Power distribution circuit for vehicle with energy regeneration

Abstract

To provide an electric aircraft having a DC bus and a plurality of batteries each coupled in parallel to the DC bus.SOLUTION: At least one switch is coupled in series between at least one battery of the plurality of batteries and a DC bus, and a plurality of inverter circuits are each coupled in parallel to the DC bus. A plurality of motors are coupled to the plurality of inverter circuits, respectively. In various embodiments, an electric aircraft further includes a plurality of switches, each switch coupled in series between respective batteries of the plurality of batteries.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 969,232, filed February 3, 2020, entitled "POWER DISTRIBUTION CIRCUITS FOR VEHICLES WITH ENERGY REGENERATION," which is incorporated by reference in its entirety for all purposes.

[0002] This application is related to U.S. utility patent application Ser. No. 17 / 165,565, entitled "REDUNDANT POWER DISTRIBUTION CIRCUITS INCLUDING DC / DC CONVERTERS," filed on February 2, 2021, and U.S. utility patent application Ser. No. 17 / 165,742, entitled "REDUNDANT POWER DISTRIBUTION CIRCUITS FOR ELECTRIC VEHICLES," filed on February 2, 2021, which are filed concurrently and are co-owned by the same applicant, and which are hereby incorporated by reference in their entireties for all purposes. [Background technology]

[0003] The described embodiments relate generally to electrical circuits for rechargeable electric vehicles. More particularly, the embodiments relate to power distribution circuits that enable regenerative charging of batteries in electric vehicles. Summary of the Invention [Problem to be solved by the invention]

[0004] Currently, there are a variety of electric vehicles that use multiple batteries to store energy used for propulsion. A new electrical circuit is needed that protects the batteries from fault events while at the same time allowing for regenerative charging of the batteries. [Means for solving the problem]

[0005] In some embodiments, the electric vehicle includes a DC bus and a plurality of batteries, each coupled in parallel to the DC bus. At least one switch is coupled in series between at least one battery of the plurality of batteries and the DC bus, and a plurality of inverter circuits are each coupled in parallel to the DC bus. A plurality of motors are each coupled to a respective inverter circuit of the plurality of inverter circuits. In various embodiments, the electric vehicle includes a plurality of switches, each coupled in series between a respective battery of the plurality of batteries.

[0006] In some embodiments, the electric vehicle comprises circuitry coupled in series with a respective battery of the plurality of batteries and arranged to unidirectionally drain current from the respective battery of the plurality of batteries to the DC bus. In various embodiments, the circuitry comprises at least one diode. In some embodiments, each switch of the plurality of switches is arranged to bypass the circuitry coupled in series with the respective battery of the plurality of batteries. In various embodiments, the electric vehicle further comprises a controller configured to detect a failed battery of the plurality of batteries and in response open a respective switch of the plurality of switches to electrically isolate the failed battery from the DC bus.

[0007] In some embodiments, the electric vehicle further comprises a controller configured to detect a regenerative event and in response close at least one switch to transfer power from the DC bus to at least one battery of the plurality of batteries. In various embodiments, each of the plurality of inverter circuits is configured to generate a polyphase AC output used to drive one or more of the plurality of motors. In some embodiments, each of the plurality of inverter circuits is configured to generate a three-phase output. In some embodiments, the three-phase output generated by each of the plurality of inverter circuits operates between 0 and 400 volts AC at a frequency between 0 and 3 KHz. In various embodiments, each of the plurality of motors is coupled to a respective propeller.

[0008] In some embodiments, each of the plurality of motors is a synchronous AC permanent magnet motor. In various embodiments, the plurality of motors includes at least twelve motors.

[0009] In some embodiments, a circuit includes a plurality of batteries and a plurality of inverters, each coupled to a respective battery of the plurality of batteries and configured to generate a plurality of input phases. A plurality of interphase transformers, each receiving one or more of the plurality of input phases, generate a combined single drive phase. A motor is configured to receive the combined single drive phase from each of the plurality of interphase transformers. In various embodiments, at least one interphase transformer of the plurality of interphase transformers receives an input phase from each of the plurality of inverters.

[0010] In some embodiments, a respective interphase transformer of the plurality of interphase transformers receives an input phase from a respective one of the plurality of inverters. In various embodiments, each interphase transformer of the plurality of interphase transformers electrically isolates each of the plurality of input phases from one another. In some embodiments, the circuit further comprises a controller configured to control operation of at least one of the inverters to control the speed and power of the motor. In various embodiments, the controller is configured to detect a failed battery of the plurality of batteries and in response disable a respective inverter coupled to the failed battery of the plurality of inverters.

[0011] In some examples, one or more of the plurality of inverters are configured to charge one or more of the plurality of batteries when the motor generates power during a regenerative event. In various examples, the motor is a synchronous AC permanent magnet motor. In some examples, the motor propels an electric vehicle. In some examples, the motor is coupled to a propeller.

[0012] In some embodiments, the electric vehicle includes a plurality of batteries and a plurality of inverters, each inverter coupled to a respective battery of the plurality of batteries and configured to generate a plurality of phases. A motor is configured to receive each of the plurality of phases from each of the plurality of inverters. In various embodiments, each inverter of the plurality of inverters is configured to generate three phases. In some embodiments, the electric vehicle further includes a controller configured to detect a failed battery and in response disable a respective inverter of the plurality of inverters coupled to the failed battery.

[0013] In some embodiments, the controller is configured to control other inverters of the plurality of inverters to continue operation of the motor with a reduced number of phases. In various embodiments, one or more of the plurality of inverters are configured to transfer power to one or more of the plurality of batteries when the motor generates power during a regeneration event. In some embodiments, the motor is coupled to a propeller. In various embodiments, the motor is a synchronous AC permanent magnet motor. In some embodiments, the electric vehicle includes at least twelve motors.

[0014] In some embodiments, the circuit comprises a plurality of batteries and a plurality of DC-DC converters, each coupled to a respective battery of the plurality of batteries. A DC bus is coupled in parallel to each of the plurality of DC-DC converters, and a plurality of inverter circuits are each coupled in parallel to the DC bus. A plurality of motors are each coupled to a respective inverter circuit of the plurality of inverter circuits. In various embodiments, the circuit further comprises a controller configured to monitor a voltage of the DC bus and a voltage of at least one battery of the plurality of batteries. In some embodiments, the controller is configured to command at least one of the plurality of DC-DC converters to deliver a voltage from the DC bus to at least one of the plurality of batteries based on a comparison of the voltage of the DC bus and the voltage of the at least one battery.

[0015] In some embodiments, the controller is configured to direct at least one of the plurality of DC-DC converters to transfer power from the DC bus to at least one of the plurality of batteries in response to at least one motor of the plurality of motors generating power during a regenerative event. In various embodiments, the controller is configured to detect a failure of at least one battery of the plurality of batteries and in response to direct one or more respective DC-DC converters coupled to one or more failed batteries of the plurality of batteries of the plurality of DC-DC converters to isolate the one or more failed batteries from the DC bus.

[0016] In some embodiments, each of the plurality of DC-DC converters includes a control circuit configured to monitor a voltage of the DC bus and to transfer power from the DC bus to a respective battery when the voltage of the DC bus exceeds a threshold voltage, the threshold voltage being based on a voltage of at least one battery of the plurality of batteries. In various embodiments, the control circuit is configured to transfer power from the DC bus to at least one of the plurality of batteries when at least one motor of the plurality of motors generates power during a regeneration event. In some embodiments, the control circuit is configured to detect a failure of at least one battery of the plurality of batteries and in response command one or more respective DC-DC converters coupled to the failed battery or batteries of the plurality of batteries to isolate the failed battery or batteries from the DC bus. In various embodiments, each of the plurality of motors is an AC motor. In some embodiments, the plurality of motors propel an electric vehicle. In some embodiments, each of the plurality of motors is coupled to a respective propeller.

[0017] In some embodiments, an electric vehicle includes a plurality of batteries and a plurality of DC-DC converters configured to generate DC power, each coupled to a respective battery of the plurality of batteries and coupled to a common DC bus, a plurality of inverter circuits coupled to the common DC bus, a plurality of electric motors each coupled to a respective inverter circuit of the plurality of inverter circuits, each motor of the plurality of electric motors propelling the vehicle.

[0018] In some embodiments, the electric vehicle further includes a controller configured to monitor a voltage of the common DC bus and a voltage of each cell of the plurality of batteries. In various embodiments, when the common DC bus voltage exceeds a voltage of at least one cell of the plurality of batteries, the controller directs at least one DC-DC converter of the plurality of DC-DC converters to transfer power from the common DC bus to a respective cell of the plurality of batteries. In some embodiments, in response to detecting a failure of a cell of the plurality of batteries, the controller directs a respective DC-DC converter of the plurality of DC-DC converters coupled to the failed cell to isolate the failed cell from the common DC bus.

[0019] In some embodiments, each DC-DC converter of the plurality of DC-DC converters includes a control circuit configured to monitor a voltage of the common DC bus and to transfer power from the common DC bus to a respective battery when the voltage of the common DC bus exceeds a threshold voltage. In various embodiments, in response to detecting a failure of a battery of the plurality of batteries, the control circuit commands a respective DC-DC converter of the plurality of DC-DC converters coupled to the failed battery to isolate the failed battery from the common DC bus. In some embodiments, each of the plurality of electric motors is an AC motor. In various embodiments, each of the plurality of electric motors is coupled to a respective propeller.

[0020] In some embodiments, a circuit includes a first battery coupled to a first DC-DC converter and a second battery coupled to a second DC-DC converter. A DC bus is coupled in parallel to the first and second DC-DC converters. A first inverter is coupled to the DC bus and a second inverter is coupled to the DC bus. A first motor is coupled to the first inverter and a second motor is coupled to the second inverter. In various embodiments, the first and second inverters are coupled in parallel to the DC bus.

[0021] In some embodiments, the circuit further comprises a controller configured to monitor a voltage of the DC bus, a voltage of the first battery, and a voltage of the second battery. In various embodiments, the controller directs the first DC-DC converter to transfer power from the DC bus to the first battery in response to the voltage of the DC bus being greater than a voltage of at least one of the first and second batteries. In some embodiments, the controller directs the first DC-DC converter to isolate the first battery from the DC bus in response to detecting a fault in the first battery. In various embodiments, the controller is configured to direct the first DC-DC converter to transfer power to the first battery when the first motor generates power during a regeneration event.

[0022] In some embodiments, the controller is configured to command the first DC-DC converter to transfer power to the first battery during a regenerative event. In various embodiments, the controller is configured to detect a fault in the first battery and in response isolate the first battery from the DC bus. In some embodiments, the first and second motors are AC motors. In various embodiments, the first and second motors propel the electric vehicle. In some embodiments, each of the first and second motors is coupled to a respective propeller.

[0023] Many benefits are achieved by the present invention over conventional techniques. For example, embodiments of the present invention provide the ability to isolate faults in the power distribution circuitry from other components and maintain power delivery to the traction motors during a fault. Embodiments also allow for regeneration events to recharge the batteries, and individual battery circuits are isolated to prevent charge shuttling between the batteries. These and other embodiments of the present invention, along with many of the advantages and features of the present invention, are described in more detail in the following text and in conjunction with the accompanying drawings.

[0024] For a better understanding of the nature and advantages of the present disclosure, reference should be made to the following description and the accompanying figures. However, it should be understood that each of the figures is provided for illustrative purposes only and is not intended as a definition of the limits of the scope of the present disclosure. Moreover, as a general rule, and unless otherwise clear from the description, when elements in different figures use the same reference numbers, the elements are generally identical or at least similar in function or purpose. [Brief description of the drawings]

[0025] [Figure 1] FIG. 2 is a schematic diagram of a power distribution circuit including protection diodes and bypass switches according to an embodiment of the present disclosure. [Diagram 2] 1 is a schematic diagram of a power distribution circuit including a breaker according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a schematic diagram of a power distribution circuit including an inverter and an interphase transformer according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram of a power distribution circuit including an inverter and a 12-phase motor according to an embodiment of the present disclosure. [Diagram 5] FIG. 2 is a schematic diagram of a power distribution circuit including a DC-DC converter coupled to an inverter via a DC bus, according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is a schematic diagram of a power distribution circuit including a common power shaft driven by multiple motors, according to an embodiment of the present disclosure. [Figure 7]FIG. 1 is a diagram of an electrically powered aerial vehicle including a power distribution circuit according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The techniques disclosed herein relate generally to electrical circuits for electric vehicles. More specifically, the techniques disclosed herein relate to power distribution circuits for electric vehicles that include energy recovery capabilities and redundant battery systems. Various inventive embodiments are disclosed herein, including methods, processes, systems, devices, and the like.

[0027] To better understand the features and aspects of the power distribution circuit for an electric vehicle according to the present disclosure, further background of the present disclosure is provided in the following section by discussing one specific embodiment of an electric vehicle according to an embodiment of the present disclosure. These embodiments are for example purposes only, and other embodiments may be used in electric vehicles such as, but not limited to, automobiles, trains, buses, motorcycles, and scooters.

[0028] FIG 1 illustrates a simplified schematic diagram of a power distribution circuit 100 for an electric vehicle, according to an embodiment of the present disclosure. As shown in FIG 1, the power distribution circuit 100 includes a number of separate batteries 105a-105c, each of which may include a number of cells. In one embodiment, each battery 105a-105c produces a DC voltage of approximately 600 volts, although in other embodiments, the batteries may produce different voltages. Any number of batteries may be used, with some embodiments including between 3 and 15 batteries.

[0029] Each battery is coupled in parallel to a common DC bus 110 that is coupled to a number of inverter circuits 115a-c. Each inverter circuit 115a-c is configured to generate a polyphase AC output that can be used to drive an individual motor 120a-c, which in one embodiment can be a synchronous AC permanent magnet type motor. In some embodiments, each inverter circuit 115a-c is configured to generate a three-phase output operating between 0 and 400 volts AC at a frequency between 0 and 3 kHz, although one skilled in the art will appreciate that other numbers of phases, output voltages, output frequencies, and types of electric motors can be used without departing from the invention.

[0030] As further shown in FIG. 1, diodes 125a-125c are coupled in series between each battery 105a-105c and the DC bus 110. The diodes 125a-125c are oriented to allow the battery 105a-105c to provide current to the DC bus 110 and to block current from flowing back from the DC bus to the battery. Such a configuration may be used to protect the battery 105a-105c in the event of a battery failing in a short circuit condition, which would cause the other batteries to bleed current to the failed battery. In a further embodiment, the diodes 125a-125c may prevent charge shuttling between the batteries 105a-105c caused by each battery having a different charge state. More specifically, in some embodiments, each battery 105a-105c may have different age and / or charge characteristics such that the diodes 125a-125c prevent batteries having a relatively higher level of charge from back-charging batteries having a relatively lower level of charge. Such charge shuttling may result in efficiency loss, heat generation, and general system instability.

[0031] Each circuit includes a bypass switch 130a-130c that selectively bypasses a respective diode 125a-125c to allow the batteries 105a-105c to receive regenerative power generated by the motors 120a-120c. More specifically, when engaged, the respective bypass switch 130a-130c allows power to be transferred from the DC bus 110 to the batteries 105a-105c so that the batteries may be recharged with power generated by the motors 120a-120c. In some embodiments, the bypass switches 130a-130c may be coupled to a controller 135 that monitors parameters of the batteries 105a-105c and the DC bus 110. The controller 135 may be configured to engage the bypass switches 130a-130c to bypass the respective diodes 125a-125c when the condition of the DC bus 110 indicates that a regenerative charging event is in progress (e.g., when the voltage level on the DC bus is greater than the voltage level of at least one of the batteries).

[0032] More specifically, in some embodiments, motors 120a-120c are configured to act as generators such that when the motors are rotated by an external mechanical force, they generate electricity that flows back through inverter circuits 115a-115c to DC bus 110. When this occurs, the voltage on DC bus 110 can rise above the voltage of batteries 105a-105c, and controller 135 can detect this rise and respond by closing one or more bypass switches 130a-130c to allow current to flow from the DC bus to one or more of the batteries. When the regeneration event ends, the voltage on DC bus 110 drops below the voltage of batteries 105a-105c, and controller 135 responds by opening the bypass switches. In some embodiments, controller 135 enables regenerative charging of batteries 105a-105c only when the voltage on DC bus 110 is above a threshold voltage, which may be set based on the maximum voltage of any one of the batteries so that charge shutting does not occur once the bypass switch is closed. In further embodiments, controller 135 may engage only one bypass switch at a time or engage a subset of the bypass switches to recharge an individual battery, which may be used in some embodiments, for example, to "top off" any batteries that have a relatively low charge.

[0033] In further embodiments, one or more of the bypass switches 130a-130c may be engaged by an external circuit, such as when the operator specifically engages in a regenerative maneuver, such as descending the airplane or depressing the brake pedal. In other embodiments, the controller 130 may have logic circuitry that can selectively engage the bypass switches 130a-130c to recharge only those batteries 105a-105c that have a charge level below a certain threshold, or to charge certain batteries in a predetermined sequence to preserve their lifespan. Those skilled in the art having the benefit of this disclosure will recognize many variations, modifications, and alternative techniques for when and how to engage the bypass switches 130a-130c.

[0034] In some embodiments, the bypass switches 130a-130c are electromechanical relay-type switches that include metal contacts that are engaged and disengaged by electromagnets, while in other embodiments, the bypass switches 130a-130c are solid-state and made from silicon, gallium nitride, silicon carbide, or other semiconductor materials.

[0035] In some embodiments, the controller 135 may include fault monitoring and detection circuitry such that when a fault is detected during regenerative operation (e.g., a battery fails as a short) and one or more of the bypass switches 130a-130c are closed, the bypass switch for that particular battery 105a-105c is opened to prevent other batteries from draining current to the failed battery. Those skilled in the art having the benefit of this disclosure will recognize many variations, modifications, and alternatives to using bypass switches.

[0036] In some embodiments, the power distribution circuit 100 of FIG. 1 may be particularly useful for aircraft that require multiple separate batteries 105a-105c for redundancy purposes. In such embodiments, separate inverter and motor circuits as shown in FIG. 1 may provide additional redundancy and improved reliability. For example, separate inverter / motor and battery circuits would provide redundancy in the event of, for example, an electrical short or a failure in the DC supply line from one battery to the DC bus 110. In some embodiments, the location of the bypass switches 130a-130c may be proximal to the batteries 105a-105c (as shown in FIG. 1), while in other embodiments, the bypass switches 130a-130c may be located proximal to the inverter circuits 115a-115c.

[0037] The batteries 105a-105c may be lead-acid batteries, nickel-metal hydride batteries, lithium-ion batteries, lithium-ion polymer batteries, alkaline batteries, or any other type of battery. The motors 120a-120c may be any type of AC motor, including but not limited to brushed, brushless, induction, or synchronous motors. The inverters 115a-115c may be any type of analog or solid state inverter circuit that converts DC power to AC power. For simplicity, various active and passive circuitry components are not shown in the power distribution circuit 100.

[0038] 2 illustrates a power distribution circuit 200 that is similar to the power distribution circuit 100 illustrated in FIG. 1, but does not include a diode positioned between each battery and the DC bus in this embodiment. Instead, as illustrated in FIG. 2, a breaker 230a-c is positioned between each battery 105a-c and the DC bus 110. During normal operation, the breakers 230a-c are in a closed position so that DC power can flow from the batteries 105a-c to the DC bus 110, through the inverter circuits 115a-c to the motors 120a-c. The controller 235 is configured to detect a system fault and in response open one or more of the breakers 230a-c to prevent further faults, as described in more detail below.

[0039] In one example, the controller 235 is configured to detect a failure of a battery 105a-105c that fails in a short circuit condition. The controller 235 then commands the breaker 230a-230c associated with that particular battery 105a-105c to open to prevent the battery from receiving current from other batteries coupled to the DC bus 110. During such a failure, the controller 235 is configured to keep the other breakers 230a-230c closed so that current may continue to be provided to the motors 120a-120c. In a further example, the controller 235 is configured to open only the necessary breakers 230a-230c and keep all other breakers closed so that power may continue to be provided to the motors 120a-120c. This mode of operation may be particularly useful for aircraft where continuous uninterrupted operation of the motors 120a-120c is an important safety consideration.

[0040] In some embodiments, the breakers 230a-c may be located proximate the batteries 105a-c (as shown in FIG. 2), while in other embodiments the breakers 230a-c may be located proximate the motors 120a-c. In further embodiments, there may be a set of breakers 230a-c proximate each battery 105a-c and another set of breakers proximate each motor 120a-c, the combination of which may be used to isolate faults in the wiring harness that runs from the batteries to the motors.

[0041] In some embodiments, breakers 230a-230c are electromechanical switches that include metal contacts, while in other embodiments breakers 230a-230c are solid-state and made from silicon, gallium nitride, silicon carbide, or other semiconductor materials.

[0042] FIG. 3 illustrates a power distribution circuit 300 according to an embodiment of the present disclosure. As shown in FIG. 3, each battery 105a-105d is coupled to a separate inverter 310a-310d that generates a respective three-phase AC output. There are also three separate interphase transformers 315a-315c that receive one input phase from each inverter 310a-310d, respectively, and combine the inputs into one respective drive phase 320a-320c that is coupled to the motor 330. Within each interphase transformer 315a-315c, each of the four phase inputs are electrically isolated from each other such that a failure in one input does not result in a failure in any of the other three inputs. In some embodiments, each interphase transformer 315a-315c is configured to inductively combine the power delivered by each of its four respective inputs to generate a combined single drive phase 320a-320c for motor 320.

[0043] Thus, each phase of the motor 320 is driven by a respective interphase transformer 315a-315c that receives approximately 25 percent of its power from each of the four separate inverter / battery sets. If one battery 105a-105d or inverter 310a-310d fails, each phase of the motor 330 will receive approximately 25 percent less power, but the motor will still operate. In some embodiments, a master controller (not shown in FIG. 3) may be used that controls each phase of each inverter 310a-310c such that the inputs to the interphase transformers 315a-315c are synchronized. In some embodiments, the motor controller circuitry may include only the inverters 310a-310d, while in other embodiments, the motor controller circuitry may also include the interphase transformers 315a-315c. Charge shuttling between the batteries 105a-105d is also not an issue due to the electrical isolation between each circuit.

[0044] During a regeneration event, when the motor 330 is rotated by an external mechanical force, the motor delivers power to each interphase transformer 315a-315c, which then sends power back to the batteries 105a-105d through a separate inverter 310a-310d. Each battery 105a-105d is isolated from one another, so that if one battery fails, power from the other batteries cannot flow to the failed battery. Essentially, each battery and each AC signal is isolated, so that each operates as an independent system. As will be appreciated by those of ordinary skill in the art having the benefit of this disclosure, the number of batteries, the number of inverters, and the number of interphase transformers are not limited to those shown in FIG. 3, and other embodiments may have different numbers of these devices or configurations. For example, six batteries may be used with each interphase transformer combining six inputs. Those of ordinary skill in the art having the benefit of this disclosure will recognize many variations, modifications, and alternatives.

[0045] FIG. 4 illustrates a power distribution circuit 400 that is similar to the power distribution circuit 300 illustrated in FIG. 3, but in this embodiment, there is no interphase transformer and the motor includes 12 separate windings. As illustrated in FIG. 4, there are four separate batteries 105a-105d, each of which has a separate inverter 310a-310d coupled to it. Each inverter 310a-310d generates a separate phase, and each phase is directly coupled to the motor 405. Thus, with the four three-phase inverters 310a-310d, 12 phases are generated, all of which are individually coupled to the motor 405.

[0046] In this embodiment, when one battery 105a-105d fails, three of the twelve phases in the motor 405 do not receive power, so that the motor still operates, but only at approximately 75 percent power. In some embodiments, the circuit may include a controller configured to control other inverters (e.g., non-failed inverters) of the plurality of inverters to continue operation of the motor with a reduced number of phases. The controller may also control an inverter coupled to the failed battery to isolate the failed battery from the circuit. Additionally, each battery 105a-105d and inverter 310a-310d are electrically isolated from each other, so that when a battery fails in a short circuit condition, current from the other batteries does not flow to the failed battery. Essentially, each set of batteries 105a-105d and inverter 310a-310d is electrically isolated from each other set of batteries and inverters. Due to the isolation, charge shuttling between the batteries 105a-105d is also not an issue.

[0047] During a regenerative event, rotational energy is applied to the motor 405, which operates as a generator and delivers current to each battery 105a-105d through the respective inverters 310a-310d. In other embodiments, the motor 405 can have any number of phases and the inverters 310a-310d can generate any number of phase outputs.

[0048] FIG. 5 illustrates a power distribution circuit 500 according to an embodiment of the present disclosure. The power distribution circuit 500 is similar to the power distribution circuit 100 illustrated in FIG. 1 and the power distribution circuit 200 illustrated in FIG. 2 that use a DC bus, but the embodiment illustrated in FIG. 5 uses a DC / DC converter in series with each battery to provide energy to a common DC bus. As illustrated in FIG. 5, each of the individual batteries 105a-105 is coupled to a separate DC / DC converter 505a-505d that converts and conditions the DC energy received from each battery to DC energy that is coupled to a common DC bus 510. The DC bus 510 is coupled in parallel to multiple inverters 515a-515c that generate three-phase AC signals that drive individual motors 520a-520c, respectively.

[0049] Each DC / DC converter 505a-505d is configured to receive power only from its respective battery 105a-105d and deliver regulated power to the DC bus 510 based on the load applied to the DC bus. More specifically, in some embodiments, each DC / DC converter 505a-505d may be independently regulated and the voltage of the DC bus 510 may be used to control the amount of power the DC / DC converter draws from its respective battery 105a-105d. In other embodiments, the controller 525 may control each DC / DC converter 505a-505d and cycle each DC / DC converter 505a-505d on and off as needed to regulate the power delivered to the DC bus 510. More specifically, each DC / DC converter 505a-505d may operate with a duty cycle in which it is on for a period of time and off for a period of time.

[0050] In this embodiment, if a battery 105a-105d fails, the DC / DC converter 505a-505d for that battery prevents power from being transferred from the DC bus 510 to the failed battery (e.g., if the battery fails in a short circuit condition). In one example, each DC / DC converter 505a-505d (or controller 525) can monitor the voltage across its respective battery 105a-105d to detect a short circuit or failure in the battery and in response interrupt the transfer of power from that battery to the DC bus 510. In a further embodiment, the DC / DC converter 505a-505d can detect a regeneration event and transfer power from the DC bus 510 to the battery 105a-105d for recharging. In some embodiments, each DC / DC converter 505a-505d can detect a regeneration event by monitoring the voltage potential on the DC bus 510 compared to the voltage available at the respective battery 105a-105d. In some embodiments, a threshold voltage may be used to initiate regenerative charging when the voltage on the DC bus 510 exceeds the threshold voltage.

[0051] In some embodiments, the DC / DC converters 505a-505d can adjust the load distribution among each of the batteries 105a-105d to maintain each battery at a similar state of charge. In one embodiment, each DC / DC converter 505a-505d monitors the voltage of each battery 105a-105d and the voltage on the DC bus 510. If the controller 525 detects a voltage of a battery 105a-105d that is relatively higher than the voltage of the other batteries, the controller can command each DC / DC converter 505a-505d to draw more power from that battery to match its state of charge to the other batteries. In a further embodiment, each DC / DC converter 505a-505d can receive the same PWM (pulse width modulated) signal from the controller 525 that controls the transfer of power from each battery 105a-105d to the DC bus 510. In some embodiments, the same PWM signal may "automatically" compensate for different charge levels in batteries 105a-105d by delivering more power from batteries that have a relatively higher charge because of their higher voltage level and delivering relatively less power from batteries that have a relatively lower charge because of their lower voltage level.

[0052] In some embodiments, the DC / DC converters 505a-505d may be located proximate the batteries 105a-105d, while in other embodiments, the DC / DC converters 505a-505d may be located proximate the motors 502a-502c. In further embodiments, the DC bus 510 may be omitted and each DC / DC converter 505a-505d may be coupled to a respective inverter 515a-515c, which may be coupled to a respective motor 520a-520c, as shown in FIGS.

[0053] In some embodiments, the DC / DC converters 505a-505d may be isolated or non-isolated switch mode converters. In various embodiments, isolated DC / DC converters 505a-505d may be preferred to isolate downstream circuitry from potential faults in the batteries 105a-105d. In some embodiments, the DC / DC converters 505a-505d may be of the following architectures, including but not limited to: step-down / buck, step-up boost, SEPIC, buck-boost, or flyback. In further embodiments, the DC / DC converters 505a-505d may use one or more solid state switches, which may include silicon, silicon carbide, gallium nitride, or any other type of solid state switch.

[0054] FIG. 6 illustrates a power distribution circuit 600 according to an embodiment of the present disclosure. The power distribution circuit 600 is similar to the power distribution circuit disclosed in FIGS. 3 and 4 with one battery coupled to each inverter, but in FIG. 6, each inverter operates redundant motors coupled to a single shaft. As shown in FIG. 6, three individual motors 605a-605c are coupled to a single propeller shaft 610. Each of the three motors 605a-605c is driven by a separate battery 105a-105c such that if one battery fails, the remaining motors and batteries are electrically isolated and can power the propeller shaft 610. Each of the individual motors 605a-605c generates power that is sent back to the respective battery 105a-105c when the propeller 615 is rotated by an external mechanical force during a regenerative event. If one battery 105a-105c or inverter 310a-310c fails, the propeller 615 is still operated by the remaining two motors 605a-605c, but with approximately 33% less power. In other embodiments, fewer than three separate motors per shaft may be used, and in some embodiments, more than three motors per shaft may be used. In still further embodiments, each motor 605a may be powered via a redundant power distribution system such as those shown in Figures 1-3 or 5.

[0055] Figure 7 illustrates a simplified plan view of an aircraft 700 according to an embodiment of the present disclosure. As shown in Figure 7, the aircraft 700 includes twelve motors 705a-705l coupled to a battery pack 710 via harnesses 715. The aircraft 700 may use one or any combination of the power distribution circuits described above and illustrated in Figures 1-6.

[0056] Although electric vehicle 700 is described and illustrated as one particular electric vehicle, embodiments of the present disclosure are suitable for use with a variety of electric vehicles. 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 cases, embodiments of the present disclosure are particularly well suited for use with aircraft due to the reliability and fault isolation of the power delivery circuitry. Although control circuits are not shown in each of the circuits illustrated in Figures 1-6, one or more control circuits may be added to any of the circuits described herein to control the operation of various components, including, but not limited to, inverters, interphase transformers, switches, motors, feedback loops, etc.

[0057] For the sake of brevity, various active and passive circuitry components are not shown in the figures. In the above specification, the embodiments of the present disclosure have been described with reference to numerous specific details that may vary from embodiment to embodiment. Therefore, the specification and drawings should be considered in an illustrative rather than a restrictive sense. The sole and exclusive indication of the present disclosure, and what is intended by the applicant to be the scope of the present disclosure, is the literal and equivalent scope of such claims as they arise from this application, including any subsequent amendments. The specific details of the particular embodiments may be combined in any suitable manner without departing from the spirit and scope of the embodiments of the present disclosure.

[0058] Additionally, spatially relative terms such as "bottom" or "top" may be used to describe the relationship of an element and / or feature to another element and / or feature, for example, as shown in the figures. It will be understood that the spatially relative terms are intended to encompass various orientations of the device in use and / or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, an element described as being on a "bottom" surface may be oriented "on top" of the other element or feature. The device may be otherwise oriented (e.g., rotated 90 degrees or otherwise oriented) and the spatially relative descriptors used herein interpreted accordingly.

[0059] As used herein, the terms "and," "or," and "one / or" may include a variety of meanings that may depend, at least in part, on the context in which such terms are used. Typically, "or," when used to link a list such as A, B, or C, is intended to mean A, B, and C, which are used herein in an inclusive sense, and A, B, or C, which are used herein in an exclusive sense. Additionally, as used herein, the term "one or more" may be used to describe any feature, structure, or characteristic in the singular, or may be used to describe several combinations of features, structures, or characteristics. However, it should be noted that this is merely an illustrative example, and claimed subject matter is not limited to this example. Additionally, the term "at least one of," when used to link a list such as A, B, or C, may be interpreted to mean any combination of A, B, and / or C, such as A, B, C, AB, AC, BC, AA, AAB, ABC, AABBCC, and the like.

[0060] Throughout this specification, reference to "one example," "one example," "some examples," or "exemplary embodiments" means that a particular feature, structure, or characteristic described in connection with a feature and / or example may be included in at least one feature and / or example of the claimed subject matter. Thus, the appearances of phrases such as "in one example," "one example," "some examples," "in some embodiments," or other similar phrases in various places throughout this specification do not necessarily all refer to the same features, examples, and / or limitations. Furthermore, particular features, structures, or characteristics may be combined in one or more examples and / or characteristics.

Claims

1. DC bus, a plurality of batteries coupled in parallel to the DC bus; at least one switch, each of the at least one switches coupled in series between at least one battery of the plurality of batteries and the DC bus; a plurality of inverter circuits coupled in parallel to the DC bus; a plurality of motors, each of the plurality of motors coupled to a respective inverter circuit of the plurality of inverter circuits; An electric aircraft comprising:

2. The electric aircraft of claim 1 , wherein the at least one switch comprises a plurality of switches, each switch of the plurality of switches coupled in series between a respective battery of the plurality of batteries and the DC bus.

3. 3. The electric aircraft of claim 2, further comprising circuitry coupled in series with each cell of the plurality of batteries and arranged to unidirectionally drain current from each cell of the plurality of batteries to the DC bus.

4. The electric aircraft of claim 3 , wherein the circuitry comprises at least one diode.

5. The electric aircraft of claim 3 , wherein each switch of the plurality of switches is positioned to bypass the circuitry coupled in series with a respective battery of the plurality of batteries.

6. 3. The electric aircraft of claim 2, further comprising a controller configured to detect a failed battery of the plurality of batteries and in response open a respective switch of the plurality of switches to electrically isolate the failed battery from the DC bus.

7. 10. The electric aircraft of claim 1, further comprising a controller configured to detect a regenerative event and in response close the at least one switch to transfer power from the DC bus to at least one battery of the plurality of batteries.

8. The electric aircraft of claim 1 , wherein each of the plurality of inverter circuits is configured to generate a polyphase AC output used to drive one or more of the plurality of motors.

9. The electric aircraft of claim 1 , wherein each of the plurality of inverter circuits is configured to generate a three-phase output.

10. 10. The electric aircraft of claim 9, wherein the three-phase output generated by each of the plurality of inverter circuits operates between 0 and 400 volts AC at a frequency between 0 and 3 KHz.

11. The electric aircraft of claim 1 , wherein each of the plurality of motors is coupled to a respective propeller of the electric aircraft.

12. The electric aircraft of claim 1 , wherein each of the plurality of motors is a synchronous AC permanent magnet motor.

13. The electric aircraft of claim 1 , wherein the plurality of motors includes twelve motors.

14. the plurality of batteries includes three batteries; the at least one switch includes three switches; the plurality of inverter circuits includes three inverter circuits, The electric aircraft of claim 12 , wherein the plurality of motors comprises three motors.

15. 1. A power distribution circuit for an aircraft, comprising: A number of batteries; a plurality of inverters, each coupled to a respective battery of the plurality of batteries and configured to generate a plurality of input phases; a plurality of interphase transformers, each of which receives one or more of the plurality of input phases and generates a single combined drive phase; a motor configured to receive the associated single drive phase from each of the plurality of interphase transformers; A power distribution circuit comprising:

16. 16. The power distribution circuit of claim 15, wherein at least one interphase transformer of the plurality of interphase transformers receives an input phase from each of the plurality of inverters.

17. 16. The power distribution circuit of claim 15, wherein each of the interphase transformers of the plurality of interphase transformers receives an input phase from a respective one of the plurality of inverters.

18. 16. The power distribution circuit of claim 15, wherein each interphase transformer of the plurality of interphase transformers electrically isolates the plurality of input phases from one another.

19. 16. The power distribution circuit of claim 15, further comprising a controller configured to control operation of at least one of the inverters to control the speed and force of the motor.

20. 20. The power distribution circuit of claim 19, wherein the controller is configured to detect a failed battery of the plurality of batteries and in response disable a respective inverter of the plurality of inverters coupled to the failed battery.

21. 16. The power distribution circuit of claim 15, wherein one or more of the plurality of inverters are configured to charge one or more of the plurality of batteries when the motor generates power during a regeneration event.

22. 16. The power distribution circuit of claim 15, wherein the motor is a synchronous AC permanent magnet motor.

23. The power distribution circuit of claim 15 , wherein the motor propels the aircraft.

24. The power distribution circuit of claim 15 , wherein the motor is coupled to a propeller of the aircraft.

25. A number of batteries; a plurality of inverters, each of the plurality of inverters coupled to a respective battery of the plurality of batteries and configured to generate a plurality of phases; a motor configured to receive each of the plurality of phases from each of the plurality of inverters; An electric aircraft comprising:

26. The electric aircraft of claim 25 , wherein each inverter of the plurality of inverters is configured to generate three phases.

27. 26. The electric aircraft of claim 25, further comprising a controller configured to detect a failed battery and in response disable each inverter of the plurality of inverters coupled to the failed battery.

28. The electric aircraft of claim 27 , wherein the controller is configured to control other inverters of the plurality of inverters to continue operation of the motor with a reduced number of phases.

29. 26. The electric aircraft of claim 25, wherein one or more of the plurality of inverters are configured to transfer power to one or more of the plurality of batteries when the motor generates power during a regeneration event.

30. 26. The electric aircraft of claim 25, wherein the motor is coupled to a propeller of the electric aircraft.

31. 26. The electric aircraft of claim 25, wherein the motor is a synchronous AC permanent magnet motor.

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