System and method for controlling pressure
First Claim
1. A method of controlling pressure in a chamber, the chamber having an exhaust valve having an associated position, the method comprising the steps of:
- (a) defining a pressure setpoint;
(b) measuring the pressure in the chamber;
(c) computing, as a linear function of the measured pressure and the pressure setpoint, a control variable representing a desired exhaust gas flow from the chamber;
(d) computing, as a function of the control variable and the measured pressure, a desired valve position using an inverse conductance curve function;
(e) adjusting the position of the exhaust valve based on the desired valve position so as to establish a chamber pressure associated with the pressure setpoint.
2 Assignments
0 Petitions
Accused Products
Abstract
A system for controlling the pressure in a chamber with a computer controlled exhaust throttle valve. A characterization relationship describes the static properties of the valve geometry, valve actuation mechanism and gas flow properties. This characterization relationship can comprise a theoretical or empirical function which associates a sufficient number of valve positions with the corresponding pressure, and may be parameterized by other auxiliary variables such as inlet gas flow values, gas types and compositions. An inverse relationship between the current measurable variables of the process, such as pressure, inlet flows and other auxiliary parameters is defined. A linearization method uses the inverse relationship to modify the effect of the valve positioning on the corresponding value of pressure in such a way that the combined behavior of the process and the linearization method yields a linear relationship between a new control variable and the pressure. A linear feedback control method then controls the modified, linearized system.
-
Citations
20 Claims
-
1. A method of controlling pressure in a chamber, the chamber having an exhaust valve having an associated position, the method comprising the steps of:
-
(a) defining a pressure setpoint; (b) measuring the pressure in the chamber; (c) computing, as a linear function of the measured pressure and the pressure setpoint, a control variable representing a desired exhaust gas flow from the chamber; (d) computing, as a function of the control variable and the measured pressure, a desired valve position using an inverse conductance curve function; (e) adjusting the position of the exhaust valve based on the desired valve position so as to establish a chamber pressure associated with the pressure setpoint. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method of controlling pressure in a chamber, the chamber having an exhaust valve having an associated position, the method comprising the steps of:
-
(a) defining a pressure setpoint; (b) measuring the pressure in the chamber; (c) computing a desired valve position as a function of (A) a difference between the pressure setpoint and the measured pressure value and (B) a feedback term, MVp, wherein M is a tuning parameter, V represents an effective volume of the chamber, and p is the measured chamber pressure, (d) adjusting the position of the exhaust valve based on the desired valve position so as to establish a chamber pressure associated with the pressure setpoint. - View Dependent Claims (14)
-
-
15. A system for controlling the pressure in a chamber comprising:
-
an inflow valve in said chamber, said inflow valve for providing gases to said chamber; a pressure sensor coupled to said chamber for measuring the pressure in said chamber; an exhaust valve, having an associated position, in said chamber; a valve actuator coupled to said exhaust valve for adjusting the position of said exhaust valve; an exhaust valve controller coupled to said valve actuator, wherein said valve controller computes a control variable representing a desired exhaust gas flow as a linear function of a pressure setpoint and the measured pressure, computes a desired valve position by applying an inverse conductance curve function to the control variable, and adjusts the position of the exhaust valve based on the desired valve position so as to establish a chamber pressure associated with the pressure setpoint. - View Dependent Claims (16, 17, 18, 19, 20)
-
Specification