Patent ID: 7454254

Claim:
An aircraft cabin pressure control system controller circuit, comprising: a comparator configured to receive a cabin pressure rate-of-change command signal and a sensed cabin pressure rate-of-change signal and operable, in response thereto, to supply a cabin rate error signal representative of a difference between the cabin pressure rate-of-change command signal and the sensed cabin pressure rate-of-change signal; and a variable gain proportional-integral (PI) controller coupled to receive the cabin rate error signal and operable, in response thereto, to generate an actuator command signal and determine a magnitude of the cabin rate error, the variable gain PI controller including a proportional function and an integrator function, the proportional function having a variable gain term, the integrator function having a variable upper saturation limit and a variable lower saturation limit, the variable gain PI controller further operable, upon receipt of the cabin rate error signal, to vary the proportional function gain term between a maximum gain value and a minimum gain value when the cabin rate error magnitude is between zero and a first predetermined magnitude, to vary the integrator function upper and lower saturation limits between minimum and maximum saturation limit magnitudes when the cabin rate error magnitude is between zero and a second predetermined magnitude and maintains the integrator function upper and lower saturation limits at the maximum saturation limit magnitude when the cabin rate error magnitude is above the second predetermined magnitude, to vary the integrator function upper and lower saturation limit magnitudes between the minimum saturation limit magnitude and an intermediate saturation limit magnitude as a first function of cabin rate error magnitude when the cabin rate error magnitude is between zero and a third predetermined magnitude that is less than the second predetermined magnitude, and to vary the integrator function upper and lower saturation limits between the intermediate saturation limit magnitude and the maximum saturation limit magnitude as a second function of cabin rate error magnitude when the cabin rate error magnitude is between the third predetermined magnitude and the second predetermined magnitude.