Two-zone fuzzy logic liquid level control
First Claim
1. A liquid level control system for a refrigeration system comprising a compressor, a condenser, an evaporator, and an adjustable valve positioned between the condenser and the evaporator, the control system comprising:
- a sensor, the sensor being configured and disposed to detect a level of liquid refrigerant in a condenser and to provide a liquid level signal corresponding to the detected level of liquid refrigerant in the condenser;
a plurality of fuzzy logic control algorithms, each fuzzy logic control algorithm of the plurality of fuzzy logic control algorithms being configured to calculate an adjustment to a position of an adjustable valve, the position of the adjustable valve being used to control the level of liquid refrigerant in the condenser;
a microprocessor, the microprocessor being configured to sample the liquid level signal at a predetermined interval during operation of a refrigeration system and to select a fuzzy logic control algorithm from the plurality of fuzzy logic control algorithms at each interval based on a deviation of the sampled liquid level signal from a predetermined setpoint level; and
wherein the microprocessor generates a control signal to position the adjustable valve of a refrigeration system using the selected fuzzy logic control algorithm.
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Abstract
A level 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 to maintain a desired liquid level in the condenser. The fuzzy logic methodology incorporates a plurality of fuzzy logic control algorithms each having different membership functions and other control parameters that can provide different degrees of level control in the condenser. A particular fuzzy logic control algorithm is selected based on the amount a measured liquid level in the condenser deviates from the desired liquid level in the condenser.
56 Citations
11 Claims
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1. A liquid level control system for a refrigeration system comprising a compressor, a condenser, an evaporator, and an adjustable valve positioned between the condenser and the evaporator, the control system comprising:
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a sensor, the sensor being configured and disposed to detect a level of liquid refrigerant in a condenser and to provide a liquid level signal corresponding to the detected level of liquid refrigerant in the condenser; a plurality of fuzzy logic control algorithms, each fuzzy logic control algorithm of the plurality of fuzzy logic control algorithms being configured to calculate an adjustment to a position of an adjustable valve, the position of the adjustable valve being used to control the level of liquid refrigerant in the condenser; a microprocessor, the microprocessor being configured to sample the liquid level signal at a predetermined interval during operation of a refrigeration system and to select a fuzzy logic control algorithm from the plurality of fuzzy logic control algorithms at each interval based on a deviation of the sampled liquid level signal from a predetermined setpoint level; and wherein the microprocessor generates a control signal to position the adjustable valve of a refrigeration system using the selected fuzzy logic control algorithm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification