System and method for a digital mass flow controller
AssigneeMykrolis Corporation
InventorEmmanuel Vyers
Life of this patent
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Abstract
A method for controlling the gas flow within a digital mass flow controller. The method calculates a digitally enhanced flow rate signal that more accurately represents an actual flow rate through the digital mass flow controller. The digitally enhanced flow rate is calculated using a sensed flow rate signal output from a flow sensor, a scaled first derivative of the sensed flow rate signal, and a scaled, filtered second derivative of the sensed flow rate signal. A set-point signal is compared to the digitally enhanced flow rate signal to generate a digital error signal. The digital error signal is provided to a digitally realized PI (proportional integral) controller. The PI controller generates a digital control signal which is used to control a valve in the digital mass flow controller.
Claims17
A digital mass flow controller for controlling the flow of gas in a process, said digital mass flow controller comprising:
- a flow sensor that measures an actual gas flow rate through said digital mass flow controller and outputs a sensed flow rate signal;
- a digital microcontroller which generates a digital control signal using said sensed flow rate signal, a first derivative of said sensed flow rate signal, a filtered second derivative of said sensed flow rate signal, and a set-point signal;
- and
- a valve in said digital mass flow controller which is controlled by said digital control signal.
A method for controlling a gas flow comprising:
- generating a sensed flow rate signal based on a measured gas flow rate;
- generating a digital control signal based on said sensed flow rate signal, a first derivative of said sensed flow rate signal, a filtered second derivative of said sensed flow rate signal, and a set-point signal;
- and
- regulating flow through a valve based on said digital control signal.
Dependencies are inferred from the claim text.