DISTRIBUTED LOW VOLTAGE POWER GENERATION ARCHITECTURE FOR BATTERY ELECTRIFIED AIRCRAFT

Abstract

Power distribution systems, battery packs, and batteries employ battery modules that are connected in series to generate a high-voltage output and in parallel to generate a low-voltage output. A battery includes battery modules and a direct current to direct current converter. The battery modules are electrically connected in series to generate a first battery high-voltage output. The battery modules are electrically connected in parallel to generate a battery modules low-voltage output. The direct current to direct current converter generates a battery low-voltage output from the battery modules low-voltage output.

Claims

1. A power distribution system comprising: a battery pack comprising: a first battery assembly comprising: a first plurality of battery modules that are electrically connected in series to generate a first high-voltage output and electrically connected in parallel to generate a first low-voltage input; and a first direct current to direct current converter configured to generate a first low-voltage output from the first low-voltage input; and a second battery assembly comprising: a second plurality of battery modules that are electrically connected in series to generate a second high-voltage output and electrically connected in parallel to generate a second low-voltage input; and a second direct current to direct current converter configured to generate a second low-voltage output from the second low-voltage input; a high-voltage distribution subsystem configured to distribute the first high-voltage output and the second high-voltage output to a set of propulsion loads; a first power distribution unit configured to distribute the first low-voltage output to a first set of system loads; and a second power distribution unit configured to distribute the second low-voltage output to a second set of system loads.

2. The power distribution system of claim 1, wherein the first plurality of battery modules is four, five, or six battery modules, and wherein the battery pack is one of six battery packs.

3. The power distribution system of claim 1, wherein the high-voltage distribution subsystem includes an in-series connection of the first high-voltage output and the second high-voltage output to generate a battery pack high-voltage output that is supplied to the set of propulsion loads.

4. The power distribution system of claim 1, further comprising: a plurality of aircraft propulsion systems configured to cause the set of propulsion loads; and a plurality of low-voltage systems configured to cause the first set of system loads and the second set of system loads.

5. The power distribution system of claim 4, wherein the plurality of low-voltage systems include a motor controller, a tilt actuator, and a control surface.

6. The power distribution system of claim 1, wherein the first low-voltage input is in a range of 36 Volts to 75 Volts.

7. The power distribution system of claim 1, wherein the first low-voltage output is in a range of 28 Volts to 30 Volts.

8. A battery pack comprising: a first battery assembly comprising: a first plurality of battery modules that are electrically connected in series to generate a first high-voltage output and electrically connected in parallel to generate a first low-voltage input; and a first direct current to direct current converter configured to generate a first low-voltage output from the first low-voltage input; and a second battery assembly comprising: a second plurality of battery modules that are electrically connected in series to generate a second high-voltage output and electrically connected in parallel to generate a second low-voltage input; and a second direct current to direct current converter configured to generate a second low-voltage output from the second low-voltage input.

9. The battery pack of claim 8, wherein each of the first plurality of battery modules and the second plurality of battery modules comprise four, five, or six battery modules.

10. The battery pack of claim 8, wherein the first high-voltage output and the second high-voltage output are connected in parallel to generate a battery pack high-voltage output.

11. The battery pack of claim 8, further comprising: current flow-control components connected to the first plurality of battery modules and configured to: block backflow of current to the first plurality of battery modules, and distribute contributions to the first low-voltage input by the first plurality of battery modules based on corresponding output voltages of the first plurality of battery modules.

12. The battery pack of claim 11, wherein the current flow-control components comprise diodes.

13. The battery pack of claim 11, wherein the first direct current to direct current converter is configured to produce a first voltage droop in the first low-voltage output, and the second direct current to direct current converter is configured to produce a second voltage droop in the second low-voltage output.

14. A battery assembly comprising: a plurality of battery modules that are electrically connected in series to generate a high-voltage output and electrically connected in parallel to generate a low-voltage input; and a direct current to direct current converter configured to generate a low-voltage output from the low-voltage input.

15. The battery assembly of claim 14, wherein the plurality of battery modules is four battery modules.

16. The battery assembly of claim 15, wherein the plurality of battery modules is five battery modules.

17. The battery assembly of claim 16, wherein the plurality of battery modules is six battery modules.

18. The battery assembly of claim 14, further comprising: current flow-control components connected to the plurality of battery modules and configured to: block backflow of current to the plurality of battery modules, and distribute contributions to the low-voltage input by the plurality of battery modules based on corresponding output voltages of the plurality of battery modules.

19. The battery assembly of claim 18, wherein the current flow-control components comprise diodes.

20. The battery assembly of claim 14, wherein the direct current to direct current converter is configured to produce a voltage droop in the low-voltage output.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 depicts an electrically powered aerial vehicle that includes a power distribution system, in accordance with embodiments.

[0028] FIG. 2 schematically illustrates low-voltage distribution aspects of the power distribution system of FIG. 1.

[0029] FIG. 3 schematically illustrates a battery pack of the power distribution system of FIG. 1.

[0030] FIG. 4 shows an example voltage droop relationship that can be implemented by direct current to direct current converters of the battery pack of FIG. 3.

[0031] FIG. 5 shows a plot illustrating an example variation of battery module output voltage with state of charge of the battery module in battery modules of the battery pack of FIG. 3.

[0032] FIG. 6 shows a plot illustrating an example variation of battery module output voltage with flight duration for the power distribution system of FIG. 1.

DETAILED DESCRIPTION

[0033] In the following description, various embodiments of the present invention will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the present invention may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiment being described.

[0034] Power distribution systems, battery packs, and batteries are presented that supply both high-voltage electrical power and low-voltage electrical power. In an illustrated embodiment, an aircraft power distribution system is configured to supply high-voltage electrical power to propulsion loads and low-voltage electrical power to system loads. The aircraft power distribution system employs batteries that include battery modules that are electrically connected in series to generate a high-voltage output used to power high-voltage propulsion loads and electrically connected in parallel to generate a low-voltage output used to power low-voltage system loads. The aircraft power distribution system employs redundant distribution of electrical power to provide for fail-saft distribution of power in the event of one or more failures in the aircraft power distribution system (e.g., battery failure, short circuits). The aircraft power distribution system employs load balancing to preferentially discharge battery modules having a higher state of charge over battery modules having a lower state of charge. The aircraft power distribution system includes battery packs. Each of the battery packs in the illustrated embodiment includes two batteries. While the battery packs and the batteries are described herein as components of the illustrated aircraft distribution system, any suitable number of the battery packs (e.g., one, two, three, or more) can be employed to store and supply electrical power in any suitable application. Likewise, any suitable number of the batteries (e.g., one, two, three, or more) can be employed to store and supply electrical power in any suitable application.

[0035] Turning now to the drawing figures in which similar reference identifiers are used to designate similar elements in the various figures, FIG. 1 depicts an electrically powered aerial vehicle 100 that includes a power distribution system 102, in accordance with embodiments. As shown in FIG. 1, the aerial vehicle 100 includes twelve motors 105a-105l. The power distribution system 102 includes six battery packs 110a, 110b, 110c, 110d, 110e, 110f, and a high-voltage distribution subsystem 115 via which the twelve motors 105a-105l are coupled to the battery packs 110a-f. In many embodiments, each of the twelve motors 105a-105l are used to drive propulsion fans 112 (e.g., tiltable lift/propulsion fans) and are configured to operate on a relatively high supply voltage (e.g., 792 V max), which is supplied by the battery packs 110a-f. The high-voltage subsystem 115 can have any suitable configuration for operatively coupling each of the motors 105a-105l to the battery packs 110a-f to meet airworthiness requirements.

[0036] In addition to the motors 105a-105l, the aerial vehicle 100 includes low-voltage systems that are also powered by the battery packs 110. The low-voltage systems include 24 motor controllers (MC) (two for each of the 12 motors to provide redundancy), 6 tilt actuators (T-act) (1 per each tilt mechanism used to tilt a corresponding pair of the motors mounted on a respective pylon), 4 aileron actuators (A-act), 2 elevator actuators (E-act), 1 rudder actuator (R-act), avionics units (A-units), passenger system line replaceable units (PAX-LRUs), lights, and miscellaneous other low-voltage systems. Each of the low-voltage systems is configured to operate on a relatively low voltage power (e.g., 28 V nominal).

[0037] FIG. 2 schematically illustrates high-level aspects of the supply of the low voltage power to the low-voltage systems. The power distribution system 102 includes a low-voltage distribution subsystem 114 via which the low voltage power is supplied to the low-voltage systems by the battery packs 110a-f. In the illustrated embodiment, the power distribution system 102 includes six of the battery packs 110a-f. Each of the battery packs 110 includes two battery assemblies 116, 118. Each of the two battery assemblies 116, 118 includes battery modules 120 and a direct current to direct current (DC/DC) converter 122. In one example embodiment, each of the battery assemblies 116, 118 includes 10 of the battery modules 120. Each of the battery assemblies 116, 118, however, can include any suitable number of the battery modules 120. In each of the battery assemblies 116, 118, the battery modules 120 are electrically coupled in parallel to supply a low-voltage input power (e.g., 36V to 75V) to the associated DC/DC converter 122. Each DC/DC converter 122 is configured to generate a low-voltage output power (e.g., 28V nominal) that is output from the battery assembly 116, 118. In the illustrated embodiment, the battery packs 110a-f have a total of 12 of the battery assemblies 116, 118.

[0038] In the illustrated embodiment, the power distribution system 102 includes 12 power distribution units (PDU1, PDU12, PDU2, PDU22, PDU3, PDU32, PDU4, PDU42, PDU5, PDU52, PDU6, PDU62). Each of the 12 power distribution units receives the low-voltage output power from an associated one of the 12 battery assemblies 116, 118. The 12 power distribution units be connected to the suitable subsets of the low-voltage systems to provide a suitable level of redundancy to the supply of power to the low-voltage systems. Each of the 12 power distribution units can include power monitoring elements (e.g., voltage sensors, current sensors) and power control elements (e.g., controlled power transistors for use in isolating failures of any one or more of the battery assemblies 116, 118).

[0039] FIG. 3 schematically illustrates one of the battery packs 110a-f and associated down-stream components of the low-voltage distribution subsystem. Each of the battery packs 110a-f includes the first battery assembly 116 and the second battery assembly 118. In the illustrated embodiment, each of the battery assemblies 116, 118 includes six of the battery modules 120, the associated DC/DC converter 122, a battery management system (BMS) 124, and a pre-charge contactor/current sense/busbar 126. While each of the battery assemblies 116, 118 includes six of the battery modules 120 in the illustrated embodiment, each of the battery assemblies 116, 118 can include any suitable number of the battery modules 120 such as, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more of the battery modules 120.

[0040] Output terminals for each of the battery modules 120 in each of the battery assemblies 116, 118 are electrically connected in series to generate the high-voltage power supplied to the twelve motors 105a-105l. The resulting high-voltage powers generated by the series connected battery modules 120 in the first and second batteries 116, 118 are electrically connected in parallel to produce a single high-voltage power output from each of the battery packs 110a-f.

[0041] The output terminals for each of the battery modules 120 in each of the battery assemblies 116, 118 are electrically connected in parallel to supply the low-voltage input power to the DC/DC converter 122. Each of the battery assemblies 116, 118 includes diodes 128 connected between the battery modules 120 and the DC/DC converter 122. Each of the diodes 128 blocks backflow of current to an associated one of the battery modules 120. The inclusion of the diodes 128 serves to preferentially discharge the battery module(s) 120 with a higher relative state of charge relative to the battery module(s) 120 with a lower relative state of charge since the battery module(s) 120 having the higher relative state of charge will output power at a relatively higher voltage thereby inhibiting output of power from the battery module(s) 120 having the relatively lower state or charge. Each of the battery modules 120 will have an internal resistance that results in a reduction of output voltage with increased power discharge rate, which further serves to distribute the discharging of the battery modules 120 based on both relative state of charge and total power supplied by the battery modules 120 to the DC/DC converter _122 at any point in time.

[0042] Each of the DC/DC converters 122 is configured to generate a low-voltage output power from the low-voltage input power and supply the low-voltage output power to the associated one of the power distribution units (PDU1-PDU62). Each of the DC/DC converters 122 includes a DC/DC circuit 130 and a controller 132. The DC/DC circuit 130 is configured to generate the low-voltage output power from the low-voltage input power. The controller 132 is configured to monitor the voltage and/or current of the low-voltage input power and control the DC/DC circuit 130 based on the low-voltage input power to generate the low-voltage output power over a range of voltages of the low-voltage input power. In many embodiments, each of the DC/DC converters 122 is configured to produce a voltage droop in the low-voltage output power to passively control distribution of power between the power distribution units, which supply low-voltage power the low-voltage systems of the aerial vehicle 100. FIG. 4 shows an example voltage droop relationship that can be implemented by each of the DC/DC converters 122.

[0043] The DC/DC converters 122 are configured to accommodate a range of different voltages of the low-voltage input power supplied by the battery modules 120 while still producing the low-voltage output power having the voltage as a function of current as shown in FIG. 4. For example, each DC/DC converter 122 can be configured to produce the low-voltage output power with a 30 Volt voltage at an output current (I-1) for any resulting voltages of the low-voltage input power in a suitable range (e.g., 36V to 75V), thereby accommodating the natural reduction in output voltage of the battery modules 120 that occurs during discharging of the battery modules 120 during high instantaneous rate of discharging due to internal resistance of the battery module 120 and due to cumulative reduction in the state of charge of the battery module 120. For example, FIG. 5 shows a plot illustrating an example variation of battery module output voltage with state of charge of the battery module 120. FIG. 6 shows a plot illustrating an example variation of battery module output voltage with flight duration for the power distribution system 102. The ability to generate suitable low-voltage output power for use by the low-voltage systems when the states of charge of the battery modules are relatively low, provides the ability to more completely utilize the electrical power stored in the battery packs 110a-f for operating the low-voltage systems, thereby providing for increased capability to support continued safe flight and landing of the aircraft when the state of charge of the battery packs 110a-f is low.

[0044] Although described herein in the context of the aerial vehicle 100, the power distribution system 102, one or more of the battery packs 110a-f, and/or one or more of the battery assemblies 116, 118 can be employed in any suitable electrically powered vehicle, system, or device. For example, any electrically powered vehicle that receives at least part of its power from one or more batteries can be used with embodiments of the disclosure. In some instances, embodiments of the disclosure are particularly well suited for use with aerial vehicles because of the reliability and failure isolation provided.

[0045] Other variations are within the spirit of the present invention. Thus, while the invention is susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention, as defined in the appended claims.

[0046] The use of the terms a and an and the and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms comprising, having, including, and containing are to be construed as open-ended terms (i.e., meaning including, but not limited to,) unless otherwise noted. The term connected is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., such as) provided herein, is intended merely to better illuminate embodiments of the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0047] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0048] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.