Patent KR-20040010500-A (KR)
Inventor: KIM DONG HWA
IPC: C02F1/00
Filed: 2003-12-30
Abstract: PURPOSE: Provided are water purification method and apparatus for precisely controlling pH of water without depending on external environment change using neural network based on PID control. CONSTITUTION: The method comprises the steps of (a) performing operation of set values to be applied to a model equation of neural network by receiving external environment change signals from a water quality analyzing sensor, (b) controlling variations of the set values, (c) outputting PI control signal by receiving the output signal of the step (b) and a signal obtained by deducting plant output variable from the output signal of the step (b), (d) controlling the variations of the set values by comparing it and the plant output variable, and outputting a signal by adding the variations of the set values to the output signal of the step (c), (e) adjusting and outputting transfer function (η) by receiving the set values output from the step (a) and the output signal of the step (d), and (f) outputting a plant control signal by adding the PI control signal output from the step (c) to the output signal of the step (e). The apparatus comprises a chemical feeding rate calculation unit for outputting set values to be applied to a model equation of a neural network by receiving an external environment change signal detected by a water quality analysis sensor; a PID controller(30) for performing a feed-back control of a chemical feeding pump by receiving the set values output from the chemical feeding rate calculation unit; and a plant(40) to be controlled, wherein the PID controller(30) includes a first transfer function unit(31) for precisely controlling variations of set values and outputs of the chemical feeding rate calculation unit using an input value (R) and the set values output from the calculation unit as inputs, a second transfer function unit(32) connected to the output terminal of the first transfer function unit(31) for performing PI function using the output signal of the first transfer function unit(31) and a plant output variable (Y) as inputs, an input variable unit(33) for outputting a signal decided by external condition which affects chemical feeding control by receiving a fuzzy variable, a third transfer function unit(34) connected to output terminals of the chemical feeding rate calculation unit(20) and the input variable unit(33) for comparing the variations of the set values (R) and the plant output variable (Y) and outputting a signal to be inputted to a third error signal processing unit(37) to be operated therein, a first error signal processing unit(35) for outputting a control signal for controlling the second transfer function unit(32) by operating the output signal of the first transfer function unit(31) and a feed-back signal from the plant(40), a second error signal processing unit(36) for outputting a control signal for controlling the third transfer function unit(34) by operating the output signal of the input variable unit(33) and the feed-back signal from the plant(40), and a third error signal processing unit(37) for outputting a control signal to control the plant(40) by performing plus operation of the output signals of the second transfer function unit(32) and the third transfer function unit(34).