Electricity: motive power systems – Switched reluctance motor commutation control
Reexamination Certificate
2000-01-21
2001-07-03
Nappi, Robert E. (Department: 2834)
Electricity: motive power systems
Switched reluctance motor commutation control
C318S132000, C363S034000
Reexamination Certificate
active
06255789
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a motor in which current supplied to plural-phase winding loads is electronically altered by means of plural transistors.
In recent years, as driving motors for OA appliances or AV apparatuses, motors in which a current path is electronically altered by means of plural transistors have been widely used.
FIG. 23
shows a motor of the prior art, and the operation of the motor will be briefly described. A rotor
501
has a field part configured by permanent magnets. In response to the rotation of the rotor
501
, a position detection part
505
produces two sets of three-phase voltage signals L
1
, L
2
, and L
3
, and L
4
, L
5
, and L
6
. A first distributing unit
506
produces three-phase negative-side conduction control signals UL
1
, UL
2
, and UL
3
responding with the voltage signals L
1
, L
2
, and L
3
, respectively, and controls the conduction of negative-side NPN-type power transistors
508
,
509
, and
510
. A second distributing unit
507
produces three-phase positive-side conduction control signals UH
1
, UH
2
, and UH
3
responding with the voltage signals L
4
, L
5
, and L
6
, respectively, and controls the conduction of positive side PNP-type power transistors
511
,
512
, and
513
. According to this configuration, the current paths to three-phase windings
502
,
503
, and
504
is controlled.
However, the above-mentioned prior art configuration has the following problems.
In the prior art configuration, in order to reduce vibration of the motor, the NPN-type power transistors
508
,
509
, and
510
and the PNP-type power transistors
511
,
512
, and
513
supplied smooth drive currents to the windings
502
,
503
, and
504
by analoguely controlling the voltages between the emitter and the collector. However, the residual voltage of each power transistor was so large that a great power loss and heat generation were formed as a product of the residual voltage and the drive currents to the windings. As a means to solve this problem, a step-down chopper circuit is provided on the positive terminal side of a DC power source
530
so as to vary output voltages in accordance with the magnitudes of the drive currents to the windings
502
,
503
, and
504
. However, as long as the power transistors were controlled analoguely, the residual voltages of the power transistors were large, which set limits to a reduction in the power loss. As another method of reducing the power loss, a switching control method can be performed to make the power transistors switching operations. However, there is no prior art that can easily smooth the drive currents to the windings
502
,
503
, and
504
; the realization of the smooth drive currents required providing a large-scale circuit, which had a problem of boosting the cost.
SUMMARY OF THE INVENTION
The object of the present invention is to dissolve the above-mentioned problems and to provide a motor which can reduce a power loss while making power transistors supply windings with smooth drive currents.
A motor in accordance with the present invention comprises: a movable body, plural-phase windings, DC power source means as power supply source, Q pieces (Q is an integer of 3 or greater) of first power amplifying means each including a first power transistor forming a current path between one terminal side of said DC power source means and one terminal of said plural-phase windings, and Q pieces of second power amplifying means each including a second power transistor forming a current path between the other terminal side of said DC power source means and one terminal of said plural-phase windings, conduction control means for controlling conduction of said first power amplifying means and said second power amplifying means, and switching control means for controlling high-frequency switching operations for one or both of the first power transistors of said first power amplifying means and the second power transistors of said second power amplifying means, wherein
said conduction control means comprises waveform shaping signal producing means for producing Q-phase waveform shaping signals each having a conduction width larger than an electric angle of 360/Q degrees, synchronous rectifying control means for controlling the timing of synchronous rectification, and drive command means for controlling conduction of at least one of said second power amplifying means in response to said waveform shaping signals and the output signal of said synchronous rectifying control means.
According to this configuration, since the power transistors of the power amplifiers perform switching operations, the power transistors have very small power loss. Hence, the motor has excellent power efficiency. A smooth change in waveform shaping signals leads to a smooth change in the drive currents to the windings. The synchronous rectifying control means achieves synchronous rectifying operations. As a result, the pulsation of the drive currents caused by the switching of the current paths is greatly reduced, and a high-performing motor having minor vibration and a small power loss can be achieved.
A motor in accordance with another aspect of the present invention comprises: a movable body, plural-phase windings, DC power source means as power supply source, Q pieces (Q is an integer of 3 or greater) of first power amplifying means each including a first power transistor forming a current path between one terminal side of said DC power source means and one terminal of said plural-phase windings, and Q pieces of second power amplifying means each including a second power transistor forming a current path between the other terminal side of said DC power source means and one terminal of said plural-phase windings, conduction control means for controlling conduction of said first power amplifying means and said second power amplifying means, and switching control means for controlling high-frequency switching operations for one or both of the first power transistors of said first power amplifying means and the second power transistors of said second power amplifying means, wherein
said conduction control means comprises: waveform shaping signal producing means for producing Q-phase waveform shaping signals each having a conduction width larger than an electric angle of 360/Q degrees; synchronous rectifying control means for controlling the timing of synchronous rectification, switch signal producing means for producing switch signals which are output in a period shorter than a conduction period of said waveform shaping signals in a conduction period larger than the 360/Q degrees of said waveform shaping signals; and drive command means for controlling conduction of at least one of said second power amplifying means in response to said waveform shaping signals, the output signals of said synchronous rectifying control means, and said switch signals.
In this configuration, because of the switching operations of the power transistors of the power amplifying means, the motor has excellent power efficiency. A smooth change in waveform shaping signals realizes a smooth change in the drive currents to the windings. In addition, the switch signals realize a decrease in the on-resistance of the power transistors and synchronous rectifying operations. As a result, the pulsation of the drive currents caused by the switching of the current paths is greatly reduced, and a high-performing motor having minor vibration and a small power loss can be achieved.
These and other configurations and operations will be detailed in the preferred embodiments.
While the novel features of the invention set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings.
REFERENCES:
patent: 4494053 (1985-01-01), Gotou
patent: 5309078 (1994-05-01), Cameron
patent: 5331258 (1994-07-01), Lankin et al.
patent: 5661382 (1997-08-0
Gotou Makoto
Mori Hideaki
Ochi Masaaki
Duda Rina I.
Matsushita Electric - Industrial Co., Ltd.
Nappi Robert E.
Pearne & Gordon LLP
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