Patent Description:
Current cooling architectures for a cryogenic and superconducting powertrain are based on industrial cryocoolers specially made for ground applications. Cryocoolers made for ground applications cannot be used for aviation applications, since they do not have the cooling capacities necessary for aviation applications.

In addition, there are also major concerns related to the weight and efficiency of such cryocoolers for aviation applications.

On the other hand, liquid hydrogen (LH<NUM>) available on-board can be used to cool-down the components of the powertrain. However, due to safety reasons, in aviation applications, LH<NUM> is not meant for direct use (i.e. for the direct cooling of electrical components).

In addition, the amount of LH<NUM> flowing from the LH<NUM> tank to the fuel cell system for a given flight phase is limited and, in general, driven by the fuel cell needs itself.

Therefore, an optimization of the cooling architecture is necessary in order to optimize the LH<NUM> consumption and to meet the cooling needs of the powertrain with the LH<NUM> flow available in a given flight phase.

A current cryogenic and superconducting powertrain comprises at least the following elements:.

For example, document <NPL> and document <CIT> disclose a cryogenic and superconducting powertrain using LH2 for cooling.

The different components of the cryogenic and superconducting powertrain have different cooling needs both in terms of maximum allowable temperature and maximum allowable temperature gradient across the components itself. In addition, the performances and the efficiency of the component itself depend on the temperature.

Table <NUM> summarizes the maximum allowable temperature and maximum allowable temperature gradient of the components in the cryogenic and superconducting powertrain:.

According to Table <NUM>, if the superconducting motor is exposed to a temperature above <NUM> (its Tmax), a risk of quench within the superconducting motor appears. Moreover, the efficiency of the superconducting motor depends on the temperature: the superconducting motor has a better efficiency at lower temperature than its Tmax (i.e. lower than <NUM>).

The maximum allowable temperature gradient of the MCU (here <NUM>) shall not be exceeded to guarantee the proper operation of the MCU. Moreover, the efficiency of the MCU depends on the temperature: the MCU has a better efficiency at a lower temperature than its Tmax (i.e. lower than <NUM>).

If the DC line is exposed to a temperature above <NUM> (its Tmax), a risk of quench appears within the DC line.

The maximum allowable temperature gradient of the DC/DC Converter (here <NUM>) shall not be exceeded to guarantee the proper operation of the DC/DC Converter. Moreover, the efficiency of the DC/DC Converter depends on the temperature: the DC/DC Converter has a better efficiency at a lower temperature than its Tmax (i.e. lower than <NUM>).

The efficiency of the main Current Leads to the fuel cell depends on the temperature: the main Current Leads have a better efficiency at a lower temperature than its Tmax (i.e. lower than <NUM>). Hence, all components of the cryogenic powertrain do not have the same cooling needs, and thus do not need to be cooled at the same temperature, since each component does not have the same maximum allowable temperature.

Thus, there is a need for a method and system for managing the cooling temperature of each component of the cryogenic and superconducting powertrain.

To this end, it is proposed a cryogenic and superconducting powertrain as claimed in claim <NUM>.

It is also proposed a method for managing a cooling temperature of cryogenic and superconducting powertrain as claimed in claim <NUM>.

The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of at least one embodiment, said description being made in relation to the attached drawings, among which:.

<FIG> represents a cooling architecture for a cryogenic and superconducting powertrain (including a Superconducting Motor, Motor Control Units, a Superconducting distribution and protection and the cryogenic DC/DC conversion) operating at cryogenic temperature.

The cryogenic and superconducting powertrain <NUM> comprises:.

In this cryogenic and superconducting powertrain <NUM>, a reduction ratio of speed is applied using the gearbox <NUM>.

The cooling architecture <NUM> comprises:.

Thus, the cooling architecture <NUM> comprises a primary cooling loop <NUM> for LH<NUM> and a secondary cooling loop <NUM> for GHe. The secondary cooling loop <NUM> is arranged and configured to cool down the powertrain components. The secondary cooling loop <NUM> is cooled by LH<NUM> flow, and in return heats the LH<NUM> that will enter in the fuel cell <NUM>.

As represented in <FIG>, the cooling architecture <NUM> comprises a first heat exchanger 36a and a second heat exchanger 36b. Each heat exchanger 36a, 36b is configured to transfer heat from a first fluid to a second fluid. In the following description, in a non-limitative way, the first fluid of each heat exchanger 36a, 36b is liquid hydrogen (H<NUM>), and the second fluid of each heat exchanger 36a, 36b is gaseous helium (He).

The second fluid of the heat exchangers 36a, 36b may be another inert fluid than helium, for instance liquid Neon or liquid Nitrogen (N<NUM>).

Preferably, gaseous helium is used in the secondary cooling loop <NUM>, since it is less expensive than Neon, and it is an inert element, reducing the safety risk significantly compared to H<NUM>, and is lightweight. Moreover, helium is the only element with a boiling point lower than H<NUM>, so it will be in its gaseous phase in all the possible aircraft scenarios. This simplifies the global cooling architecture <NUM> for the cryogenic and superconducting powertrain <NUM>, since no compressors and/or buffers need to be introduced in the architecture (which have an impact on the global weight of the cooling architecture and its reliability).

The cooling architecture <NUM> also comprises:.

According to the invention, LH<NUM> is used for cooling the cryogenic and superconducting powertrain <NUM>. This allows to facilitate the subsequent conditioning of H<NUM> (before injection into the fuel cell <NUM>), since H<NUM> rejected by the cooling architecture <NUM> of the cryogenic and superconducting powertrain <NUM> will be at an intermediate temperature between the boil temperature (<NUM> at atmospheric pressure) and the injection temperature (around <NUM>) into the fuel cells <NUM>, reducing the needs in terms of electrical heaters for H<NUM> conditioning.

As an example, Table <NUM> represents the operations at maximum power for a typical <NUM>. 1MW cryogenic and superconducting powertrain <NUM>:.

According to Table <NUM>, the superconducting motor <NUM> is dissipating 3100W in use of the superconducting and cryogenic powertrain <NUM>. Such dissipation is advantageously extracted with the fluids (more precisely with helium cooled by H<NUM>) flowing through the superconducting motor <NUM>. Helium, firstly cooled by H<NUM>, is warmed up by the heat dissipating from the superconducting motor <NUM>, allowing the superconducting motor <NUM> to stay at its stable working temperature, even if the superconducting motor <NUM> dissipates 3100W. The same principle applies to all components of the powertrain <NUM>.

Cooling architecture with one heat exchanger:
<FIG> represents a cooling architecture <NUM> of a cryogenic and superconducting powertrain <NUM> in which all components of the powertrain <NUM> are cooled in series, in order to minimize the impact of the cooling lines. As shown in <FIG> dotted boxes indicate a dedicated cryostat for the respective components which need to be maintained at low temperatures. As mentioned previously, the superconducting motor <NUM> and the MCUs are arranged in the same cryostat <NUM>. Each superconducting distribution and protection device <NUM> is arranged in a dedicated cryostat 48a, 48b. The current leads <NUM> and a DC/DC converter <NUM> are arranged in a common cryostat 50a, 50b. More precisely, as represented in <FIG>, current leads <NUM> and the DC/DC converters <NUM> of the powertrain <NUM> are divided into two electric lines, each electric line of the current leads <NUM> and a DC/DC converter <NUM> is arranged in a dedicated cryostat 50a, 50b. The cryogenic fan <NUM> and the heat exchanger <NUM> are also arranged in a common cryostat <NUM>.

In the cooling architecture of <FIG>, only one heat exchanger <NUM> is arranged to transfer heat between H<NUM> and helium.

In <FIG>, the temperature of H<NUM> at the H<NUM> inlet of the heat exchanger <NUM> (i.e. on the cryogenic insulated line of LH<NUM> <NUM> coming from the LH<NUM> tank <NUM>) may be between <NUM> and <NUM> (here around <NUM>), the temperature of H<NUM> at the H<NUM> outlet of the heat exchanger <NUM> (i.e. on the LH<NUM> line <NUM> in direction to the fuel cells <NUM>) may be between <NUM> and <NUM> (here around <NUM>), and the flow of H<NUM> may be between <NUM>/s and <NUM>/s (here around <NUM>/s).

The flow of helium may be between <NUM>/s and <NUM>/s (here around <NUM>/s). The temperature of helium between the cryogenic fan <NUM> and the input of the heat exchanger <NUM> (on the cryogenic insulated line 54f) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between the output of the heat exchanger <NUM> and the superconducting motor <NUM> (on the cryogenic insulated line 54a) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between the superconducting motor <NUM> and the MCUs <NUM> (on the cryogenic insulated line 54b) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between the DC distribution <NUM> and the MCU <NUM> (on the cryogenic insulated line 54c) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between the DC/DC converter <NUM> and the DC distribution <NUM> (on the cryogenic insulated line 54d) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between the current leads <NUM> and the DC/DC converter <NUM> (on the cryogenic insulated line 54e) may be between <NUM> and <NUM> (here around <NUM>). Helium is then transmitted from the current leads <NUM> to the cryogenic fan <NUM> through the cryogenic insulated line <NUM>.

According to this embodiment of the invention, in the cooling architecture <NUM> of the cryogenic and superconducting powertrain <NUM> represented in <FIG>, a predetermined amount of second fluid is cooled at a predetermined temperature, using the first fluid, before being injected in the superconducting motor <NUM> of the powertrain <NUM>. For example, helium (He) is cooled at a temperature around <NUM> by hydrogen (H<NUM>). The amount of second fluid to be cooled is calculated depending on the constraints coming from the powertrain <NUM>. For example, the flow of He circulating from the heat exchanger <NUM> to the superconducting motor <NUM> is around <NUM>/s.

In the architecture represented in <FIG>, the main constraint is the maximum temperature gradient allowed by the DC/DC converter <NUM> (here <NUM>). In order to respect a maximum temperature gradient for the DC/DC converter <NUM> of <NUM>, the flow of He circulating through the whole powertrain <NUM>, and thus through the DC/DC converter <NUM>, is around <NUM>/s.

The temperature increase of He through a powertrain component, assuming that helium is absorbing all the power dissipated by said powertrain component, is calculated according to the following equation: <MAT>.

In the architecture represented in <FIG>, another major constraint is the inlet temperature of the superconducting motor <NUM>, that needs to be kept as low as possible.

Taking into account that the flow of helium entering into the powertrain <NUM> is <NUM>/s, and knowing the dissipation of each component of the powertrain <NUM> (see Table <NUM>), the temperature at each point of the cooling architecture <NUM> is calculated accordingly.

In a summary, according to the invention, and as represented in <FIG>, a method for managing the cooling temperature of the powertrain components comprises the steps of:.

The limiting parameters of the powertrain components are determined based on the technical features of said components. Tests can be realized to determine such limiting parameters.

Other limiting parameters than the maximum allowable temperature and/or the maximum temperature gradient of each component of the powertrain <NUM> can be determined.

The superconducting motor <NUM> is the powertrain component having the most limiting of the limiting parameters. Thus, first flow and temperature for helium are calculated taking into account the limiting parameters of the superconducting motor <NUM>. Then, for each component of the powertrain <NUM>, taking into account its limiting parameters, second flow and temperature for helium are calculated. The second flow and temperature of helium are compared to the first flow and temperature of helium calculated for the superconducting motor <NUM> of the powertrain <NUM>. If the second flow of helium is lower than the first flow of helium that has been calculated for the superconducting motor <NUM>, the first flow of helium is selected, and no adjustment of flow of helium is realized. If the second flow of helium is higher than the first flow of helium that has been calculated for the superconducting motor <NUM>, the second flow of helium is selected so that the flow of helium is adjusted. If the second temperature of helium is higher than the first temperature of helium that has been calculated for the superconducting motor <NUM>, the first temperature of helium is selected, and no adjustment of temperature of helium is realized. If the second temperature of helium is lower than the first temperature of helium that has been calculated for the superconducting motor <NUM>, the second temperature of helium is selected so that the temperature of helium is adjusted.

According to the invention, in order to respect all limiting constraints of each powertrain component, the flow and temperature of helium finally selected correspond to the flow and temperature of helium the most limiting for the cooling architecture <NUM>. Generally, the lower temperature of helium, either firstly calculated or adjusted, is selected for the cooling architecture <NUM>; and the higher flow of helium, either firstly calculated or adjusted, is selected for the cooling architecture <NUM>.

According to the invention, LH<NUM> at around <NUM> (<NUM> in <FIG>) stored in a pressurized tank <NUM> is used as a cooling source. A working fluid of gaseous helium (GHe) is used in a closed circuit to cool-down the electrical components of the cryogenic and superconducting powertrain <NUM>. The flow of GHe in the closed circuit is regulated by a circulation fan <NUM> (also called cryofan or cryogenic fan). This flow of GHe is also regulated based on the cooling power requirements of the powertrain <NUM>. In <FIG>, one GHe/LH<NUM> heat exchanger <NUM> is used.

LH<NUM> enters at around <NUM> in the heat exchanger <NUM> from the LH<NUM> tank <NUM>. In the heat exchanger <NUM>, warm GHe (around <NUM>) is cooled down to around <NUM> (<NUM> in <FIG>) by LH<NUM>. Cold GHe is then used to maintain the superconducting motor <NUM>, the Motor Control Unit <NUM> (MCU), the DC/DC converter <NUM> and the main current leads <NUM> (CL) to the Fuel Cell <NUM> (FC) at the desired low temperature.

GHe coming out from the superconducting motor <NUM> may also be used to cool-down the Direct Current (DC) line <NUM> and other components of the powertrain <NUM>.

Warm GHe out of the current leads <NUM> is then fed back to the heat exchanger <NUM> through the return line <NUM> with the help of the cryofan <NUM>.

This cooling architecture <NUM> also comprises remote control valves <NUM> to regulate the flow in different components. For instance, in <FIG>, a valve <NUM> is arranged on the LH<NUM> line <NUM>. The cryostat <NUM> housing the cryogenic fan <NUM> and the heat exchanger <NUM> is equipped with rupture disks <NUM> and a non-return valve with spring <NUM> to allow an evacuation of the fluid of the cryostat <NUM>. The functioning of the valves is not detailed here.

For instance, GHe entering the superconducting motor <NUM> is at a first temperature between <NUM> and <NUM> (here around <NUM>), GHe is warmed by the superconducting motor <NUM> up to a second temperature between <NUM> and <NUM> (here around <NUM>), due to the dissipation of the superconducting motor <NUM>. GHe then enters to the MCU <NUM>, and is warmed by the MCU <NUM> to a third temperature between <NUM> and <NUM> (here around <NUM>), due to the dissipation of the MCU <NUM>. GHe then enters to the DC line <NUM>, and is warmed by the DC line <NUM> to a fourth temperature between <NUM> and <NUM> (here around <NUM>), due to the dissipation of the DC line <NUM>. GHe then enters to the DC/DC converter <NUM>, and is warmed by the DC/DC converter <NUM> to a fifth temperature between <NUM> and <NUM> (here around <NUM>), due to the dissipation of the DC/DC converter <NUM>. Then, GHe enters to the current leads <NUM> to the fuel cell <NUM>, and is warmed by said current leads <NUM>, due to the dissipation of said current leads <NUM>, before being cooled by the cryogenic fan <NUM> to a temperature between <NUM> and <NUM> (here around <NUM>). GHe then passes through the heat exchanger <NUM> to be cooled, thanks to LH<NUM>, to the first temperature.

According to Table <NUM>, none of the powertrain components is subjected to a temperature above its maximum allowable temperature.

As regards to Table <NUM>, since the MCU <NUM> and the DC/DC converter <NUM> have a higher dissipation than the other components of the powertrain <NUM>, the rise of temperature of GHe is higher through the MCU <NUM> and the DC/DC converter <NUM> (a rise of temperature above <NUM>) than through other components of the powertrain <NUM> (a rise of temperature below <NUM>).

In order to reduce the overall consumption of LH<NUM>, the cooling architecture <NUM> preferably comprises two heat exchangers He/H<NUM> 36a, 36b.

Cooling architecture with two heat exchangers:
In <FIG>, the cooling architecture <NUM> of a cryogenic powertrain <NUM> is presented for a single superconducting motor <NUM> with two channels. A single channel configuration refers to the cryogenic powertrain <NUM> with one superconducting electric motor <NUM> coupled with a single Motor Control Unit <NUM> (MCU), Direct Current (DC) cable <NUM>, DC/DC converter <NUM> and current leads <NUM> to the fuel cell <NUM>.

In <FIG>, the temperature of H<NUM> at the H<NUM> inlet (from the LH<NUM> tank <NUM>, on the LH<NUM> line <NUM>) may be between <NUM> and <NUM> (here around <NUM>), the temperature of H<NUM> at the H<NUM> outlet (on the LH<NUM> line <NUM> in direction to the fuel cell <NUM>) may be between <NUM> and <NUM> (here around <NUM>), and the flow of H2 may be between <NUM>/s and <NUM>/s (here around <NUM>/s).

The flow of helium may be between <NUM>/s and <NUM>/s (here around <NUM>/s). The temperature of helium between the cryogenic fan <NUM> and the heat exchangers 36a, 36b (on the cryogenic insulated line 54f) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between the first heat exchanger 36a and the superconducting motor <NUM> (on the cryogenic insulated line 54j) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between the second heat exchanger 36b and the MCU <NUM> (at the connection side of the superconducting motor <NUM> with the MCU <NUM>, on the cryogenic insulated line <NUM>) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between MCUs <NUM> (on the cryogenic insulated line 54i) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between the DC distribution <NUM> and the MCU <NUM> (at the connection side of the superconducting motor <NUM> with the MCU <NUM>, on the cryogenic insulated line <NUM>) may be between <NUM> and <NUM> (here around <NUM>). The MCUs <NUM> are connected between the DC line <NUM> and the DC/DC converter <NUM> through the cryogenic insulated line <NUM>. The temperature of helium at the output of the DC/DC converter <NUM> (on the cryogenic insulated line 54d arranged between the DC/DC converter <NUM> and the DC line <NUM>) may be between <NUM> and <NUM> (here around <NUM>). The temperature of helium between the cryogenic fan <NUM> and the current leads <NUM> (on the cryogenic insulated line <NUM>) may be between <NUM> and <NUM> (here around <NUM>).

According to this embodiment of the invention, in the cooling architecture <NUM> of the cryogenic and superconducting powertrain <NUM> represented in <FIG>, a predetermined amount of second fluid is cooled at a predetermined temperature, using the first fluid, before being injected in the superconducting motor <NUM> of the powertrain <NUM>. For example, helium (He) is cooled at a temperature around <NUM> by hydrogen (H<NUM>). The amount of second fluid to be cooled is calculated depending on the constraints coming from the powertrain. For example, the flow of He circulating from the heat exchanger 36a, 36b to the superconducting motor <NUM> is around <NUM>/s.

Taking into account that the flow of helium entering into the powertrain is <NUM>/s, and knowing the dissipation of each component of the powertrain <NUM> (see Table <NUM>), the temperature at each point of the cooling architecture <NUM> is calculated accordingly.

According to the invention, LH<NUM> at around <NUM> (at <NUM> in <FIG>) stored in a pressurized tank <NUM> is used as a cooling source. A working fluid of gaseous helium (GHe) is used in a closed circuit to cool-down the electrical components of the cryogenic and superconducting powertrain <NUM>. The flow of GHe in the closed circuit is regulated by the cryogenic fan <NUM>. The flow of GHe is also regulated based on the cooling power requirements of the powertrain <NUM>. Here, two separate GHe/LH<NUM> heat exchangers 36a, 36b are used, because for the superconducting motor <NUM>, a low mass flow rate is needed, with much lower temperature inlet (about <NUM>, <NUM> in <FIG>), whereas for the motor control unit <NUM> and DC/DC converter <NUM>, high flow rate at comparatively higher temperature inlet (about <NUM>) is needed.

LH<NUM> enters at around <NUM> in both the heat exchangers 36a, 36b. In the first heat exchanger 36a, warm GHe around <NUM> (<NUM> in <FIG>) is cooled down to around <NUM> (<NUM> in <FIG>) by LH<NUM>. Cold GHe is then used to maintain the superconducting motor <NUM> at the desired low temperature. GHe coming out from the superconducting motor <NUM> may also be used to cool-down the Direct Current (DC) line <NUM> and other components of the powertrain <NUM> (as represented in <FIG>).

In the second heat exchanger 36b, warm GHe around <NUM> is cooled down to <NUM> (<NUM> in <FIG>) by LH<NUM>. Cold GHe is then used to maintain the Motor Control Unit <NUM> (MCU), DC/DC converter <NUM> and the main current leads <NUM> (CL) to the Fuel Cell <NUM> (FC) at the required cold temperature. Warm GHe out of current leads <NUM> is then fed back to the heat exchangers 36a, 36b through the return line <NUM> with the help of the cryofan <NUM>. This cooling architecture <NUM> comprises remote control valves <NUM> to regulate the flow in different components. For instance, in <FIG>, valves <NUM> are arranged on each LH<NUM> line <NUM> to the heat exchanger 36a, 36b, on the cryogenic insulated lines <NUM>, <NUM>. The functioning of the valves is not detailed here.

For instance, GHe coming from the first heat exchanger 36a and entering the superconducting motor <NUM> is at a first temperature between <NUM> and <NUM> (here around <NUM>), GHe is warmed by the superconducting motor <NUM> up to a second temperature between <NUM> and <NUM> (here around <NUM>), due to the dissipation of the superconducting motor <NUM>. GHe coming out from the superconducting motor <NUM> enters to the DC line <NUM>, and is warmed by the DC line <NUM>, due to the dissipation of the DC line <NUM>. GHe coming from the MCU <NUM> and from the DC line <NUM> enters to the DC/DC converter <NUM> at a temperature between <NUM> and <NUM> (here around <NUM>), and is warmed by the DC/DC converter <NUM>, due to the dissipation of the DC/DC converter <NUM>. GHe coming from the second heat exchanger 36b is at a temperature between <NUM> and <NUM> (here around <NUM>). GHe coming out from the superconducting motor <NUM> (here around <NUM>) is melted with GHe coming from the second heat exchanger 36b (here around <NUM>) before entering the MCU <NUM>. Thus, GHe enters to the MCU <NUM> at a temperature between <NUM> and <NUM> (here around <NUM>), and is warmed by the MCU <NUM>, due to the dissipation of the MCU <NUM>. Then, GHe enters to the current leads <NUM> to the fuel cell <NUM>, and is warmed by said current leads <NUM> up to a temperature between <NUM> and <NUM> (here around <NUM>), due to the dissipation of said current leads <NUM>. Then, GHe passes through the cryogenic fan <NUM>, and through the heat exchangers 36a, 36b to be cooled from a temperature between <NUM> and <NUM> (here around <NUM>), thanks to LH<NUM>, to the first temperature.

As regard to Table <NUM>, since the MCU <NUM> and the DC/DC converter <NUM> have a higher dissipation than the other components of the powertrain <NUM>, the rise of temperature of GHe is higher through the MCU <NUM> and the DC/DC converter <NUM> than through other components of the powertrain <NUM>.

The cryogenic fan <NUM> and the heat exchangers 36a, 36b are arranged in a common cryostat <NUM>. Preferably, the heat exchangers 36a, 36b are arranged in a cryostat <NUM>, near to the fuel cell <NUM>, to reduce the weight of the cooling architecture <NUM>. Generally, this cryostat <NUM> and fuel cell <NUM> are arranged close to each other, for instance at one or two meters one from the other.

With the above cooling architecture <NUM>, various configurations of the cryogenic and superconducting powertrain <NUM> are possible.

First configuration of the cryogenic and superconducting powertrain:
In a first configuration, <FIG> shows a powertrain <NUM> comprising a single superconducting motor <NUM> with two separate electrical channels. Here, two channels are used in order to omit the electrical dependency on a single channel. Thus, even with a failure of a single electrical channel, the powertrain <NUM> would be able to work, in a degraded mode.

A gearbox <NUM> is used to control the rotating speed of the motor shaft, through the electric line <NUM>. In this architecture, a reduction ratio of speed will be applied using a gearbox <NUM>.

A motor control unit <NUM> is required to control all the functioning aspects of the superconducting motor <NUM>. A DC/DC converter <NUM> is used because the main current leads <NUM> and the DC cables <NUM> are working at different voltage levels. Fuel cells <NUM> in this architecture are used as a source of DC power supply.

According to this configuration, the superconducting motor <NUM> and the two MCUs <NUM> are arranged in a common cryostat <NUM>. Each DC line <NUM> is arranged in a distinct cryostat 48a, 48b. The DC/DC converter <NUM> and the main currents leads <NUM> to the fuel cell <NUM> of the first electrical channel are arranged in a common cryostat 50a. The DC/DC converter <NUM> and the main currents leads <NUM> to the fuel cell <NUM> of the second electrical channel are arranged in a common cryostat 50b. The two heat exchangers 36a, 36b and the cryofan <NUM> are arranged in a common cryostat <NUM>.

In this configuration of the powertrain <NUM>, cold H<NUM> is firstly used to cool helium, through first and second heat exchangers 36a, 36b, and then H<NUM> at an intermediate temperature (on the H<NUM> line <NUM>) is used to cool the Thermal Management System (TMS) <NUM> coolant, with another heat exchanger <NUM> arranged in a "cold" box <NUM> (another cryostat).

Warm H<NUM> is then used to feed the fuel cell <NUM>. Warm H<NUM> passes from the heat exchanger <NUM> (via a H<NUM> line <NUM>) through a manifold <NUM> to be divided into two H<NUM> lines 70a, 70b. Each H<NUM> line 70a, 70b is equipped with a PGM <NUM>, and then connected to the fuel cells <NUM> through the H<NUM> line <NUM>.

Each main current leads <NUM> to the fuel cells <NUM> can be bypassed, through the bypass lines 110a, 110b.

This cooling architecture <NUM> also comprises remote control valves <NUM> to regulate the flow in different components. For instance, in <FIG>, a valve <NUM> is arranged on the LH<NUM> line <NUM>, and on each LH<NUM> line <NUM> to the heat exchanger 36a, 36b, on the cryogenic insulated lines <NUM>, <NUM>, on the bypass lines 110a, 110b of the main current leads <NUM>, on the coolant lines 112a, 112b from and to the TMS <NUM>. The cryostat <NUM> housing the heat exchanger <NUM> is equipped with rupture disks <NUM> and a non-return valve with spring <NUM> to allow an evacuation of the fluid of the cryostat <NUM>. A throttle valve <NUM> is arranged on the cryogenic insulated line <NUM> coming from the H<NUM> tank <NUM> to the heat exchangers 36a, 36b.

Second configuration of the cryogenic and superconducting powertrain:
In a second configuration, <FIG> show a cryogenic and superconducting powertrain <NUM> with two superconducting motors <NUM> with two electrical channels each, along with cross-links for the two cooling loops. <FIG> represents a box "motor assembly" 112a, 112b. <FIG> represents a box "heat exchanger assembly" 136a, 136b. In order to increase the redundancy, the powertrain <NUM> comprises two superconducting motors <NUM> with two parallel electrical channels for each superconducting motor <NUM>, and two cooling architectures <NUM>. The two cooling architectures <NUM> are independent one from the other, but with cross-links between them in order to be able to continue to cool both superconducting motors <NUM> in case of a failure (of a fan <NUM> or a valve <NUM> for instance) or of LH<NUM> flow reduction (due to a fuel cell <NUM> failure).

In a nominal situation, cold H<NUM> (coming from the H<NUM> tank <NUM> through the LH<NUM> line <NUM>) entering the first "cold" box 74a (first cryostat) is used to cool He in the first heat exchanger assembly 136a. H<NUM> at an intermediate temperature results. Then, H<NUM> at an intermediate temperature (on the H<NUM> line 116a) is used to cool the TMS <NUM> coolant in the heat exchanger 62a. Resulting warm H<NUM> is then used to feed the fuel cell <NUM> of the first motor assembly 112a passing through a manifold <NUM> and PGM <NUM>, and via the H<NUM> line <NUM>.

Cold H<NUM> (coming from the H<NUM> tank <NUM>) entering the second "cold" box 74b (second cryostat) is used to cool He in the second heat exchanger assembly 136b. H<NUM> at an intermediate temperature results. Then, H<NUM> at an intermediate temperature (on the H<NUM> line 116b) is used to cool the TMS <NUM> coolant in the heat exchanger 62b. Resulting warm H<NUM> is then used to feed the fuel cell <NUM> of the second motor assembly 112b.

In a degraded mode, in case of failure on a H<NUM> line, warm H<NUM> from either the first or second "cold" box 74a, 74b can be used to feed the fuel cell <NUM> of the first motor assembly 112a and the fuel cell <NUM> of the second motor assembly 122b. Indeed, cross-links 76a, 76b are arranged on the H<NUM> circulation pipes 70a-d between the manifold <NUM> of the "cold" boxes 74a, 74b and the PGMs <NUM>. More precisely, H<NUM> circulation pipes 70a, 70b between the first "cold" box 74a and the PGMs <NUM> connected to the first motor assembly 112a comprise branching 76a, 76b to the H<NUM> circulation pipes 70c, 70d between the second "cold" box 74b and the PGMs <NUM> connected to the second motor assembly 112b.

In a degraded mode, in case of failure on a He line, He from either the first or second heat exchanger assembly 136a, 136b can be used to cool the first motor assembly 112a and the second motor assembly 112b. Indeed, cross-links 78a-c are arranged on the He circulation pipes 80a-b between the heat exchanger assemblies and the motor assemblies. More precisely, He circulation pipes between the first heat exchanger assembly and the first motor assembly comprise branching to the He circulation pipes between the second heat exchanger assembly and the second motor assembly.

Third configuration of the cryogenic and superconducting powertrain:
In a third configuration (not shown in the Figs. ), the powertrain comprises two superconducting motors with one electrical channel per superconducting motor, and two cooling architectures, with cross-links between the two cooling loops, to be able to use each cooling loop for both motors in a degraded mode.

The systems and devices described herein may include a controller or a computing device comprising a processing and a memory which has stored therein computer-executable instructions for implementing the processes described herein. The processing unit may comprise any suitable devices configured to cause a series of steps to be performed so as to implement the method such that instructions, when executed by the computing device or other programmable apparatus, may cause the functions/acts/steps specified in the methods described herein to be executed. The processing unit may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof.

The memory may be any suitable known or other machine-readable storage medium. The memory may comprise non-transitory computer readable storage medium such as, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory may include a suitable combination of any type of computer memory that is located either internally or externally to the device such as, for example, random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like. The memory may comprise any storage means (e.g., devices) suitable for retrievably storing the computer-executable instructions executable by processing unit.

The methods and systems described herein may be implemented in a high-level procedural or object-oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of the controller or computing device. Alternatively, the methods and systems described herein may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems described herein may be stored on the storage media or the device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein.

Claim 1:
A cryogenic and superconducting powertrain (<NUM>) comprising:
- at least a superconducting e-motor (<NUM>), including a motor shaft,
- at least a motor control unit (<NUM>) configured to control the functioning aspects of the superconducting e-motor (<NUM>),
- a propeller (<NUM>) lead by the superconducting e-motor (<NUM>),
- a gearbox (<NUM>), arranged between the superconducting e-motor (<NUM>) and the propeller (<NUM>), and configured to control a rotating speed of the motor shaft,
- at least a fuel cell (<NUM>), which comprises a DC power supply,
- main current leads (<NUM>) to the fuel cell (<NUM>),
- at least a DC line (<NUM>), and
- at least a DC/DC converter (<NUM>) to adapt voltage levels between the DC line (<NUM>) and the main current leads (<NUM>), wherein the main current leads (<NUM>) and the DC line (<NUM>) have different working voltage levels, a Thermal Management System (<NUM>) for managing the temperature of the fuel cell (<NUM>), and,
- a cooling architecture (<NUM>) comprising:
- a liquid hydrogen (LH<NUM>) tank (<NUM>) for LH<NUM> storage at cryogenic temperature,
- LH<NUM> circulation pipes (<NUM>) starting and ending at the LH<NUM> tank (<NUM>),
- a first heat exchanger (<NUM>, 36a, 36b) configured to exchange heat between a first fluid and a second fluid,
- a first cryostat (<NUM>) of second fluid for cooling the motor control unit (<NUM>) and the superconducting e-motor (<NUM>),
- a second cryostat (50a, 50b) of second fluid for cooling the DC/DC converter (<NUM>), and
- second fluid circulation pipes (<NUM>, 54a-k), starting and ending at each cryostat (<NUM>, 50a, 50b).