Electricity: motive power systems – Switched reluctance motor commutation control
Reexamination Certificate
2000-01-28
2002-06-11
Dang, Khanh (Department: 2837)
Electricity: motive power systems
Switched reluctance motor commutation control
C318S721000
Reexamination Certificate
active
06404152
ABSTRACT:
BACKGROUND OF THE INVENTION
Present invention relates to a control device of a rotating electrical machinery and especially relates to the rotating electrical machinery which is improved so as to reduce electromagnetic oscillation in a diameter direction of a stator of a permanent magnet rotating electrical machinery and undesired sound caused by the electromagnetic oscillation. Permanent magnet rotating electrical machinery usually has a stator and a rotor.
The stator has a stator core formed plural winding slots respectively keeping a same interval and a stator winding which is wound in the winding slot mentioned above.
Magnetomotive force distribution of the stator winding is formed so as to superimpose a space harmonic wave on a sine wave (fundamental wave) and is varied in time in proportion to a stator winding current.
Moreover in an inner diameter side of the stator, an opening part of the winding slot and a teeth part of the stator core are disposed alternatively keeping a same interval, and a magnetism permeance distribution of the stator becomes to contain ripple haveing a cycle made by the winding slot of the stator core.
Magnetic flux density of the magnetic field that the stator forms in the air gap is detemined by a product of a magnetomotive force distribution of this stator and a magnetism permeance of said stator, and this magnetic flux density contains a space harmonic component.
Moreover, the rotor has a permanent magnet fixed by being inserted in a groove provided in the rotor core keeping certain interval.
Accordingly, a magnetic flux density of the magnetic field that the rotor provides in the air gap, contains the ripple in the same way and changes in time because of being turned.
As the magnetic flux density of the air gap is provided by composing the magnetic flux that the stator forms and the magnetic flux that the rotor forms, the magnetic flux density in this air gap is distributed so as to superimpose the harmonic component on the fundamental wave component, and changes in time.
Because a torque acting on the rotor is an angle differentiation of a magnetic energy saved in the air gap, a ripple occurs to a torque generated by the ripple of the magnetic flux density of this air gap.
This torque ripple sometimes causes a case as that a big oscillation in permanent magnet rotating electrical machinery and an undesired sound thereby appears.
In order to reduce the ripple of the torque by controlling the stator winding current, a phase current correction means to correct so as to increase or decrease up to a maximum value of the sine wave within a range of +30 degree of an electrical angle where magnitude of each phase current becomes maximum, and a control device of a synchronism motor prepared with a balancing means which provides a total of the phase current balance are disclosed, for example, in Japanese patent Laid-open No. 8-331884 and U.S. Pat. No. 4,240,020.
By using these means, a method how to correct decreasing of the torque in a rotational direction occured in the transposition of the phase current is suggested.
As a cause of the electromagnetic undesired sound of the rotating electrical machinery, a circular ring oscillation of the stator may be pointed out besides the torque ripple in a rotational direction thereof.
The electromagnetic force of the diameter direction acting on the stator causes the circular ring oscillation of this stator, and it is propagated to a stator frame of a stator periphery so as to vibrate said stator frame to the diameter direction and to generate the undesired sound.
When space degree and frequency of the electromagnetic force harmonic component in the diameter direction, accords to resonance mode and frequency of the stator, the stator produces a resonance so as to occur a big undesired sound. Because the torque ripple is time variation of the electromagnetic force in a tangent direction, the conventional control device to reduce the torque ripple in the rotation direction which is performed up to now, cannot reduce the undesired sound caused by the magnetic force in the diameter direction.
SUMMARY OF THE INVENTION
An object of the present invention is to reduce the oscillation generated by a drift of the electromagnetic force in the diameter direction of the stator in the rotating electrical machinery.
In a control device of a rotating electrical machinery comprising, an inverter disposed between a stator winding and a direct current power supply of said rotating electrical machinery having a rotor formed a stator and the magnetic pole provided a stator winding on a stator core, an activation waveform generating circuit to occur an activation current wave form signal that met a magnetic pole position of said rotor, and a current control circuit to control the inverter so as to supply said activation electric current to the stator winding based on said activation current wave form signal and a stator winding current detecting signal, the present invention is characterised by comprising
an electromagnetic force drift memory for memorizing a drift information of the electromagnetic force in diameter direction of the stator to act on the stator core having a stator winding thereon, and
an activation waveform correction means to correct an amplitude of said activation current wave form signal based on an electromagnetic force drift information which is read from said electromagnetic force drift memory according to the magnetic pole position of the rotor.
Futhermore, the present invention is characterised by comprising
an electromagnetic force drift detecting means for detecting a drift of the electromagnetic force in a diameter direction of the stator to act on the stator core having a stator winding thereon,
an electromagnetic force harmonic operation device to calculate an electromagnetic force harmonic component on the basis of a signal detected by said electromagnetic force drift detecting means,
a correction information generating circuitry to occur a correction information to correct an electromagnetic force drift in the diameter direction of the stator by reading out the electromagnetic force harmonic component from the electromagnetic force harmonic operation device according to the magnetic pole position of the rotor, and
an activation waveform correction means to correct the amplitude of the activation current wave form signal based on the correction information.
REFERENCES:
patent: 4088934 (1978-05-01), D'Atre et al.
patent: 4240020 (1980-12-01), Okuyama et al.
patent: 4724373 (1988-02-01), Lipo
patent: 5134349 (1992-07-01), Kruse
patent: 5334923 (1994-08-01), Lorenz et al.
patent: 5463301 (1995-10-01), Kim
patent: 1-318579 (1989-12-01), None
patent: 2-106192 (1990-04-01), None
patent: 2-206382 (1990-08-01), None
patent: 8-331884 (1996-12-01), None
patent: 10-234196 (1998-09-01), None
Kawamata Shoichi
Kobayashi Takashi
Koizumi Osamu
Masaki Ryoso
Matsunobu Yutaka
Crowell & Moring LLP
Dang Khanh
Hitachi , Ltd.
LandOfFree
Motor control device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Motor control device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Motor control device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2909367