SYSTEM IDENTIFICATION OF REFRIGERATING SYSTEM TRANSFER FUNCTION BY PARTITION STEP-RESPONSE

System identification of refrigerating system is hard to realize by mechanism analysis because of the complexity of system.This paper proposes a method based on partition step-response to get the transfer function of a refrigerating system.According to an experiment，the transfer function we get indicates that as the temperature of the FPA grows，the steady-state gain of the system decreases which verifies the theoretical derivation.It has set up a foundation for the development of the system control algorithm.