Motor with electronic distributing configuration

Details Motor with electronic distributing configuration Motor with electronic distributing configuration

1998-05-18

2001-01-09

Martin, David (Department: 2837)

Electricity: motive power systems

Switched reluctance motor commutation control

C318S132000, C318S434000

Reexamination Certificate

active

06172474

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a motor that electronically switches current paths by using a plurality of transistors.
PRIOR ART
In recent years, motors that electronically switch current paths by using a plurality of transistors have been widely used as motors for driving office automation apparatus and audio visual apparatus. Examples of such motors include a motor that switches current paths to windings by using PNP-type power transistors and NPN-type power transistors.
FIG. 32
shows a prior art motor, the operation of which will be described. A rotor
2011
has a field part due to a permanent magnet, and a position detecting block
2041
generates two sets of three-phase voltage signals, K
1
, K
2
, K
3
and K
4
, K
5
, K
6
, responding with the rotation of the rotor
2011
. A first distributing block
2042
creates three-phase lower part conduction control signals L
1
, L
2
, and L
3
responding with the voltage signals K
1
, K
2
, and K
3
, and controls the conduction of lower part NPN-type power transistors
2021
,
2022
, and
2023
. A second distributing block
2043
creates three-phase upper part conduction control signals M
1
, M
2
, and M
3
responding with the voltage signals K
4
, K
5
, and K
6
, and controls the conduction of upper part PNP-type power transistors
2025
,
2026
, and
2027
. Three-phase drive voltages are thus supplied to windings
2012
,
2013
, and
2014
.
However, this prior art motor has the following problems.
(1) Large Power Loss
In the prior art configuration, the emitter-collector voltages of the NPN-type power transistors
2021
,
2022
, and
2023
and the PNP-type power transistors
2025
,
2026
, and
2027
are controlled analoguely (that is in analogue fashion), thereby supplying drive currents of the necessary amplitude to the windings
2012
,
2013
, and
2014
. As a result, the voltage drop across the power transistor in activated period is large, and this residual voltage multiplied by the conduction current of the transistor has led to a large power loss. In particular, since the drive currents to the motor windings are large, the power loss has been extremely large. As a result, the motor has a very low power efficiency.
(2) High Cost
In order to reduce the cost, it is effective to assemble transistors and resistors into a single integrated circuit (IC) chip. However, a large chip area is required to form the PNP-type power transistors
2025
,
2026
, and
2027
, thereby producing a large factor of increasing the cost. Further, it has been difficult to operate the PNP-type power transistors at high speed because of the effects of parasitic capacitances when they are implemented in an integrated circuit form. Moreover, integrated circuit implementation has been difficult because of the large power loss of the power transistors. In particular, the large drive currents to the motor windings increase the danger of thermal breakdown of the integrated circuit due to the temperature rise of the power transistors. Further, when a radiating plate is mounted in order to prevent such thermal breakdown, the cost is greatly increased.
(3) Large Motor Vibration
In recent years, in optical disk apparatus such as DVD-ROM and magnetic disk apparatus such as HDD, there has been a need for a motor with reduced vibration because of high density recording and/or playbacking of a high-density disk. In the prior art configuration, however, abrupt switching of the power transistors has caused spike voltages in the windings, thereby pulsating the drive currents. As a result, the generated force of the motor is pulsated and a large motor vibration occurs.
It has been eagerly desired to develop a motor in which each of or all of these problems are solved.
An object of the present invention is to provide a motor that solves the above-enumerated problems individually or simultaneously, and that has the configuration suitable for implementation in integrated circuit form.
BRIEF SUMMARY OF THE INVENTION
The motor having the configuration according to the present invention comprises:
a movable member;
plural-phase windings;
voltage supplying means including a FET switching transistor for performing high-frequency switching of a power supplying path of a DC power source thereby to output a converted DC voltage obtained by converting a DC voltage of said DC power source;
Q pieces (Q is an integer of 2 or more) of first power amplifying means each including a first FET power transistor for forming a current path from a negative output terminal side of said voltage supplying means to one of said plural-phase windings;
Q pieces of second power amplifying means each including a second FET power transistor for forming a current path from a positive output terminal side of said voltage supplying means to one of said plural-phase windings;
altering signal producing means for producing plural-phase altering signals;
first distribution control means for controlling said Q pieces of first power amplifying means responding with output signals of said altering signal producing means so as to cause at least one of Q pieces of said first FET power transistors to perform an ON operation with a resistive voltage drop;
second distribution control means for controlling said Q pieces of second power amplifying means responding with output signals of said altering signal producing means so as to cause at least one of Q pieces of said second FET power transistors to perform an ON operation with a resistive voltage drop; and
conversion control means for varying said converted DC voltage between said positive output terminal side and said negative output terminal side of said voltage supplying means in synchronization with a moving operation of said movable member.
The ON operation with a resistive voltage drop in the above-mentioned configuration refers to the full ON state of the three states of FET transistor, the full ON state, the half ON state, and the OFF state. And an active operation refers to the full ON state and the half ON state, inclusive.
With the above-mentioned configuration, the power loss of the first FET power transistors, the second FET power transistors, and the FET switching transistor was significantly reduced, and the power efficiency of the motor was drastically improved. Accordingly, the power devices, such as the FET switching transistor and the FET power transistors, can be formed at high density within a single-chip integrated circuit together with necessary semiconductor devices, and an inexpensive motor can thus be realized.
Further, the conversion control means varies the converted DC voltage of the voltage supplying means, and this achieves a reduction in the pulsation of the generated force of the motor by reducing bad influence of the back electromotive forces of the windings. Further, by supplying smoothly varying first Q-phase current signals and second Q-phase current signals to the conduction control terminals of the first power amplifying means and second power amplifying means, for example, smoothly varying bidirectional drive currents can be supplied to the windings, and the pulsation of the drive currents can thus be reduced greatly. As a result, the pulsation of the generated force is remarkably reduced, and a high performance motor can thus be realized.
The motor according to another configuration of the present invention comprises:
a movable member;
plural-phase windings;
voltage supplying means for supplying a DC voltage;
Q pieces (Q is an integer of 2 or more) of first power amplifying means each including a first FET power transistor for forming a current path from a negative output terminal side of said voltage supplying means to one of said plural-phase windings;
Q pieces of second power amplifying means each including a second FET power transistor for forming a current path from a positive output terminal side of said voltage supplying means to one of said plural-phase windings;
altering signal producing means for producing plural-phase altering signals;
first distribution control means for controllin

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