Mass flow controller and controller algorithm

A method for controlling flow of a fluid through a mass flow controller, the method comprising:

• receiving the fluid through an inlet;
• regulating the flow of the fluid out of an outlet of the mass flow controller by controlling operation of the valve using a valve actuator;
• receiving a desired fluid flow rate;
• receiving from at least one sensor measurement of at least one of a pressure, a temperature, a flow rate, and fluid type relating to flow of the fluid through a flow path;
• and
• controlling the gain of the mass flow controller by controlling a linear response of the valve using the desired fluid flow rate and the at least one of the pressure, the temperature, the flow rate, and the fluid type;
• wherein the linear response is controlled by determining change in an actuator drive value and a change in flow of the fluid, dDrive/dFlow;
• wherein the desired fluid flow rate is determined from a rate limiting and low-pass filtered set point value, at least one real-time fluid parameter value, valve model data, an actuator gain, and a valve model gain.

A process control system for use in a mass flow controller, the control system comprising:

• a linearization module communicable coupled with a valve actuator and a memory device that controls the gain of the mass flow controller by controlling a linear response of a valve using a desired fluid flow rate and from at least one sensor at least one of a pressure, a temperature, a flow rate, and fluid type relating to flow of the fluid through a flow path;
• wherein the linearization module further includes:
• a flow modeling system to determine fluid properties according to the at least one of the pressure, the temperature, the flow rate, and the fluid type;
• and
• a valve modeling system to determine required operational characteristics of the valve according to valve specifications and the determined fluid properties;
• and
• wherein the desired fluid flow rate is determined from a rate limiting and low-pass filtered set point value, at least one real-time fluid parameter value, valve model data, an actuator gain, and a valve model gain.