Method for contactless communication between a fixed reference frame and a rotating reference frame by encoding a power signal

Abstract

Disclosed is a method for communicating data for a system for de-icing a turbomachine that comprises a fixed reference frame and a rotating reference frame, the system comprising a contactless rotating electrical transformer (RTU) a primary of which is tied to the fixed reference frame and a secondary of which is tied to the rotating reference frame, the fixed reference frame comprising an ice protection and control unit (IPC) and a power supply device (DC / AC) for supplying an AC current to the primary, the protection and control unit (IPC) transmitting instructions to the power supply device (DC / AC) to adjust a level of electric power delivered to the primary, the rotating reference frame comprising a propeller (1) to which resistors are secured, and a switch for sequentially distributing, to the resistors, electric power that is transmitted to the secondary. The protection and control unit (IPC) is programmed to transmit switching orders to the switch via the power supply device (DC / AC) and the transformer (RTU), by giving the power supply device (DC / AC) instructions (Ic1, Ic2, Ic3, Ic4, Ic5, Intl) to encode a train of voltage waves (To) applied to the primary, the switch being programmed to decode the train of voltage waves (To) recovered at the secondary.

Description

[0001] DESCRIPTION

[0002] TITLE: Method of contactless communication between a fixed reference frame and a rotating reference frame by encoding a power signal

[0003] Technical field

[0004] The present invention relates to a method of communication between a fixed reference frame and a rotating reference frame, such as the stator and the rotor of a machine. More particularly, the invention relates to communication between reference frames of an aircraft turbomachine, for the electrical de-icing of a propeller.

[0005] State of the prior art

[0006] Because it is subject to variations in humidity and temperature, the aircraft is likely to become covered in frost at least on certain parts. This is the case, for example, for a propeller of an aircraft turbomachine.

[0007] To prevent or reduce the formation of ice, the propeller blades and cone are equipped with heating mats in areas exposed to ice. The mats operate by electrothermal effect, based on a network of resistors integrated into the propeller.

[0008] There are various embodiments for the transfer of electrical power and controls between a fixed part and a rotating part, for the supply of an electrothermal de-icing system for a turbomachine propeller.

[0009] Some designs offer electrical power transmission and contact controls.

[0010] For example, according to document US 8,120,228 B2, the transmission of electrical power and controls is done between brushes of the stator and tracks of the rotor, which carries the propeller. This embodiment is interesting because of its simplicity, but has the disadvantage of a limited lifespan due to the friction of the brushes on the tracks. It may be acceptable on a military aircraft, for which maintenance is frequent. It is less appropriate, or not at all, on a commercial civil aircraft, especially for use with many daily journeys. Indeed, in this case, the maintenance and operating costs become excessive.

[0011] As an alternative, some embodiments propose a contactless transmission of electrical power and controls. For example, it is known to carry out transmission by magnetic induction by superimposing a low-energy high-frequency signal, for the controls, on a power signal, for the electrothermal effect. This embodiment is interesting, in particular because it is compact. But this embodiment is complex to implement, because of the constraints linked to the management of interference between the two superimposed signals, on the one hand, and the risks of alteration of the transmitted data, on the other hand. The reliability of this embodiment is not assured, given the multitude of sources of disturbance: presence of transient effects linked to load switching in a rotating control unit, large air gap, variations in the air gap due to radial and axial displacements of the moving part relative to the fixed part.

[0012] Another example of magnetic induction transmission of power and control uses a second auxiliary rotating transformer dedicated to the transmission of control signals. This design is expensive, bulky, and difficult to install on the turbomachine.

[0013] Another example of power and control transmission involves a capacitive effect. This design is suitable for applications where the transformer is equipped with its own bearings, thus with a small air gap, of the order of a millimeter, and also controlled.

[0014] Statement of the invention

[0015] The invention seeks to overcome the aforementioned drawbacks and has the general aim of improving the transfer of power and controls between a fixed reference frame and a rotating reference frame, particularly for an aircraft turbomachine.

[0016] The invention seeks in particular to optimize the sequencing of the power supplies of electrical resistors for deicing propeller blades. The invention also seeks to obtain a long service life and limit maintenance work on the turbomachine. The invention also seeks to simplify the transfer of power and the transfer of controls by reducing, or even eliminating, interference and alterations. Another aim of the invention is to simplify the structure of a turbomachine. Another aim is to limit manufacturing and usage costs. Finally, the invention seeks to implement its specific features on turbomachines whose rotating part has a large diameter, for example one meter or more.

[0017] In view of the above, the subject of the invention is a method of communicating data for a de-icing system of a turbomachine which comprises a fixed reference frame and a rotating reference frame, the system comprising a contactless rotating electrical transformer of which a primary is subject to the fixed reference frame and of which a secondary is subject to the rotating reference frame, the fixed reference frame comprising an ice protection and control unit as well as a device for supplying the primary with an alternating current, the protection and control unit transmitting instructions to the supply device to adjust a level of electrical power supplied to the primary, the rotating reference frame comprising a propeller to which resistors are subject, and a switch for the sequential distribution to the resistors of the electrical power transmitted to the secondary.

[0018] The protection and control unit is programmed to transmit switching orders to the switch, via the power supply device and the transformer, giving the power supply device instructions to encode a train of voltage waves applied to the primary, the switch being programmed to decode the train of voltage waves recovered from the secondary.

[0019] The communication method uses the channel dedicated to power transmission to also transmit switching commands. The same channel transmits values ​​of a different nature. This is why the defrosting system has a simple structure, in the sense that it is not necessary to provide a specific channel to transmit switching commands. Among the resulting advantages, we can mention the control of mass, size, as well as those of manufacturing and maintenance costs.

[0020] The voltage wave train has activation durations, pre-calibrated fixed interruption durations, and variable interruption durations. The different durations are recognized and used by the switch to distribute electrical power to the resistors. In this way, the power supply device of the fixed reference acts as a transmitter, and the switch of the rotating reference acts as a receiver. This makes it possible to manage two quantities, a defrost activation duration and a defrost cycle duration. A resulting advantage is the reliability of transmission of switching orders and, consequently, high defrosting efficiency.

[0021] A switching operation is performed by the switch when the voltage wave train is interrupted. As a corollary, a continuity of the wave train maintains the switch in its current state. A very short interruption of the wave train is sufficient to manage the switching operations. This advantageously results in the transmission of electrical power to the resistors being carried out with the best efficiency.

[0022] Switch operations are performed at low current and voltage, or even at low voltage. This reduces stress on the switching components and improves energy efficiency by canceling out switching losses. Only conduction losses need to be considered.

[0023] The power supply device measures the primary current in order to monitor and protect the rotating reference system. In fact, the measurement is carried out on the fixed reference system side. By this means, the power supply device is able to monitor the operation of the system on the rotating reference system side. One advantage of this is the detection of faults such as a short circuit or an open circuit. Another advantage is ease of maintenance by identifying faulty sectors. In addition, the rotating electronics are simplified.

[0024] The power supply device converts a direct voltage into an alternating voltage. In this case, in a non-limiting manner, the direct voltage is high, which makes it possible to supply the device with electrical power with a low mass wiring. This advantageously results in an aircraft equipped with the system for implementing the method being lighter.

[0025] The power supply is doubled. The system operates with two power supplies to improve defrost availability.

[0026] The propeller comprises at least one pair of blades. Preferably, the two blades of a pair are diametrically opposed and heated at the same time. Thus, the deicing action is simultaneous on both blades. This advantageously preserves the dynamic balance of the propeller, even if all pairs of blades are not at the same deicing level.

[0027] The invention also relates to a system implementing the data communication method for deicing a turbomachine which comprises a fixed reference frame and a rotating reference frame. The invention also relates to an aircraft comprising the system implementing the method.

[0028] Brief description of the drawings

[0029] Other aims, characteristics and advantages of the invention will appear on reading the following description, given with a non-limiting example, and made with reference to the appended drawings in which:

[0030] [Fig. 1] is a descriptive diagram of an electrical power supply of a defrosting system of a turbomachine according to the proposed example of the invention,

[0031] [Fig.2] schematically represents a propeller comprising twelve blades, for the turbomachine implementing a de-icing process for the system of [Fig. l],

[0032] [Fig.3] illustrates a power cycle of a pair of blades of the propeller of [Fig.2],

[0033] [Fig.4] illustrates a principle of switching from one pair of blades to the next, for intermittent deicing, for the propeller of [Fig. l ] and [Fig.2],

[0034] [Fig.5] illustrates a voltage wave train, for data communication according to the proposed example.

[0035] Detailed description

[0036] Generally speaking, without this being shown, an aircraft is powered for example by at least one turbomachine comprising a propeller.

[0037] The turbomachine comprises a fixed frame of reference and a rotating frame of reference, the first being integral with the structure of the aircraft, the second being guided by the first and carrying the propeller.

[0038] A propeller de-icing system includes the fixed reference frame, the rotating reference frame, and a contactless rotating electrical transformer RTU, one primary of which is subject to the fixed reference frame and one secondary of which is subject to the rotating reference frame. The RTU transformer is part of the diagram in Figure 1, to which reference is made.

[0039] In a non-limiting manner, the RTU rotating transformer includes, for example, a radial air gap or an axial air gap. Whatever its structure, the RTU transformer ensures a contactless transfer of electrical power between the fixed reference frame and the rotating reference frame. The power passes from the primary to the secondary. The absence of electrical contact increases the longevity of the RTU transformer and contributes to better cleanliness. Indeed, no wear dust from an electrically conductive part is produced.

[0040] The fixed reference system includes an IPC frost protection and control unit and a DC / AC primary power supply device using alternating current, the IPC protection and control unit transmitting instructions to the DC / AC power supply device to adjust a level of electrical power supplied to the primary of the RTU transformer.

[0041] Without limitation, the system includes two power supply devices to increase its availability.

[0042] The turbomachine is connected to an electrical network providing high-voltage direct current (HVDC), which allows it to be powered with a low-mass electrical chain. Values ​​of 450V or 800V for direct current are very suitable. In fact, the primary power supply device converts direct current into alternating current. Thus, the voltage available to power the primary of the RTU transformer is alternating, which allows the power to pass to the secondary, through the action of an alternating magnetic field.

[0043] The IPC protection and control unit transmits instructions to the DC / AC power supply device to adjust a level of electrical power supplied to the primary.

[0044] The rotating frame, for its part, includes the propeller to which resistances are attached. These are, for example, made in the form of heating mats operating by electrothermal effect, mats integrated into the blades in areas exposed to frost.

[0045] The rotating reference also includes a switch for the sequential distribution to the resistors of the electrical power transmitted to the secondary.

[0046] The IPC protection and control unit is programmed to transmit switching orders to the switch, via the DC / AC power supply device and the RTU transformer, by giving the DC / AC power supply device instructions to encode a train of voltage waves applied to the primary, the switch being programmed to decode the train of voltage waves transmitted to the secondary by the primary. An encoding creates activation times and interruption times in a train of voltage waves. Consequently, the latter carries the electrical power on the one hand, and codes used for the operation of the switch on the other hand.

[0047] In the example described, as shown in Figure 2 in a non-limiting manner, a propeller 1 comprises six pairs of blades P1, P2, P3, P4, P5, P6, each pair being called a segment. The two blades of a segment are diametrically opposed. The blades are distributed regularly around the periphery of the propeller, with two series of blades P1 to P6. The angular gap between two successive blades is 30°, and the angular gap between two blades of a segment is 180°.

[0048] Without limitation, blades PI to P6 all have the same structure. They all have the same length.

[0049] The sequential distribution of electrical power to the resistors is done by segment. The two blades of the same segment are powered simultaneously. Segments PI to P6 are powered in turn, according to cycles, for example successively.

[0050] Figure 3 shows the power supply of the first segment PI, with a defrost activation duration DI along the abscissa Ox, a cycle duration D along the abscissa Ox, and the electrical power intensity along the ordinate Oy. The duration DI is variable and depends on the icing conditions. The switch receives the information on the icing conditions intrinsically by adjusting the duration DI.

[0051] Figure 4 shows the successive power supply of the six pairs of blades or segments PI, P2, P3, P4, P5 and P6. In a non-limiting manner, the respective deicing activation durations D1, D2, D3, D4, D5 and D6, along the abscissa Ox, are equal. These durations are variable, depend on the icing conditions, and are calculated by the system supervisor. The switch receives the information on the icing conditions intrinsically by adjusting the durations D1 to D6. The cycle duration D is also referenced in Figure 4. An activation interruption I separates two successive activation sequences of the segments PI to P6.

[0052] The sequential distribution of power is carried out by the switch, on instructions from the IPC frost protection and control unit, as shown in Figure 5. The wave train supplied to the switch, referenced To, is carried out in time along the abscissa axis Ox, with intensity along the ordinate axis Oy. The IPC protection and control unit interrupts the wave train To with different durations.

[0053] First, fixed duration interruptions Ic i , Ic2, Ic3 , Ic4 and Ic5 are provided. These are interpreted by the switch as segment change orders, to move from segment n to segment n+1. Then, variable duration Intl interruptions are provided depending on the icing conditions, each of them being interpreted by the switch as the end of a power supply sequence for all segments PI to P6. The duration of this Intl interruption is adjusted to take into account the duration D of a defrost cycle. A variable Intl interruption duration can occur at any time.

[0054] The switch is programmed to restart a new defrost sequence starting from the first PI segment, when the power is switched back on.

[0055] Each switching operation performed by the switch, both opening and closing, is carried out at low current and voltage, or even at low voltage. This reduces stress on the components and improves efficiency by canceling switching losses.

[0056] By controlling the applied cycles, the power supply device is aware at all times of the reference of the supplied segment. Thus, by measuring the current at the primary of the transformer, on the fixed side, the power supply device is able to monitor the rotating reference; it can detect faults such as a short circuit or an open circuit for each of the segments PI to P6.

[0057] A variation of the described example is to introduce an additional coding of the interruption duration to transmit the segment reference P l , P2, P3 , P4, P5 , P6 to the switch. The fixed interruption duration Ic i , Ic2, Ic3 , Ic4, Ic5 is replaced by a set of duration ranges, according to the following values.

[0058] Segment P l: when switched on,

[0059] Segment P2: interruption duration for example 10 to 15ms,

[0060] Segment P3: interruption duration for example 20 to 25ms,

[0061] Segment P4: interruption duration for example 30 to 35ms,

[0062] Segment P5: interruption duration for example 35 to 40ms,

[0063] Segment P6: interruption duration for example 45 to 50ms.

[0064] Pause between two cycles with a variable duration depending on the cycles. Generally speaking, the invention has the advantage of simplicity, its implementation being done by specific programming at the level of the protection and control unit, as well as at the level of the switch.

[0065] Obviously, the invention is not limited to the example of embodiment and implementation described above, and includes all equivalents which fall within the scope of the claims which follow.

[0066] In particular, it is possible to provide a different number of blades. Again, a power supply device can use an alternating voltage available on the aircraft.

Claims

CLAIMS 1. Data communication method for a de-icing system of a turbomachine which comprises a fixed reference frame and a rotating reference frame, the system comprising a contactless rotating electrical transformer (RTU) of which a primary is subject to the fixed reference frame and a secondary of which is subject to the rotating reference frame, the fixed reference frame comprising an ice protection and control unit (IPC) as well as a device for supplying power (DC / AC) to the primary by an alternating current, the protection and control unit (IPC) transmitting instructions to the power supply device (DC / AC) to adjust a level of electrical power supplied to the primary, the rotating reference frame comprising a propeller (1) to which resistors are subject, and a switch for the sequential distribution to the resistors of the electrical power transmitted to the secondary,characterized by the fact that the protection and control unit (IPC) is programmed to transmit switching orders to the switch, via the power supply device (DC / AC) and the transformer (RTU), by giving the power supply device (DC / AC) instructions (Ic i , Ic2, Ic3 , Ic4, Ic5 , Intl) to encode a train of voltage waves (To) applied to the primary, the switch being programmed to decode the train of voltage waves (To) recovered from the secondary., 2. Method according to claim 1, in which the voltage wave train (To) has activation durations (D l , D2, D3 , D4, D5 , D6), pre-calibrated fixed interruption durations (Ic i , Ic2, Ic3 , Ic4, Ic5), and variable interruption durations (Intl).

3. Method according to claim 1 or 2, wherein switching is performed by the switch upon interruption of the voltage wave train.

4. Method according to one of claims 1 to 3, in which switching of the switch is carried out at low current and voltage, or even at low voltage.

5. Method according to any one of claims 1 to 4, in which the power supply device (DC / AC) measures the primary current, in order to monitor and protect the rotating reference frame.

6. Method according to any one of claims 1 to 5, for which the power supply device (DC / AC) converts a direct voltage into an alternating voltage.

7. Method according to any one of claims 1 to 6, for which the power supply device (DC / AC) is doubled.

8. Method according to any one of claims 1 to 7, for which the propeller (1) comprises at least one pair of blades (P1, P2, P3, P4, P5, P6).

9. System implementing the method according to any one of claims 1 to 8.

10. Aircraft comprising the system according to claim 9.

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