Battery power supply architecture

Abstract

The invention relates to a battery power supply device of a battery power supply system for aircraft, comprising at least two battery modules (21, 22) which are connected to a DC power network through a positive line (P), a negative line (N) and power switching elements (3, 4), for which each module comprises at least one switching device (10a, 10b) for isolating said module from said network or connecting said module to the network.

Description

Description Title: Battery-Powered Power Supply Architecture technical field

[0001] This disclosure relates to the field of electrical power generation and electrical power distribution circuits for aircraft. These distribution circuits allow the distribution of electrical power from internal sources, for example generators or batteries, or from external sources, such as power units or a battery bank, to payloads or to other distribution boxes on the aircraft and to protect said sources against short circuits in particular.

[0002] With the evolution of energy storage chemistry technologies and the increased use of electrical energy on board aircraft, batteries are taking on an increasingly important role in onboard electrical systems. Previous technique

[0003] It is known to use lithium-ion (Li-ion) battery modules for generating electricity in aircraft, comprising a plurality of Li-ion cells grouped into battery packs associated with a management and protection device including electronic boards, switching devices and fuses.

[0004] At the level of the architecture of a Li-ion battery module, power switching devices allow the module to be protected and isolated.

[0005] In general, the architecture of Li-ion battery systems is as described in Figure 1.

[0006] Battery module 2 contains cells 1. The arrangement of cells 1 to construct this battery module 2 is determined by the required voltage level (number of cells in series, given a specific chemistry). (cell voltage is defined and known), power and energy (number of cells in parallel).

[0007] To achieve these arrangements, series S cells are connected in parallel in quantities P, or vice versa, to obtain the required voltage and ampere-hour capacity. Controllable power switching devices 3, 4, such as resettable circuit breakers (particularly SSPC type), switches, or contactors, connect the battery module 2 to the aircraft's DC power grid via a connector 7. Upstream of the power switching devices, permanent connections to a charging device 5 and a hot bus (hot bus) with one or more devices 6 to be powered in standby mode via a current limiter are present. A fuse 8 protects the line connecting one terminal of the battery module to the aircraft's DC power grid. Technical problem

[0008] In some cases, these arrangements can be adjusted either statically, in which case the configuration is fixed, or in a matrix fashion, which however introduces complexity and a large number of switching nodes that is oversized for the actual need, which does not require all possible combinations. Description of the invention

[0009] In view of the prior art, the present application proposes an architecture where the battery pack is broken down into several battery modules that can be connected in series or in parallel, or in an adaptable manner in series or in parallel as needed.

[0010] To this end, this disclosure proposes a battery power supply device for an aircraft electrical power supply system comprising a battery pack having at least two battery modules connected to a direct current electrical network via a positive line, a negative line and power switching devices, wherein each module includes at least one switching device suitable for isolating said module from said network or connect said module to the network upstream of said power switches, the device comprising a control device for said switching devices configured to control the switching of said switching devices in order to select the module(s) to be connected to the network or different configurations of connection of said modules to the network, the control device being able to be configured to control the switching of the switching devices so as to balance the current supplied by the battery pack between the different configurations according to the power requirements according to the different phases of flight of the aircraft.

[0011] This allows for a modular power supply system. Furthermore, switching devices not intended for power switching can be sized solely based on the current flowing through them, rather than the need to interrupt that current or a specific type of current such as a short-circuit current. This selection can also be changed during the aircraft's flight. This also allows for optimized sizing of the aircraft's electrical power cables.

[0012] The characteristics described in the following paragraphs correspond to embodiments that can be implemented independently of each other or in combination with each other:

[0013] The power supply device may include for each module a plurality of switching devices for which said configurations include: a series configuration for which at least two modules are connected in series to said positive line and negative line, a parallel configuration for which said modules are connected in parallel to said positive line and negative line, a configuration for which only one of said modules is connected to said positive line and negative line. This allows the configuration to be adapted to the demand for voltage or current supply capacity.

[0014] The control device is advantageously adapted to control the switching of the switching devices to allow at least a selection of a maximum network voltage during the takeoff phase of the aircraft, an intermediate network voltage during the climb phase of the aircraft and a reduced network voltage during the cruise phase of the aircraft.

[0015] The control device is advantageously configured to control the switching of the power switching devices so as to cut off the power before switching said switching devices to change configuration, to switch said switching devices at reduced or zero power and to restore the power once the switching devices have been switched into a new configuration.

[0016] This allows for small switching devices, as the current they have to interrupt is zero or very low.

[0017] The switching device(s) are preferably semiconductor or non-conductive relays. Brief description of the drawings

[0018] Other features, details, and advantages of the invention will become apparent upon reading the following detailed description of non-limiting embodiments and analyzing the accompanying drawings, in which:

[0019] [Fig. 1] shows a traditional battery architecture;

[0020] [Fig. 2] shows a first embodiment of a battery architecture according to the present disclosure;

[0021] [Fig. 3] shows a second embodiment of a battery architecture according to the present disclosure in a parallel configuration;

[0022] [Fig. 4] shows the second embodiment of a battery architecture according to the present disclosure in serial configuration;

[0023] [Fig. 5] shows a third embodiment of a battery architecture according to the present disclosure comprising three battery modules;

[0024] [FIG. 6] shows a table corresponding to the voltages / power of an architecture according to the demand with three or four modules. Description of the implementation methods

[0025] The drawings and description below contain elements that can not only help to better understand the present invention, but also contribute to its definition, if necessary.

[0026] The present disclosure as represented in figures 2 to 4 proposes an architecture where a battery pack is decomposed into several battery modules 21, 22.

[0027] Figure 2 shows a simplified embodiment in which two battery modules 21, 22, forming a battery pack, are each equipped with a switching device 10a, 10b upstream of the power switching unit 3 on a first line connected to the aircraft's DC power supply via a connection device 7. The DC power supply may have power sources other than the battery pack 21, 22. A second power switching unit 4 isolates the battery pack from the negative line of the DC power supply so that the power switching units 3 and 4 galvanically isolate the battery pack from the power supply in the event of a fault. These switching or disconnecting units must be able to provide protection and isolation in the event of a short circuit downstream of the battery pack to prevent the electrical fault from propagating to the aircraft wiring.They must therefore have a high breaking capacity corresponding to the short-circuit current of the battery pack, typically a few hundred Amps.

[0028] Power switching devices can notably be of the SSPC type.

[0029] The battery modules 21 and 22 are connected together or isolated via the switching devices 10a and 10b, which can be semiconductor or non-conductive relays, SSPC devices, or switches, for example. These switching devices are located upstream of the power switches, i.e., on the module side as opposed to the DC network side of the power switches. The switching devices do not have a breaking capacity of the short-circuit current of the modules and they connect the modules unloaded before the connection of the battery pack to the continuous network called DC of the aircraft by means of the closing of the power switching devices 3, 4. Thus the switching devices do not provide any protection of the pack against short circuits and it can therefore be small relays with a breaking capacity just sufficient to cut off the supply of the permanent bus 5, 6, a few Amperes for example.

[0030] In the embodiment of Figure 2, the battery modules 21, 22 can be used independently or connected in parallel for an increase in current.

[0031] The switching of the switching devices is managed by a control device 9 configured to control the switching of said switching devices according to the desired configuration: offline modules, single module, or modules in parallel. The control device 9 includes a bus 9a for controlling the switching devices 10a and 10b.

[0032] According to Figures 3 and 4, double switch devices can be used to manage a change of configuration between a parallel connection of the modules or a series connection of the modules which allows each module 21, 22 to be used alone, to increase the available power by putting modules 21, 22 in parallel in the case of Figure 3 or allows an increase in the output voltage of the battery pack by putting modules 21, 22 in series in the case of Figure 4.

[0033] To achieve this, six switching devices 11, 12a, 12b, 13a, 13b, and 14 are used. These switching devices are also controlled by a control device 9 via a control bus 9a.

[0034] The first module 21 includes a first switch device 11 on its positive pole, a second switch device 12a and a third switch device 12b on its negative pole.

[0035] The first switch device 1 1 connects the positive pole of the first module to the positive line P connecting the battery modules to the network or cuts this connection.

[0036] The second switch device 12a connects the negative pole of the first module 21 to the negative line connecting the battery modules to the network or cuts this connection.

[0037] The third switch device 12b connects the negative pole of the first module 21 to the positive pole of the second module 22 through the fourth switch device 13a or cuts this connection (a single switch replacing switches 12b and 13a can also be used).

[0038] The second module 21 includes a fourth switching device 13a on its positive pole, a fifth switching device 13b and a sixth switching device 14 on its negative pole.

[0039] The fourth switch device 13a connects the positive pole of the second module 22 to the negative pole of the first module 21 through the third switch device 12b as seen above.

[0040] The fifth switch device 13b connects the positive pole of the second module to the positive line P connecting the battery modules to the network or cuts this connection.

[0041] The sixth switch device 14 connects the negative pole of the second module 22 to the negative line connecting the battery modules to the network or cuts this connection.

[0042] The six-switch assembly described allows switching from a single-module configuration where each module can be used separately to a parallel modules configuration or a series modules configuration.

[0043] In the configuration of Figure 3 for which the switch devices 11, 12a, 13b and 14 are closed while the switch devices 12b, 13a are open, the modules 21, 22 are put in parallel to benefit from the full current capacity of all the battery modules.

[0044] In the configuration of Figure 4, the switch devices 11, 12b, 13a and 14 are closed so as to put the two modules 21 and 22 in series.

[0045] The series configuration has the advantage of allowing the available power to be increased compared to a single module without additional current and therefore without impact on the sizing of the cabling which can be calibrated to the nominal current of a module in the case where the parallel configuration is not used.

[0046] It is also possible, by cutting switches 14, 13b and 13a, to use only module 21; similarly, by cutting switches 11, 12a and 12b, it is possible to use only module 22.

[0047] The device as shown in Figures 3 and 4 thus allows: switching from operation on a single module to operation on the two modules in series, which allows the battery voltage to be increased to meet specific power supply needs such as motor starting or a "boost" of electrical machines while remaining compatible with the electrical installation (cable gauges); switching between a high-capacity power supply device with parallel connection of the modules to a high-power device without increasing the current with the modules in series.

[0048] To maintain compact switching devices, configuration changes are made after power interruption using power switching devices 3 and / or 4, which are sized according to the maximum power to be interrupted and the short-circuit current of the modules. This optimizes the design of the switching devices and reduces their mass and size, as they are only activated when the current flowing through them is zero or significantly reduced. The control device 9 manages the power switches to isolate the modules and interrupt the power before switching the devices, then restores the modules and power supply after said switching.

[0049] The switching devices can be solid-state relay-type switches, such as SSPC modules for example.

[0050] In the case of the device in Figures 3 and 4, the control device 9 is configured to control the switching of said switching devices between the various configurations: one module, two modules in series, two modules in parallel.

[0051] The principle described can be extended beyond the 2 modules presented previously to a larger number of modules, which allows for finer modulation of the power supply while maintaining a relatively stable current.

[0052] Figure 5 shows a power supply unit with three modules 21, 22, 23 and a switching module 15 equipped with a plurality of switching devices. These switching devices are also controlled by a control device 9 via a control bus 9a. The switching devices grouped in module 15 are wired so as to allow the battery modules to be connected to the network either individually, in series two by two, all three in series, in parallel two by two, or all three in parallel.

[0053] The table in Figure 6 represents a voltage (30 on the x-axis) / power (33 on the y-axis) table with the resulting rounded currents (32) according to flight phases (31). This table shows that it is possible to smooth the current by arranging the modules in the following configurations: one module in cell 32c, two modules in series in cell 32b, and three modules in series in cell 32c, while still providing the necessary power for the aircraft's flight phases: takeoff, climb, and cruise. Thus, for an electrical installation capable of carrying a given current, the power supply allows for significantly different power profiles to be obtained for the various flight phases. In this example, during takeoff, the power required is 90 kW and the chosen voltage is 800 V. During climb, the power is 70 kW and the chosen voltage is 540 V. In steady cruise flight, the power is 30 kW and the chosen voltage is 270 V.For these powers and voltages, the current rounded to the nearest whole number is respectively 113 A, 130 A and 111 A. According to this example, the current is therefore smoothed around 100 A to 140 A for all the power-consuming flight phases which allows the wiring mass to be optimized.

[0054] Similarly, a configuration, for example with four 250V modules allowing a voltage of 1000V to be obtained during takeoff, makes it possible to further reduce the current required to 90A for maximum power delivered, whereas for a voltage of 270V, the current would be 333A, which would require very large cable cross-sections.

[0055] The device also has the advantage of being able to reduce the network voltage during stabilized flight at high altitude, which is favorable because the breakdown voltage is reached more quickly with altitude, meaning that, for example, a low voltage at altitude will be preferred.

[0056] Such a power / voltage adaptation also makes it possible to take full advantage of the power cable gauges installed in aircraft and not to have to oversize them knowing that the mass of large cables is quickly significant in the mass balance of an aircraft such as an airplane.

[0057] Furthermore, having switch devices at the module level makes it possible to isolate a module that would be detected as faulty, broken down or out of service among n modules and to continue to use the energy stored in the n-1 modules, in reduced or degraded mode to ensure an end of flight for example.

[0058] As mentioned above, to maintain low mass and size switching devices, configuration change operations between single module, series modules and parallel modules can be carried out after disconnecting the modules using the power switching devices, with the modules being reconnected after the configuration change.

[0059] The control device 9 is for example a computer equipped for example with an FPGA or a processor with non-volatile memory containing a control program for said switching elements and switching devices, with RAM, with digital outputs for controlling the switching elements and switching devices and possibly equipped with sensors and inputs for monitoring the state of the switching devices and switching elements. Industrial application

[0060] The invention may be applicable in particular to electrical power supply systems for avionics systems or aircraft engine systems.

[0061] The invention is not limited to the examples described above, which are only by way of example, but encompasses all the variants that a person skilled in the art may consider within the framework of the protection sought.

Claims

Demands

1. Battery power supply device for an aircraft electrical power supply system comprising a battery pack having at least two battery modules (21, 22, 23) connected to a direct current electrical network through a positive line (P), a negative line (N) and power switching elements (3, 4), and wherein each module has at least one switching device (10a, 10b, 11, 12a, 12b, 13a, 13b, 14, 15), adapted to isolate said module from said network or connect said module to the network, upstream of said power switches, characterized in that it has a control device (9) for said switching devices, configured to control the switching of said switching devices in order to select the module(s) to be connected to the network or different configurations for connecting said modules to the network,said control device (9) being configured to control the switching of the switching devices (10a, 10b, 11, 12a, 12b, 13a, 13b, 14, 15) so as to balance the current supplied by the battery pack between the different configurations according to the power requirements during the different flight phases of the aircraft.

2. Battery power supply device according to claim 1 comprising for each module a plurality of switching devices (11, 12a, 12b, 13a, 13b, 14) for which said configurations comprise: - a series configuration in which at least two modules (21, 22, 23) are connected in series to said positive and negative lines, - a parallel configuration in which said modules (21, 22) are connected in parallel to said positive line and negative line, - a configuration in which only one of said modules (21, 22) is connected to said positive line and negative line.

3. A battery power supply device according to claim 1 or 2 comprising at least three modules and wherein the control device is adapted to control the switching of the switching devices to allow at least one selection of a maximum mains voltage during the takeoff phase of the aircraft, with an intermediate network voltage during the aircraft's climb phase and a reduced network voltage during the aircraft's cruise flight phase.

4. A battery power supply device according to claim 3, wherein said control device (9) is configured to control the switching of the power switching elements (3, 4) so ​​as to cut off the power before switching said switching devices to change configuration, switch said switching devices to reduced or zero power, and restore power once the switching devices have been switched into a new configuration.

5. A battery power supply device according to any one of the preceding claims, wherein the switching device(s) (10a, 10b, 11, 12a, 12b, 13a, 13b, 14, 15) are semiconductor or non-conductive relays.

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