Hitachi, Ltd.

Hitachi Taga Engineering, Ltd.

Hitachi Taga Engineering Co., Ltd.

Kazuaki Takada

Eiji Toyoda

Fumio Tajima

Kunio Miyashita

Hisao Hanmura

Jun Matsubayashi

Kuniaki Kubokura

Masayuki Kanari

Makoto Yajima

A deceleration apparatus of an AC servo motor for use in an industrial sewing machine performs a regenerating braking operation during a motor deceleration period. At an early time in the regenerating braking operation of the motor, an intermittent regenerating braking operation is carried out by supplying a current in a control circuit of a motor drive circuit. Subsequently, a continuous regenerating braking operation in the motor is carried out. A drive element comprising a switching element or a transistor in the control circuit is protected in accordance with an intermittent regenerating braking operation or a small regenerating braking current.

Deceleration apparatus for motor and drive circuit for use in motor

A rotor of a permanent magnet type synchronous motor facing a stator having a number of slots comprises a rotor core fixed to a motor shaft and an even number of permanent magnets in a circumferential direction of the rotor core. Projecting portions are formed in the shape of a protruding portion of the rotor core over each permanent magnet. The width (A) of each projecting portion is different from the pitch (B) of the slots of the stator. A position detector for detecting the permanent magnet position of the rotor comprises detectors of the normal rotation and other detectors of the reverse rotation. These detectors are arranged having predetermined phase differences (.alpha., .beta.) to a center line. A pattern generating circuit is provided for switching the conducting position to the stator winding corresponding to the phase differences.

Permanent magnet reversible synchronous motor

A bogie is provided with a center detection coil, a right-hand detection coil and a left-hand detection coil in order to make the vehicle to run automatically along an electro-magnetic induction line installed in a running path in dependence on a steering signal produced by composing a vector of a voltage induced in the center detection coil by the magnetic flux generated by the induction line and a vector of selected one of the induced voltages of the right-hand and the left-hand detection coil. A correcting circuit is provided to produce a correcting voltage signal added to the steering signal so that the latter signal becomes zero when the center detection coil is positioned directly above the induction line.

Electromagnetic guidance system

Growing community of inventors

Katsuta, Japan

Kazuaki Takada