Electricity: motive power systems – Induction motor systems – Reversing
Patent
1992-07-02
1994-02-22
Shoop, Jr., William M.
Electricity: motive power systems
Induction motor systems
Reversing
318812, 318439, H02P 140
Patent
active
052890996
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a direct current motor used as a drive source or the like for a constant-speed drive, constant-torque drive, or servo control in various industrial machines, more particularly to a high-speed three-phase d.c. motor.
2. Background Art
Conventionally, as the high-speed motors, for example, the semiconductor motors including the coreless motor having a small inductance (brushless motors) are used. Usually, the motors of this type include the direct-current power supply for rectifying the output of an alternating-current power supply, and thus have disadvantages such as being large-sized and expensive. Particularly, in the case wherein an inverter is used, this drawback will become conspicuous. Further, the above conventional motors have a maximum speed of 3000 to 6000 revolutions per minute, and a reduction of the maximum speed is unavoidable when a higher output is required.
If however, the voltage applied to the motor is increased to increase the rotational speed, the efficiency of the motor falls and the practicality of the motor will be lost.
Furthermore, there has not yet been developed any electric circuit for a constant-torque drive, constant-speed drive or servo control which is capable of guaranteeing stable operation, especially efficient operation, during the high-speed operation of the motor.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a small-size and inexpensive direct current motor capable of operating at high-speeds and a high speed and a high-efficiency.
To achieve the above object, this invention provides a direct current motor comprising: a position detection device for successively delivering a first position detection signal group and a second position detection signal group in accordance with a rotational position of a rotor of the direct current motor, the first position detection signal group including a plurality of position detection signals equal in number to phases of the direct current motor and to each of such phases, the second position detection signal group including a plurality of position detection signals having a predetermined phase difference with respect to corresponding ones of the first position detection signal group; an energization control circuit connected to a direct current power supply for successively energizing armature coils of the individual phases in a forward direction in accordance with the first position detection signal group, and successively energizing the armature coils of the individual phases in a reverse direction in accordance with the second position detection signal group; a group of diodes for preventing a reverse current, provided between the direct current power supply and the armature coils of the respective phases; capacitors connected to the diodes respectively; and circuit means for charging magnetic energy, which is stored in the armature coil of each phase when an energization thereof is interrupted, in the capacitor connected to the diode associated with the armature coil, thereby rapidly reducing the stored magnetic energy, and for rapidly raising an armature current passing through the armature coil of each phase in the reverse direction, by a voltage charged in the capacitor when an energization of the armature coil in the reverse direction is started.
Preferably, the direct current motor further comprises a chopper circuit for interrupting the energization of the armature coil of each phase when the armature current flowing therethrough becomes greater than an upper limit, as well as for restarting the energization when the armature current becomes smaller than a lower limit.
As described above, according to this invention, the capacitor is charged with the magnetic energy stored in the armature coil, of which the energization is interrupted, not only for quickly reducing the stored magnetic energy but also for causing the inverse armature current to rise rapidly by the voltage of the capacitor when the inverse energization of the armature c
REFERENCES:
patent: Re30761 (1981-10-01), Ban et al.
patent: 4295083 (1981-10-01), Leenhouts
patent: 4392098 (1983-07-01), Min
patent: 4558264 (1985-12-01), Weischedel
patent: 4672290 (1987-06-01), Ghosh et al.
patent: 4719399 (1988-01-01), Wrege
patent: 4959573 (1990-07-01), Roberts
patent: 5075610 (1991-12-01), Harris
patent: 5138244 (1992-08-01), Bahn
Kabushikigaisha Sekogiken
Martin David
Shoop Jr. William M.
LandOfFree
Direct current motor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Direct current motor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Direct current motor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-174420