Patent ID: 12252261

The elements having the same functions in the different embodiments have the same references in the FIGURES.

DETAILED DESCRIPTION

FIGS.2and3show a hybrid propulsion unit100of an aircraft, for example of the helicopter or airplane type, with multi-rotor rotary wing according to the disclosure. For example, the unit100can be integrated into an aircraft weighing less than 5000 kg, with an on-board mechanical power of between 50 kW and 2000 kW.

An internal combustion engine112, such as a turbomachine, for example an Auxiliary Power Unit (APU), is coupled to an electric generator114. In operation, the electric generator114is driven by the engine112.

The electric generator114may be a motor-generator, i.e., it may be capable of operating in both generator mode and motor mode. In other words, the electric generator114may operate in generator mode, in particular as when driven by the engine112, or in a motor mode. The electric generator114may be a synchronous or asynchronous electrical machine. Thus, the electric generator114may be a reversible electrical machine. The electric generator114allows to provide a bidirectional mechanical-to-electrical energy conversion, i.e., a mechanical-to-electrical conversion and an electrical-to-mechanical conversion. The electric generator114may generate a polyphase electrical current, for example a three-phase current as shown inFIGS.2and3.

The engine112and the electric generator114provide a primary source of generation for the unit100. Although a single main generation source is shown inFIGS.2and3, the unit100may comprise a plurality of main generation sources.

The rotational speed N1of the shaft of the rotor of the engine112connected to the electric generator114can be controlled by control means102(EECU, Electronic Engine Control Unit). These control means102may control parameters of the engine112, such as the fuel weight flow, noted WF, on the basis of the rotation speed N1and other parameters, such as the frequency N1* of the electric generator114or an anticipation of the load Ω1*, Ω2*, Ω3*, Ω4* for each electrical propulsion chain.

An auxiliary gearbox106may be arranged between the engine112and the electric generator114.

A rectifier116is connected to an input to the electric generator114and configured to convert the alternative current delivered by the electric generator114into a direct current. The rectifier116may be current reversible. A capacitive element130, such as a capacitor, may be arranged in parallel with the electric generator114.

An electrical network120connects in parallel an output of the rectifier116to inputs of conversion means118a,118b,118c,118d.

The conversion means118a,118b,118c,118dare configured to convert a direct current into an alternative current. The conversion means118a,118b,118c,118dmay comprise direct current to alternative current converters.

The conversion means118a,118b,118c,118dmay comprise inverters. InFIGS.2and3, DC means direct current and AC means alternative current. Each inverter may comprise three inverter arms respectively delivering the three phases119,121,123(referenced only for the conversion means118d) of alternative current to each of the electric motors122a,122b,122c,122d.

The conversion means118a,118b,118c,118d, and in particular the inverters, may be current reversible. A capacitive element136a,136b,136c,136d, for example a capacitor, may be arranged in parallel with each of the conversion means118a,118b,118c,118d.

The electrical network120may be bidirectional, that is, the electrical current may flow from the rectifier116to the conversion means118a,118b,118c,118d, and in the opposite direction.

Electric motors122a,122b,122c,122dare connected to the conversion means118a,118b,118c,118d. In operation, the electric motors122a,122b,122c,122dare supplied with alternative current by the conversion means118a,118b,118c,118d.

The electric motors122a,122b,122c,122dmay be polyphase synchronous motors. These motors can be of different types, such as induction motors or variable reluctance motors. These motors can be of the single-stator or multi-rotor type. This advantageously allows to reduce the mass and the volume of the electric motors122a,122b,122c.122d.

The connection between the electric generator114and the electric motors122a,122b,122c,122dis operated in direct current, at a relatively high voltage, so as to improve the stability of the electrical network120and the power management. The rectifier116thus allows to ensure the conversion of the alternative current delivered by the electric generator120into direct current, while the conversion means118a,118b,118c,118densure the conversion of this direct current into alternative current intended for the electric motors122a,122b,122c,122d.

Propellers124a,124b,124c,124dare coupled to the electric motors122a,122b,122c,122d. In operation, the propellers124a,124b,124c,124dare driven by the electric motors122a,122b,122c,122d. The propellers124a,124b,124c,124dmay be coaxial counter-rotating propellers.

In particular, the conversion means118a, respectively118b,118c,118d, the electric motor122a, respectively122b,122c,122d, and the propeller or the propellers124a, respectively1246,124c,124d, form an electrical propulsion chain125a, respectively125b,125c,125d. InFIGS.2and3, there are therefore four electrical propulsion chains125a,125b,125c,125d.

For each electrical propulsion chain125a,125b,125c,125d, the rotational speed Ω1, Ω2, Ω3, Ω4of the shaft connecting the electric motor122a,122b,122c,122dand the propellers124a,124b,124c,124d, via a gearbox134a,134b,134c,134d, can be controlled by control means132a,132b,132c,132d. Similarly, the voltage U1, U2, U3, U4from the conversion means118a,118b,118c,118dfor supplying each electric motor122a,122b,122c,122dcan be controlled by control means132a,132b,132c,132d. These control means132a,132b,132c,132dmay control parameters of the conversion means118a,118b,118c,118d, such as the voltage U1, U2, U3, U4of the electric motors122a,122b,122c,122dand the machine frequency F1, F2, F3, F4based on the rotational speed Ω1, Ω2, Ω3, Ω4and the voltage U1, U2, U3, U4of the electric motors122a,122b,122c,122d, and other parameters, such as the load anticipation Ω1*, Ω2*, Ω3*, Ω4*.

Storage means126are connected to the electrical network120. These storage means126allow to absorb an excess of electrical energy from the HVDC bus of the electrical network120. The storage means126may also be configured to temporarily supply the electric motors122a,122b,122c,122dby supplementing or substituting the electric generator114.

The storage means126comprises one or a plurality of primary storage elements138and one or a plurality of secondary storage elements140.

A secondary storage element140may comprise one or a plurality of batteries, one or a plurality of capacitors, or one or a plurality of supercapacitors.

A primary storage element138may be formed by one or a plurality of electrochemical couples. The plurality of electrochemical couples may be arranged in series, in parallel, or in series-parallel, i.e., some electrochemical couples may be arranged in series, and this series of electrochemical couples is arranged in parallel to another series of electrochemical couples or to another electrochemical couple.

A primary storage element138may be formed by one or more ignited electrochemical couples. These ignited electrochemical couples are said “ready to use”, since the electrolyte wets the anode and the cathode. The primary storage element138may be a battery.

A primary storage element138may be formed by one or more ignitable electrochemical couples. These ignitable electrochemical couples are said “inert”, since the electrolyte does not wet the anode and the cathode.

The primary storage element138may be a separate electrolyte battery. Specifically, the electrolyte is arranged in a reservoir adjacent to the area containing the anode and the cathode, and is released only upon the activation of the primary storage element so that it comes into contact with both the anode and the cathode.

The electrochemical couples can be thermally ignitable. The primary storage element138may then be a thermal battery. Specifically, the electrolyte is solid at room temperature, and is heated upon the activation of the primary storage element. The electrolyte quickly liquefies and then comes into contact with both the anode and the cathode.

These couples have the advantage of being electrically and chemically “inert” when not activated.

InFIGS.2and3, the primary storage element138is shown as a battery, with + indicating the positive terminal and − indicating the negative terminal of the battery.

According to a first embodiment shown inFIG.2, the primary storage element138is arranged in parallel with the secondary storage element140. The hybrid storage means126are then connected in parallel to the electrical network120.

The primary storage element138may be activated in case of emergency in a variety of ways, for example by a pyrotechnic activation, or by an electrical activation.

A contactor142, referred to as first contactor, may be arranged between the primary storage element138and the secondary storage element140so as to be able to disconnect the primary storage element138when activated.

Since no precautions need to be taken in connecting the primary storage element138to the electrical network120in the case of an inert electrochemical couple, the first contactor142may be optional.

According to a second embodiment shown inFIG.3, the primary storage element138is connected in series with the electrical network120. Specifically, the primary storage element138is connected in series with the motor112and with the electric generator114. The secondary storage element140is connected in parallel to the electrical network120.

A contactor144, referred to as second contactor, may be arranged in parallel with the primary storage element138so that the primary storage element138may be added in series with the motor112and with the electric generator114.

When the primary storage element138is activated, it is in series with the electrical network120associated with the rectifier116.

The electrical energy required for an emergency event is delivered by the primary storage element138and the electrical network120, which allows the primary storage element138to be undersized in terms of power and energy to be delivered. The rectifier116can then be sized to accept the resulting voltage and allow the full amount of the electrical power to be transmitted in case of emergency.

A diode146may be arranged in series with the primary storage element138so as to prevent any current feedback across the terminals of the rectifier116if the voltage level of the primary storage element138is or becomes higher than the rectifier output voltage116.

Filtering means (not shown) may be arranged upstream of the rectifier116.

A contactor148, referred to as third contactor, may be arranged in parallel with the electric generator114.

The first embodiment is advantageously more autonomous than the second embodiment in terms of main generation. Thus, in the second embodiment, the main generation may be decoupled and only the primary storage element138then supplies the electrical energy to the various electrical propulsion chains125a,125b,125c,125d, by closing the contactor148. The rectifier116may then no longer conduct current on the HVDC bus.

The contactors142,144,148can be of the electromechanical or static type.