Patent ID: 6370888
Filing Date: 2002-04-16
Classification: F04B,F25B,Y02B

Abstract:
A method for controlling at least one compressor of a chiller system with a variable speed drive, comprising the steps of:a) checking to see if additional compressor capacity is needed by said system; b) ensuring said at least one compressor is running from said variable speed drive if additional compressor capacity is needed by said system; c) monitoring a current in said variable speed drive; d) closing an electronic expansion valve by a specified amount in said system if said current is greater than a specified percentage of a maximum current; e) increasing a frequency of said variable speed drive by a specified amount if said current is less than or equal to said specified percentage of said maximum current, f) checking to see if said additional compressor capacity needed by said system is satisfied by step (e); g) checking whether said frequency of said variable speed drive is equal to a frequency of line power powering said variable speed drive, and if not, performing steps (c) through (f) again; and h) transitioning said at least one compressor from variable speed drive to directly on line.