Mass flow controller algorithm with adaptive valve start position

摘要

A mass flow controller (MFC), a method for calibrating an MFC, and a method for operating an MFC are disclosed. The MFC may include a valve that is adjustable between a closed position and an open position to control a flow rate of a fluid responsive to a control signal, a thermal mass flow sensor that provides an indication of the flow rate of the fluid, calibration data including data that relates the control signal to the flow rate of the fluid at a plurality of fluid flow rates, and a control system that provides, based upon the calibration data and run time data, an adjustable non-zero starting control signal to the valve when the valve is closed to more quickly respond to a set point signal.

主权项

1. A mass flow controller comprising:
a valve that is adjustable between a closed position and an open position to control a flow rate of a fluid responsive to a valve control signal; a thermal mass flow sensor that provides an indication of the flow rate of the fluid; a control system that provides the valve control signal based upon the indication of the flow rate of the fluid and a flow set point signal; calibration data including data that relates the valve control signal to the flow rate of the fluid at a plurality of fluid flow rates; and wherein the control system includes an adaptive valve start component that provides, based upon the calibration data and run time data, an adjustable non-zero starting valve control signal to the valve when the valve is closed to more quickly respond to the flow set point signal, and wherein the adaptive valve start component is configured to;
determine a difference between an actual valve control signal level at a particular flow rate during operation and a calibration control signal level at the particular flow rate; andadjust the adjustable non-zero starting valve control signal based upon the difference between the actual valve control signal level and the calibration control signal level.