GAS DELIVERY METHOD AND SYSTEM INCLUDING A FLOW RATIO CONTROLLER USING ANTISYMMETRIC OPTIMAL CONTROL

摘要

The antisymmetric optimal control algorithm is disclosed for a gas delivery system including a flow ratio controller (106) for dividing a single mass flow into at least two flow lines (122a, 122b) . Each flow line includes a flow meter (124) and a valve (126) . Both valves of the flow ratio controller are controlled through a ratio feedback loop by the antisymmetric optimal controller which includes a single input single output SISO controller, an inverter and two linear saturators . The output of the SISO controller is split and modified before being applied to the two valves. The two valve control commands are virtually antisymmetric to the maximum allowable valve conductance position. Due to the fact that these two valve commands are passing through respective linear saturators with the maximum allowable valve conductance position as one of the two saturation limits, the net effect is that one valve is kept at the maximum allowable valve conduction position at any moment of time while the other is actively controlled to maintain the flow ratio.