Control system for at least one actuator of an aircraft turbomachine comprising a flight test computer and flight test method

Abstract

A method for flight testing a control system (10) of at least one actuator (7) of an aircraft turbomachine comprising an electric motor (6) and a power device (DP) comprising at least one energy storage module (3) configured to be charged by an aircraft electrical network (1), a DC-DC conversion module (4), a DC-AC conversion module (5), the method comprising steps consisting in comparing the voltage across the energy storage module (3) with the voltage across the DC-DC conversion module (4), providing a setpoint voltage as input in order to verify that the output voltage complies with a predetermined conversion ratio of the DC-DC conversion module, closing all of the low transistors, opening all of the high transistors and issuing a first input pulse command in order to verify that the output voltage is zero. Abstract figure: Figure 2

Description

Title of the invention: Control system for at least one actuator of an aircraft turbomachine comprising a flight test computer and flight test method Technical field

[0001] The present invention relates to the field of flight testing of a control system for an actuator of an aircraft turbomachine, in particular, of a thrust reverser flap of a nacelle.

[0002] In a known manner, an aircraft comprises a propulsion system comprising a turbomachine mounted in a nacelle. In order to reduce the speed of the aircraft, it is known to provide thrust reverser flaps on the nacelle. As illustrated in [Fig.l], thrust reverser flaps 104 are moved by an electric motor 103 controlled by a power device 102 which is powered by an electrical network of the aircraft 101, in particular, a three-phase network in 115V AC. The power device 102 and the electric motor 103 together form a control system 105 for the reverser flaps 104.

[0003] Before starting a descent phase of the aircraft, it is necessary to test the control system 105 in flight in order to ensure the effective deployment of the reversing flaps 104 during the descent phase to brake the aircraft. In practice, the test of the control system 105 is complex. Indeed, it is difficult to guarantee with a sufficiently high probability that a test does not lead to an effective opening of a reversing flap 104, which would be problematic when the aircraft is in flight.

[0004] In order to absorb the power demand peaks when controlling a reversing flap 104, it has been proposed to use a power device 102 comprising a three-phase inverter to power the electric motor 103 and a charging module, in particular a supercapacitor, to power the three-phase inverter. A charging module makes it possible to avoid direct power supply between the electrical network of the aircraft 101 and the electric motor 103, which reduces the risk of accidental actuation. However, this prohibits the implementation of a test method according to the prior art.

[0005] The invention aims to eliminate at least some of these drawbacks. PRESENTATION OF THE INVENTION

[0006] The invention relates to a method for in-flight testing a control system for at least one actuator of an aircraft turbomachine comprising an electric motor configured to move the actuator and a power device supplying the electric motor in order to control it, the power device comprising at least one energy storage module configured to be charged by an aircraft electrical network, a DC-DC conversion module configured to be powered by the energy storage module, the DC-DC conversion module having a predetermined conversion ratio, a DC-AC conversion module connected to the electric motor configured to be powered by the DC-DC conversion module, the DC-AC conversion module comprising a transistor bridge, comprising high transistors and low transistors, and a flight test computer, the method comprising steps consisting of: • Compare the voltage across the energy storage module to the voltage across the DC-DC conversion module to verify that they are equal, • E2 activate the DC-DC conversion module and provide it with a set voltage as input in order to verify that the output voltage complies with the predetermined conversion ratio of the DC-DC conversion module, • E3 activate the DC-AC conversion module, close all the low transistors, open all the high transistors and issue a first input pulse command to verify that the output voltage of the DC-AC conversion module is zero.

[0007] Preferably, the test steps are performed consecutively. If a test step fails, a fault is detected and the control system is made safe, for example, by cutting off the power supply.

[0008] Thanks to the invention, the storage module, the DC-DC conversion module and the DC-AC conversion module are tested consecutively in order to detect a fault early on to avoid propagation of a fault in the control system. Each element of the control system is powered when the elements located upstream have been tested and validated. This guarantees a rigorous and relevant test of the control system. Any characteristic malfunction of the storage module, the DC-DC conversion module and the DC-AC conversion module is tested in order to avoid involuntary control of the electric motor and, consequently, the actuator. Such a test method is suitable for a control system comprising an energy storage module allowing isolation from the aircraft electrical network, which limits the risk of fault.

[0009] Preferably, the flight test method comprises a step consisting of activating the DC-AC conversion module, closing all of the high transistors, opening all of the low transistors and issuing a second input pulse command in order to verify that the output voltage of the DC-AC conversion module is equal to its input voltage supplied by the conversion module.

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[0015] continuous-continuous. Such a test step allows to control the “high” behavior of the DC-AC conversion module. Preferably, the flight test method comprises a step of closing all of the high transistors, closing all of the low transistors and issuing a third input pulse command in order to verify that the DC-AC conversion module is protected against overcurrents. Preferably, during step E2, the input reference voltage is a zero voltage in order to verify that the output voltage of the DC-DC conversion module is zero. According to one aspect of the invention, the DC-DC conversion module having an operating input voltage range, during the step, several input setpoint voltage values are tested successively in order to ensure the correct operation of the DC-DC conversion module over its operating input voltage range. The invention also relates to a system for controlling at least one actuator of an aircraft turbomachine comprising an electric motor configured to move the actuator and a power device supplying the electric motor in order to control it, the power device comprising: • at least one energy storage module configured to be charged by an aircraft electrical network, • a DC-DC conversion module configured to be powered by the energy storage module, the DC-DC conversion module having a predetermined conversion ratio, • a DC-AC conversion module connected to the electric motor configured to be powered by the DC-AC conversion module, the DC-AC conversion module comprising a transistor bridge comprising high transistors and transistors The control system is notable in that the power device includes a flight test computer configured to: • compare the voltage across the energy storage module to the voltage across the DC-DC conversion module to verify that they are equal, • activate the DC-DC conversion module and supply it with a set voltage at the input in order to verify that the output voltage complies with the predetermined conversion ratio of the DC-DC conversion module, • activate the DC-AC conversion module, close all the low transistors, open all the high transistors and emit a first input pulse command to verify that the output voltage of the DC-AC conversion module is zero.

[0016] Preferably, the energy storage module comprises a plurality of supercapacitors.

[0017] Preferably, the control system comprises a DC-DC preconversion module for powering the energy storage module.

[0018] Preferably, the DC-DC conversion module is in the form of an active double bridge converter. Such a converter is particularly suitable for high powers. Preferably, the DC-DC conversion module comprises galvanic isolation so as to limit the risk of electrical fault.

[0019] The invention also relates to an assembly comprising an aircraft electrical network, an actuator of an aircraft turbomachine and a control system as presented previously, powered by the aircraft electrical network, for moving the actuator.

[0020] The invention also relates to an aircraft comprising an assembly as presented previously. PRESENTATION OF FIGURES

[0021] The invention will be better understood on reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0022] [Fig.l] is a schematic representation of a control system according to the prior art.

[0023] [Fig. 2] is a schematic representation of a first embodiment of a control system according to the invention.

[0024] [Fig.3] is a schematic representation of a flight test method according to the invention.

[0025] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0026] The invention will be presented with reference to [Fig.2] which shows a control system 10 of an actuator 7 of an aircraft turbomachine. In this example, the actuator 7 is a thrust reverser flap but it goes without saying that this could be different.

[0027] As previously presented, the control system 10 comprises a motor electric motor 6 configured to move the actuator 7 and a power device DP supplying the electric motor 6 in order to control it. The electric motor 6 is preferably a three-phase motor comprising a moving rotor mounted in a stator.

[0028] As illustrated in [Fig.2], the power device DP is powered by an aircraft electrical network 1, in particular, a high voltage DC network, for example 270 Vdc / 540Vdc, or low voltage 28Vdc. In this example, the power device DP is powered directly by a DC-DC pre-conversion module 2 powered by the aircraft electrical network 1. As will be presented later, the DC-DC pre-conversion module 2 makes it possible to charge the energy storage module 3 (energy in a capacity is: Ec=0.5*C*V2) but also to lower / raise the voltage according to the needs of the power device. The DC-DC pre-conversion module 2 advantageously makes it possible to store energy and to create galvanic isolation guaranteeing a physical separation between the aircraft electrical network 1 and the electric motor 6 with a very low failure rate.Thus, it is not possible to supply energy to the electric motor 6 when the DC-DC pre-conversion module 2 is not controlled.

[0029] With reference to [Fig.2], the power device DP comprises an energy storage module 3 configured to be charged by the DC-DC pre-conversion module 2. Preferably, the energy storage module 3 comprises one or more supercapacitors.

[0030] The DP power device also comprises a DC-DC conversion module 4 configured to be powered by the energy storage module 3. In a known manner, the DC-DC conversion module 4 has a predetermined conversion ratio which corresponds to the ratio of the output voltage to the input voltage. The DP power device also comprises a DC-AC conversion module 5 connected to the electric motor 6 configured to be charged by the DC-DC conversion module 4.

[0031] In this example, the DC-DC conversion module 4 is connected to the DC-AC conversion module 5 by a bus regulated by the DC-DC conversion module 4.

[0032] According to the invention, the DC-AC conversion module 5 comprises a transistor bridge comprising high transistors and low transistors to enable AC conversion. In particular, the transistors define a “high” or “on” state and a “low” or “open” state.

[0033] The DC-AC conversion module 5 has several phases which are connected to phases of the electric motor 6. In this example, the DC-AC conversion module 5 is in the form of an inverter, in particular, a three-phase inverter.

[0034] Preferably, the DC-DC converter 4 comprises isolation means. Preferably, it is in the form of a dual active bridge converter, better known by its English abbreviation DAB for “Dual Active Bridge”. Such a DC-DC converter 4 is particularly suitable for high powers. It advantageously allows the current to be regulated, which allows it to be associated with a DC-AC conversion module 5 comprising components normally in the open state (for example JFET type transistors). The DC-AC conversion module 5 is configured to short-circuit the phases of the electric motor 6 when the DC-AC conversion module 5 is not powered. It goes without saying that other types of DC-DC converter 4 could be suitable.

[0035] In practice, the DC-DC converter 4 comprises, at the output, a capacitor for filtering current ripples which has a value at least 100 times lower than the capacitor of an input LC filter of the DC-AC conversion module 5. Also, the output capacitor of the DC-DC converter 4 cannot store enough energy to maintain currents in the electric motor 6 once its control has been stopped. Safety is thus improved.

[0036] On the other hand, the DC-DC converter 4 is reversible. Its control makes it possible not to depend on the natural dynamics of the electric motor 6 to force the discharge of its output capacitance and therefore bring the voltage back to 0V immediately. This makes it possible to put in place protection in the event of measurement of unharmed currents in the phases of the electric motor 6. Preferably, the DC-DC converter 4 is configured to raise the voltage between its input and its output when it is connected to a low-voltage aircraft electrical network 1. Depending on the needs, the DC-DC converter 4 can be a voltage step-up / step-down converter.

[0037] The DC-DC pre-conversion module 2, the energy storage module 3, the DC-DC conversion module 4 and the DC-AC conversion module 5 are known to those skilled in the art and will not be presented again.

[0038] The control system 10 makes it possible to effectively control the actuator 7, effectively absorbing current demand peaks thanks in particular to the energy storage module 3. Such a new generation control system 10 must be tested in flight in order to guarantee safety.

[0039] According to the invention, with reference to [Fig.2], the control system 10 comprises a flight test computer 8 configured to implement a plurality of test steps in order to detect a possible malfunction in the power device DP and the electric motor 6. The flight test computer 8 is preferably in the form of a digital controller.

[0040] The flight test computer 8 is configured to activate elements of the device of DP power, send instructions to said elements and measure parameters of said elements. The parameters of the DC-DC conversion module 4 are, for example, voltage and current measurements, in particular, at the level of a primary and a secondary of the DC-DC conversion module 4, measurements of alternating voltages and currents on the phases of the inverter (DC-AC conversion module 5). The parameters of the DC-AC conversion module 5 are, for example, voltage and current measurements.

[0041] Preferably, the flight test computer 8 is also configured to measure parameters of the electric motor 6, for example, measurements of speed and angular position of the rotor of the electric motor 6.

[0042] The present invention proposes to implement a test method in which the elements of the control system 10 are tested sequentially in order to avoid any accidental actuation. This prevents a fault from propagating to the other elements of the power device DP which are inactive. An involuntary power supply to the electric motor 6 is thus highly unlikely.

[0043] According to an exemplary implementation, with reference to [Fig. 3], several test steps E1-E5 implemented by the flight test computer 8 are schematically represented. In the event of failure of a test step, the control system 10 is considered to be defective POK.

[0044] Each test step E1-E5 will now be presented individually.

[0045] The test steps are performed sequentially. A test step is only performed if the previous test step is successful. In the event of a POK fault, the control method is immediately stopped. Preferably, the power supply to the power device DP is also switched off.

[0046] As illustrated in [Fig.3], in the initial state INIT, the DC-DC conversion module 4 and the DC-AC conversion module 5 are turned off.

[0047] The method comprises a test step E1 consisting of comparing the voltage across the energy storage module 3 with the voltage across the DC-DC conversion module 4 to verify that they are equal. In the event of a difference, the control system 10 is considered to be defective POK.

[0048] Such a test step E1 advantageously makes it possible to detect any loss of energy characteristic of a fault, for example, a leak from a supercapacitor or a break in the connection.

[0049] During this test step E1, accidental actuation can only occur in the event of a simultaneous fault in the DC-AC conversion module 5, the DC-DC conversion module 4 and the flight test computer 8, which is very unlikely.

[0050] Thanks to the energy storage module 3, all the functions contributing to providing the power can be tested independently of the presence of the aircraft electrical network 1. It is sufficient to store a minimum of energy in the energy storage module 3 to carry out the test.

[0051] The method comprises a test step E2 consisting of activating the DC-DC conversion module 4 and providing it with a set voltage at the input in order to verify that the output voltage complies with the predetermined conversion ratio of the DC-DC conversion module 4.

[0052] For example, the input reference voltage is a zero voltage and it is verified that the output voltage of the DC-DC conversion module 4 is zero. If the output voltage is non-zero, the control system 10 is considered to be defective POK. Such a test step E2 advantageously makes it possible to detect any internal malfunction of the DC-DC conversion module 4.

[0053] Preferably, several input setpoint voltage values can be tested successively in order to ensure the correct operation of the DC-DC conversion module 4 over its voltage range. Preferably, the test computer 8 sends pulse commands to the DC-DC conversion module 4 to modify the input setpoint voltage. This step can be carried out iteratively. Advantageously, this makes it possible to control the DC-DC conversion module 4 but also the test computer 8.

[0054] Such a test step E2 makes it possible to verify the operation of the DC-DC conversion module 4 over its operating range.

[0055] Preferably, the DC-DC conversion module 4 is configured to regulate the voltage between its input and its output. The output voltage, which is supplied to the DC-AC conversion module 5, is advantageously of very low value (a few Volts), which ensures that the voltage applied to the DC-AC conversion module 5 is insufficient to generate currents (and therefore torque) in the electric motor 6. The actuator 7 thus has a very low probability of being moved.

[0056] During this test step E2, accidental actuation can only occur in the event of a simultaneous fault in the DC-AC conversion module 5, the power supply of the DC-AC conversion module 5, the DC-DC conversion module 4 and the flight test computer 8, which is very unlikely.

[0057] The method comprises a test step E3 consisting of activating the DC-AC conversion module 5, closing all of the low transistors, opening all of the high transistors and issuing a first input pulse command. This makes it possible to verify that the DC-AC conversion module 5 does not generate a voltage in the “low state” configuration. Indeed, in this configuration of the transistor bridge of the DC-AC conversion module 5, no voltage must be transmitted.

[0058] Preferably, prior to sending an input pulse command, it is verified that the voltage of the DC-DC conversion module 4 is zero following activation of the DC-AC conversion module 5.

[0059] Preferably, the test computer 8 emits the first pulse command via the DC-DC conversion module 4, previously tested. Measuring the voltages on each of the phases of the DC-AC conversion module 5 makes it possible to verify the correct switching of each of the arms.

[0060] The method comprises a test step E4 consisting of activating the DC-AC conversion module 5, closing all of the high transistors, opening all of the low transistors and issuing a second input pulse command. This makes it possible to verify that the DC-AC conversion module 5 transmits the voltage of the DC-AC conversion module 4. Indeed, in this “high state” configuration of the transistor bridge of the DC-AC conversion module 5, the input voltage of the DC-AC conversion module 5 is equal to its output voltage.

[0061] In a similar manner to previously, the test computer 8 emits a second pulse command via the second DC-DC converter 4, previously tested.

[0062] During these test steps E4, accidental actuation can only occur in the event of a simultaneous fault in the DC-AC conversion module 5, a pulse control error and a transistor bridge control error, which is very unlikely.

[0063] Optionally, the method comprises a test step E5 consisting of closing all of the high transistors, closing all of the low transistors and issuing a third input pulse command. This makes it possible to verify that the DC-AC conversion module 5 is protected against overcurrents.

[0064] Optionally, the method comprises a test step consisting of measuring the currents of the transistor bridge, in particular, at the foot of the transistor bridge in order to detect any malfunction.

[0065] When all the tests have been carried out, it is considered that the control system 10 is operational OK. Thus, when the aircraft lands, the probability that the actuator 7 opens following a command from the pilot is certain, which ensures optimal safety.

[0066] Preferably, the phase currents of the electric motor 6 are constantly measured to ensure the absence of torque in the electric motor 6. If one of the measured currents is not of zero value, the DC-DC conversion module 4 immediately imposes a zero output voltage in order to stop the power supply to the DC-AC conversion module 5.

Claims

Claims

1. A method for flight testing a control system (10) of at least one actuator (7) of an aircraft turbomachine comprising an electric motor (6) configured to move the actuator (7) and a power device (DP) powering the electric motor (6) in order to control it, the power device (DP) comprising at least one energy storage module (3) configured to be charged by an aircraft electrical network (1), a DC-DC conversion module (4) configured to be powered by the energy storage module (3), the DC-DC conversion module (4) having a predetermined conversion ratio, a DC-AC conversion module (5) connected to the electric motor (6) configured to be powered by the DC-DC conversion module (4), the DC-AC conversion module (5) comprising a transistor bridge, comprising high transistors and low transistors, and a flight test computer (8),the method comprising steps of:, • (El) compare the voltage across the energy storage module (3) to the voltage across the DC-DC conversion module (4) to verify that they are equal, • (E2) activate the DC-DC conversion module (4) and provide a set input voltage in order to verify that the output voltage complies with the predetermined conversion ratio of the DC-DC conversion module (4), • (E3) activate the DC-AC conversion module (5), close all the low transistors, open all the high transistors and issue a first input pulse command in order to verify that the output voltage of the DC-AC conversion module (5) is zero.

2. A flight test method according to claim 1 comprising a step of: • (E4) activate the DC-AC conversion module (5), close all the high transistors, open all the low transistors and issue a second input pulse command in order to verify that the output voltage of the DC-AC conversion module (5) is equal to its input voltage supplied by the DC-DC conversion module (4).

3. Flight test method according to one of claims 1 to 2 comprising a step consisting of: • (E5) closing all of the high transistors, closing all of the low transistors and issuing a third input pulse command in order to verify that the DC-AC conversion module (5) is protected against overcurrents.

4. Flight test method according to one of claims 1 to 3, wherein, during step (E2), the input reference voltage is a zero voltage in order to verify that the output voltage of the DC-DC conversion module (4) is zero.

5. Flight test method according to one of claims 1 to 4, in which, the DC-DC conversion module (4) having an operating input voltage range, during step (E2), several input setpoint voltage values are tested successively in order to ensure the correct operation of the DC-DC conversion module (4) over its operating input voltage range.

6. Control system (10) of at least one actuator (7) of an aircraft turbomachine comprising an electric motor (6) configured to move the actuator (7) and a power device (DP) powering the electric motor (6) in order to control it, the power device (DP) comprising: • at least one energy storage module (3) configured to be charged by an aircraft electrical network (1), • a DC-DC conversion module (4) configured to be powered by the energy storage module (3), the DC-DC conversion module (4) having a predetermined conversion ratio, • a DC-AC conversion module (5) connected to the electric motor (6) configured to be powered by the DC-DC conversion module (4), the DC-AC conversion module (5) comprising a transistor bridge comprising high transistors and transistors, control system control (10) characterized in that the power device (DP) comprises a flight test computer (8) configured to: • (El) compare the voltage across the energy storage module (3) with the voltage across the DC-DC conversion module (4) to verify that they are equal, • (E2) activate the DC-DC conversion module (4) and provide it with a setpoint voltage at the input to verify that the output voltage complies with the predetermined conversion ratio of the DC-DC conversion module (4), • (E3) activate the DC-AC conversion module (5), close all the low transistors, open all the high transistors and issue a first input pulse command to verify that the output voltage of the DC-AC conversion module (5) is zero.

7. A control system according to claim 6 wherein the energy storage module (3) comprises a plurality of supercapacitors.

8. Control system according to one of claims 6 to 7 in which the DC-DC conversion module (4) is in the form of an active double bridge converter.

9. Assembly comprising an aircraft electrical network (1), an actuator (7) of an aircraft turbomachine and a control system (10) according to one of claims 6 to 8, powered by the aircraft electrical network (1), for moving the actuator (7).

10. An aircraft comprising an assembly according to claim 9.

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