Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1994-11-22
2000-09-26
Ramirez, Nestor
Electrical generator or motor structure
Dynamoelectric
Rotary
318696, H02K 3704, H02K 3702
Patent
active
061246514
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved method of driving a 5-phase hybrid stepping motor.
2. Description of Related Art
Hybrid stepping motors have been well known for over a quarter of a century as actuators appropriated for highly accurate positioning movements. The hybrid stepping motors are widely used in various machine tools, e.g. with fully automated production lines, as well as computer related instruments including printers, plotters, facsimile machines, and disk drive units.
For increasing the versatility of use, there is made an attempt to minimize the step angle of such a hybrid stepping motor. To this respect, four- and five-phase types of stepping motors are now commonly provided.
The conventional four- or five-phase stepping motors however have some disadvantages in that torque stiffness is unstable, static torque is varied depending on the stop position, and the step angle does not provide high accuracy. It is an object of the present invention to eliminate the foregoing disadvantages.
SUMMARY OF THE INVENTION
For achievement of the above object, a method of driving a multi-phase hybrid type stepping motor which has a NS=K(S0-S1)+10(S1-1+B) where K is an integer from 2 to 5, S0 and S1 are smallest possible integers or may be equal, and B is a fraction of 1 so that 10B (ten times of B) is always an integer, the ten stator windings on their respective fixed magnetic poles being coupled to one another in a circular order of P3, P8, P6, P1, P9, P4, P2, P7, P5, and P10, five terminals disposed between P10 and P3, P8 and P6, P1 and P9, P4 and P2, and P7 and P5 respectively, and by magnetization of the ten windings at each step of the rotating movement, N and S poles of the same number being generated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross sectional view showing one embodiment of the present invention;
FIG. 2 is a longitudinal sectional view of the embodiment of FIG. 1 of the present invention;
FIG. 3 is a front view of a stator system according to another embodiment of the present invention;
FIG. 4a and 4b are vector diagrams of a North Pole and South Pole of a rotor according to an embodiment of the present invention;
FIG. 5 is a wiring diagram according to an embodiment of the present invention;
FIG. 6 is a chart showing the magnetic shift at fixed magnetic poles in full-step mode; and
FIG. 7 is a chart showing the magnetic shift at the fixed magnetic poles in half-step mode.
THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION
Preferred embodiments of the present invention will be described in more detail while referring to the accompanying drawings.
FIGS. 1 and 2 illustrate in cross section a stepping motor according to the present invention. FIG. 1 is a cross sectional view of FIG. 2 taken along the line extending at a right angle to a rotary shaft 4. As shown, a stator 1 has ten fixed magnetic poles S, S' arranged inwardly thereof. Each of the fixed magnetic poles S or S' has a stator coil 2 wound thereon and is provided at an inward end with a set of small teeth 3. It is assumed that the total number of the small teeth 3 is NS. The rotary shaft 4 has a rotor 5 mounted about a center thereto. The rotor 5 has a permanent magnet 7 mounted to the axial center thereof and two rotor caps 8 fitted to both sides of the magnet 7 respectively, as best shown in FIG. 2. The rotor caps 8 have a plurality of teeth 6 provided on the circumferential surface thereof. It is now assumed that the total number of the teeth 6 is NR. FIG. 1 is a cross sectional view taken along the line I--I of FIG. 2. The ten stator coils 2 are numbered from P1 to P10. Magnetic bundle passage 20 is illustrated by a dashed line.
A first embodiment of the present invention is intended to have a five-phase stepping motor with the ten fixed magnetic poles S, S' improved in torque stiffness, step angle precision, and efficiency of movement when NR=50 (where a shift angle between two adjacent fixed magnetic poles is 1/5Tp, Tp being a pitch of the small
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patent: 4385247 (1983-05-01), Satomi
patent: 5315192 (1994-05-01), Satomi
patent: 5374865 (1994-12-01), Yoshimura et al.
patent: 5444316 (1995-08-01), Ohya et al.
Yoshida Kenji
Yoshimura Noriyuki
Minebea Co. Ltd.
Ramirez Nestor
Tamai Karl
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