Linear compressor and internal collision mitigation

Abstract

A linear compressor or method of operation may provide for driving a motor of the linear compressor to a reference current and detecting a sampled current during driving the motor. The linear compressor or method may also provide for calculating a variance in current using the sampled current, determining the calculated variance exceeds a variance threshold, and restricting the reference current based on determining the calculated variance exceeds the variance threshold.

What is claimed is: 
     
         1 . A method of operating a linear compressor to correct an internal collision between a linear compressor and a shell enclosing the linear compressor, the method comprising:
 driving a motor of the linear compressor to a reference current;   detecting a sampled current during driving the motor;   calculating a variance in current using the sampled current;   determining the calculated variance exceeds a variance threshold; and   restricting the reference current based on determining the calculated variance exceeds the variance threshold.   
     
     
         2 . The method of  claim 1 , wherein the sampled current comprises a peak supply current value, and wherein the reference current comprises a reference peak current value. 
     
     
         3 . The method of  claim 1 , wherein the sampled current comprises a root mean square (RMS) current value, and wherein the reference current comprises a reference RMS current value. 
     
     
         4 . The method of  claim 1 , wherein the calculated variance is a recursive variance. 
     
     
         5 . The method of  claim 1 , wherein calculating variance comprises
 calculating a difference in a previously sampled current and the sampled current, and   calculating variance based on the difference in a previously sampled current and the sampled current.   
     
     
         6 . The method of  claim 1 , wherein driving the motor comprises driving the motor over a plurality of electrical cycles, and wherein detecting the sampled current comprises detecting a discrete sampled current value for each electrical cycle of the plurality of electrical cycles. 
     
     
         7 . The method of  claim 6 , wherein the sampled current value is a maximum absolute value of current for a corresponding electrical cycle. 
     
     
         8 . The method of  claim 1 , wherein detecting the sampled current comprises detecting a predetermined-number set of sampled current values, and wherein calculating variance comprises calculating variance of the predetermined-number set of sampled current values. 
     
     
         9 . The method of  claim 8 , wherein calculating variance comprises calculating a mean value of the predetermined-number of set of sampled current values. 
     
     
         10 . The method of  claim 1 , wherein determining the calculated variance exceeds the variance threshold comprises determining multiple calculated variance values exceed the predetermined variance, and wherein restricting the reference current is contingent on determining multiple calculated variance values exceed the predetermined variance. 
     
     
         11 . A method of operating a linear compressor to correct an internal collision between a linear compressor and a shell enclosing the linear compressor, the method comprising:
 driving a motor of the linear compressor to a reference current over a plurality of electrical cycles;   detecting a sampled current, detecting the sampled current comprising detecting a discrete sampled current value for each electrical cycle of the plurality of electrical cycles;   calculating a variance in current using the sampled current;   determining the calculated variance exceeds a variance threshold; and   restricting the reference current based on determining the calculated variance exceeds the variance threshold independent of a piston position of the motor.   
     
     
         12 . The method of  claim 11 , wherein the sampled current comprises a peak supply current value, and wherein the reference current comprises a reference peak current value. 
     
     
         13 . The method of  claim 11 , wherein the sampled current comprises a root mean square (RMS) current value, and wherein the reference current comprises a reference RMS current value. 
     
     
         14 . The method of  claim 11 , wherein the calculated variance is a recursive variance. 
     
     
         15 . The method of  claim 11 , wherein calculating variance comprises
 calculating a difference in a previously sampled current and the sampled current, and   calculating variance based on the difference in a previously sampled current and the sampled current.   
     
     
         16 . The method of  claim 11 , wherein the sampled current value is a maximum absolute value of current for a corresponding electrical cycle. 
     
     
         17 . The method of  claim 11 , wherein detecting the sampled current comprises detecting a predetermined-number set of sampled current values, and wherein calculating variance comprises calculating variance of the predetermined-number set of sampled current values. 
     
     
         18 . The method of  claim 17 , wherein calculating variance comprises calculating a mean value of the predetermined-number of set of sampled current values. 
     
     
         19 . The method of  claim 11 , wherein determining the calculated variance exceeds the variance threshold comprises determining multiple calculated variance values exceed the predetermined variance, and wherein restricting the reference current is contingent on determining multiple calculated variance values exceed the predetermined variance.