Research And Realization Of Compressor Speed Measurement Method Based On Discharge Pressure Pulsation

Hermetic reciprocating compressor is the core part of the household refrigerator and its performance directly affects energy saving of the refrigerator and cooling effect.Essentially,the operation of the compressor is the rotation of the motor.Compressor speed is a very important parameter when testing hermetic compressors,which affects the refrigerating capacity of the refrigeration system,valve life,heating exchange and so on.To measure compressor speed can guide the optimization design of compressor and improve compressor refrigeration effect and energy saving performance.Due to the small reciprocating compressor adopts full enclosed,the traditional measurement method is no longer applicable.To accurately measure compressor speed of hermetic reciprocating compressor,this paper presents a method that based on discharge pressure pulsation to obtain the accurate compressor speed.The main research contents and achievements at this stage mainly as follows:Firstly,this paper researched the actual work cycle of reciprocating compressor and analyzed the mechanism of pressure pulsation.In view of the pressure pulsation phenomenon,this paper proposed a method that based on discharge pressure pulsation to obtain the accurate compressor speed.Secondly,the theory of digital signal processing was described,especially the frequency spectrum zooming technology.Then,draw a conclusion that a chirp Z transform method is the best to improve the accuracy of compressor speed.Thirdly,a system was designed to measure compressor speed that based on Lab VIEW software combined with MATLAB.Fourthly,an open type reciprocating compressor system was set up to measure compressor speed through the incremental encoder to verify the feasibility and accuracy of the method that had proposed.Finally,the platform based on DSP was designed to achieve data transmission by interruption for compressor speed measurement.In this paper,the method through the discharge pressure pulsation to measure compressor speed overcome the hermetic compressor defects such as low speed measuring precision and long testing time,and has high value of engineering application.This method is not only suitable for small reciprocating refrigeration compressor,also applies to have periodic pressure fluctuation of the compressor.