Pressure control using an external trigger
A gas delivery system and associated method includes a flow channel, a control valve, a downstream pressure sensor, and a controller. The control valve controls flow of gas in the flow channel. The downstream pressure sensor, located downstream of the control valve, measures gas pressure in the flow channel. The controller has an external trigger input to receive a trigger signal applied to a shutoff valve downstream from the control valve. The controller operates in separate modes based on a state of the trigger signal. In a non-triggered mode, the controller controls pressure at the pressure sensor via the control valve in accordance with a first gain schedule. In the triggered mode, the controller controls the pressure at the pressure sensor via the control valve in accordance with a second gain schedule that is distinct from the first gain schedule.
1. A gas delivery system comprising:
a flow channel;
a control valve configured to control flow of gas in the flow channel;
a downstream pressure sensor, downstream of the control valve, configured to measure gas pressure in the flow channel; and
a control unit having an external trigger input configured to receive a trigger signal applied to a shutoff valve downstream from the control valve, the control unit configured for separate modes of operation based on a state of the trigger signal, the separate modes of operation including:
a non-triggered mode in which the control unit is configured to control pressure at the downstream pressure sensor via the control valve in accordance with a first gain schedule; and
a triggered mode in which the control unit is configured to control the pressure at the downstream pressure sensor via the control valve in accordance with a second gain schedule distinct from the first gain schedule.
2. The gas delivery system of claim 1 wherein the trigger input includes a trigger pressure sensor configured to determine the state of the trigger signal based on pressure at the trigger input.
3. The gas delivery system of claim 2 wherein the trigger input taps a pneumatic line that opens and closes the shutoff valve, the trigger pressure sensor configured to sense pressure at the pneumatic line.
4. The gas delivery system of claim 3 wherein the trigger input taps the pneumatic line between a pneumatic control valve and the shutoff valve.
5. The gas delivery system of claim 2 wherein the trigger pressure sensor receives the trigger signal via a pneumatic line controlled by a host controller.
6. The gas delivery system of claim 1 wherein the trigger signal is an electrical signal indicating an open or close state of the shutoff valve.
7. The gas delivery system of claim 1 wherein each of the first and second gain schedules has gain parameters including at least one of a proportional control gain, an integral control gain, and a derivative control gain.
8. The gas delivery system of claim 1 wherein the control unit, in the triggered and non-triggered modes, controls pressure at the downstream pressure sensor based on a comparison of the measured pressure against a setpoint pressure.
9. The gas delivery system of claim 1 further comprising a host controller configured to control the shutoff valve to deliver a pulse of gas flow through the flow channel.
10. The gas delivery system of claim 9 wherein the triggered mode corresponds to delivery of the pulse of gas flow and the non-triggered mode corresponds to an absence of the delivery of the pulse of gas flow.
11. A method of gas delivery comprising:
providing a control valve configured to control flow of gas in a flow channel and a downstream pressure sensor, downstream of the control valve, configured to measure gas pressure in the flow channel; and
with a control unit having an external trigger input configured to receive a trigger signal applied to a shutoff valve downstream from the control valve, controlling the control valve in separate modes of operation, based on a state of the trigger signal, including:
a non-triggered mode in which pressure at the downstream pressure sensor is controlled via the control valve in accordance with a first gain schedule; and
a triggered mode in which the pressure at the downstream pressure sensor is controlled via the control valve in accordance with a second gain schedule distinct from the first gain schedule.
12. The method of claim 11 further comprising determining the state of the trigger signal based on pressure at the trigger input.
13. The method of claim 12 wherein determining the state of the trigger signal includes sensing pressure at a pneumatic line that opens and closes the shutoff valve.
14. The method of claim 13 wherein the trigger input taps the pneumatic line between a pneumatic control valve and the shutoff valve.
15. The method of claim 12 further comprising receiving the trigger signal via a pneumatic line controlled by a host controller.
16. The method of claim 11 wherein the trigger signal is an electrical signal indicating an open or close state of the shutoff valve.
17. The method of claim 11 wherein each of the first and second gain schedules has gain parameters including at least one of a proportional control gain, an integral control gain, and a derivative control gain.
18. The method of claim 11 further comprising, in the triggered and non-triggered modes, controlling pressure at the downstream pressure sensor based on a comparison of the measured pressure against a setpoint pressure.
19. The method of claim 11 further comprising controlling the shutoff valve to deliver a pulse of gas flow through the flow channel.
20. The method of claim 19 wherein the triggered mode corresponds to delivery of the pulse of gas flow and the non-triggered mode corresponds to an absence of the delivery of the pulse of gas flow.
21. A pressure controller comprising:
as an integral assembly,
a flow channel;
a control valve configured to control flow of gas in the flow channel;
a downstream pressure sensor, downstream of the control valve, configured to measure gas pressure in the flow channel; and
a control unit having an external trigger input configured to receive a trigger signal applied to a shutoff valve downstream from the control valve, the control unit configured for separate modes of operation based on a state of the trigger signal, the separate modes of operation including:
a non-triggered mode in which the control unit is configured to control pressure at the downstream pressure sensor via the control valve in accordance with a first gain schedule; and
a triggered mode in which the control unit is configured to control the pressure at the downstream pressure sensor via the control valve in accordance with a second gain schedule distinct from the first gain schedule.
22. The pressure controller of claim 21 wherein the trigger input includes a trigger pressure sensor configured to determine the state of the trigger signal based on pressure at the trigger input.
23. The pressure controller of claim 21 wherein the trigger signal is an electrical signal indicating an open or close state of the shutoff valve.
24. The pressure controller of claim 21 wherein each of the first and second gain schedules has gain parameters including at least one of a proportional control gain, an integral control gain, and a derivative control gain.