Self-tuning pull-down fuzzy logic temperature control for refrigeration systems

摘要

A pull-down control algorithm for an HVAC refrigeration system is provided. The control algorithm utilizes a fuzzy logic methodology to automatically adjust a flow of refrigerant in the system during a pull-down to maintain a desired pull-down rate. The desired pull-down rate is decreased proportionately as the temperature of the fluid being pulled down approaches a desired operating setpoint to avoid or minimize any overshoot of the operating setpoint. The desired pull-down rate is obtained by adjusting a rate sensitivity factor used in the control algorithm. When the temperature of the fluid being pulled down is above a predetermined value from the operating setpoint, the control algorithm uses a fuzzy logic methodology to determine a rate sensitivity that results in the desired pull-down rate that approaches the operating setpoint without overshoot.