Patent ID: 9164516
Filing Date: 2015-10-20
Classification: F15B,G05D

Abstract:
1. A positioner ( 102 ) for controlling a fluid operated actuator ( 101 ) including a first fluid chamber ( 109 ) and a second fluid chamber ( 110 ), the positioner ( 102 ) comprising: a first fluid conduit ( a second fluid conduit ( a fluid control valve in communication with the first fluid conduit and second fluid conduit, wherein the fluid control valve is configured to control the fluid operated actuator; a differential pressure control loop comprising a differential pressure controller ( a position controller in communication with a position sensor and the differential pressure controller, wherein the position sensor is coupled to the fluid operated actuator; an outer control loop comprising the position sensor, the position controller, the fluid control valve, the fluid operated actuator, and the differential pressure controller, wherein the position controller is configured to send a signal indicating the desired differential pressure to the differential pressure controller if a measured position of the fluid operated actuator is different from a desired actuator position by more than a second threshold value; and wherein the second threshold value of the outer control loop is greater than the first threshold value of the differential pressure control loop such that the differential pressure control loop comprises a primary control loop.