting step of supplying an exciting current to the armature coils after the second holding step. In this method, the frequency f.sub.1 of the first holding step is larger than the characteristic frequency F.sub.0 of the rotation system of the motor (f.sub.1 &gt;F.sub.0) and the frequency f.sub.2 of the second holding step is smaller than the characteristic frequency F.sub.0 of the rotation system (f.sub.2 &lt;F.sub.0).

Method of starting a motor

A DC motor having a housing, a hub member rotatably supported by the housing, a flexible printed circuit board fixedly mounted on the housing, and an IC chip mounted on the flexible printed circuit board and located facing a recess formed in the housing. The hub member has a shaft rotatably supported by a bearing within the recess. The flexible printed circuit board has a metal layer for mounting the IC chip, the metal layer being isolated from a wiring pattern formed on the printed circuit board. The wiring pattern on the flexible printed circuit board is directly connected to a connection pin connected to the motor wiring.

IC controlled DC motor

A brushless polyphase DC motor is applied to a spindle motor for a disk device and has a stator generating a magnetic field in an excited state and a rotor obtaining turning force by the electromagnetic interaction with the stator. When an electrical charge current is intermittently and alternately supplied to the coil of the stator in opposite directions, for example, if electrical charge is stopped after current in the normal direction is supplied, a residual magnetic field density is generated in the stator during the stopping period. The residual magnetic flux density is employed for performing electrical charge in the reverse direction by supplying current in the reverse direction. In this case, a high torque is generated by increasing a change in the magnetic flux density.

Brushless polyphase DC motor

In a sensorless multiphase dc motor which is started by repeating a sequence of steps in order to supply the stator with a series of discrete currents for rotating the rotor in a desired direction, the start-up sequence has a step(s) of conducting a magnetizing shift action by changing the flow of current from one direction to the reverse direction or vice versa thus reducing its time consumption and also, each of the plural phase coils is energized with a high amplitude of current to produce a higher torque thus enhancing the start-up characteristics of the motor. In particular, the magnetizing shift action from one direction to the reverse direction or vice versa is conducted multiple times in each of the plural phase coils during the start-up sequence and the start-up sequence itself is repeated multiple times. As the result, the start-up characteristics of the motor will be more enhanced.

Method of starting a sensorless multiphase dc 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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Moriyama, Japan

Isao Kaneda