Title: Apparatus and method for controlling driving of linear motor
Abstract: An apparatus and method for controlling driving of a linear motor, which is configured to increase efficiency of a linear compressor and stably drive the linear motor when the linear motor is overloaded. The apparatus includes a detector that detects a current applied to a motor, a controller that outputs a control signal based on the detected current and a switch that varies the number of windings of the linear motor coil on the basis of the control signal.
Patent Number: 6,998,736 Issued on 02/14/2006 to Lee,   et al.
| Inventors:
|
Lee; Jae-Mo (Seoul, KR);
Heo; Kyung-Bum (Gyeonggi-Do, KR)
|
| Assignee:
|
LG Electronics Inc. (Seoul, KR)
|
| Appl. No.:
|
649629 |
| Filed:
|
August 28, 2003 |
Foreign Application Priority Data
| Dec 06, 2002[KR] | 10-2002-0077413 |
| Current U.S. Class: |
310/12 |
| Current Intern'l Class: |
H02K 41/00 (20060101) |
| Field of Search: |
310/12
417/417
368/157
|
References Cited [Referenced By]
U.S. Patent Documents
| 3149254 | Sep., 1964 | Carter et al.
| |
| 3255582 | Jun., 1966 | Zam.
| |
| 3455102 | Jul., 1969 | Wolf.
| |
| 3798889 | Mar., 1974 | Chadwick.
| |
| 3968417 | Jul., 1976 | Dials.
| |
| 4228806 | Oct., 1980 | Lidow.
| |
| 4370602 | Jan., 1983 | Jones, Jr. et al.
| |
| 4642547 | Feb., 1987 | Redlich.
| |
| 4645353 | Feb., 1987 | Kavoussi et al.
| |
| 4821247 | Apr., 1989 | Grooms.
| |
| 5089998 | Feb., 1992 | Rund.
| |
| 5282181 | Jan., 1994 | Entner et al.
| |
| 5948303 | Sep., 1999 | Larson.
| |
| 6236622 | May., 2001 | Blackman.
| |
| 6753665 | Jun., 2004 | Ueda et al.
| |
| Foreign Patent Documents |
| 2002-0054154 | Jul., 2002 | KR.
| |
| 10-2003-75740 | Sep., 2003 | KR.
| |
| 10-0404108 | Oct., 2003 | KR.
| |
Other References
English language Abstract of Korean 10-2003-75740, Oct. 2003.
English language Abstract of Korean 10-0404108, Oct. 2004.
|
Primary Examiner: Schuberg; Darren
Assistant Examiner: Jones; Judson H.
Attorney, Agent or Firm: Greenblum & Bernstein, P.L.C.
Claims
What is claimed is:
1. An apparatus that controls driving of a linear motor, comprising:
a detector that detects a current applied to the linear motor;
a controller that outputs a control signal based on the detected current; and
a switch that varies the number of windings of a linear motor coil on the basis
of the control signal,
wherein the linear motor comprises a first coil wound with a first predetermined
number of windings and a second coil wound with a second predetermined number of
windings and connected to the first coil in series.
2. The apparatus of claim 1, wherein when a current dead zone where a current
value from the current detector unit is zero for a predetermined time exists, the
controller outputs a first control signal to the switch to increase the number
of winding of the linear motor coil.
3. The apparatus of claim 1, wherein when a current dead zone, where a current
value output from the current detector is zero for a predetermined time does not
exist, the controller outputs a second control signal to the switch to decrease
the number of winding of the linear motor coil.
4. The apparatus of claim 1, wherein the controller outputs a first control signal
to the switch to increase the number of winding of the linear motor coil when a
current dead zone, where a current value output from the current detector is zero
for a predetermined time exists, and outputs a second control signal to the switch
to decrease the number of winding of the linear motor coil when the current dead
zone does not exist.
5. The apparatus of claim 4, wherein the switch is connected to the first coil
and the second coil when the first control signal is received, the first coil being
connected to the second coil in series, and is connected to the first coil when
the second control signal is received.
6. The apparatus of claim 1, wherein the switch varies the number of winding
of the linear motor coil on the basis of the control signal and thereby varies
a current applied to the linear motor.
7. The apparatus of claim 1, wherein the switch is a relay.
8. The apparatus according to claim 1, wherein said motor is installed in a linear compressor.
9. A method for controlling a driving of a linear motor, comprising:
detecting a current applied to the linear motor;
generating a control signal based on the detected current; and
varying the number of windings of a linear motor coil on the basis of the control signal,
wherein the linear motor comprises a first coil wound with a first predetermined
number of windings and a second coil wound with a second predetermined number of
windings and connected to the first coil in series.
10. The method of claim 9, wherein the generating the control signal comprises:
generating a first control signal to increase the number of windings of the linear
motor coil when a current dead zone, where a current value output from a current
detecting unit is zero for a predetermined time exists, and
generating a second control signal to decrease the number of windings of the
linear motor coil when the current dead zone does not exist.
11. The method of claim 10, wherein the varying the number of winding of the
linear motor coil comprises:
supplying power to the linear motor through the second coil when the first control
signal is received; and
supplying power to the linear motor through the first coil when the second control
signal is received.
12. The method of claim 9, wherein the number of winding of the linear motor
coil varies on the basis of the control signal and a current applied to the linear
motor varies due to a variation in the number of winding of the linear motor coil.
13. The method according to claim 9, wherein the linear motor is provided in
a linear compressor.
Description
RELATED APPLICATIONS
The present disclosure relates to subject matter contained in Korean Application
No. 10-2002-0077413, filed on Dec. 6, 2002, which is expressly incorporated herein
by reference it its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor, and an apparatus and method for controlling
a driving of a linear motor mounted in a linear compressor.
2. Description of the Related Art
Generally, a linear compressor, especially, a linear motor arranged in
a linear compressor is not provided with a crankshaft which converts a rotational
movement into a linear movement and thus has reduced frictional loss. According
to this, a compression efficiency of the linear compressor is better than that
of a general compressor.
When the linear motor compressor is used in a refrigerator or an air conditioner,
a stroke voltage input into the linear motor is varied to thus vary a compression
ratio of the linear compressor, thereby controlling a freezing or cooling capacity.
The linear compressor will be explained with reference to FIG. 1.
FIG. 1 is a sectional view showing a linear compressor in accordance with the
conventional art.
As shown in FIG. 1, the conventional linear compressor comprises: a casing 2
having a gas suction pipe 5 and a gas discharge pipe 1 installed
therein. A frame unit 6 is installed in the casing 2 and a linear
motor 100 is fixed to the frame unit 6 for a linear movement. A compression
unit 7 is coupled to a movable element 100-3 of the linear
motor 100 and is supported at the frame unit 6 and a resonance spring
unit 4 is provided for elastically supporting the movable element 100-3
of the linear motor 100 for movement in a linear movement direction and
thus inducing a resonance movement. Herein, the linear motor is composed of the
movable element 100-3, an outer stator 100-1, and an
inner stator 100-2.
The linear motor 100 installed in the linear compressor is composed of
a coil having a plurality of windings. The linear motor 100 will be explained
with reference to FIG. 2.
FIG. 2 shows an equivalence circuit of the motor arranged in the linear compressor
in accordance with the conventional art.
As shown in FIG. 2, the equivalence circuit of the linear motor 100 is
composed of one coil L having the predetermined number of winding and a resistor
R. That is, the number of winding of the linear motor coil L is designed to correspond
to a normal load.
However, in the linear compressor according to the conventional art, the
number of winding of the linear motor coil is designed in advance so as to correspond
to the normal load and a triac (not shown) which controls an alternating current
power supplied to the linear motor when the motor is driven with a normal mode
generates harmonics loss, thereby lowering a compressor efficiency.
That is, the conventional linear motor can not vary the number of winding of
the inner coil, so that efficiency of the compressor is lowered by the harmonics loss.
Also, the linear motor mounted in the conventional linear compressor and having
one coil stops when it is overloaded. That is, when the overload is generated at
the linear motor, electric current for driving the linear motor can not be increased.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an apparatus
and a method for controlling a driving of a linear motor, which is configured to
increase the efficiency of a linear compressor (or in any other type of compressor
or other device in which the linear motor is installed) by varying the number of
winding of the linear motor coil on the basis of a current applied to the linear
motor provided in the linear compressor.
Another object of the present invention is to provide an apparatus and a
method for controlling driving of a linear motor, which is configured to stably
drive a linear motor when the linear motor is overloaded by varying the number
of winding of the linear motor coil on the basis of a current applied to the linear motor.
To achieve these and other advantages and in accordance with the purpose of the
present invention, as embodied and as broadly described herein, an apparatus is
provided for controlling driving of a linear motor, including: a current detector
that detects a current applied to the linear motor installed in a linear compressor;
a controller that outputs a control signal based on the detected current; and a
switch that varies the number of winding of the linear motor coil on the basis
of the control signal.
To achieve these and other advantages and in accordance with the purpose of the
present invention, as embodied and broadly described herein, a method is also provided
for controlling driving of a linear motor, including: detecting a current applied
to the linear motor generating a control signal based on the detected current and
varying the number of winding of the linear motor coil on the basis of the control signal.
The foregoing and other objects, features, aspects and advantages of the present
invention will become more apparent from the following detailed description of
the present invention when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further understanding
of the invention and are incorporated in and constitute a part of this specification,
illustrate embodiments of the invention and together with the description serve
to explain the principles of the invention.
In the drawings:
FIG. 1 is a sectional view showing a linear compressor in accordance with the
conventional art;
FIG. 2 shows an equivalence circuit of a motor arranged in the linear compressor
in accordance with the conventional art;
FIG. 3 shows an apparatus for controlling a driving of a linear motor according
to the present invention; and
FIGS. 4A and 4B show waveforms of a current detected by a current detecting
unit of FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to the preferred embodiments of the
present invention, examples of which are illustrated in the accompanying drawings.
An apparatus and a method for controlling driving of a linear motor, which is
configured to increase the efficiency of a linear compressor or other device employing
the linear motor by detecting a current applied to the linear motor arranged in
the linear reciprocating compressor, generating a control signal based on the detected
current, and varying the number of winding of the linear motor coil on the basis
of the control signal and which is configured to stably drive the linear motor
when the linear motor is overloaded will be explained with reference to FIGS. 3,
4A, and
4B.
FIG. 3 shows an apparatus for controlling driving of a linear motor according
to the present invention.
As shown in FIG. 3, the apparatus for controlling driving of a linear motor
200
arranged in the linear compressor (not shown) includes: a current detecting unit
201 that detects a current applied to the linear motor
200; a controlling
unit
202 that outputs a switching control signal based on the detected current;
and a switch that receives an alternating current power AC and varies the number
of winding of the linear motor
200 according to the switching control signal.
The linear motor linear
200 includes a first coil L
1 wound with a
first predetermined number of winding and a second coil L
2 wound with a
second predetermined number of winding and connected to the first coil in series.
Also, an equivalence circuit of the linear motor
200 includes the two coils
L
1 and L
2 respectively having the predetermined number of winding
and a resistor R.
Accordingly, the switch
203 supplies the alternating current
to the first coil L
1 on the basis of the control signal or to the second
coil L
2 connected to the first coil L
1 in series, thereby controlling
a current applied to the linear motor
200. That is, the switch
203
is connected to the first coil L
1 or to the second coil L
2 together
with the first coil L
1 connected in series on the basis of the control signal,
thereby varying the number of winding of the linear motor coil. Also, the linear
motor coil can be formed with a plurality of coil units, not only two. Additionally,
the first and second predetermined number of winding may be equal but need not
be equal to each other.
Hereinafter, operations of the apparatus for controlling a driving of
the linear motor will be explained with reference to FIGS. 4A and 4B.
FIGS. 4A and 4B show waveforms of a current detected by a current detecting
unit of FIG. 3.
First, the current detecting unit
201 detects a current applied to
the linear motor
200 and outputs the detected current to the controlling
unit
202.
The controlling unit
202 outputs a first control signal for driving the
linear motor
200 into a high efficiency mode to the switch
203 when
the linear motor
200 arranged in the compressor is initially driven. Herein,
the high efficiency mode is a mode for supplying the alternating current power
AC through both the first coil L
1 and the second coil L
2 connected
to the first coil L
1 in series when the linear motor
200 is driven.
That is, the high efficiency mode decreases the current applied to the linear motor
200 by increasing the number of winding of the linear motor coil and thus
decreases harmonics loss by a triac which controls the alternating current power
supplied to the motor
200, thereby increasing the efficiency of the compressor.
The switch
203 is connected to B contact point of the second coil L
2
by receiving the first control signal. That is, the linear motor
200 is
driven by receiving the alternating current power AC through both the first coil
and the second coil connected to the first coil in series. Herein, the switch
203
preferably uses a relay.
Accordingly, if the linear motor
200 is driven in the high efficiency
mode, the harmonics loss by the conventional triac is decreased, thereby increasing
efficiency of the compressor.
In the meantime, when a current dead zone, where a current value output from
the
current detecting unit
201 is zero for a predetermined time does not exist
as shown in FIG. 4A, the control unit
202 recognizes that the linear motor
is in an overload state, and thereby outputs a second control signal for driving
the linear motor
200 in an overload corresponding mode to the switch
203.
Herein, the overload corresponding mode compensates a deficient voltage due to
the overload of the motor, thereby preventing a phenomenon of voltage deficiency.
That is, the overload corresponding mode decreases the number of winding of the
linear motor coil when the linear motor
200 is overloaded and thus increases
the current applied to the linear motor
200, and thereby drives the linear
motor
200 in a stable fashion.
The switch
203 is connected to contact point A between the first coil
L
1 and the second coil L
2 by receiving the second control signal.
At this time, the linear motor
200 is driven by receiving the alternating
current power AC through only the first coil. That is, the switch
203 converts
"the high efficiency mode" into "the overload corresponding mode" on the basis
of the second control signal. In other words, the switch
203 decreases the
number of winding of the motor coil, prevents the voltage deficiency phenomenon,
and thus stably drives the linear motor. That is, when the linear motor is overloaded,
the number of winding of the linear motor is varied to control the current applied
to the motor, and thereby drives the linear motor in a stable fashion.
Hereinafter, when a current dead zone, where a current value output
from the current detecting unit
201 is zero for a predetermined time, exists
as shown in FIG. 4B, the controlling unit
202 outputs the first control
signal for driving the linear motor
200 into 'the high efficiency mode'
to the switch
203.
The switch
203 is connected to the B contact point of the second coil
L
2 by receiving the first control signal. That is, the linear motor
200
is driven by receiving the alternating current power AC through both the first
coil and the second coil connected to the first coil in series.
In the meantime, the current detecting unit
201 can increase the current
dead zone where a current value applied to the linear motor is zero for more than
a predetermined time and output a current value corresponding to the increased
current dead zone to the controlling unit
202, so that the controlling unit
202 can easily recognize that the linear motor is in 'the high efficiency mode'.
As aforementioned, the present invention decreases the harmonics loss by the
triac
which controls the alternating current power supplied to the linear motor
200
by varying the number of winding of the linear motor coil on the basis of the current
supplied to the linear motor arranged in the linear compressor, and thereby increases
the compressor efficiency. That is, in the present invention, when the current
dead zone, where a current supplied to the motor arranged in the linear compressor
is zero for a predetermined time exists, the number of winding of the linear motor
coil is increased to decrease the current applied to the linear motor, thereby
serving to decrease the harmonics loss by the triac which controls the alternating
current power supplied to the linear motor
200 and thus serving to increase
the efficiency of the linear compressor.
Also, in the present invention, since the number of winding of the linear motor
coil varies on the basis of the current applied to the linear motor arranged in
the linear compressor, when the linear motor is overloaded, the linear motor is
stably driven. That is, in the present invention, when the current dead zone, where
a current value supplied to the linear motor arranged in the linear compressor
is not present at all, or the current dead zone is not present for a predetermined
period time, that is, when the linear motor is overloaded, the number of winding
of the linear motor coil is decreased to increase the current applied to the linear
motor. As a result, when the linear motor is overloaded, the linear motor is stably driven.
As the present invention may be embodied in several forms without departing from
the spirit or essential characteristics thereof, it should also be understood that
the above-described embodiments are not limited by any of the details of the foregoing
description, unless otherwise specified, but rather should be construed broadly
within its spirit and scope as defined in the appended claims, and therefore all
changes and modifications that fall within the metes and bounds of the claims,
or equivalence of such metes and bounds are therefore intended to be embraced by
the appended claims.
*