Motor driving device for motor having multi-phase coils

Details Motor driving device for motor having multi-phase coils Motor driving device for motor having multi-phase coils

2002-05-22

2004-03-23

Duda, Rina I. (Department: 2837)

Electricity: motive power systems

Switched reluctance motor commutation control

C318S132000, C318S434000, C318S432000, C318S434000, C318S599000, C318S811000, C318S685000

Reexamination Certificate

active

06710559

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a motor driving device suitable for driving a brushless DC motor, which is employed in e.g., an air-conditioner, air cleaner, hot water supply, and information apparatus such as a copy machine, printer, optical medium apparatus, and hard disc apparatus. It also relates to a motor driving device suitable for driving an induction motor and a reluctance motor and the like. More particularly, it relates to a motor driving device that can substantially reduce torque ripples, vibrations and noises of the motor in operation. The present invention also provides an apparatus including the same motor driving device.
BACKGROUND ART
A brushless DC motor is widely used as a driving motor of an air conditioner and an information apparatus because of its advantages such as a long service life, high reliability, and simplicity of speed control.
FIG. 9
is a circuit diagram of a conventional motor driving device, and
FIG. 10
shows signal waveforms at respective sections of the circuit shown in
FIG. 9
with respect to motor rotating angles (electrical angle).
As shown in
FIG. 9
, a driving device for the brushless DC motor (hereinafter referred to as simply “a motor”), in general, detects a rotor position with a plurality of position detectors
901
,
903
and
905
which are formed of Hall elements. Three-phase distributor
890
receives position signals Hu, Hv and Hw from the position detectors, and outputs three-phase distributing signals UH
0
, UL
0
, VH
0
, VL
0
, WH
0
and WL
0
. These signals are modulated by pulse width modulator (PWM)
840
into signals having a pulse width responsive to set-signal S prepared by speed setter
860
. Gate driver
830
controls six switches, forming power feeder
820
, to switch on or off sequentially based on output signals from modulator
840
and output signals from three-phase distributor
890
. Power feeding to three-phase coils
811
,
813
and
815
disposed to a stator is thus sequentially switched responsive to a rotor position, such as signals U, V, W shown in
FIG. 10
, thereby rotating the motor.
FIG. 11
shows torque generated in the motor.
The torque shown in
FIG. 11
is described hereinafter. If we direct our attention to phase-U coil
811
, differential signal U-N between signal U and neutral point signal N is applied to coil
811
. Signal U-N is a rectangular wave signal as shown in FIG.
11
. When back electromotive force of phase-U coil
811
shapes in a sine wave such as signal Ue, the torque due to coil
811
is roughly proportional to the product of signal U-N multiplied by signal Ue, and the torque becomes what is shown by torque Tu in FIG.
11
. In the same manner, the torque due to phase-V coil
813
and phase-W coil
815
become what are shown by torque Tv and Tw. Torque generated in the entire motor is thus torque “Tall” that is the sum of the torque of respective phases.
Torque “Tall” has a certain size of ripple as shown in FIG.
11
. This torque ripple causes vibrations while the motor is driven, and the vibrations can resonate with the apparatus in which the motor is mounted, thereby producing noises. The vibrations also prevent the apparatus from being finely controlled, which blocks the performance of the entire apparatus from improving.
SUMMARY OF THE INVENTION
The present invention addresses the problem discussed above and aims to provide a simply structured motor driving device that can restrain torque ripples, vibrations and noises generated while a motor is driven. This motor driving device can also drive an object with higher power and in a higher efficient manner.
The motor driving device of the present invention comprises the following elements:
a motor having three-phase driving coils;
a wide-angle feeding device for feeding power to respective phase-coils in a width of 150° electric angle; and
a controller for controlling an amount of power to be fed to the respective phase-coils by the wide-angle feeding device.
The wide-angle feeding device can detect overlapping periods in which adjacent two coils out of three coils stay in the same fed condition. The controller controls an amount of power to be fed during the overlapping periods as a first amount and another amount of power to be fed during the other periods than the overlapping periods as a second amount.
This structure discussed above allows the motor driving device of the present invention to reduce substantially the torque ripples, vibrations and noises of the motor in operation.


REFERENCES:
patent: 4832576 (1989-05-01), Deguchi et al.
patent: 5300866 (1994-04-01), Yasohara et al.
patent: 5729067 (1998-03-01), Janutka
patent: 5821722 (1998-10-01), Forbes et al.
patent: 2000-308383 (2000-11-01), None

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