Component 408: 'Sticky' Proportional Controller by HVACSIM+ General Description This component represents a proportional controller with upper and lower limits on the rate of change of the output control signal. The limits are determined by the second parameter, B. If the error signal changes by an amount less than B, the change is ignored and the output control signal remains constant until the cumulative changes in error equal or exceed B. A change in the error signal with a magnitude greater than 2B is treated as a change in error of magnitude B. Thus for purposes of calculating the output control signal, all changes in error lie between B and 2B. The measured input signal, generally representing a temperature, must be a control variable between zero and one, which can be obtained by passing a temperature through the Component 409 temperature sensor model. NOTE: this component is to be used only to pass control signals between superblocks. The variable defined by its output should not be solved simultaneously. Nomenclature B - error band C - output control signal (0 <= C <= 1) CTm - measured temperature input control signal (0 <= CTm < 1) CTs - temperature setpoint control signal (0 <= CTs <= 1) E - effective error at current simulation time Eo - effective error at previous simulation time Ko - offset Kp - proportional gain Mathematical Description DeltaE = CTs - CTm - Eo If (|DeltaE| < B) E = Eo If (B <= |DeltaE| <= 2B) E = CTs - CTm If (2B < |DeltaE|) E = Eo + (B)*sign(DeltaE) C = Ko + Kp*E If (C < 0) C = 0 If (C > 1) C = 1 Component 408 Configuration Inputs Description 1 CTm - measured temperature input control signal 2 CTs - temperature setpoint control signal Outputs Description 1 C - controller output Parameters Description 1 Kp - proportional gain 2 B - error band 3 Ko - offset Reference: 1. HVACSIM+ Building Systems and Equipment Simulation Program Reference Manual (NBSIR 84-2996) Daniel R. Clark United States Department of Commerce National Institute of Standards and Technology Gaithersburg, Maryland 20899-0001