Hitachi, Ltd.

Hitachi Automotive Systems, Ltd.

Hitachi Industrial Equipment Systems Co., Ltd.

Hitachi Car Engineering Co., Ltd.

Ryoichi Takahata

Satoshi Kikuchi

Shinichi Wakui

Miyoshi Takahashi

Yoshitaka Iwaji

Haruo Koharagi

Keiji Noma

Kazuaki Tobari

Shigehisa Aoyagi

Hiroshi Hirayama

Kenji Miyata

Kazuo Tahara

Kohji Maki

Masaharu Senoh

Masaharu Senoo

Shigeya Kawaminami

Takashi Seshimo

Takashi Okada

Takahiro Suzuki

Susumu Sasaki

Hiroshi Kanazawa

Masaki Hano

Kim Houng Joong

Kouki Yamamoto

Yusaku Onuma

Kaoru Kawabata

An electric motor drive deviceincludes: an inverterthat drives a motor, a voltage division circuitthat serves as a neutral point potential detection unit that detects a neutral point potential of a stator winding of the motor; and a controllerthat estimates a rotor position of the motorbased on the detected neutral point potential, and that controls the inverterbased on an estimation result. A ground potential of the controlleris set to a negative side potential or a positive side potential of a DC voltage that is supplied to the inverter. The voltage division circuitdetects the neutral point potential with reference to the negative side potential or the positive side potential. The controllerestimates the rotor position based on a difference between a first neutral point potential detected during the ON/OFF operation of the inverterand a first fixed reference potential (&#x2154;)Emax, and based on a difference between a second neutral point potential detected during the ON/OFF operation and a second fixed reference potential (&#x2153;)Emax.

Electric motor drive device

A drive system of a synchronous electrical motor includes a synchronous electrical motor; a power converter that is connected to the motor with a plurality of switching elements; a controller that outputs a voltage instruction to the power converter; a voltage detection unit for open phases upon application of respective positive and negative pulse voltages between respective two phases out of three-phase windings of the motor; an induced voltage difference for calculating an induced voltage difference that is a difference between an induced voltage detected by the voltage detection unit at each of the open phases upon application of the positive voltage pulse between the corresponding two phases and an induced voltage detected by the voltage detection unit at the open phase upon application of the negative voltage pulse between the two phases.

Drive system for synchronous electrical motor

In sequentially selecting and driving two phases of the three-phase stator windings of a synchronous motor, detect a speed electromotive voltage of a de-energized phase, relate the speed electromotive voltage to rotor position information beforehand, then count rotor position information backward based on the detected the speed electromotive voltage to estimate rotor position; and then detect rotation speed from the change rate of the rotor position information so as to achieve highly accurate position and speed control.

Synchronous motor drive system and synchronous motor

A synchronous electric motor drive system capable of driving at speeds near zero is provided. An energization mode determination unit switches six energization modes successively based on a terminal potential detected of the de-energized phase of a three-phase synchronous electric motor or on a stator winding wire connection point potential (neutral point potential) detected of the three-phase synchronous transmission unit. A voltage command correction unit corrects by a correction amount &#x394;V an applied voltage command destined for the synchronous electric motor to supply the synchronous electric motor with a repeated waveform of a positive pulse, negative pulse, and zero voltage as a line voltage waveform of the energized phases in each of the six energization modes, the positive pulse voltage being polarized to cause the synchronous electric motor to generate a forward rotation torque, the negative pulse voltage causing the synchronous electric motor to generate a reverse rotation torque.

Synchronous electric motor drive system

A permanent magnet type electric rotary machine includes a stator including a stator core having teeth and slots, and a rotor provided with permanent magnets as magnet poles in a rotor core. A pole core portion which between each of the permanent magnets and an outer surface of the rotor core is provided with a plurality of pole slits. A region of the pole core portion is defined by concave portions provided on q-axes to be interpolars on both sides of the pole core portion, and thereby configured that a gap between the outer surface on the q-axis of the rotor core and an inner surface of the stator core is larger than a gap between the outer surface on the d-axis of the pole core portion and the inner surface of the stator, so that magnetic fluxes from the permanent magnet pass through the pole core portion concentrately.

Permanent magnet type electric rotary machine and compressor using the same

A vehicular alternator is provided which can effectively utilize the magnetic flux of a permanent magnet disposed between claw-type magnetic poles and can improve an output of the alternator. The vehicular alternator comprises a rotor and a stator constituted by coiling stator windings over a stator core, the rotor comprising a pair of claw-type magnetic poles arranged in an opposed relation, a permanent magnet disposed between adjacent two of a plurality of claws provided on the pair of claw-type magnetic poles, and field windings coiled radially inward of the plurality of claws. Each of the plurality of claws of the rotor is formed to have a shape coming into contact with the whole of a magnetic pole surface of the permanent magnet.

Vehicular alternator

In a permanent magnet type rotating electric machine comprising a stator of which concentratedly wound armature windings are disposed in a plurality of slots formed in a stator core so as to surround teeth and a rotor accommodating permanent magnets in a plurality of permanent magnet insertion holes formed in a rotor core, a part of outer circumferential faces of slots is formed to extend substantially in parallel with a part of inner circumferential faces of the teeth, thereby, a permanent magnet type rotating electric machine with limited noises can be realized.

Permanent magnet type rotating electric machine

A permanent magnetic type electric rotating machine includes: a stator having armature winding arranged in several slots formed in a stator core; and a rotor having permanent magnets held in several permanent magnetic insertion holes formed in a rotor core, in which a peripheral surface of the rotor core is configured to be a combination of arcs around two points different from a center of the rotor core for each magnetic pole in such a manner that when an axis extending in a central direction of a magnetic pole of the rotor is a d axis, and an axis extending in a direction between magnetic poles that is offset from the central direction of the magnetic pole by 90 electrical degrees is a q axis, a radial distance from a center of the rotor core to a periphery of the rotor is reduced gradually from the d axis to the q axis.

Permanent magnet type electric rotating machine

There is provided a linear motor, having an armature and a needle with magnetism, in which the armature has at least a magnetic pole of a first polarity having a first opposed part and another magnetic pole of a second polarity having a second opposed part; the needle is held by the first opposed part, and is further held by the second opposed part; and a distribution of magnetism of the needle according to a position in the movable direction thereof. In this way, a leak of a magnetic flux from pole teeth passing between the pole teeth of the armature is decreased to increase a thrust and braking force of the needle, which is thereby enabled to generate a greater or smaller thrust in a specific section or sections than the thrust during usual linear movement.

Linear motor

Growing community of inventors

Hitachi, Japan

Ryoichi Takahata