Systems and methods for stabilizing DC bus voltage in a hybrid electric aircraft

Abstract

The hybrid electric genset (hybrid electric generator) includes a direct current (DC) bus, an engine, and a generator configured to receive mechanical power from the engine and generate a first alternating current (AC) power. The hybrid electric genset further includes an inverter configured to convert the first AC power to DC power and output the DC power to the DC bus. The hybrid electric genset further includes a controller configured to control the engine to increase or decrease the AC power output by the generator. The DC bus is configured to be attached to at least one battery pack or supercapacitor. The at least one battery pack or supercapacitor is configured to maintain a nominal voltage of the DC bus approximately at a nominal battery pack voltage of the at least one battery pack.

Description

[Technical field]

[0001] (Reference to Related Application) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 280,585, filed November 17, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] New aircraft designs are increasingly using electric motors for propulsion for a wide variety of reasons. Electric motors have a high power-to-weight ratio, a favorable torque curve, and mechanical simplicity, all of which are useful for aerospace applications such as vertical take-off and landing (VTOL) and / or fixed-wing aircraft. Electric motors use large amounts of power, and they may require a weight-optimized, reliable, on-board power source for the aircraft. Hybrid-electric powertrain systems can deliver significantly more energy than battery packs with available battery chemistries. Summary of the Invention

[0003] An exemplary HYBRID-ELECTRIC GENSET includes a direct current (DC) bus, an engine, and a generator configured to receive mechanical power from the engine and generate a first alternating current (AC) power. The HYBRID-ELECTRIC GENSET further includes an inverter configured to convert the first AC power to DC power and output the DC power to the DC bus. The HYBRID-ELECTRIC GENSET further includes a controller configured to control the engine to increase or decrease the AC power output by the generator. The DC bus is configured to attach to at least one battery pack or supercapacitor. The at least one battery pack or supercapacitor is configured to maintain a nominal voltage of the DC bus approximately at a nominal battery pack voltage of the at least one battery pack. [Brief description of the drawings]

[0004] [Figure 1] FIG. 1 is a schematic diagram of an example system for providing a direct current (DC) bus having a stable voltage, in accordance with an example embodiment.

[0005] [Diagram 2] 1 is a flowchart illustrating an example method for maintaining a stable DC bus voltage based on communications from an aircraft-level controller in accordance with an example embodiment.

[0006] [Diagram 3] 1 is a flowchart illustrating an example method for maintaining a stable DC bus voltage based on measurements by a hybrid electric genset level controller in accordance with an example embodiment.

[0007] [Figure 4] FIG. 1 is a schematic diagram of an example computing environment, according to an illustrative embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Described herein are various embodiments for implementing a hybrid electric aircraft. Such aircraft may utilize a high voltage electric bus to distribute power to various components of the aircraft, such as motors for the propulsion of the aircraft. In such hybrid electric aircraft, it may be desirable to stabilize the high voltage electric bus within a certain predetermined voltage range (e.g., near a nominal voltage level) so that the propulsion motors may operate satisfactorily. Since various embodiments described herein may use a direct current (DC) bus, in particular, it may be desirable to maintain a desired DC voltage range. Advantageously, various embodiments herein provide for efficiently maintaining a desired DC voltage range on the DC bus by directly connecting at least one battery or supercapacitor (supercapacitor) to the DC bus and further maintaining sufficient charge on the at least one battery or supercapacitor to maintain the desired DC voltage range on the DC bus. Such embodiments may prevent voltage spikes that may damage components of the hybrid electric or electric aircraft (e.g., electric motors and inverters for propulsion) and may avoid voltage spikes or sags (SAGS) that may adversely affect the reliability and / or performance and safety of the aircraft or systems of the aircraft.

[0009] In electrified aviation, various embodiments of the overall architecture may include one or more ELECTRIC POWER CREATION DEVICES (e.g., generators) connected via a low impedance connection to a high voltage DC bus and supplying power and energy to the bus. In the same vehicle, attached to that same DC bus may be one or more power consuming devices (e.g., electric motors) that receive power and energy from the DC bus. Various embodiments of an electrified aircraft may include energy storage devices such as battery packs or capacitors (e.g., supercapacitors) that may receive or deliver power as desired depending on the bus voltage and battery pack voltage.

[0010] If a high voltage generator is generating DC power directly or is operating through a passive rectifier, for example, the DC voltage generated by the motor may be primarily a function of the motor revolutions per minute (RPM) of the shaft that rotates the generator. For example, a permanent magnet electric motor may generate a voltage based on the rotational speed (RPM). In many applications, the coupling of voltage with RPM may create problems with motor control that limit the value of that electric motor in the system. To obtain additional utility from a brushless motor without permanent magnets, an EXTERNAL VOLTAGE REFERENCE may be used to maintain a desired voltage level. A unique problem in aviation is that flight safety requires precise control of power consumers over a wide range of flight conditions (electric motors driving fans, propellers, or other devices) that may not match the characteristics of the contributors (such as electric brushless generators). If the high voltage generator used is rotating slower than expected for any reason, the bus voltage may be lower than desired and any motors on that bus may operate lower than expected, which may result in an unsafe or undesirable condition. If such a high voltage generator is rotating faster than expected, the bus voltage may be high and motor performance may again deviate from expected or desired values. Thus, for applications of generators and motors sharing a common bus, it is desirable to design the generators and motors used accordingly. For energized aviation, precise control of any motor is desirable to provide lift, thrust, aircraft attitude, etc. for an aircraft. Thus, compared to other non-aviation related embodiments, it is desirable to better control the power supplied to any motor (e.g., through a DC bus) by maintaining the power supplied to the motor at a voltage that keeps the motor operating at a desired performance level.Additionally, the power supplied to the motor may be rapidly adjustable so that the pilot or control system of the aircraft may control the motor over a wide range of uses as needed (e.g., to provide the pilot or control system with flexibility and a wide range over which the motor may be controlled). In various embodiments, an inverter may be used to regulate the output voltage of an upstream generator that may be used to supply the high voltage bus. The inverter may be used to precisely control the downstream motor under various load conditions.

[0011] Inverters may allow system designers to extend the operating envelope of any motor and / or generator by controlling the current. For these inverters to function properly, the bus voltage supplying power to the inverter may advantageously be set and maintained by other means than the motor RPM (because the voltage on the bus is difficult to precisely control if only the motor RPM is used). Maintaining the bus voltage is related to expected variations in capacitance and loads that are present under all system operating conditions. If the bus has, for example, a rapidly changing load or too low a capacitance (which acts like inertia in a similar mechanical system), the high voltage bus and power electronic system may become unstable.

[0012] In various embodiments, the bus voltage may be established and maintained using a battery pack, a capacitor, or any combination thereof. Such devices may add capacitance and / or electrical inertia to the bus and may be passive, meaning that their intended function is entirely governed by physics and may not require control or intervention (e.g., by a controller or control system). Supercapacitors (or ultracapacitors) typically lack significant energy storage, but additionally have the desirable configuration of high capacitance. Supercapacitors may respond to very rapid fluctuations with enormous power (e.g., energy over time). In short, they may provide stability to the bus for fluctuations of relatively short duration, low amplitude, or where the product of those two values ​​is relatively low. Batteries may be desirable because they have significant capacitance for bus stability and may store high energy. Batteries may not be able to respond to voltage changes as quickly as supercapacitors. This is because batteries often have a more limited rate of power usage, especially in charging (where the discharge power capacity is often 10X or more higher than the charge capacity). For example, if it is necessary to draw current from the bus to maintain a desired voltage level (e.g., to charge the battery), the battery may not absorb that current as quickly as desired in a particular embodiment (depending on the special characteristics of the selected battery). However, in some embodiments, one or more battery packs alone may be sufficient to maintain the desired voltage level on the bus.

[0013] Thus, various embodiments are described herein that allow independent control of one or more upstream generators and downstream motors by adding battery packs and / or supercapacitors with appropriate designs to maintain a desired voltage on the DC bus. In an architecture where the voltage and capacitance of those storage elements are directly electrically connected to the main motor control elements on the bus (and are not shielded by other switches, chargers, or similar devices), the battery packs and / or supercapacitor banks provide a lightweight and effective anchor or set point for the high voltage DC bus.

[0014] Battery packs in aircraft may be deployed with hybrid power generation systems to support system safety standards applicable to flight articles. If these battery packs and / or supercapacitors are selected not only to provide the required power or energy, but also to be set to the correct or desired voltage and connected to the high voltage motor controller, the battery packs and / or supercapacitor banks may provide a second valuable advantage of bus stabilization by connecting the battery packs and / or supercapacitor banks directly to the DC bus. The battery packs and / or supercapacitor banks may be advantageously selected for a given aircraft such that it has a target voltage, but the actual voltage on the bus may naturally vary with state of charge (SOC) and varying electrical loads. The battery packs and / or supercapacitor banks may be advantageously selected such that the actual voltage is unlikely to fall outside the desired range. If the actual voltage falls outside the desired range, or is expected to fall outside the desired range, the aircraft controller or a HYBRID-ELECTRIC GENSET on the aircraft may adjust the power (e.g., torque) provided to the generator to add or reduce power provided to the DC bus to maintain the voltage within the appropriate desired range. The RPM may also be maintained at a constant or relatively constant level or within a predetermined range. Thus, the power provided to the generator or otherwise output to the power shaft may be adjusted by adjusting the torque output by the engine, rather than through adjustment of the RPM of the engine's output. Furthermore, it may be desirable to maintain an actual voltage set point, which may vary, within a desired tolerance range for operating the aircraft's electric motors or other components. In addition, the battery pack may advantageously serve as a supplemental power source for driving the aircraft's motors or other components in the event of a failure of the hybrid-electric genset's generator or other components.This may therefore provide an added level of system safety and FAULT TOLERANCE.

[0015] FIG. 1 is a schematic diagram of an exemplary system 100 for providing a direct current (DC) bus with a stable voltage, according to an exemplary embodiment. The system 100 includes a hybrid-electric genset 161 including a controller 162, an engine 163 connected to a generator 165 by a shaft 164, an inverter 166, and a direct current (DC) bus 167. The engine 163 may provide mechanical (e.g., rotational) power to the generator 165 via the shaft 164, such that the generator 165 generates electrical power (e.g., alternating current (AC) power). The AC power from the generator 165 is converted to DC power by the inverter 166 and provided to the DC bus 167. The inverter 166 may also be able to convert AC power from the DC bus 167 to AC power, which the generator 165 may use to provide electrical power output to the shaft (e.g., when the generator 165 serves as a motor to power aircraft components such as propulsion). The controller 162 may control any of the components of the hybrid electric genset 161 (e.g., control the RPM output to the generator 165). The controller 162 may also measure characteristics of the DC bus 167, such as the voltage on the DC bus and / or the current flowing through the DC bus 167.

[0016] The system 100 further includes aircraft components such as inverters 172 and 176 connected to the DC bus 167, electric motors 174 and 178 connected to the inverters 172 and 176, a controller 180, and battery packs 182 and 184. In various embodiments, the aircraft components may have supercapacitors instead of or in addition to the battery packs 182 and 184. In various embodiments, one or more battery packs and / or supercapacitors may be included as part of the hybrid electric genset 161 and may be connected directly to a DC bus in the hybrid electric genset 161, regardless of whether the aircraft components have separate batteries and / or supercapacitors. Although FIG. 1 shows multiple connections running from the DC bus 167 of the hybrid electric genset 161 to the aircraft components 170, other configurations are contemplated herein, such as a single connection to another bus of the aircraft components 170 or where the DC bus 167 is itself part of the aircraft components 170. The controller 180 may be in communication with the control device 162. In this manner, controller 180 may send information to controller 162 about how inverters 172 and 176, electric motors 174 and 178 are currently being controlled / used, or how the controller plans to use these components in the future. Controller 180 may monitor and measure the status of battery packs 182 and 184 and send information related to their status (e.g., any measurements related to state of charge, voltage, current flowing to or from the batteries, etc.) to controller 162. In embodiments in which a battery or supercapacitor is included in hybrid electric jump set 161, controller 162 may monitor such components for similar information.

[0017] Battery packs 182 and 184 may represent a single battery module or may be two or more separable modules. Regardless of the form factor, the battery cells, packs, modules, etc. may be combined to maintain a DC bus voltage as described herein. For example, in an exemplary aircraft, the batteries may maintain an equal nominal voltage, such as 400 volts (V), 800V, etc. For example, a battery system may be one or more batteries connected in series to set the voltage of the battery system and the DC bus. For example, a battery module may be 200 volts (V), so one battery module may be used to have a 200V system, two modules may be used in series to have a 400V system, four modules may be used in series to have an 800V system, etc. The modules may be further connected in parallel with other battery modules to increase the power available from the battery system at the desired voltage. The batteries may be designed or selected to have a desired capacitance such that the battery system can effectively maintain a nominal voltage on the DC bus as described herein, even while power is being input to the DC bus (e.g., generated by a motor / generator) and / or output from the DC bus (e.g., consumed by an electric motor of a propulsion system). For example, a set of four battery modules connected in series for an 800V system may have a capacitance of 29 Farads (F) such that the batteries act as a capacitor connected to the DC bus. If two sets of four series connected battery modules are connected in parallel to provide more power in an 800V system, the two sets together may have a capacitance of 58F. If three sets of four series connected battery modules are connected in parallel to provide even more power in an 800V system, the two sets may have a capacitance of 87F.Thus, in various examples, different configurations of batteries may provide a capacitance to the DC bus between 20 and 110 Farads (F), or may provide a capacitance to the DC bus much higher than 110 F. As the examples described herein are illustrative only, the batteries may be sized and designed to desirably provide a particular capacitance for the aircraft DC bus.

[0018] In various embodiments, an aircraft may include fewer, additional, or different elements than those shown in FIG.

[0019] FIG. 2 is a flow chart illustrating an example method 200 for maintaining a stable DC bus voltage based on communication from an aircraft-level controller, according to an example embodiment. In operation 202, a controller (e.g., controller 162 of FIG. 1 ) may receive communication including power consumption information or battery status information from an aircraft controller (e.g., controller 180 of FIG. 1 ). Power consumption information may relate to how power is currently being used, for example, by an aircraft inverter or electric motor. Power consumption information may relate to how power is being used by an aircraft inverter or electric motor (e.g., information about how a controller intends to increase or decrease power provided to a motor at a particular time in the future). Battery status information may include state of charge, actual voltage, and / or current flowing into or out of the system's batteries or SUPERCAPACITORS.

[0020] Thus, in operation 204, the controller may determine how the power output of the hybrid-electric genset should be adjusted to maintain the desired voltage range on the DC bus. For example, if the charge level of the battery is too low to maintain the desired voltage, the controller may send a command in operation 206 to increase the power output of the hybrid-electric genset so that there is enough power to charge the battery. In another example, if the aircraft motors are expected to require significantly more power than currently being used or currently being used, the controller may send a command in operation 206 to increase the power output of the hybrid-electric genset. The power output may also be reduced as well. In either case, the controller may adjust this overall power output to the DC bus by varying the RPM provided by the engine to the generator. Thus, since the battery pack and / or supercapacitor can maintain the DC bus at a desired voltage level, the battery pack and / or supercapacitor may reduce the need to provide real-time adjustments to the power output of the hybrid-electric genset, although some control or adjustment of the RPM may still be desirable in various embodiments.

[0021] 3 is a flow chart illustrating an example method 300 for maintaining a stable DC bus voltage based on measurements by a hybrid electric genset level controller, according to an example embodiment. Method 300 is similar to method 200, except that method 300 contemplates measurements that may be made by the hybrid electric genset controller (e.g., controller 162) itself, rather than receiving such measurements or information from another controller (e.g., an overall aircraft system controller, such as controller 180 of FIG. 1).

[0022] At operation 302, aspects of the power available at or flowing through the DC bus are measured by the controller. If the DC bus is measurable by the system-wide aircraft controller, operation 302 may also be performed by the system-wide aircraft controller. Similarly, if the battery and / or supercapacitor are packaged as part of the hybrid-electric genset rather than located as part of the overall aircraft system, the controller may also measure the state of the battery / supercapacitor (e.g., state of charge, current, voltage, etc.) at operation 302. At operation 304, the controller determines how the power output of the hybrid-electric genset should be adjusted based on the measurements. For example, if the DC bus voltage is approaching outside of a desired range, it may be desirable to send instructions to components of the hybrid-electric genset at operation 306 to adjust the power output of the hybrid-electric genset based on the determination at operation 304 to ensure that the DC bus voltage remains within the desired voltage range.

[0023] 4 is a schematic diagram of an example of a computing environment including a general-purpose computing system environment 100, such as a desktop computer, laptop, smartphone, tablet, or any other such device capable of executing instructions, such as, for example, instructions stored in a non-transitory computer-readable medium. Various computing devices as disclosed herein (e.g., controller 162, controller 180, or any other computing devices in communication with those controllers that may be part of other components of the aircraft) may be similar to computing system 100 or may include some components of computing system 100. Additionally, while described and illustrated in the context of a single computing system 100, those skilled in the art will also understand that various tasks described below may be performed in a distributed environment having multiple computing systems 100 linked via a local or wide area network where executable instructions may be associated with and / or executed by one or more of the multiple computing systems 100.

[0024] In its most basic configuration, the computing system environment 100 typically includes at least one processing unit 102 and at least one memory 104, which may be linked via a bus 106. Depending on the exact configuration and type of computing system environment, the memory 104 may be volatile (such as RAM 110), non-volatile (such as ROM 108, flash memory, etc.), or a combination of the two. The computing system environment 100 may have additional configuration and / or functionality. For example, the computing system environment 100 may include additional storage devices (removable and / or non-removable), including, but not limited to, magnetic or optical disks, tape drives, and / or flash drives. Such additional memory devices may be made accessible to the computing system environment 100, for example, by a hard disk drive interface 112, a magnetic disk drive interface 114, and / or an optical disk drive interface 116. As will be appreciated, these devices, each linked to the system bus 306, enable reading from and writing to the hard disk 118, reading from and writing to the removable magnetic disk 120, and / or reading from and writing to a removable optical disk 122, such as a CD / DVD ROM or other optical medium. The drive interfaces and their associated computer-readable media enable non-volatile storage of computer-readable instructions, data structures, program modules, and other data for the computing system environment 100. Those skilled in the art will further appreciate that other types of computer-readable media capable of storing data may be used for this same purpose.Examples of such media devices include, but are not limited to, magnetic cassettes, flash memory cards, digital video disks, Bernoulli cartridges, random access memory, nano drives, memory sticks, other read / write and / or read-only memory, and / or any other method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Any such computer storage media may be part of the computing system environment 100.

[0025] A number of program modules may be stored in one or more of the memory / media devices. For example, a basic input / output system (BIOS) 124, containing the basic routines that help to transfer information between elements within the computing system environment 100, such as during start-up, may be stored in ROM 108. Similarly, the RAM 110, the hard drive 118, and / or the peripheral memory devices may be used to store computer-executable instructions, including an operating system 126, one or more application programs 128 (which may include functionality disclosed herein, for example), other program modules 130, and / or program data 122. Additionally, computer-executable instructions may be downloaded to the computing environment 100 as needed, for example, via a network connection.

[0026] An end user may enter commands and information into the computing system environment 100 through input devices such as a keyboard 134 and / or a pointing device 136. Although not shown, other input devices may include a microphone, joystick, game pad, scanner, etc. These and other input devices are typically connected to the processing unit 102 by a peripheral interface 138, which is in turn coupled to the bus 106. The input devices may be connected directly or indirectly to the processor 102 through an interface such as, for example, a parallel port, game port, Firewire, or universal serial bus (USB). To view information from the computing system environment 100, a monitor 140 or other type of display device may be connected to the bus 106 through an interface, for example, through a video adapter 132. In addition to the monitor 140, the computing system environment 100 may also include other peripheral output devices, not shown, such as speakers and printers.

[0027] The computing system environment 100 may utilize logical connections to one or more computing system environments. Communications between the computing system environment 100 and a remote computing system environment may be exchanged through an additional processing device, such as a network router 152, responsible for network routing. Communications with the network router 152 may occur through a network interface component 154. Thus, within such a networked environment, e.g., the Internet, the World Wide Web, a LAN, or other similar types of wired or wireless networks, it will be understood that program modules illustrated relative to the computing system environment 100, or portions thereof, may be stored in memory storage devices of the computing system environment 100.

[0028] The computing system environment 100 may include localization hardware 186 for determining a location of the computing system environment 100. In some examples, the localization hardware 156 may include, by way of example only, a GPS antenna, an RFID chip or reader, a WIFI antenna, or other computing hardware that may be used to capture or transmit signals that may be used to determine the location of the computing system environment 100.

[0029] Although the present disclosure has described specific embodiments, it will be understood that the claims are not intended to be limited to these embodiments unless expressly set forth in the claims. On the contrary, the present disclosure is intended to cover alternatives, modifications, and equivalents that may be included within the spirit and scope of the present disclosure. Moreover, in the detailed description of the present disclosure, numerous specific details are described in order to provide a thorough understanding of the disclosed embodiments. However, it will be apparent to those skilled in the art that systems and methods consistent with the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure various aspects of the present disclosure.

[0030] Some portions of the detailed description of this disclosure are presented in terms of procedures, logic blocks, processing, and other symbolic representations of operations on data bits within a computer or digital system memory. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. A procedure, logic block, process, or the like, is herein generally conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, although not necessarily, these physical manipulations take the form of electrical or magnetic data that can be stored, transferred, combined, compared, and otherwise manipulated in a computer system or similar electronic computing device. For convenience, and with common usage, such data will be referred to as bits, values, elements, symbols, characters, terms, numbers, or the like with respect to the various embodiments presently disclosed.

[0031] However, it should be noted that these terms should be interpreted as referring to physical operations and quantities, and are merely convenient labels to be further interpreted in light of the terms commonly used in the art.Unless otherwise indicated, as will be apparent from the discussion herein, throughout the discussion of the present embodiments, discussions using terms such as "determine" or "output" or "transmit" or "record" or "arrange" or "store" or "display" or "receive" or "recognize" or "utilize" or "generate" or "provide" or "access" or "confirm" or "notify" or "deliver" will be understood to refer to the operations and processes of a computing system or similar electronic computing device that manipulates and transforms data.Data is represented as physical (electronic) quantities in the registers and memory of the computer system, and is transformed into other data similarly represented as physical quantities in the computer system memory or registers, or other such information storage, transmission, or display devices as described herein or otherwise understood by those skilled in the art.

[0032] In an example embodiment, any of the operations described herein may be implemented, at least in part, as computer-readable instructions stored on a computer-readable medium or memory. After execution of the computer-readable instructions by a processor, the computer-readable instructions may cause a computing device to perform an operation.

[0033] The foregoing description of exemplary embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or limited to the precise form disclosed, and modifications and variations are possible in light of the above teachings or from practice of the disclosed embodiments. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims

1. Hybrid electric Genset and an aircraft component; The hybrid electric generator set comprises: a direct current (DC) bus; The engine and a generator configured to receive mechanical power from the engine and generate a first alternating current (AC) power; a first inverter configured to convert the first AC power to DC power and output the DC power to the DC bus; a controller configured to control the engine to increase or decrease the AC power output by the generator; The aircraft component comprises: an electric motor; a second inverter configured to receive DC power from the DC bus and convert the DC power to second AC power for use by the electric motor; at least one battery pack connected to the DC bus, the at least one battery pack configured to maintain a nominal voltage of the DC bus approximately at a nominal battery pack voltage of the at least one battery pack; system.

2. The system described in claim 1, wherein the controller is a first controller, and further wherein the aircraft component further includes a second controller in communication with the first controller, and the first controller is configured to receive communications from the second controller including information regarding at least one of the state of charge of the at least one battery pack, the current power consumption of the electric motor, or the estimated future power consumption of the electric motor.

3. 3. The system of claim 2, wherein the first controller is configured to determine, based on the communication, how to adjust the engine to achieve a desired power output of the hybrid-electric genset, and the first controller is further configured to adjust an output of the engine to achieve the desired power output.

4. 10. The system of claim 1, wherein the controller is configured to receive a measurement of a characteristic of power on or passing through the DC bus, the characteristic being an actual voltage of the DC bus or a current flowing through the DC bus, and the controller is configured to adjust the engine to achieve a desired power output of the hybrid-electric genset based on the measurement.

5. 2. The system of claim 1, wherein the DC power is a first DC power, and wherein the hybrid-electric genset further includes a third inverter configured to receive second DC power from the DC bus and convert the second DC power to third AC power for use by the generator.

6. The system of claim 1 , wherein the electric motor is configured to drive a propulsion mechanism of an aircraft.

7. The system of claim 1 , wherein the hybrid-electric genset and the aircraft component are each installed on a single aircraft.

8. The system of claim 1 , wherein the at least one battery pack is directly electrically connected to the DC bus.

9. 10. The system of claim 1, wherein the at least one battery pack has a nominal capacitance of 29 Farads (F), 58 F, or 87 F.

10. 1. A method for controlling a voltage of a DC bus of an aircraft, comprising: connecting at least one battery pack or supercapacitor to the DC bus, wherein the at least one battery pack or supercapacitor is electrically connected directly to the DC bus; controlling, with a controller, a mechanical power output by the engine to a generator, the generator outputting a first alternating current (AC) power from the mechanical power output of the engine; converting the first AC power from the generator to direct current (DC) power with a first inverter; outputting the DC power from the first inverter to the DC bus; controlling, by the controller, a second inverter configured to convert the DC power from the DC bus into second AC power, and providing the second AC power to drive an electric motor of the aircraft; at least one battery pack or supercapacitor configured to maintain a nominal voltage of the DC bus approximately at a nominal battery pack voltage of the at least one battery pack; method.

11. the at least one battery pack or supercapacitor having a low charge; the second AC power used by the electric motor is currently above or will be above a predetermined threshold; or the actual voltage of the DC bus or the actual current flowing through the DC bus is outside a predetermined desired range; further comprising determining The method of claim 10.

12. the at least one battery pack or supercapacitor having the low charge; the second AC power used by the electric motor is currently above or will be above the predetermined threshold; or the actual voltage of the DC bus or the actual current flowing through the DC bus being outside the predetermined desired range; Based on the above decision, adjusting, by the controller, the mechanical power output of the engine to achieve a desired power output. The method of claim 11.

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