| 摘要 |
PURPOSE:To correct the nonlinearity of opening extent-flow rate characteristics of a flow control valve by calculating the gain of a controlled system from the opening extent of the flow control valve and obtaining a PI control proportional gain so that a specified control response is obtained constantly. CONSTITUTION:The current opening extent U detected by an opening extent detector 2 is used to calculate the value of a characteristic function F from a graph in a figure which is stored in a characteristic function storage means 8, and the gain of a proportional system is calculated by a gain arithmetic means 9 from the value of the function F and the flow rate Q detected by a flow detector 3. Then, a PI control proportional gain arithmetic means 10 calculates the proportional gain KP of a PI controller from the gain K of a proportional system. Namely, the proportional gain KP of a PI controller 6 shown by an PI arithmetic expression is varied automatically corresponding to the current opening extent of the flow control valve 1. Consequently, a constant control response is obtained following up the opening extent-flow rate nonlinearity of the valve. |
