Abstract: A method for controlling operation of a centrifugal cooling apparatus, which has at least one of an evaporator, a centrifugal compressor having a magnetic bearing system, a condenser, and an expansion device, includes monitoring an operating condition of the magnetic bearing system, and controlling compressor flow stability based upon the operating condition of the magnetic bearing system.

Abstract: A control system and a method for controlling a centrifugal chiller through which a fluid to be chilled passes includes a chilling apparatus having at least one of each of the following components; an evaporator, a compressor, preferably a magnetic bearing compressor, a condenser and an expansion device. A plurality of sensors measure and generate signals representing operating conditions within the chilling apparatus. A chiller control unit including a signal processor receives the signals generated by the plurality of sensors. The chiller control unit further includes a memory device that stores information relating to thermodynamic properties of specific fluids and a comparison device programmed with a comparison algorithm that compares the received signals generated by the plurality of sensors to thermodynamic properties of the specific fluid contained in the memory device.