Distributed Low-Voltage Power Generation Architecture for Battery-Electric Aircraft

Abstract

The power distribution system, the battery pack, and the battery employ battery modules connected in series to generate a high-voltage output and connected in parallel to generate a low-voltage output. The battery includes a battery module and a DC / DC 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 module low-voltage output. The DC / DC converter generates a battery low-voltage output from the battery module low-voltage output.

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Application No. 63 / 430,313, filed December 5, 2022, the disclosure of which is incorporated herein by reference. [Background technology]

[0002] Aircraft typically include various power systems and devices, such as propulsion systems, avionics, control surfaces, lights, high-lift devices, and passenger systems and devices. Power systems and devices typically have different power requirements. In battery-electric aircraft, different power (electrical) requirements may dictate different voltages used to power the power systems and devices. For example, a relatively high voltage may be used to power high-power consumption systems, such as propulsion systems (e.g., lift / thrust fan units). A relatively low voltage may be used to power low-power consumption systems, such as avionics, control surfaces, lights, and passenger systems and devices. However, employing both high and low voltages in battery-electric aircraft presents challenges with respect to meeting aircraft design requirements, such as safety, weight, aircraft manufacturing costs, and aircraft operating costs. Summary of the Invention [Problem to be solved by the invention]

[0003] The following presents a simplified summary of some embodiments of the invention in order to provide a basic understanding of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key / critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some embodiments of the invention in a simplified form as a prelude to the more detailed description that is presented later. [Means for solving the problem]

[0004] A power distribution system, battery pack, and battery that provide both high-voltage and low-voltage power are presented. In one example, the aircraft power distribution system is configured to provide high-voltage power to a propulsion load and low-voltage power to a system load. The aircraft power distribution system includes batteries, each having a battery module. The battery modules are electrically connected in series to generate a high-voltage output. The battery modules are also electrically connected in parallel to generate a low-voltage output. The parallel connection between the battery modules employs passive current flow control components (e.g., diodes) to distribute the contribution to the low-voltage output among the battery modules based on the voltage of the battery modules, allowing battery modules with higher states of charge to be preferentially discharged. The battery may include a DC / DC converter for generating the low-voltage output of the battery from the combined output of the battery modules. The DC / DC converter may implement a voltage droop on the low-voltage output of the battery and passively balance it with the low-voltage outputs of one or more other batteries, allowing batteries with higher states of charge to be preferentially discharged. The output from two or more batteries can be combined to provide fail-safe redundancy in the power supply from the two or more batteries in the event that one of the two or more batteries fails.

[0005] Thus, in one aspect, an aircraft power distribution system for powering high-voltage propulsion loads and low-voltage system loads includes a battery pack, a first power distribution unit, and a second power distribution unit. The battery pack includes a first battery and a second battery. The first battery includes a first battery module and a first DC / DC converter. The second battery includes a second battery module and a second DC / DC converter. The first battery modules are electrically connected in series to generate a first battery high-voltage output. The second battery modules are electrically connected in series to generate a second battery high-voltage output. The first battery high-voltage output and the second battery high-voltage output are used to supply power to a set of high-voltage propulsion loads. The first battery modules are electrically connected in parallel to generate a first battery module low-voltage output. The first DC / DC converter generates a first battery low-voltage output from the first battery module low-voltage output. The second battery module is electrically connected in parallel to generate a second battery module low-voltage output. The second DC / DC converter generates a second battery low-voltage output from the second battery module low-voltage output. The first power distribution unit distributes the first battery low-voltage output to a first set of low-voltage system loads. The second power distribution unit distributes the second battery low-voltage output to a second set of low-voltage system loads.

[0006] Each of the first and second batteries can include any suitable number of battery modules. For example, the first battery can include two, three, four, five, six, or more first battery modules. Similarly, the second battery can include two, three, four, five, six, or more second battery modules.

[0007] The first battery high-voltage output and the second battery high-voltage output may be combined in any suitable manner. For example, the first battery high-voltage output and the second battery high-voltage output may be electrically connected in parallel to generate a battery pack high-voltage output that is supplied to a set of high-voltage propulsion loads. In another example, the first battery high-voltage output and the second battery high-voltage output may be electrically connected in series to generate a battery pack high-voltage output that is supplied to a set of high-voltage propulsion loads.

[0008] By employing current flow control components such as diodes, the discharge of the battery modules can be passively controlled, with priority given to discharging battery modules with higher states of charge. For example, a first battery can include a first current flow control component (e.g., a diode) connected between the first battery module low-voltage output and the first battery module, blocking current flow from the first battery module low-voltage output to the first battery module and allocating the first battery module's contribution to the first battery module low-voltage output based on the first battery module's output voltage. A second battery can include a second current flow control component (e.g., a diode) connected between the second battery module low-voltage output and the second battery module, blocking current flow from the second battery module low-voltage output to the second battery module and allocating the second battery module's contribution to the second battery module low-voltage output based on the second battery module's output voltage.

[0009] Each of the first battery and the second battery can incorporate a voltage droop in its respective low-voltage output to passively balance the discharge of the first battery and the second battery. For example, the first DC / DC converter can be configured to generate a first battery low-voltage output from the first battery module low-voltage output and to generate a first voltage droop in the first battery low-voltage output. The second DC / DC converter can be configured to generate a second battery low-voltage output from the second battery module low-voltage output and to generate a second voltage droop in the second battery low-voltage output.

[0010] The aircraft power distribution system may further include a second battery pack, a third power distribution unit, and a fourth power distribution unit. The second battery pack may include a third battery and a fourth battery. The third battery may include a third battery module and a third DC / DC converter. The fourth battery may include a fourth battery module and a fourth DC / DC converter. The third battery modules may be electrically connected in series to generate a third battery high-voltage output. The fourth battery modules may be electrically connected in series to generate a fourth battery high-voltage output. The third battery high-voltage output and the fourth battery high-voltage output may be used to power a second set of high-voltage propulsion loads. The third battery modules may be electrically connected in parallel to generate a third battery module low-voltage output. The third DC / DC converter may be configured to generate a third battery low-voltage output from the third battery module low-voltage output. The fourth battery module may be electrically connected in parallel to generate a fourth battery module low-voltage output. The fourth DC / DC converter may be configured to generate a fourth battery low-voltage output from the fourth battery module low-voltage output. The third power distribution unit may be configured to distribute the third battery low-voltage output to a third set of low-voltage system loads. The fourth power distribution unit may be configured to distribute the fourth battery low-voltage output to a fourth set of low-voltage system loads.

[0011] The aircraft power distribution system may be configured for redundancy in the distribution of power. For example, the first power distribution unit, the second power distribution unit, the third power distribution unit, and the fourth power distribution unit may be electrically connected to low-voltage system loads such that each of the low-voltage system loads is supplied with power by at least two of the first power distribution unit, the second power distribution unit, the third power distribution unit, and the fourth power distribution unit.

[0012] Each of the third battery and the fourth battery can include any suitable number of battery modules. For example, the third battery can include two, three, four, five, six, or more third battery modules. Similarly, the fourth battery can include two, three, four, five, six, or more fourth battery modules.

[0013] The third battery high-voltage output and the fourth battery high-voltage output may be combined in any suitable manner. For example, the third battery high-voltage output and the fourth battery high-voltage output may be electrically connected in parallel to generate a second battery pack high-voltage output that is supplied to a second set of high-voltage propulsion loads. In another example, the third battery high-voltage output and the fourth battery high-voltage output may be electrically connected in series to generate a second battery pack high-voltage output that is supplied to a second set of high-voltage propulsion loads.

[0014] The discharge of the third and fourth battery modules can be passively controlled by employing current flow control components such as diodes to prioritize the discharge of the battery module with a higher state of charge. For example, the third battery can include a third current flow control component (e.g., a diode) connected between the third battery module low-voltage output and the third battery module, blocking current flow from the third battery module low-voltage output to the third battery module and allocating the third battery module's contribution to the third battery module low-voltage output based on the third battery module's output voltage. The fourth battery can include a fourth current flow control component (e.g., a diode) connected between the fourth battery module low-voltage output and the fourth battery module, blocking current flow from the fourth battery module low-voltage output to the fourth battery module and allocating the fourth battery module's contribution to the fourth battery module low-voltage output based on the fourth battery module's output voltage.

[0015] The third battery and the fourth battery may each incorporate a voltage droop in their respective low-voltage outputs to passively balance the discharge of the third battery and the fourth battery. For example, the third DC / DC converter may be configured to generate a third battery low-voltage output from the third battery module low-voltage output and to generate a third voltage droop in the third battery low-voltage output. The fourth DC / DC converter may be configured to generate a fourth battery low-voltage output from the fourth battery module low-voltage output and to generate a fourth voltage droop in the fourth battery low-voltage output.

[0016] In another aspect, a battery pack includes a first battery and a second battery. The first battery includes a first battery module and a first DC / DC converter. The first battery modules are electrically connected in series to generate a first battery high-voltage output. The first battery modules are electrically connected in parallel to generate a first battery module low-voltage output. The first DC / DC converter is configured to generate a first battery low-voltage output from the first battery module low-voltage output. The second battery includes a second battery module and a second DC / DC converter. The second battery modules are electrically connected in series to generate a second battery high-voltage output. The second battery modules are electrically connected in parallel to generate a second battery module low-voltage output. The second DC / DC converter is configured to generate a second battery low-voltage output from the second battery module low-voltage output.

[0017] Each of the first and second batteries in the battery pack can include any suitable number of battery modules. For example, the first battery can include two, three, four, five, six, or more first battery modules. Similarly, the second battery can include two, three, four, five, six, or more second battery modules.

[0018] The first battery high-voltage output and the second battery high-voltage output of the battery pack can be combined in any suitable manner. For example, the first battery high-voltage output and the second battery high-voltage output can be electrically connected in parallel to generate the battery pack high-voltage output. In another example, the first battery high-voltage output and the second battery high-voltage output can be electrically connected in series to generate the battery pack high-voltage output.

[0019] The battery pack can employ current flow control components, such as diodes, to passively control the discharge of the battery modules and prioritize the discharge of battery modules with higher states of charge. For example, a first battery can include a first current flow control component (e.g., a diode) connected between the first battery module low-voltage output and the first battery module, blocking current flow from the first battery module low-voltage output to the first battery module and allocating the first battery module's contribution to the first battery module low-voltage output based on the first battery module's output voltage. A second battery can include a second current flow control component (e.g., a diode) connected between the second battery module low-voltage output and the second battery module, blocking current flow from the second battery module low-voltage output to the second battery module and allocating the second battery module's contribution to the second battery module low-voltage output based on the second battery module's output voltage.

[0020] Each of the first and second batteries in the battery pack can incorporate a voltage droop in its respective low-voltage output to passively balance the discharge of the first and second batteries. For example, a first DC / DC converter can be configured to generate a first battery low-voltage output from a first battery module low-voltage output and to generate a first voltage droop in the first battery low-voltage output. A second DC / DC converter can be configured to generate a second battery low-voltage output from a second battery module low-voltage output and to generate a second voltage droop in the second battery low-voltage output.

[0021] In another aspect, a battery includes battery modules and a DC / DC 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 module low-voltage output. The DC / DC converter is configured to generate a battery low-voltage output from the battery module low-voltage output.

[0022] The battery may include any suitable number of battery modules, for example, the battery may include two, three, four, five, six, or more battery modules.

[0023] The battery may include a current flow control component, such as a diode, to passively control the discharge of the battery modules and prioritize the discharge of battery modules with higher states of charge. For example, the battery may include a current flow control component (e.g., a diode) connected between the battery module low-voltage output and the battery module to block current flow from the battery module low-voltage output to the battery module and to allocate the battery module's contribution to the battery module low-voltage output based on the battery module's output voltage.

[0024] A battery can passively balance the discharge of the battery and one or more other batteries by incorporating a voltage droop in the battery low voltage output. For example, a DC-to-DC converter can be configured to generate a battery low voltage output from a battery module low voltage output and to generate a voltage droop in the battery low voltage output.

[0025] For a more complete understanding of the nature and advantages of the present invention, reference should be made to the following detailed description and accompanying drawings. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 illustrates an electric flying vehicle including a power distribution system, according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram illustrating the low voltage distribution aspect of the power distribution system of FIG. 1. [Figure 3] FIG. 2 is a schematic diagram of a battery pack of the power distribution system of FIG. 1. [Figure 4] FIG. 4 illustrates an exemplary voltage droop relationship that may be realized by the DC / DC converter of the battery pack of FIG. 3. [Figure 5] 4 is a plot illustrating an exemplary variation of battery module output voltage with the state of charge of the battery module in the battery pack of FIG. 3. [Figure 6] 2 is a plot showing an example variation of battery module output voltage with flight duration for the power distribution system of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0027] In the following description, various embodiments of the present invention are 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 be apparent to those skilled in the art that the present invention may be practiced without these specific details. Additionally, well-known features may be omitted or simplified so as not to obscure the described embodiments.

[0028] A power distribution system, battery pack, and battery for supplying both high-voltage and low-voltage power are presented. In the illustrated embodiment, the aircraft power distribution system is configured to supply high-voltage power to propulsion loads and low-voltage power to system loads. The aircraft power distribution system employs batteries including battery modules electrically connected in series to generate a high-voltage output used to power the high-voltage propulsion loads and electrically connected in parallel to generate a low-voltage output used to power the low-voltage system loads. The aircraft power distribution system employs redundant distribution of power to provide fail-safe distribution of power in the event of one or more failures (e.g., battery failure, short circuit) in the aircraft power distribution system. The aircraft power distribution system employs load balancing to preferentially discharge battery modules having a higher state of charge relative to battery modules having a lower state of charge. The aircraft power distribution system includes battery packs. In the illustrated embodiment, each of the battery packs includes two batteries. Although battery packs and batteries are described herein as components of the illustrated aircraft distribution system, any suitable number of battery packs (e.g., one, two, three, or more) may be employed to store and supply power for any suitable application. Similarly, any suitable number of batteries (e.g., one, two, three, or more) may be employed to store and supply power for any suitable application.

[0029] Referring now to the drawings, wherein like reference numerals are used to denote like elements in each figure, FIG. 1 illustrates an electric air vehicle 100 including a power distribution system 102, according to an embodiment. As shown in FIG. 1, the air vehicle 100 includes twelve motors 105a-105l. The power distribution system 102 includes six battery packs 110a, 110b, 110c, 110d, 110e, and 110f and a high-voltage distribution subsystem 115 through which the twelve motors 105a-105l are coupled to the battery packs 110a-110f. In many embodiments, each of the twelve motors 105a-105l is used to drive a propulsion fan 112 (e.g., a tilting lift / thrust fan) and is configured to operate at a relatively high supply voltage (e.g., up to 792V) provided by the battery packs 110a-110f. High voltage subsystem 115 may have any suitable configuration for operably coupling each of motors 105a-105l to battery packs 110a-110f to meet airworthiness requirements.

[0030] In addition to motors 105a-105l, air vehicle 100 also includes a low-voltage system powered by battery pack 110. The low-voltage system includes 24 motor controllers (MCs) (two for each of the 12 motors for redundancy), six tilt actuators (T-acts) (one for each tilt mechanism used to tilt the corresponding motor pair mounted on each pylon), four aileron actuators (A-acts), two elevator actuators (E-acts), one rudder actuator (R-acts), an avionics unit (A-unit), a passenger system line replaceable unit (PAX-LRU), lights, and various other low-voltage systems. Each of the low-voltage systems is configured to operate on relatively low-voltage power (e.g., nominal 28V).

[0031] FIG. 2 illustrates a high-level schematic of the supply of low-voltage power to a low-voltage system. The power distribution system 102 includes a low-voltage distribution subsystem 114, through which low-voltage power is supplied to the low-voltage system by battery packs 110a-110f. In the illustrated embodiment, the power distribution system 102 includes six battery packs 110a-110f. Each battery pack 110 includes two battery assemblies 116, 118. Each of the two battery assemblies 116, 118 includes a battery module 120 and a direct current to direct current (DC / DC) converter 122. In one exemplary embodiment, each battery assembly 116, 118 includes ten battery modules 120. However, each battery assembly 116, 118 may include any suitable number of battery modules 120. In each of the battery assemblies 116, 118, the battery modules 120 are electrically coupled in parallel and provide low-voltage input power (e.g., 36V-75V) to an associated DC / DC converter 122. Each DC / DC converter 122 is configured to generate low-voltage output power (e.g., nominal 28V) from the battery assembly 116, 118. In the illustrated embodiment, the battery packs 110a-110f include a total of 12 battery assemblies 116, 118.

[0032] In the illustrated embodiment, power distribution system 102 includes twelve power distribution units (PDU1, PDU12, PDU2, PDU22, PDU3, PDU32, PDU4, PDU42, PDU5, PDU52, PDU6, and PDU62). Each of the twelve power distribution units receives low-voltage output power from an associated one of the twelve battery assemblies 116, 118. The twelve power distribution units may be connected to a suitable subset of the low-voltage systems to provide a suitable level of redundancy in power supply to the low-voltage systems. Each of the twelve power distribution units may include power monitoring elements (e.g., voltage sensors, current sensors) and power control elements (e.g., control power transistors for use in isolating a fault in any one or more of the battery assemblies 116, 118).

[0033] 3 schematically illustrates one of the battery packs 110a-110f and associated downstream components of the low-voltage distribution subsystem. Each of the battery packs 110a-110f includes a first battery assembly 116 and a second battery assembly 118. In the illustrated embodiment, each of the battery assemblies 116, 118 includes six battery modules 120, an associated DC / DC converter 122, a battery management system (BMS) 124, and a precharge contactor / current sense / busbar 126. In the illustrated embodiment, each of the battery assemblies 116, 118 includes six battery modules 120, although each of the battery assemblies 116, 118 may include any suitable number of battery modules 120, such as, for example, two, three, four, five, six, seven, eight, nine, ten, or more battery modules 120.

[0034] The output terminals of each of the battery modules 120 in each of the battery assemblies 116, 118 are electrically connected in series to generate high voltage power supplied to the twelve motors 105a-105l. The resulting high voltage power generated by the series connected battery modules 120 in the first and second batteries 116, 118 is electrically connected in parallel to generate a single high voltage power output from each of the battery packs 110a-110f.

[0035] The output terminals of each of the battery modules 120 in each of the battery assemblies 116, 118 are electrically connected in parallel to provide low-voltage input power to the DC / DC converter 122. Each of the battery assemblies 116, 118 includes a diode 128 connected between the battery module 120 and the DC / DC converter 122. Each of the diodes 128 blocks reverse current flow to an associated one of the battery modules 120. The inclusion of the diodes 128 serves to preferentially discharge battery modules 120 with higher relative states of charge over battery modules 120 with lower relative states of charge, since battery modules 120 with higher relative states of charge output power at a relatively higher voltage, thereby inhibiting power output from battery modules 120 with lower relative states of charge. Each battery module 120 will have an internal resistance that causes the output voltage to decrease with increasing power discharge rate, which in turn serves to distribute the discharge of the battery modules 120 based on both their relative state of charge and the total power supplied by the battery modules 120 to the DC / DC converter 122 at any given time.

[0036] Each DC / DC converter 122 is configured to generate low-voltage output power from low-voltage input power and supply the low-voltage output power to an associated one of the power distribution units (PDU1-PDU62). Each DC / DC converter 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 the voltage range of the low-voltage input power. In many embodiments, each DC / DC converter 122 is configured to generate a voltage droop in the low-voltage output power and passively control power distribution among the power distribution units that supply the low-voltage power to the low-voltage system of the air vehicle 100. FIG. 4 illustrates an example voltage droop relationship that may be achieved by each DC / DC converter 122.

[0037] The DC / DC converters 122 are configured to accommodate different voltage ranges of the low-voltage input power supplied by the battery modules 120 while still generating low-voltage output power with voltage as a function of current, as shown in FIG. 4. For example, each DC / DC converter 122 can accommodate the natural decrease in the output voltage of the battery modules 120 that occurs during discharge of the battery modules 120 at high instantaneous discharge rates due to the internal resistance of the battery modules 120 and the cumulative decrease in the state of charge of the battery modules 120 by generating a low-voltage output power with a voltage of 30 volts at the output current (I-1) for any resulting voltage of the low-voltage input power in a suitable range (e.g., 36 V to 75 V). For example, FIG. 5 shows a plot illustrating an example variation of the battery module output voltage with the state of charge of the battery modules 120. FIG. 6 shows a plot illustrating an example variation of the 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 system when the battery modules have a relatively low state of charge allows the power stored in the battery packs 110a-110f to be more fully utilized to operate the low-voltage system, thereby increasing the aircraft's ability to support continued safe flight and landing even when the battery packs 110a-110f have a low state of charge.

[0038] Although described herein with respect to an air vehicle 100, the power distribution system 102 may employ one or more battery packs 110a-110f and / or one or more battery assemblies 116, 118 in any suitable electric vehicle, system, or device. For example, any electric vehicle that receives at least a portion of its power from one or more batteries may be used with embodiments of the present disclosure. In some instances, embodiments of the present disclosure are particularly well-suited for use in air vehicles due to the reliability and fault isolation provided.

[0039] Other variations are within the scope of the present invention. Accordingly, while the invention is susceptible to various modifications and alternative constructions, specific illustrated embodiments thereof are shown in the drawings and have been described above in detail. It is to be understood, however, that it is not intended to limit the invention to the particular 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 by the appended claims.

[0040] The use of the terms "a," "an," and "the," and similar referential terms in the context of describing the present invention (particularly in the context of the claims below) shall be interpreted as covering both the singular and the plural, unless otherwise indicated herein or the context clearly contradicts. The terms "comprising," "having," "including," and "containing" shall be interpreted as open-ended terms (i.e., meaning "including, but not limited to"), unless otherwise stated. The term "connected" shall be interpreted as partially or wholly contained within, attached to, or joined to one another, even if there are intervening components. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referencing each separate value within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if set forth individually herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or the context clearly contradicts. The use of any examples or exemplary language (e.g., "etc.") provided herein is intended merely to further clarify 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.

[0041] Preferred embodiments of the present invention are described herein, including the best mode known to the inventors. Variations of these preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors also intend that the invention may 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, all combinations of the above-described elements in all possible variations thereof are encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0042] All references cited in this specification, including publications, patent applications, and patents, are herein 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.

Claims

1. 1. An aircraft power distribution system for supplying power to high voltage propulsion loads and low voltage system loads, comprising: A battery pack comprising a first battery and a second battery, the first battery comprising a first battery module and a first DC / DC converter, the second battery comprising a second battery module and a second DC / DC converter, the first battery modules being electrically connected in series to produce a first battery high voltage output, the second battery modules being electrically connected in series to produce a second battery high voltage output, the first battery high voltage output and the second battery high voltage output being coupled to the high voltage thrust. a battery pack used to power a set of monolithic loads, the first battery modules being electrically connected in parallel to generate a first battery module low voltage output, the first DC / DC converter generating a first battery low voltage output from the first battery module low voltage output, the second battery modules being electrically connected in parallel to generate a second battery module low voltage output, and the second DC / DC converter generating a second battery low voltage output from the second battery module low voltage output; a first power distribution unit that distributes the first battery low voltage output to a first set of the low voltage system loads; a second power distribution unit that distributes the second battery low voltage output to a second set of the low voltage system loads; An aircraft power distribution system comprising:

2. the first battery comprises four of the first battery modules; The system of claim 1 , wherein the second battery comprises four of the second battery modules.

3. the first battery comprises five of the first battery modules; The system of claim 2 , wherein the second battery comprises five of the second battery modules.

4. the first battery comprises six of the first battery modules; The system of claim 3 , wherein the second battery comprises six of the second battery modules.

5. 2. The system of claim 1, wherein the first battery high voltage output and the second battery high voltage output are connected in parallel to produce a battery pack high voltage output that supplies the set of high voltage propulsion loads.

6. the first battery includes a first current flow control component connected between the first battery module low voltage output and the first battery module, the first current flow control component blocking current flow from the first battery module low voltage output to the first battery module and allocating the first battery module's contribution to the first battery module low voltage output based on the output voltage of the first battery module; 2. The system of claim 1, wherein the second battery comprises a second current flow control component connected between the second battery module low voltage output and the second battery module, the second current flow control component blocking current flow from the second battery module low voltage output to the second battery module and allocating the second battery module's contribution to the second battery module low voltage output based on the output voltage of the second battery module.

7. The system of claim 6 , wherein the first current flow control component and the second current flow control component each include a diode.

8. the first DC / DC converter is configured to generate the first battery low voltage output from the first battery module low voltage output and to cause a first voltage droop in the first battery low voltage output; 7. The system of claim 6, wherein the second DC / DC converter is configured to generate the second battery low voltage output from the second battery module low voltage output and to generate a second voltage droop on the second battery low voltage output.

9. a second battery pack comprising a third battery and a fourth battery, the third battery comprising a third battery module and a third DC / DC converter, the fourth battery comprising a fourth battery module and a fourth DC / DC converter, the third battery modules being electrically connected in series to produce a third battery high-voltage output, the fourth battery modules being electrically connected in series to produce a fourth battery high-voltage output, the third battery high-voltage output and the fourth battery high-voltage output being coupled to the high-voltage propulsion load; a second battery pack used to power a second set of loads, the third battery modules being electrically connected in parallel to generate a third battery module low voltage output, the third DC / DC converter generating a third battery low voltage output from the third battery module low voltage output, the fourth battery modules being electrically connected in parallel to generate a fourth battery module low voltage output, and the fourth DC / DC converter generating a fourth battery low voltage output from the fourth battery module low voltage output; a third power distribution unit that distributes the third battery low voltage output to a third set of the low voltage system loads; a fourth power distribution unit that distributes the fourth battery low-voltage output to a fourth set of the low-voltage system loads; The system of claim 8 further comprising:

10. 10. The system of claim 9, wherein the first power distribution unit, the second power distribution unit, the third power distribution unit, and the fourth power distribution unit are electrically connected to the low voltage system loads, whereby each of the low voltage system loads is supplied with power by at least two of the first power distribution unit, the second power distribution unit, the third power distribution unit, and the fourth power distribution unit.

11. the third battery comprises four third battery modules; 10. The system of claim 9, wherein the fourth battery comprises four of the fourth battery modules.

12. the third battery comprises five third battery modules; The system of claim 11 , wherein the fourth battery comprises five of the fourth battery modules.

13. the third battery comprises six of the third battery modules; The system of claim 12 , wherein the fourth battery comprises six of the fourth battery modules.

14. 10. The system of claim 9, wherein the third battery high voltage output and the fourth battery high voltage output are connected in parallel to produce a second battery pack high voltage output that supplies the second set of high voltage propulsion loads.

15. the third battery includes a third current flow control component connected between the third battery module low voltage output and the third battery module, the third current flow control component blocking current flow from the third battery module low voltage output to the third battery module and allocating the third battery module's contribution to the third battery module low voltage output based on the output voltage of the third battery module; 10. The system of claim 9, wherein the fourth battery comprises a fourth current flow control component connected between the fourth battery module low voltage output and the fourth battery module, the fourth current flow control component blocking current flow from the fourth battery module low voltage output to the fourth battery module and apportioning the fourth battery module's contribution to the fourth battery module low voltage output based on the output voltage of the fourth battery module.

16. 16. The system of claim 15, wherein the third current flow control component and the fourth current flow control component each include a diode.

17. the third DC / DC converter is configured to generate the third battery low voltage output from the third battery module low voltage output and to generate a third voltage droop on the third battery low voltage output; 16. The system of claim 15, wherein the fourth DC / DC converter is configured to produce the fourth battery low voltage output from the fourth battery module low voltage output and to generate a fourth voltage droop on the fourth battery low voltage output.

18. a first battery comprising a first battery module and a first DC / DC converter, the first battery modules being electrically connected in series to produce a first battery high-voltage output, the first battery modules being electrically connected in parallel to produce a first battery module low-voltage output, and the first DC / DC converter producing a first battery low-voltage output from the first battery module low-voltage output; a second battery comprising a second battery module and a second DC / DC converter, the second battery modules electrically connected in series to produce a second battery high-voltage output, the second battery modules electrically connected in parallel to produce a second battery module low-voltage output, and the second DC / DC converter producing a second battery low-voltage output from the second battery module low-voltage output; 1. A battery pack comprising:

19. the first battery comprises four of the first battery modules; 20. The battery pack of claim 18, wherein the second battery comprises four of the second battery modules.

20. the first battery comprises five of the first battery modules; 20. The battery pack of claim 19, wherein the second battery comprises five of the second battery modules.

21. the first battery comprises six of the first battery modules; 21. The battery pack of claim 20, wherein the second battery comprises six of the second battery modules.

22. 20. The battery pack of claim 18, wherein the first battery high voltage output and the second battery high voltage output are connected in parallel to produce a battery pack high voltage output.

23. the first battery includes a first current flow control component connected between the first battery module low voltage output and the first battery module, the first current flow control component blocking current flow from the first battery module low voltage output to the first battery module and allocating the first battery module's contribution to the first battery module low voltage output based on the output voltage of the first battery module; 20. The battery pack of claim 18, wherein the second battery comprises a second current flow control component connected between the second battery module low voltage output and the second battery module, the second current flow control component blocking current flow from the second battery module low voltage output to the second battery module and apportioning the second battery module's contribution to the second battery module low voltage output based on the output voltage of the second battery module.

24. 24. The battery pack of claim 23, wherein the first current flow control component and the second current flow control component each include a diode.

25. the first DC / DC converter is configured to generate the first battery low voltage output from the first battery module low voltage output and to cause a first voltage droop in the first battery low voltage output; 24. The battery pack of claim 23, wherein the second DC / DC converter is configured to produce the second battery low voltage output from the second battery module low voltage output and to induce a second voltage droop in the second battery low voltage output.

26. a battery module electrically connected in series to produce a first battery high voltage output and a battery module electrically connected in parallel to produce a second battery low voltage output; a DC / DC converter that generates a battery low voltage output from the battery module low voltage output; A battery comprising:

27. 27. The battery of claim 26, comprising four of said battery modules.

28. 28. The battery of claim 27, comprising five of said battery modules.

29. 30. The battery of claim 28 comprising six of said battery modules.

30. 27. The battery of claim 26, further comprising a current flow control component connected between the battery module low voltage output and the battery module, the current flow control component blocking current flow from the battery module low voltage output to the battery module and apportioning the contribution of the battery module to the battery module low voltage output based on the output voltage of the battery module.

31. 31. The battery of claim 30, wherein the current flow control component includes a diode.

32. 27. The battery of claim 26, wherein the DC / DC converter is configured to generate the battery low voltage output from the battery module low voltage output and to cause a voltage droop in the battery low voltage output.

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