Method for operating a linear compressor

Patent metadata

Field	Value
Publication number	US-10830230-B2
Application number	US-201715397770-A
Country	US
Kind code	B2
Filing date	Jan 4, 2017
Priority date	Jan 4, 2017
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

A method for operating a linear compressor includes establishing a set of predictors, and establishing a model for an estimated head clearance of the linear compressor with the set of predictors. Coefficients of the model for the estimated head clearance of the linear compressor may also be established. The model for the estimated head clearance of the linear compressor may be used to calculate an estimated head clearance during operation of the linear compressor.

First claim

What is claimed is:

1. A method for operating a linear compressor, comprising: supplying a motor of the linear compressor with a time varying voltage having a peak motor voltage and an excitation frequency; measuring a peak motor current of the linear compressor while the time varying voltage is supplied to the motor of the linear compressor; determining an observed minimum velocity of the motor of the linear compressor and an observed stroke length of the motor of the linear compressor, wherein a set of predictors comprises the peak motor voltage, the excitation frequency, the peak motor current, the observed minimum velocity and the observed stroke length; removing redundant predictors from the set of predictors in order to establish a reduced set of predictors; establishing a model for an estimated head clearance of the linear compressor with the reduced set of predictors, the model for the estimated head clearance of the linear compressor is a linear combination of each predictor of the reduced set of predictors with each predictor from the reduced set of predictors being multiplied by a respective coefficient; establishing a value for each coefficient of the model for the estimated head clearance of the linear compressor; and saving the coefficients and the model for the estimated head clearance of the linear compressor in a memory of a controller such that the controller is configured operable to adjust operation of the linear compressor towards a desired head clearance using the model for the estimated head clearance of the linear compressor, wherein the linear compressor does not have a position sensor for detecting a position of a piston of the linear compressor.

2. The method of claim 1 , wherein determining the observed minimum velocity of the motor of the linear compressor and the observed stroke length of the motor of the linear compressor comprises:
estimating a back-EMF of the motor of the linear compressor using an electrical dynamic model for the motor of the linear compressor and a robust integral of the sign of the error feedback;
determining an observed velocity of the motor of the linear compressor based at least in part on the back-EMF of the motor; and
calculating the observed stroke length of the motor of the linear compressor based at least in part on the observed velocity of the motor.

3. The method of claim 2 , wherein the electrical dynamic model for the motor comprises

di
dt

=

v
a

L
i

-

r
i

⁢
i

L
i

-

α
⁢

⁢

x
.

L
i

where
v a is a voltage across the motor of the linear compressor;
r i is a resistance of the motor of the linear compressor;
i is a current through the motor of the linear compressor;
α is a motor force constant;
{dot over (x)} is a velocity of the motor of the linear compressor;
t is time; and
L i is an inductance of the motor of the linear compressor.

4. The method of claim 3 , wherein estimating the back-EMF of the motor of the linear compressor using the robust integral of the sign of the error feedback comprises solving
{circumflex over (f)} =( K 1 +1) e ( t )+∫ t 0 t [( K 1 +1) e (σ)+ K 2 sgn( e (σ))] d σ−( K 1 +1) e ( t 0 )

where
{circumflex over (f)} is an estimated back-EMF of the motor of the linear compressor;
K 1 and K 2 are real, positive gains;
e is an error given as {circumflex over (ι)}−i;
{circumflex over (ι)} is an observed current through the motor of the linear compressor;
e(σ) is e as a function of σ;
e(t) is e as a function of time; and
e(t 0 ) is e at time t 0 .

5. The method of claim 1 , further comprising:
establishing the desired head clearance of the linear compressor;
calculating the estimated head clearance of the linear compressor with the model for the estimated head clearance of the linear compressor; and
adjusting the peak motor current of the linear compressor in order to reduce a difference between the desired head clearance of the linear compressor and the estimated head clearance of the linear compressor.

6. The method of claim 5 , wherein the motor of the linear compressor is sealed within a hermetic shell prior to the desired head clearance is established, the estimated head clearance is calculated, and the peak motor current is adjusted.

7. The method of claim 5 , wherein the controller establishes the desired head clearance, calculates the estimated head clearance, and adjusts the peak motor current.

8. The method of claim 1 , wherein the set of predictors further comprises at least one product of any two of the peak motor voltage, the excitation frequency, the peak motor current, the observed minimum velocity and the observed stroke length.

9. The method of claim 1 , wherein the set of predictors further comprises one or more of the square of the peak motor voltage, the square of the excitation frequency, the square of the peak motor current, the square of the observed minimum velocity and the square of the observed stroke length.

10. The method of claim 1 , wherein the set of predictors further comprises:
each product of two of the peak motor voltage; the excitation frequency, the peak motor current, the observed minimum velocity and the observed stroke length; and
each respective square of the peak motor voltage, the excitation frequency, the peak motor current, the observed minimum velocity and the observed stroke length.

11. The method of claim 1 , wherein the reduced set of predictors further comprises a product of the peak motor voltage and the excitation frequency, a product of the peak motor voltage and the observed stroke length; and a product of the excitation frequency and the observed minimum velocity.

12. The method of claim 1 , wherein establishing the model for the estimated head clearance comprises conducting a best subsets regression with the reduced set of predictors.

13. The method of claim 1 , wherein establishing the coefficients of the model for the estimated head clearance comprises establishing the coefficients of the model for the estimated head clearance with a least-squares method.

14. A method for operating a linear compressor, comprising: supplying a motor of the linear compressor with a time varying voltage having a peak motor voltage and an excitation frequency; measuring a peak motor current of the linear compressor while the time varying voltage is supplied to the motor of the linear compressor; determining an observed minimum velocity of the motor of the linear compressor and an observed stroke length of the motor of the linear compressor; establishing a set

Assignees

• Haier Us Appliance Solutions Inc
• Univ Louisville Res Found Inc

Inventors

• Hahn Gregory William
• Kusumba Srujan
• Mcintyre Michael Lee
• Latham Joseph W

Classifications

• F04B39/121

  Casings · CPC title

• F04B2203/00

  Motor parameters · CPC title

• F04B49/065

  and making use of computers · CPC title

• F04B49/16 Primary

  by adjusting the capacity of dead spaces of working chambers · CPC title

• F04B35/04

  the means being electric · CPC title