Fluid control device and flow rate ratio control device

A flow rate ratio control device that controls a flow rate ratio of fluid flowing through multiple branch flow paths branching from an end of a supply gas flow path through which the fluid is supplied, the flow rate ratio control device comprising:

• multiple fluid control devices that are respectively provided in the respective branch flow paths and each of which is provided with a valve, a flow rate sensor, and a valve control part adapted to control an opening level of the valve so that a deviation between an inputted set flow rate and a measured flow rate by the flow rate sensor decreases;
• a pressure sensor provided in the supply gas flow path or on an upstream side of the valves of the respective fluid control devices in the respective branch flow paths;
• and
• a set flow rate generator that is inputted with a measured pressure measured by the pressure sensor and, on a basis of a pressure-flow rate map, outputs a set flow rate corresponding to the measured pressure, wherein
• the set flow rate generator comprises:
• a target total flow rate determination part that, on a basis of the measured pressure and the pressure-flow rate map, determines a target total flow rate that has a target value of a sum of flow rates flowing through the respective branch flow paths;
• and
• a flow rate distribution part that, on a basis of the target total flow rate and a predetermined target flow rate ratio of the fluid to be flowed through the respective branch flow paths, determines a set flow rate to be inputted to a fluid control device provided in each of the branch flow paths, and
• the set flow rate generator controls the set flow rate so that the measured pressure has a value equal to or less than a limit pressure.