Motor with electronic distributing configuration

Details Motor with electronic distributing configuration Motor with electronic distributing configuration

1999-06-04

2001-07-17

Nappi, Robert E. (Department: 2837)

Electricity: motive power systems

Induction motor systems

Primary circuit control

C318S254100, C318S434000, C318S599000, C318S139000

Reexamination Certificate

active

06262557

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor that electronically alters current paths by using plural transistors.
2. Description of the Related Art
In recent years, many office automation apparatus and audio visual apparatus use motors that electronically alters current paths by using plural transistors. For example, there is a motor that alters current paths to windings by using both PNP-type power transistors and NPN-type power transistors.
FIG. 34
shows such a prior art motor, the operation of which will be described. A rotor
2011
has a field part formed by a permanent magnet. According to the rotation of the rotor
2011
, a position detecting block
2041
generates two pairs of three-phase voltage signals K
1
, K
2
, K
3
and K
4
, K
5
, K
6
. A first distributing block
2042
generates three-phase lower conduction control signals L
1
, L
2
, and L
3
corresponding to the voltage signals K
1
, K
2
, and K
3
, and controls the conduction of lower NPN-type power transistors
2021
,
2022
, and
2023
. A second distributing block
2043
generates three-phase upper conduction control signals M
1
, M
2
, and M
3
corresponding to the voltage signals K
4
, K
5
, and K
6
, and controls the conduction of upper PNP-type power transistors
2025
,
2026
, and
2027
. Consequently, three-phase drive voltages are supplied to three-phase windings
2012
,
2013
, and
2014
.
This prior art motor, however, has the following various 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 in analogue fashion, thereby supplying drive currents of necessary amplitude to the windings
2012
,
2013
, and
2014
. Consequently, the residual voltage drop across the power transistor in activated period becomes large, and the product of this residual voltage drop and the conducted current of the power transistor causes a large power loss. Especially, 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) Expensive Cost
In order to reduce the manufacturing cost of a motor, it is very effective to integrate transistors, resistors, and the like onto a single chip as an IC. However, a large chip area is required to compose those PNP-type power transistors
2025
,
2026
, and
2027
, thereby increasing the cost. In addition, when those transistors and resistors are integrated on an IC chip, it is also difficult to carry out a fast operation of PNP-type power transistors due to the effects of parasitic capacitances. Moreover, power loss and heat generation of the power transistors are also too large to integrate them into an IC. Especially, since the drive currents to motor windings are large, the IC is likely confronted with a thermal breakdown caused by the heat generation from those power transistors. If a radiating plate is provided to the IC in order to prevent such a thermal breakdown, the cost is then increased greatly.
(3) Large Motor Vibration
In recent years, in optical disk apparatus such as DVD-ROM and magnetic disk apparatus such as HDD and FDD, a motor with reduced vibration is strongly demanded because of higher density recording and/or playing back on/from such disks. In the prior art configuration, however, when a power transistor is changed over abruptly, a spike voltage is generated in a winding, thereby pulsating the drive currents. Consequently, the generated force of the motor is pulsated and a large motor vibration occurs.
It has been strongly desired to develop a motor in which each of or all of these problems are solved.
It is therefore an object of the present invention to solve the above problems, respectively or concurrently and provide a motor that has the configuration suitable for implementation in integrated circuit form.
SUMMARY OF THE INVENTION
The motor 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 3 or more) of first power amplifying means each including a first FET power transistor for forming a current path between a negative terminal side of said voltage supplying means and 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 between a positive terminal side of said voltage supplying means and 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;
second distribution control means for controlling said Q pieces of second power amplifying means responding with output signals of said altering signal producing means; and
switching operation means for causing at least one piece of said Q pieces of first power amplifying means and said Q pieces of second power amplifying means to perform high-frequency switching, and that
said first distribution control means and said second distribution control means include means for supplying at least a current signal, varying smoothly or substantially smoothly at least in rising and/or falling slopes to a conduction control terminal side of at least one piece of said Q pieces of first power amplifying means and said Q pieces of second power amplifying means and said Q pieces of second power amplifying means.
With the above-mentioned configuration, some of the first power amplifying means and the second power amplifying means are caused to execute high-frequency switching operation so that the power loss of these power amplifying means can be reduced remarkably. As a result, the power efficiency of the motor is also improved significantly. In the case that some of the first and second power amplifying means execute high-frequency switching operations, smooth altering operation of current paths to the plural-phase windings can be achieved by supplying a current signal, varying smoothly or substantially smoothly at least in rising and/or falling slopes among the rising slope portion, the falling slope portion and flat portion, to the conduction control terminal side of power amplifying means. As a result, the drive current signals to the plural-phase windings are altered smoothly, thereby reducing pulsation or fluctuation of the generated torque of the motor. Therefore, an excellent motor with reduced vibration and reduced power loss can be realized. Further, power transistors of the first and second power amplifying means can be integrated on a single IC chip together with other transistors and resistors. Consequently, the above motor can be obtained at low cost.
Furthermore, the motor in accordance with another configuration of the invention comprises:
a movable member;
plural-phase windings;
voltage supplying means for supplying a DC voltage;
Q pieces (Q is an integer of 3 or more) of first power amplifying means each including a first FET power transistor for forming a current path between one output terminal side of said voltage supplying means and one of said plural-phase windings, and for amplifying an input current to the conduction control terminal side;
Q pieces of second power amplifying means each including a second FET power transistor for forming a current path between the other output terminal side of said voltage supplying means and one of said plural-phase windings, and for amplifying an input current to the conduction control terminal side;
first distribution control means for supplying first Q-phase current signals, each having an active electrical angle larger than 360/Q degrees, to a conduction control terminal side of each of said Q pieces of first power amplifying means;
second distribution control means for supplying second Q-phase current signals, each having an

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