Method and system for controlling a turbomachine with control saturations management

Abstract

Method for controlling a first, a second and a third variable of a turbomachine as a function of a first, a second and a third control quantity of a turbomachine which can each be saturated as a function of the operating parameters of the turbomachine. The method comprises a first multivariable correction (120) delivering a first value for the three control quantities, a selection (130) of the first control quantity to be delivered as a function of a minimum value, of a maximum value and of the value determined by the first correction, a second multivariable correction (140) delivering a second value for the second and third control quantities, and a selection (150) of the values of the second and third control quantities to be delivered in the values determined during the first correction and those determined during the second correction.

Claims

1. A method for controlling a first, a second and a third variable of a turbomachine as a function of a first, a second and a third control quantity of a turbomachine which each saturates depending on the operating parameters of the turbomachine, the control method comprising: a measurement of the values of the three variables of the turbomachine, a receipt, for each of said three variables received, of a corresponding setpoint, a first determination in which the first values of the three control quantities of the turbomachine are determined from the values of the three variables and said three corresponding setpoints, a selection of the value of the first control quantity to be delivered to the turbomachine among a maximum value of the first control quantity, a minimum value of the first control quantity and the value of the first control quantity resulting from said first determination, the first selection depending on the operating parameters of the turbomachine, a second determination in which second values of the second and third control quantities of the turbomachine are determined from the values of the three variables, from the second and third corresponding setpoints, and from the value of the first control quantity selected during the selection, a choice of the pair of values of the second and third control quantities to be delivered to the turbomachine between the pair of the second and third control quantities determined during the first determination and the pair of the second and third control quantities determined during the second determination, the choice of the pair of values of the second and third control quantities to be delivered depending on the value of the first control quantity to be delivered selected during the selection, and a transmission to the turbomachine of the value of the first control quantity selected and of the values of the second and third control quantities selected.

2. The control method according to claim 1, further comprising an integration of the value of the first control quantity selected and of the values of the second and third control quantities selected before their transmission to the turbomachine.

3. The control method according to claim 1, wherein the first variable corresponds to the speed of rotation of a low-pressure compressor of the turbomachine, the second variable corresponds to the speed of rotation of an upstream propeller of the turbomachine, and the third variable corresponds to the speed of rotation of a downstream propeller of the turbomachine, the first control quantity corresponds to the fuel flow rate of the turbomachine, the second control quantity corresponds to the pitch of the upstream propeller of the turbomachine and the third control quantity corresponds to the pitch of the downstream propeller of the turbomachine.

4. A system for controlling a first, a second and a third variable of a turbomachine as a function of a first, a second and a third control quantity of a turbomachine which each saturates depending on the operating parameters of the turbomachine, the control system comprising: receiving as input the values of the three variables of the turbomachine as well as, for each of said three variables received, a corresponding setpoint, and outputting three outputs corresponding to the three control quantities of the turbomachine, selecting, as a function of the operating parameters of the turbomachine, the value of the first control quantity to be delivered to the turbomachine among a maximum value of the first control quantity, a minimum value of the first control quantity and the value of the first control quantity resulting from said first determination, receiving as input the values of the three variables of the turbomachine as well as the setpoint of the second variable and the setpoint of the third variable and the value of the first control quantity, and outputting two outputs corresponding to the second and third control quantities of the turbomachine, and outputting either the pair of second and third control quantities or the pair of second and third control quantities, the control system outputting, to control the turbomachine, the value of the first control quantity and the values of the second and third control quantities.

5. The control system according to claim 4, further comprising receiving as input the value of the first control quantity delivered and the values of the second and third control quantities, and delivering the processed values of the first, second and third control quantities to the turbomachine.

6. The control system according to claim 4, wherein the first variable corresponds to the speed of rotation of a low-pressure compressor of the turbomachine, the second variable corresponds to the speed of rotation of an upstream propeller of the turbomachine, and the third variable corresponds to the speed of rotation of a downstream propeller of the turbomachine, the first control quantity corresponds to the fuel flow rate of the turbomachine, the second control quantity corresponds to the pitch of the upstream propeller of the turbomachine and the third control quantity corresponds to the pitch of the downstream propeller of the turbomachine.

7. An aircraft comprising at least one turbomachine and at least one control system according to claim 4 controlling at least one of said at least one turbomachine.

8. The aircraft according to claim 7, wherein at least one of said at least one turbomachine controlled by said at least one control system is a turbomachine with unducted fan.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1, already described, represents a turbomachine with unducted fan according to the state of the art.

(2) FIG. 2, already described, schematically represents a control system according to the state of the art for the unducted fan of FIG. 1.

(3) FIG. 3 schematically represents a system for controlling a turbomachine according to one embodiment of the invention.

(4) FIG. 4 represents a flowchart of a method for controlling a turbomachine according to one mode of implementation of the invention.

DESCRIPTION OF THE EMBODIMENTS

(5) FIG. 3 is schematically represents a system for controlling 10 a turbomachine according to one embodiment of the invention. The turbomachine controlled by the control system 10 according to the invention may be a turbomachine 1 with unducted fan such as the one described in FIG. 2.

(6) The control system 10 comprises a first corrector 11, a second corrector 12, a first selection unit 13, a second selection unit 14 and an integrator 15.

(7) The first corrector 11 comprises three outputs delivering a first value for each of the three control quantities. The first control quantity corresponds to the fuel flow rate WF of the open rotor 1, the second control quantity corresponds to the pitch ?.sub.1 of the upstream propeller of the open rotor 1 and the third control quantity corresponds to the pitch ?.sub.2 of the downstream propeller of the open rotor 1.

(8) The first corrector 11 receives as input the values of three variables of the open rotor 1, the first variable corresponding to the speed of rotation XNP of a low-pressure compressor of the open rotor 1, the second variable corresponding to the speed of rotation XN1 of an upstream propeller of the open rotor 1, and the third variable corresponding to the speed of rotation XN2 of a downstream propeller of open rotor 1. The first corrector 11 also receives as input a rotation speed setpoint XNP.sub.dmd of the low-pressure compressor, a rotation speed setpoint XN1.sub.dmd of the upstream propeller, and a rotation speed setpoint XN2.sub.dmd of the downstream propeller.

(9) The first selection unit 13 receives as input the value determined by the first corrector 11 for the fuel flow rate WF, a maximum value of the first control quantity WFmax, and a minimum value of the first control quantity WFmin.

(10) The first selection unit 13 is configured to output one of the three preceding values WF, WFmax or WFmin as a function of the operating parameters of the open rotor 1. The value outputted from the first selection unit 13 corresponds to the value of the first control quantity, WF, to be delivered to the open rotor 1.

(11) The second corrector 12 comprises two outputs delivering a second value for the second and third control quantities ?.sub.1 and ?.sub.2. Like the first corrector 11, the second corrector 12 receives as input the values of three output variables of the open rotor 1 measured by the corresponding sensors, that is to say the speed of rotation XNP of the low-pressure compressor, the speed of rotation XN1 of the upstream propeller and the speed of rotation XN2 of the downstream propeller. The second corrector 12 also receives as input the rotation speed setpoint XN1.sub.dmd of the upstream propeller and the rotation speed setpoint XN2.sub.dmd of the downstream propeller, but not the rotation speed setpoint XNP.sub.dmd of the low-pressure compressor. The second corrector 12 further receives as input the value of the fuel flow rate outputted from the first selection unit 13.

(12) The second corrector 12 is configured to determine a second value for each of the second and third control quantities ?.sub.1 and ?.sub.2 of the open rotor 1 as a function in particular of the value selected for the first control quantity, that is to say here the fuel flow rate WF.

(13) The second selection unit 14 receives as input two pairs of values and an indicator. The first pair of values received corresponds to the pair comprising the first value of the second control quantity ?.sub.1 and the first value of the third control quantity ?.sub.2, and the second pair of values received comprises the second value of the second control quantity ?.sub.1 and the second value of the third control quantity ?.sub.2. The indicator received by the selection unit 14 corresponds to an indication delivered by the first selection unit 13 and indicating which of the three values of the first control quantity WF has been selected.

(14) The second selection unit 14 is configured to output the pair of values of the second and third control quantities selected as a function of the indicator delivered by the first selection unit. The second selection unit 14 thus outputs either the pair of first values of second and third control quantities determined by the first corrector 11, or the pair of second values of second and third control quantities determined by the second corrector 12, the selection depending on the value of the first control quantity selected by the first selection unit 13. The values outputted from the second selection unit 14 correspond to the values of the second and third control quantities, ?.sub.1 and ?.sub.2, to be delivered to the open rotor 1.

(15) Before being transmitted to the open rotor 1, the value of the first control quantity WF selected by the first selection unit 13 and the values of the second and third control quantities ?.sub.1 and ?.sub.2 selected by the second selection unit 14 are delivered to an integrator 15 to avoid the jolts in the command of the open rotor 1. The integrator 15 then delivers to the open rotor 1 the values of the first, second and third control quantities thus processed.

(16) FIG. 4 illustrates a flowchart of a control method implemented by the control system 10.

(17) According to the mode of implementation presented in FIG. 4, the control method comprises a first step 100 in which the values of the three variables XNP, XN1 and XN2 of the open rotor 1 are measured from different dedicated sensors and transmitted to the first corrector 11 and to the second corrector 12.

(18) In a following step 110, setpoints are received for each of the three variables of the open rotor 1. More particularly, in this step 110, the first corrector 11 receives the rotation speed setpoint XNP.sub.dmd of the low-pressure compressor, the rotation speed setpoint XN1.sub.dmd of the upstream propeller, and the rotation speed setpoint XN2.sub.dmd of the downstream propeller, and the second corrector 12 receives the rotation speed setpoint XN1.sub.dmd of the upstream propeller and the rotation speed setpoint XN2.sub.dmd of the downstream propeller.

(19) In a next step 120, first values for the three control quantities of the open rotor 1 are determined from the values of the three variables XNP, XN1 and XN2 and from the three corresponding setpoints XNP.sub.dmd, XN1.sub.dmd and XN2.sub.dmd.

(20) In a following step 130, the value of the first control quantity to be delivered to the open rotor 1 is selected among a maximum value of the first control quantity, a minimum value of the first control quantity and the value of the first control quantity resulting from the determination in the previous step 120, the selection depending on the operating parameters of the open rotor 1.

(21) In a following step 140, second values for the second and third control quantities of the open rotor 1 are determined from the values of the three variables XNP, XN1 and XN2, from the second and third corresponding setpoints XN1.sub.dmd and XN2.sub.dmd, and from the value of the first control quantity WF selected during the first selection in the previous step 130.

(22) In a following step 150, a choice is made of the pair of values of the second and third control quantities to be delivered to the open rotor 1 between the pair of the second and third control quantities determined in step 120 and the pair of the second and third control quantities determined in step 140, the choice of the pair of values of the second and third control quantities to be delivered depending on the value of the first control quantity to be delivered selected in step 130.

(23) In a following step 160, each of the values selected is integrated in step 130 and in step 150, using an integrator, then in a following step 170, the integrated values of the first, second and third control quantities are transmitted to the open rotor 1.

(24) The control method according to the invention thus allows guaranteeing in a simple and efficient manner the decoupling of the output quantities that is to say of the three variables of the turbomachine, despite the complex management of one of the control quantities such as the fuel flow rate.