Continuously variable capacity refrigeration system.

摘要

A refrigeration compressor system using a reciprocating compressor (42) with continuously variable capacity. The speed of the compressor (42) can be varied substantially continuously over predefined range of speeds. A controller (40) for the compressor (42) monitors one or more physical parameters indicative of the temperature of the application being refrigerated, such as the temperature itself and/or pressure in the compressor's refrigerant suction line. Using a predefined algorithm, the controller (40) adjusts the speed of said compressor (42) so as to keep said monitored parameter within a predefined target range. In a preferred embodiment, the compressor (42) is an open direct drive compressor. The compressor's motor (44) has a substantially continuous range of useable operating speeds which varies by a ratio of more than two to one. Furthermore, the controller (40) has a plurality of control strategies for adjusting the speed of the compressor's motor (44), including one for adjusting the motor's speed in accordance with the difference between the measured temperature and a specified target temperature, one for adjusting the motor's speed in accordance with the difference between the pressure in the compressor's refrigerant suction line and a specified target temperature, and one for adjusting the motor's speed in accordance with both the temperature and suction pressure.