Pumps – Condition responsive control of pump drive motor – By control of electric or magnetic drive motor
Reexamination Certificate
2002-01-09
2003-09-23
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of pump drive motor
By control of electric or magnetic drive motor
C417S053000, C417S044110, C417S018000, C417S045000, C417S212000, C417S417000
Reexamination Certificate
active
06623246
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear motor compressor, and in particular to an apparatus and a method for controlling operation of a linear motor compressor which is capable of operating a linear motor compressor in an optimum condition.
2. Description of the Prior Art
Generally, by eliminating the use of a crankshaft for converting a rotary motion into a linear motion, a linear motor compressor has a low frictional loss, and accordingly the linear motor compressor is superior to a general compressor in the compressing efficiency aspect.
When the linear motor compressor is used for a refrigerator or an air conditioner, a cooling capacity of the refrigerator or the air conditioner can be controlled by varying a compression ratio of the linear motor compressor by varying a stroke voltage applied to the linear motor compressor. The linear motor compressor will be described with reference to accompanying FIG.
1
.
FIG. 1
is a schematic block diagram illustrating the construction of an apparatus for controlling the operation of a linear motor compressor in accordance with the prior art.
As depicted in
FIG. 1
, the apparatus for controlling the operation of a linear motor compressor in accordance with the prior art applies a stroke voltage to an internal motor (not shown) of a linear motor compressor
13
for varying an internal stroke supplied according to a stroke reference value set by a user, thereby adjusting a cooling capacity by moving an internal piston (not shown) back and forth. A voltage detecting unit
14
detects a voltage generated in the linear motor compressor
13
according to the variation of the stroke, and a current detecting unit
12
detects a current generated in the linear motor compressor
13
according to the variation of the stroke. A microcomputer
15
calculates the stroke by using the voltage detected by the voltage detecting unit
14
and the current detected from the current detecting unit
12
, comparing the calculated stroke with the stroke reference value and outputting a switching control signal according to the comparison result. And a power supply unit
11
supplies the stroke voltage to the linear motor compressor
13
by on-off controlling the supplying of AC power to the linear motor compressor
13
using a triac Tr
1
controlled by the switching control signal from the micro-computer
15
. Hereinafter, the operation of the apparatus for controlling the operation of the linear motor compressor will be described.
First, the stroke of the linear motor compressor
13
is varied in accordance with the voltage supplied to the motor according to the stroke reference value, and thereby adjusts the cooling capacity by moving the piston back and forth according to the varied stroke. Herein, the term “stroke” means a distance over which the piston inside the linear motor compressor
13
moves while performing a reciprocating motion (moving back and forth).
When the triac Tr
1
of the power supply unit
11
has a longer turn-on duration in accordance with the switching control signal outputted from the microcomputer
15
, at this time the AC turn-on power is supplied to the linear motor compressor
13
, and the linear motor compressor
31
operates. Herein, the voltage detecting unit
14
and the current detecting unit
12
respectively detect a voltage and a current applied to the linear motor compressor
13
and respectively output the detected voltage and current to the microcomputer
15
.
The microcomputer
15
calculates the stroke by using the voltage and the current detected from the voltage detecting unit
14
and the current detecting unit
12
, compares the calculated stroke with the stroke reference value and outputs the switching control signal according to the comparison result. In more detail, when the calculated stroke value is smaller than the stroke reference value, the microcomputer
15
increases the stroke voltage supplied to the linear motor compressor
13
by outputting a switching control signal for lengthening the turn-on cycle of the triac Tr
1
in the power supply unit
11
.
On the contrary, when the calculated stroke value is larger than the stroke reference value, the microcomputer
15
decreases the stroke voltage supplied to the linear motor compressor
13
by outputting a switching control signal for shortening the turn-on cycle of the power supply unit
11
.
However, because the linear motor compressor control apparatus according to the prior art controls the operation of the linear motor compressor by comparing the calculated stroke with the stroke reference value and outputting a switching control signal to the power supply unit according to the comparison result, accordingly the operation of the linear motor compressor can not be controlled accurately. In more detail, since the linear motor compressor control apparatus according to the prior art has a severe non-linearity in its mechanical motion functions, the operation of the linear motor compressor can not be performed precisely and accurately by a linear control method without considering the non-linearity.
In addition, in the linear motor compressor control apparatus according to the prior art, when the linear motor compressor is operated continually in accordance with an initial detected switching control signal, a position of the piston may deviate from TDC (Top Dead Center)=0 due to a load variation according to changes in a refrigerator and other circumstances.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an apparatus and a method for controlling the operation of a linear motor compressor which is capable of operating a linear motor compressor precisely and accurately by detecting a peak value of a current waveform generated in a linear motor compressor, recognizing the peak value of the current waveform as a point TDC=0 and operating the linear motor compressor according to a duty-ratio corresponding to maintaining the point TDC =0.
It is another object of the present invention to provide an apparatus and a method for controlling the operation of a linear motor compressor which is capable of operating a refrigerator efficiently by detecting a current peak value in an optimum operation condition as TDC=0 when the load varies due to changes in a refrigerator and the operating circumstances, recognizing the detected peak value of the current waveform as a position in TDC=0 and operating a linear motor compressor according to a duty-ratio corresponding to maintaining the recognized point TDC=0.
It is yet another object of the present invention to provide an apparatus and a method for controlling the operation of a linear motor compressor which is capable of operating a refrigerator efficiently by periodically detecting a current peak value as TDC=0 when a load change according to changes in a refrigerator and the operating circumstances, recognizing the detected peak value of the current waveform as a position TDC=0 and operating the linear motor compressor according to a duty-ratio corresponding to maintaining the recognized point TDC=0.
It is still another object of the present invention to provide an apparatus and a method for controlling operation of a linear motor compressor which is capable of operating a linear motor compressor in an optimum operation condition by detecting load variation due to changes in a refrigerator and the circumstances with a quantity of power consumption, comparing the quantity of power consumption with a maximum power quantity and a minimum power quantity and detecting a current peak value in TDC= according to the comparison result.
It is yet still another object of the present invention to provide an apparatus and a method for controlling operation of a linear motor compressor which is capable of operating a linear motor compressor in an optimum condition by checking load variation of a refrigerator with current variation by using currents generated in a l
Chung Ui Yeop
Hwang Yin Young
Park Jin Koo
Park Joon Hyung
Seo Sang Ho
Freay Charles G.
LG Electronics Inc.
Rodriguez William H.
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