Method for operating a linear compressor
A method for operating a linear compressor includes measuring a current induced in a motor of the linear compressor and calculating an observed current of the motor of the linear compressor using at least an electrical dynamic model for the linear compressor and a robust integral of the sign of the error feedback. The method also includes detecting a head crash within the linear compressor if an error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is greater than a crash threshold.
1. A method for operating a linear compressor, comprising:
supplying a motor of the linear compressor with a time varying voltage;
measuring a current induced in the motor of the linear compressor during said step of supplying;
calculating an observed current of the motor of the linear compressor using at least an electrical dynamic model for the linear compressor and a robust integral of the sign of the error feedback;
determining an error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor;
calculating a soft crash threshold and a hard crash threshold based at least in part on a peak voltage of the time varying voltage supplied to the motor of the linear compressor; and
detecting a head crash within the linear compressor if an error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is greater than a crash threshold.
2. The method of claim 1 , wherein the soft crash threshold is calculated with the following
T
SC
=
(
min
{
V
peak
-
194
40
+
5
*
10
-
4
,
10
-
3
}
)
*
2
*
10
-
4
where
T SC is the soft crash threshold, and
V peak is the peak voltage of the time varying voltage supplied to the motor of the linear compressor.
3. The method of claim 1 , wherein the hard crash threshold is calculated with the following
T
HC
=
(
min
{
V
peak
-
194
40
+
5
*
10
-
4
,
10
-
3
}
)
*
7
*
10
-
4
where
T HC is the hard crash threshold, and
V peak is the peak voltage of the time varying voltage supplied to the motor of the linear compressor.
4. The method of claim 1 , wherein said step of detecting the head crash comprises detecting a soft head crash if the error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is greater than the soft crash threshold and detecting a hard head crash if the error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is greater than the hard crash threshold.
5. The method of claim 1 , wherein said step of detecting the head crash further comprises detecting no head crash within the linear compressor if the error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is less than the crash threshold.
6. The method of claim 1 , further comprising obtaining a moving average of the error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor.
7. The method of claim 6 , wherein said step of detecting the head crash comprises detecting the head crash if the moving average of the error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is greater than the crash threshold.
8. The method of claim 1 , further comprising filtering the measured current induced in the motor of the linear compressor.
9. A method for operating a linear compressor, comprising:
supplying a motor of the linear compressor with a time varying voltage;
measuring a current to the motor of the linear compressor during said step of supplying;
filtering the measured current induced in the motor of the linear compressor;
calculating an observed current of the motor of the linear compressor using at least an electrical dynamic model for the linear compressor and a robust integral of the sign of the error feedback;
determining an error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor;
obtaining a moving average of the error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor;
calculating a soft crash threshold and a hard crash threshold based at least in part on a peak voltage of the time varying voltage supplied to the motor of the linear compressor; and
detecting a head crash within the linear compressor if the moving average of an error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is greater than a crash threshold.
10. The method of claim 9 , wherein the soft crash threshold is calculated with the following
T
SC
=
(
min
{
V
peak
-
194
40
+
5
*
10
-
4
,
10
-
3
}
)
*
2
*
10
-
4
where
T SC is the soft crash threshold, and
V peak is the peak voltage of the time varying voltage supplied to the motor of the linear compressor.
11. The method of claim 9 , wherein the hard crash threshold is calculated with the following
T
HC
=
(
min
{
V
peak
-
194
40
+
5
*
10
-
4
,
10
-
3
}
)
*
7
*
10
-
4
where
T HC is the hard crash threshold, and
V peak is the peak voltage of the time varying voltage supplied to the motor of the linear compressor.
12. The method of claim 9 , wherein said step of detecting the head crash comprises detecting a soft head crash if the error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is greater than the soft crash threshold and detecting a hard head crash if the error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is greater than the hard crash threshold.
13. The method of claim 9 , wherein said step of detecting the head crash further comprises detecting no head crash within the linear compressor if the error between the observed current of the motor of the linear compressor and the measured current induced in the motor of the linear compressor is less than the crash threshold.
14. The method of claim 9 , wherein a period of the moving average is about one millisecond.