AN IMPROVED PATTERN RECOGNITION ADAPTIVE CONTROLLER

Seem (1998) described a pattern recognition adaptive controller (PRAC) that tunes PI controllers. PRAC has successfully been used in over 500,000 controllers for heating, ventilating, and air-conditioning equipment. However, there have been three reported problems: 1) PRAC will detune under capacity systems that are repeatedly restarted, 2) PRAC may not tune PI controllers with extremely large values for initial controller gain, and 3) PRAC may detune in the presence of oscillating load disturbances. This paper describes new equations and logic that corrects these three problems.