Method and system for flywheel-based high-power electric vehicle charging

Abstract

Systems for storing input power and providing output power, such as for use with electric vehicle charging, can include an AC motor, a flywheel, an AC generator, or any combination thereof. The motor can be electrically coupled to an AC power source and receive AC power from the source. The flywheel can be coupled to a rotor external to the motor. The generator can be coupled to the flywheel and electrically coupled to a controller for charging one or more batteries of a vehicle, for supplying power to a load such as an electric vehicle, etc.

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 394,886, filed Aug. 3, 2022, and U.S. Provisional Patent Application No. 63 / 486,985, filed Feb. 25, 2023, which are hereby incorporated by reference in their entirety.

[0002] Description of Research or Development Supported by the Federal Government Not applicable.

[0003] Reference to Index Not applicable.

[0004] This disclosure relates generally to electric vehicle charging stations, and more particularly to high-power electric vehicle charging stations.

Background Art

[0005] Description of Related Art Electric vehicles (EVs) are increasing rapidly in number. With this rapid increase in EVs, millions of chargers will need to be deployed each year. Many of these will be low-power residential chargers that can utilize existing power grid connections, but many of them will now be high-power direct current fast chargers (DCFCs) that are at a height of 350 kW in power draw. Some applications, such as electric trucks, can utilize much higher power draws, such as 3 MW. These new, higher power charging requirements can impose a burden on our power grid and require costly, time-consuming, and complex installation processes, including laying additional power distribution lines, procuring large transformers, and paying high demand charges for peak power consumption.

[0006] As an alternative to upgrading the power grid connection to support these high-power chargers, modular energy storage systems can be installed at EV charging station sites as a simple solution to mitigate these upgrade requirements. These modular energy storage systems can be charged at low power from the existing power grid connection to store energy and then discharged at high power when an electric vehicle enters the charging station. By this method, power is not drawn from the grid at these higher electricity rates. Instead, the lower power draw from the grid charges the energy storage system over a longer period. The stored energy can then be utilized to increase the output power required by the high-power charger. Thus, the grid never "sees" the high power draw, and the costs and time for installing the charger can be dramatically reduced.

[0007] Furthermore, modular energy storage systems can be installed at EV charging station sites to avoid drawing power from the grid during peak or partial or full power grid outages. Many parts of the power grid in our country (the United States) are already at or near maximum capacity, especially during certain times of the day. Drawing additional power from the grid during peak times can cause or exacerbate an overloaded grid. Additionally, some power companies charge more for electricity drawn during peak times. Instead of drawing power from the grid during peak times, the energy stored during peak times or outages can be used to supply the charger.

[0008] This application may use an electrochemical battery, such as a lithium-ion battery. However, for power transmission from the power grid to the battery, AC to DC, i.e., AC / DC conversion is required, and subsequently, since conventional DCFCs are typically designed to receive AC input power from the power grid, DC / AC conversion from the battery to the DCFC is necessary. Then, the DCFC itself converts the AC back to DC for the vehicle to receive. A combined battery / DCFC system may be used such that the power grid AC is temporarily converted to DC. However, this may limit or eliminate the possibility of supporting existing DCFC hardware or expanding existing DCFC facilities.

[0009] Conventional flywheel energy storage systems have the additional benefits of high cycle life and high power density, which can both be important for EV charging. However, these typically involve the same level of complexity as electrochemical solutions in terms of power electronics. Since the flywheel rotates at a variable speed, at the input, conversion from the fixed 60Hz power grid frequency to its variable frequency is required. Further, at the output, conversion from the variable frequency to the fixed 60Hz frequency that the DCFC can receive is needed. Both steps require AC / DC / AC conversion and expensive power electronics.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Means for Solving the Problems

[0011] The applicants have created a newly useful device, system, and method for a high-power electric vehicle charging station that uses a flywheel for energy storage. As one possible implementation of the present disclosure, a charging station for an electric vehicle is contemplated, but the devices, systems, and methods of the present disclosure can be used in other high-power charging stations.

[0012] In at least one embodiment, the power electronics can be limited or entirely removed. In at least one embodiment, by using a line-start synchronous motor (LSSM) at the power input, the AC signal supplied by the power grid can be used to excite the motor throughout the full speed range, typically represented in revolutions per minute (RPM). At lower frequencies, the LSSM can act as an induction motor, where the slip frequency results in torque in the rotor. The motor can act as a synchronous motor as the frequency of the rotor approaches the power grid frequency, and the main interaction is between the DC field of the rotor and the AC field of the signal supplied by the power grid to the stator.

[0013] In at least one embodiment, the rotor can be designed such that its maximum speed matches the power grid frequency. In at least one embodiment, despite a lower maximum RPM, the use of a larger diameter rotor can be utilized to store sufficient energy. In at least one embodiment, the rotor operation can mainly occur between 50% - 100% of the maximum speed so that the slip frequency does not increase significantly enough to cause a large inrush current from the power grid. In other words, by avoiding low rotor / flywheel RPMs, the power grid does not need to provide the high inrush currents typically associated with LSSMs.

[0014] In at least one embodiment, the variable frequency and / or variable voltage output is directly connected to the input of the DCFC. In at least one embodiment, the frequency and / or voltage range at the rotor is configured to be within the operating range of the AC / DC converter of the DCFC and not to fall below a threshold that would cause excessive energy accumulation during the cycle on the AC / DC converter.

[0015] In at least one embodiment, the power from the power grid can be stored in the flywheel and / or rotor. In at least one embodiment, the power from the power grid can be combined in the DCFC with the power stored in the flywheel and / or rotor. In at least one embodiment, in order to provide the required output power, the power drawn from the power grid in the DCFC is limited, but this is by the power stored in the flywheel and / or rotor being combined with them. In at least one embodiment, all of the output power can be drawn directly from the flywheel and / or rotor. In at least one embodiment, the power drawn from the power grid can be limited such that the flywheel and / or rotor decelerate as output power is drawn from them. In at least one embodiment, the power drawn from the power grid is limited and the flywheel and / or rotor can be configured to decelerate or reduce speed as output power is drawn from the system and exceeds that limit.

[0016] In at least one embodiment, the synchronous motor connected to the power grid can also stabilize the power grid. For example, the LSSM can be designed to idle at a frequency of 60 Hertz (Hz), i.e., 3600 RPM. In at least one embodiment, when the power grid frequency drops below the flywheel frequency, power can flow from the flywheel into the power grid. The flywheel "idling" frequency can be adjusted and / or selected according to the location and the power grid frequency (e.g., 60 Hz is commonly used in the United States and 50 Hz is commonly used in the United Kingdom).

[0017] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include an AC motor, a flywheel, and an AC generator. In at least one embodiment, the motor and the generator can be the same machine. In at least one embodiment, the motor can be electrically coupled to an AC power source. In at least one embodiment, the motor can have a rotor and can be configured to receive AC power from a power source. In at least one embodiment, the flywheel can be mechanically coupled to a rotor external to the motor. In at least one embodiment, the generator can have a rotor mechanically coupled to the flywheel. In at least one embodiment, the generator can be configured to be electrically coupled to a controller to supply power to a load.

[0018] In at least one embodiment, the motor can be a line-start synchronous motor. In at least one embodiment, the generator can be a synchronous generator. In at least one embodiment, the load can be an electric vehicle.

[0019] In at least one embodiment, the generator can be configured to supply AC power to a controller. In at least one embodiment, the controller can be configured to convert the AC power to DC power for delivery to a load. In at least one embodiment, the motor can be configured to receive AC power from a power source at a first level. In at least one embodiment, the generator can be configured to supply AC power to a controller at one or more other levels, such as a second level higher than the first level.

[0020] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include an AC motor and a flywheel. In at least one embodiment, the motor can be configured to be electrically coupled to an AC power source. In at least one embodiment, the motor can have a rotor. In at least one embodiment, the motor can be configured to receive AC power from a power source. In at least one embodiment, the flywheel can be mechanically coupled to the rotor external to the motor. In at least one embodiment, the flywheel can be configured to mechanically store the power received from the power source through the motor. In at least one embodiment, the motor can be configured to be electrically coupled to a controller to supply power to a load.

[0021] In at least one embodiment, the motor can be a line-start synchronous motor. In at least one embodiment, the load can be an electric vehicle. In at least one embodiment, the motor can be configured to supply AC power to a controller. In at least one embodiment, the controller can convert the AC power to DC power for delivery to the load.

[0022] In at least one embodiment, the motor can be configured to receive AC power from a power source at a first level. In at least one embodiment, the motor can be configured to supply AC power to a controller at another level, such as a second level higher than the first level. In at least one embodiment, the motor can be configured to add power from the flywheel to the AC power received from the power source to supply AC power to the controller at the second level. In at least one embodiment, the motor can be configured to limit the AC power received from the power source to the first level.

[0023] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include a controller, an AC motor, and a flywheel. In at least one embodiment, the controller can be configured to be electrically coupled to an AC power source and a load. In at least one embodiment, the controller can be configured to convert AC power to DC power for delivery to the load. In at least one embodiment, the motor can be electrically coupled to the controller. In at least one embodiment, the motor can have a rotor. In at least one embodiment, the motor can be configured to receive AC power from a power source through the controller. In at least one embodiment, the flywheel can be mechanically coupled to the rotor, such as outside or external to the motor. In at least one embodiment, the flywheel can be configured to mechanically store power received from the power source through the motor.

[0024] In at least one embodiment, the motor can be a line-start synchronous motor. In at least one embodiment, the motor can be configured to receive AC power from the controller and supply AC power to the controller. In at least one embodiment, the load can be an electric vehicle.

[0025] In at least one embodiment, the controller can be configured to receive AC power from a power source at a first level. In at least one embodiment, the controller can be configured to supply DC power to a load at a second level higher than the first level. In at least one embodiment, the controller can be configured to add power from the flywheel to the AC power received from the power source to supply DC power to the load at the second level. In at least one embodiment, the controller can be configured to limit the AC power received from the power source to the first level.

[0026] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include a controller configured to be electrically coupled to an AC power source and a load, and at least one flywheel energy storage system configured to mechanically store power received from the power source. In at least one embodiment, the controller can be configured to convert AC power to DC power for delivery to the load. In at least one embodiment, each flywheel energy storage system can include a flywheel mechanically coupled to a rotor and an AC motor electrically coupled to the controller and mechanically coupled to the rotor. In at least one embodiment, the motor can be configured to receive AC power from the power source. In at least one embodiment, the load can be an electric vehicle.

[0027] In at least one embodiment, the motor can be a line-start synchronous reluctance motor. In at least one embodiment, the motor can be further configured to supply AC power to the controller. In at least one embodiment, the at least one flywheel energy storage system comprises a plurality of flywheel energy storage systems.

[0028] In at least one embodiment, each flywheel energy storage system can also include an AC generator electrically coupled to the controller and mechanically coupled to the rotor. In at least one embodiment, the generator can be configured to supply AC power to the controller. In at least one embodiment, the AC generator can be a synchronous AC generator.

[0029] In at least one embodiment, the rotor can be supported by at least one high-temperature superconducting magnetic bearing. For example, the rotor can be supported axially by one high-temperature superconducting magnetic bearing at the upper end and / or by another high-temperature superconducting magnetic bearing at the lower end. In at least one embodiment, the flywheel can be supported by at least one magnetic levitation bearing. For example, the flywheel can be supported from below by a repulsive-mode permanent magnet levitation bearing and / or from above by an attractive-mode permanent magnet levitation bearing.

[0030] In at least one embodiment, the controller can be configured to receive AC power from a power source at a first level and supply DC power to a load at a second level. In at least one embodiment, the second level can be higher than the first level. In at least one embodiment, the controller can be configured to add power from the flywheel to the AC power received from the power source to supply DC power to the load at the second level. In at least one embodiment, the controller can be configured to limit the AC power received from the power source to one or more levels, such as a first level.

[0031] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include a controller, a line-start synchronous AC motor, a flywheel, a synchronous AC generator, or any combination thereof. In at least one embodiment, the controller can be electrically coupled to an AC power source and / or a load. In at least one embodiment, the controller can convert AC power to DC power for delivery to the load at a first level.

[0032] In at least one embodiment, the line-start synchronous AC motor can be electrically coupled to an AC power source. In at least one embodiment, the motor can have a first rotor and / or can receive AC power from the power source at a second level. In at least one embodiment, the second level can be lower than the first level. In at least one embodiment, the controller can limit the AC power received from the power source to the second level. In at least one embodiment, the flywheel can be mechanically coupled to the first rotor external to the motor.

[0033] In at least one embodiment, the synchronous AC generator can have a second rotor mechanically coupled to the flywheel. In at least one embodiment, the generator can be electrically coupled to the controller to supply power to a load. In at least one embodiment, the load can be an electric vehicle. In at least one embodiment, the generator can supply AC power to the controller.

Brief Description of the Drawings

[0034]

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DETAILED DESCRIPTION OF THE INVENTION

[0035] The above figures, and the following description written about specific structures and functions, are not shown to limit the scope of what the applicants have invented, or the scope of the appended claims. Rather, the figures, and the written description, are provided to teach those skilled in the art how to make and use the present invention for which patent protection is sought. Those skilled in the art will understand that not all features of a commercial embodiment of the present invention are described for clarity and understanding. Those skilled in the art will also understand that the development of an actual commercial embodiment incorporating aspects of the present invention will require numerous implementation-specific decisions to achieve the ultimate goal of the developer for the commercial embodiment. Such implementation-specific decisions may include, but are not limited to, system-related, business-related, government-related, and other constraints that can vary depending on the specific implementation, location, and time. The efforts of the developer can be complex and time-consuming in an absolute sense, but nevertheless, such efforts would be routine for those skilled in the art having the benefit of this disclosure. It should be understood that the present invention disclosed and taught herein is capable of numerous and various modifications and alternative forms.

[0036] The use of the singular form, such as “a” or “one,” is not intended to limit the number of items. Also, the terms “above,” “below,” “left,” “right,” “upper,” “lower,” “down,” “up,” “across,” and other relational terms are used in the specification for clarity in reference to the figures and are not intended to limit the scope of the present invention and the appended claims. The terms “including” and “such as” are illustrative and not restrictive. The terms “couple,” “coupled,” “coupling,” “coupler,” and the like are used broadly herein and include, for example, mechanically, magnetically, electrically, chemically, operably, directly, or indirectly through an intervening element, methods or devices for securing, binding, bonding, attaching, joining, inserting, forming thereon or therein, communicating, or otherwise relating portions of one or more members together, and further, without limitation, may include integrally forming one functional member with another in a unitary fashion. A coupling can occur in any direction, including a rotational direction. Additionally, all parts and components of the present disclosure that are physically realizable inherently include virtual and real characteristics, whether or not those characteristics are explicitly described herein, and include, without limitation, features such as axes, ends, inner and outer surfaces, internal spaces, upper, lower, side, boundaries, dimensions (e.g., height, length, width, thickness), mass, weight, volume, and density.

[0037] The process flowcharts discussed in this specification illustrate the operations of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart can represent a module, segment, or portion of code that can include one or more executable instructions for performing a particular logical function. It should also be noted that in some implementations, the functions written within a block can occur in an order different from that shown in the figure. For example, blocks shown in succession can actually be executed substantially simultaneously. It should also be noted that one or more blocks in the flowchart diagram can be implemented by a dedicated hardware-based system for performing a particular function or operation, or by a combination of dedicated hardware and computer instructions.

[0038] Applicants have created newly useful devices, systems, and methods for high-power electric vehicle charging stations that use flywheels for energy storage. While charging stations for electric vehicles are contemplated, the devices, systems, and methods of the present disclosure can be used in other high-power charging stations. In at least one embodiment, the system according to the present disclosure, such as an energy storage system, or a system for storing input power and providing output power, can include one or more controllers for converting AC power to DC power for delivery to a load, and one or more flywheel energy storage systems for mechanically storing the power received from a power source. In at least one embodiment, the flywheel energy storage system according to the present disclosure can include one or more flywheels mechanically coupled to one or more rotors, and one or more alternating current motors, such as a line-start synchronous motor, for receiving AC power from a power source.

[0039] FIG. 1 is a block diagram of one of many embodiments of a system for storing input power and providing output power according to the present disclosure. FIG. 2 is a block diagram of the system for storing input power and providing output power of FIG. 1, showing the power flow. FIG. 3 is a block diagram of another one of many embodiments of a system for storing input power and providing output power according to the present disclosure. FIG. 4 is a block diagram of the system for storing input power and providing output power of FIG. 3, showing the power flow during the charging period. FIG. 5 is a block diagram of the system for storing input power and providing output power of FIG. 3, showing one possible power flow during the discharging period. FIG. 6 is a block diagram of the system for storing input power and providing output power of FIG. 3, showing another possible power flow during the discharging period. FIG. 7 is a block diagram of yet another one of many embodiments of a system for storing input power and providing output power according to the present disclosure. FIG. 8 is a block diagram of the system for storing input power and providing output power of FIG. 7, showing the power flow during the charging period. FIG. 9 is a block diagram of the system for storing input power and providing output power of FIG. 7, showing one possible power flow during the discharging period. FIG. 10 is a block diagram of the system for storing input power and providing output power of FIG. 7, showing another possible power flow during the discharging period. FIG. 11 is a block diagram of a selected component of one of many embodiments of a system for storing input power and providing output power according to the present disclosure. FIG. 12 is a block diagram of a selected component of another one of many embodiments of a system for storing input power and providing output power according to the present disclosure. FIG. 13 is a block diagram of yet another one of many embodiments of a system for storing input power and providing output power according to the present disclosure. FIG. 14 is a block diagram of a selected component of another one of many embodiments of a system for storing input power and providing output power according to the present disclosure. FIGS. 1-14 are described in relation to each other.

[0040] In at least one embodiment, system 100 according to the present disclosure, such as an energy storage system or a system for storing input power and providing output power, can include one or more AC motors 200, one or more flywheels 300, one or more AC generators 400, or any combination thereof. In at least one embodiment, motor 200 and generator 400 can be the same machine. In at least one embodiment, motor 200 can be electrically coupled to one or more AC power sources 500, such as a conventional power transmission network. In at least one embodiment, motor 200 can have one or more rotors 210 and / or can be configured to receive AC power from power source 500. In at least one embodiment, flywheel 300 can be mechanically coupled to rotor 210 external to motor 200. In at least one embodiment, generator 400 can have one or more rotors 410 mechanically coupled to flywheel 300. In at least one embodiment, generator 400 can be configured to be electrically coupled to one or more controllers 600 to supply power to one or more loads 700.

[0041] In at least one embodiment, motor 200 can be a line-start synchronous motor. In at least one embodiment, motor 200 can be a three-phase two-pole line-start synchronous reluctance motor. In at least one embodiment, generator 400 can be a synchronous generator. In at least one embodiment, generator 400 can be a three-phase four-pole single-pole synchronous machine. In at least one embodiment, load 700 can be an electric vehicle, such as a passenger car, bus, or commercial transport vehicle.

[0042] In at least one embodiment, the generator 400 can be configured to supply AC power to the controller 600. In at least one embodiment, the controller 600 can be configured to convert the AC power to DC power for delivery to the load 700. In at least one embodiment, the motor 200 can be configured to receive AC power from the power source 500 at a first level. In at least one embodiment, the generator 400 can be configured to supply AC power to the controller 600 at a second level higher than the first level.

[0043] In at least one embodiment, the generator 400 can be configured to supply AC power at the same voltage and frequency as that received by the motor 200 from the power grid 500. In at least one embodiment, the generator 400 can be configured to supply AC power at a different voltage and / or a different frequency than that received by the motor 200 from the power grid 500. For example, the motor 200 and / or the generator 400 can be mechanically coupled to the flywheel 300 through one or more gear systems, thereby providing a gear ratio and thereby different voltages and / or frequencies.

[0044] When the output power supplied to the controller 600 is greater than the input power received from the power grid 500, the flywheel 300 can decelerate. In this way, the flywheel 300 can supply some of the power supplied by the controller 600. In at least one embodiment, when the flywheel 300 is completely depleted, the flywheel 300 can reach a complete stop. Restarting the flywheel 300 from a complete stop and / or a low speed can cause a large inrush current. Therefore, the flywheel 300 and / or other components of the system 100 can be designed to supply the power required to charge the load 700 before the flywheel 300 is completely depleted. In at least one embodiment, the flywheel 300 does not deplete by more than 50%. In at least one embodiment, the flywheel 300 does not deplete by more than 75%. In at least one embodiment, the flywheel 300 does not deplete by more than 90%.

[0045] In at least one embodiment, the flywheel 300 can be "charged" by rotating the flywheel 300 up to its maximum designed RPM while the system 100 is not being used to charge the load 700. In at least one embodiment, when the system 100 is being used to charge the load 700, the energy stored in the flywheel 300 can supply some or all of the power required to charge the load 700. Since at least the flywheel 300 can be designed to store a large amount of energy, the system 100 can supply the load 700 with more power than it receives at any given time. In other words, the system 100 can draw power from the power grid 500 at a lower speed and / or over a longer period of time, and deliver that power to the load 700 at a higher speed and / or over a shorter period of time.

[0046] One or more of the features described herein may be particularly useful when there is a maximum power level that can be drawn from the power grid 500 without upgrading the equipment and / or without paying a higher fee, and it is desirable to supply the load 700 at a higher speed. One or more of these features may also be used to purchase and store power from the power grid 500 during off-peak hours when the power is cheaper and otherwise preferable, and to supply power to the load 700 whenever necessary, including, for example, during peak hours or when the power grid 500 is experiencing a voltage drop or a power outage.

[0047] In at least one embodiment, a system 100 for storing input power and providing output power according to the present disclosure, such as for use with electric vehicle charging, may include one or more AC motors 200 and / or one or more flywheels 300. In at least one embodiment, the motor 200 may be configured to be electrically coupled to one or more AC power sources 500. In at least one embodiment, the motor 200 may have one or more rotors 210. In at least one embodiment, the motor 200 may be configured to receive AC power from the power source 500. In at least one embodiment, the flywheel 300 may be mechanically coupled to the rotor 210 external to the motor 200. In at least one embodiment, the flywheel 300 may be configured to mechanically store the power received from the power source 500 through the motor 200. In at least one embodiment, the motor 200 may be configured to be electrically coupled to one or more controllers 600 to supply power to one or more loads 700.

[0048] In at least one embodiment, the motor 200 can be a line start synchronous motor. In at least one embodiment, the motor 200 can be a three-phase two-pole line start synchronous reluctance motor. In at least one embodiment, the load 700 can be one or more electric vehicles (or their power sources such as batteries or battery banks), such as passenger cars, buses, commercial transport vehicles, or any combination thereof. In at least one embodiment, the motor 200 can be configured to supply AC power to the controller 600. In at least one embodiment, the controller 600 can convert AC power to DC power for delivery to the load 700.

[0049] In at least one embodiment, the motor 200 can be configured to receive AC power from the power source 500 at one or more levels, such as a first level. In at least one embodiment, the motor 200 can be configured to supply AC power to the controller 600 at one or more levels, such as a second level higher than the first level. In at least one embodiment, the motor 200 can be configured to add the power from the flywheel 300 to the AC power received from the power source 500 to supply AC power to the controller 600 at the second level. In at least one embodiment, the motor 200 can be configured to limit the AC power received from the power source 500 to the first level.

[0050] In at least one embodiment, the controller 600 or portions thereof can be integrated within the motor 200. For example, the controller 600 or portions thereof can be integral with the motor 200. In at least one embodiment, the motor 200 can include one or more current control and / or limiting devices. In at least one embodiment, such devices can be controlled by the controller 600. In this way, the motor 200, the controller 600, or both can be configured to limit the AC power received from the power source 500 to the first level.

[0051] In at least one embodiment, motor 200 may be configured to convert electrical energy received from power grid 500 into mechanical energy sent to flywheel 300, regardless of whether system 100 is being used to supply power to load 700. In this way, the AC power received from power source 500 can be used to reduce the deceleration of flywheel 300 when system 100 is being used to supply power to load 700.

[0052] In at least one embodiment, when system 100 is being used to supply power to load 700, motor 200 may be configured to combine electrical energy received from power grid 500 with mechanical energy from flywheel 300. In this way, the AC power received from power source 500 can be used to supplement depleted power from flywheel 300, thereby reducing the deceleration of flywheel 300 when system 100 is being used to supply power to load 700.

[0053] In at least one embodiment, a system 100 for storing input power and providing output power according to the present disclosure, such as for use with electric vehicle charging, can include one or more controllers 600, one or more AC motors 200, one or more flywheels 300, or any combination thereof. In at least one embodiment, the controller 600 can be configured to be electrically coupled to one or more AC power sources 500, one or more loads 700, or any combination thereof. In at least one embodiment, the controller 600 can be configured to convert AC power to DC power for delivery to the load 700. In at least one embodiment, the motor 200 can be electrically coupled to the controller 600. In at least one embodiment, the motor 200 can have one or more rotors 210. In at least one embodiment, the motor 200 can be configured to receive AC power from the power source 500 through the controller 600. In at least one embodiment, the flywheel 300 can be mechanically coupled to the rotor 210 external to the motor 200. In at least one embodiment, the flywheel 300 can be configured to mechanically store the power received from the power source 500 through the motor 200.

[0054] In at least one embodiment, the motor 200 can be a line-start synchronous motor. In at least one embodiment, the motor 200 can be a three-phase two-pole line-start synchronous reluctance motor. In at least one embodiment, the load 700 can be one or more electric vehicles, such as one or more passenger vehicles, one or more buses, one or more commercial transport vehicles, or any combination thereof.

[0055] In at least one embodiment, the controller 600 may be configured to receive AC power from the power supply 500 at a first level. In at least one embodiment, the controller 600 may be configured to supply DC power to the load 700 at a second level that is higher than the first level. In at least one embodiment, the controller 600 may be configured to add the power from the flywheel 300 to the AC power received from the power supply 500 in order to supply DC power to the load 700 at the second level. In at least one embodiment, the controller 600 may be configured to limit the AC power received from the power supply 700 to the first level. In at least one embodiment, the controller 600 may include one or more current control and / or limiting devices for controlling the motor 200. In this way, the motor 200, the controller 600, or both may be configured to limit the AC power received from the power supply 500 to the first level.

[0056] In at least one embodiment, the controller 600 can be configured to feed the electrical energy received from the power grid 500 into the motor 200, where it can be converted into mechanical energy that is sent to the flywheel 300 regardless of whether the system 100 is being used to supply power to the load 700. In this way, the AC power received from the power supply 500 can be used to reduce the deceleration of the flywheel 300 when the system 100 is being used to supply power to the load 700.

[0057] In at least one embodiment, when the system 100 is being used to supply power to the load 700, the controller 600 may be configured to combine the electrical energy received from the power grid 500 through the motor 200 with the electrical energy received from the flywheel 300. In this way, the AC power received from the power source 500 can be used to supplement the depleted power from the flywheel 300, thereby reducing the deceleration of the flywheel 300 when the system 100 is being used to supply power to the load 700.

[0058] In at least one embodiment, a system 100 for storing input power and providing output power according to the present disclosure, such as for use with electric vehicle charging, can include one or more controllers 600 configured to be electrically coupled to one or more AC power sources 500 and / or one or more loads 700, and one or more flywheel energy storage systems 800 configured to mechanically store the power received from the power source 500, or any combination thereof. In at least one embodiment, the controller 600 may be configured to convert AC power to DC power for delivery to the load 700. In at least one embodiment, any or all of the flywheel energy storage systems 800 may include one or more flywheels 300 mechanically coupled to one or more rotors 310, one or more AC motors 200 electrically coupled to the controller 600 and / or mechanically coupled to the rotor 310, or any combination thereof. In at least one embodiment, the motor 200 may be configured to receive AC power from the power source 500. In at least one embodiment, the load 700 can be one or more electric vehicles.

[0059] In at least one embodiment, the flywheel energy storage system 800 can include a plurality of flywheel energy storage systems 800. In at least one embodiment, the system 100 can include two, three, four, or more flywheel energy storage systems 800, thereby providing scalability to the system 100. For example, the system 100 according to the present disclosure configured to charge a passenger vehicle can include one or two flywheel energy storage systems 800. As another example, the system 100 according to the present disclosure configured to charge a passenger vehicle and larger vehicles can include two, three, or more flywheel energy storage systems 800. As another example, the system 100 configured to charge a passenger vehicle and / or larger vehicles during a power outage or peak times can include four, or more flywheel energy storage systems 800, thereby minimizing or eliminating any power drawn from the power grid during a power outage or peak times.

[0060] In at least one embodiment, the motor 200 can be a line-start synchronous motor. In at least one embodiment, the motor 200 can be a three-phase two-pole line-start synchronous reluctance motor. In at least one embodiment, the motor 200 can be further configured to supply AC power to the controller 600. In at least one embodiment, the motor 200 can be directly connected to the power grid 500 without any power electronics interface, such as a variable frequency drive. In at least one embodiment, the motor 200 can be directly connected to the power grid 500 through one or more breakers, such as a molded case circuit breaker (MCCB) for household power.

[0061] In at least one embodiment, the flywheel energy storage system 800 can also include one or more alternators 400 that are electrically coupled to the controller 600 and mechanically coupled to the rotor 310. In at least one embodiment, the alternator 600 can be configured to supply AC power to the controller 600. In at least one embodiment, the alternator 600 can be a synchronous alternator. In at least one embodiment, the alternator 600 can be a three-phase four-pole single-pole synchronous machine.

[0062] In at least one embodiment, the rotor 310 can be supported by one or more high-temperature superconducting magnetic bearings 320. For example, the rotor 310 can be axially supported by one or more high-temperature superconducting magnetic bearings 320 at the upper end and / or by one or more other high-temperature superconducting magnetic bearings 320 at the lower end. In at least one embodiment, the flywheel 300 can be supported by one or more magnetic levitation bearings 330, 340. For example, the flywheel 300 can be supported from below by one or more repulsive-mode permanent magnet levitation bearings 330 and / or from above by one or more attractive-mode permanent magnet levitation bearings 340.

[0063] In at least one embodiment, the rotor 310 can be common with the motor 200, the flywheel 300, the alternator 400, or any combination thereof. For example, in at least one embodiment, the motor 200 can have its own rotor 210, which can be mechanically coupled to the rotor 310 of the flywheel 300. Similarly, in at least one embodiment, the alternator 400 can have its own rotor 410, which can be mechanically coupled to the rotor 310 of the flywheel 300. In at least one embodiment, the flywheel 300 can be configured to rotate about any of the rotors 210, 310, 410 in a horizontal plane. In at least one embodiment, the flywheel 300 can be configured to rotate about any of the rotors 210, 310, 410 in a vertical plane.

[0064] In at least one embodiment, the flywheel 300 can be disposed between the motor 200 and the generator 400. In at least one embodiment, the motor 200 can be disposed between the flywheel 300 and the generator 400. In at least one embodiment, the generator 400 can be disposed between the motor 200 and the flywheel 300.

[0065] In at least one embodiment, the controller 600 can be configured to receive AC power from the power source 500 at a first level and supply DC power to the load 700 at a second level. In at least one embodiment, the second level can be higher than the first level. In at least one embodiment, the controller 600 can be configured to add power from the flywheel 300 to the AC power received from the power source 500 in order to supply DC power to the load 700 at the second level. In at least one embodiment, the controller 600 can be configured to limit the AC power received from the power source 500 to the first level. In at least one embodiment, the controller 600 can include one or more rectifiers. In at least one embodiment, the controller 600 can include one or more adjustable rectifiers, whereby the output voltage of the DC power supplied to the load 700 can be adjusted. In at least one embodiment, the controller 600 can control one or more separate adjustable rectifiers, whereby the output voltage of the DC power supplied to the load 700 can be adjusted.

[0066] In at least one embodiment, the generator 400 can be a unipolar generator magnetized through a stationary DC field winding fixed to the stator. In at least one embodiment, a proportional-integral-derivative (PID) control system can adjust the field current to achieve a desired output voltage that can be different for different loads, such as a passenger vehicle, a bus, or a commercial transport vehicle, and can be or include any output voltage required or desired according to the implementation of the present disclosure. In at least one embodiment, the desired output voltage can be specified by the load 700, the user, the controller 600, or any combination thereof. For example, the controller 600 can detect which type of load 700 is connected thereto and can set a reference voltage for the PID control system accordingly. In at least one embodiment, the PID control system can be integrated with the controller 600. In at least one embodiment, the PID control system can be independent of the controller 600.

[0067] In at least one embodiment, the system 100 can include one or more flywheels 300, bearings 320, 330, 340, and / or other components disclosed in any of U.S. Patent Application No. 17 / 348,716, filed June 15, 2021, U.S. Patent No. 11,105,368, issued August 31, 2021, U.S. Patent No. 10,077,805, issued September 18, 2018, U.S. Patent No. 9,404,532, issued August 2, 2016, and / or U.S. Provisional Patent Application No. 61 / 884,766, filed July 10, 2013, the entire contents of each of which are incorporated herein by reference.

[0068] In at least one embodiment, a system 100 according to the present disclosure for storing input power and providing output power, such as for use with electric vehicle charging, can provide an adjustable output voltage for various vehicles without any DC / DC converter that may suffer from a high failure rate. For example, the controller 600 can be configured to charge various vehicles without a DC / DC converter, each having a different charging speed and / or voltage.

[0069] In at least one embodiment, the system 100 according to the present disclosure can provide a stable voltage and power rating during charging regardless of the capacity and fluctuations in the power transmission network 500. In at least one embodiment, the system 100 according to the present disclosure can provide very fast charging because very high power can be used regardless of the capacity and fluctuations in the power transmission network 500. In at least one embodiment, the system 100 according to the present disclosure can provide scalability according to a desired charging station rating, which can be of any rating or can include any rating, according to the implementation form of the present disclosure.

[0070] In at least one embodiment, the system 100 according to the present disclosure can operate without a power grid connection interface, such as a variable frequency drive or an unreliable load interface. For example, generally available DC / DC chargers can have a high failure rate. Further, the system 100, which can be configured without a DC / DC charger, can have higher reliability, a simpler structure, lower installation costs, and lower maintenance requirements.

[0071] In at least one embodiment, a flywheel energy storage system 800 according to the present disclosure can have negligible idling losses and a long expected life, especially when compared to alternative energy storage systems. For example, the flywheel energy storage system 800 can be configured to avoid voltage drops typically associated with battery systems.

[0072] In at least one embodiment, a system 100 for storing input power and providing output power according to the present disclosure, for use with electric vehicle charging and the like, can include one or more controllers 600, one or more line-start synchronous AC motors 200, one or more flywheels 300, one or more synchronous AC generators 400, or any combination thereof. In at least one embodiment, the controller 600 can be electrically coupled to one or more AC power sources 500 and / or one or more loads 700. In at least one embodiment, the controller 600 can convert AC power to DC power for delivery to the load 700 at a first level.

[0073] In at least one embodiment, the motor 200 can be electrically coupled to the source 500. In at least one embodiment, the motor 200 can have one or more rotors 210 and / or can receive AC power from the source 500 at a second level. In at least one embodiment, the second level can be lower than the first level. In at least one embodiment, the controller 600 can limit the AC power received from the source 500 to the second level. In at least one embodiment, the flywheel 300 can be mechanically coupled to the rotor 210 external to the motor 200.

[0074] In at least one embodiment, the generator 400 can have one or more rotors 410 mechanically coupled to the flywheel 300. In at least one embodiment, the generator 400 can be electrically coupled to the controller 600 to supply power to the load 700. In at least one embodiment, the load 700 can be one or more electric vehicles. In at least one embodiment, the generator can supply AC power to the controller 600.

[0075] In at least one embodiment, the power electronics can be limited or even removed entirely. In at least one embodiment, by using a line-start synchronous motor (LSSM) at the power input, the AC signal supplied by the power grid can be used to excite the motor throughout the full speed range, typically expressed in revolutions per minute (RPM). At lower frequencies, the LSSM acts as an induction motor, where the slip frequency results in torque in the rotor. As the frequency of the rotor approaches the power grid frequency, the motor acts as a synchronous motor, and the main interaction is between the DC field of the rotor and the AC field of the signal supplied by the power grid to the stator.

[0076] In at least one embodiment, the rotor can be designed such that its maximum speed matches the power grid frequency. In at least one embodiment, despite a lower maximum RPM, the use of a larger diameter rotor can be employed to store sufficient energy. In at least one embodiment, the rotor operation can occur primarily between 50% - 100% of the maximum speed so that the slip frequency does not increase significantly enough to cause a large inrush current from the power grid. In other words, by avoiding low rotor / flywheel RPMs, the power grid does not need to provide the high inrush currents typically associated with LSSMs.

[0077] In at least one embodiment, a variable frequency and / or variable voltage output is directly connected to the input of the DCFC. In at least one embodiment, the frequency and / or voltage range at the rotor is configured to be within the operating range of the AC / DC converter of the DCFC and not to fall below a threshold that would cause excessive energy accumulation between cycles on the AC / DC converter.

[0078] In at least one embodiment, power from the power grid is stored in the flywheel and / or rotor. In at least one embodiment, power from the power grid is combined in the DCFC with power stored in the flywheel and / or rotor. In at least one embodiment, in order to provide the required output power, in the DCFC, the power stored in the flywheel and / or rotor is combined with them, and the power drawn from the power grid is limited. In at least one embodiment, all of the output power is drawn directly from the flywheel and / or rotor. In at least one embodiment, the power drawn from the power grid is limited such that the flywheel and / or rotor decelerate as output power is drawn from them. In at least one embodiment, the power drawn from the power grid is limited, the output power exceeds that limit, and the flywheel and / or rotor decelerate as output power is drawn from the system.

[0079] In at least one embodiment, a synchronous motor connected to the power grid can also stabilize the power grid. For example, the LSSM can be designed to idle at a frequency of 60 Hertz (Hz), i.e., 3600 RPM. In at least one embodiment, when the power grid frequency drops below the flywheel frequency, power can flow from the flywheel into the power grid. The flywheel "idling" frequency can be adjusted and / or selected according to the location and the power grid frequency (e.g., 60 Hz is generally used in the United States and 50 Hz is generally used in the United Kingdom).

[0080] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include an AC motor, a flywheel, and an AC generator. In at least one embodiment, the motor and the generator can be the same machine. In at least one embodiment, the motor can be electrically coupled to an AC power source. In at least one embodiment, the motor can have a rotor and can be configured to receive AC power from a power source. In at least one embodiment, the flywheel can be mechanically coupled to the rotor external to the motor. In at least one embodiment, the generator can have a rotor mechanically coupled to the flywheel. In at least one embodiment, the generator can be configured to be electrically coupled to a controller to supply power to a load.

[0081] In at least one embodiment, the motor can be a line-start synchronous motor. In at least one embodiment, the generator can be a synchronous generator. In at least one embodiment, the load can be an electric vehicle.

[0082] In at least one embodiment, the generator can be configured to supply AC power to a controller. In at least one embodiment, the controller can be configured to convert the AC power to DC power for delivery to a load. In at least one embodiment, the motor can be configured to receive AC power from a power source at a first level. In at least one embodiment, the generator can be configured to supply AC power to a controller at a second level higher than the first level.

[0083] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include an AC motor and a flywheel. In at least one embodiment, the motor can be configured to be electrically coupled to an AC power source. In at least one embodiment, the motor can have a rotor. In at least one embodiment, the motor can be configured to receive AC power from a power source. In at least one embodiment, the flywheel can be mechanically coupled to the rotor external to the motor. In at least one embodiment, the flywheel can be configured to mechanically store the power received from the power source through the motor. In at least one embodiment, the motor can be configured to be electrically coupled to a controller to supply power to a load.

[0084] In at least one embodiment, the motor can be a line-start synchronous motor. In at least one embodiment, the load can be an electric vehicle. In at least one embodiment, the motor can be configured to supply AC power to a controller. In at least one embodiment, the controller can convert the AC power to DC power for delivery to the load.

[0085] In at least one embodiment, the motor can be configured to receive AC power from a power source at a first level. In at least one embodiment, the motor can be configured to supply AC power to a controller at a second level higher than the first level. In at least one embodiment, the motor can be configured to add the power from the flywheel to the AC power received from the power source to supply AC power to the controller at the second level. In at least one embodiment, the motor can be configured to limit the AC power received from the power source to the first level.

[0086] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include a controller, an AC motor, and a flywheel. In at least one embodiment, the controller can be configured to be electrically coupled to an AC power source and a load. In at least one embodiment, the controller can be configured to convert AC power to DC power for delivery to the load. In at least one embodiment, the motor can be electrically coupled to the controller. In at least one embodiment, the motor can have a rotor. In at least one embodiment, the motor can be configured to receive AC power from a power source through the controller. In at least one embodiment, the flywheel can be mechanically coupled to an external rotor of the motor. In at least one embodiment, the flywheel can be configured to mechanically store power received from the power source through the motor.

[0087] In at least one embodiment, the motor can be a line-start synchronous motor. In at least one embodiment, the motor can be configured to receive AC power from the controller and supply AC power to the controller. In at least one embodiment, the load can be an electric vehicle.

[0088] In at least one embodiment, the controller can be configured to receive AC power from a power source at a first level. In at least one embodiment, the controller can be configured to supply DC power to a load at a second level higher than the first level. In at least one embodiment, the controller can be configured to add power from the flywheel to the AC power received from the power source to supply DC power to the load at the second level. In at least one embodiment, the controller can be configured to limit the AC power received from the power source to the first level.

[0089] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include a controller configured to be electrically coupled to an AC power source and a load, and at least one flywheel energy storage system configured to mechanically store power received from the power source. In at least one embodiment, the controller can be configured to convert AC power to DC power for delivery to the load. In at least one embodiment, each flywheel energy storage system can include a flywheel mechanically coupled to a rotor and an AC motor electrically coupled to the controller and mechanically coupled to the rotor. In at least one embodiment, the motor can be configured to receive AC power from the power source. In at least one embodiment, the load can be an electric vehicle.

[0090] In at least one embodiment, the motor can be a line-start synchronous reluctance motor. In at least one embodiment, the motor can be further configured to supply AC power to the controller. In at least one embodiment, the at least one flywheel energy storage system comprises a plurality of flywheel energy storage systems.

[0091] In at least one embodiment, each flywheel energy storage system can also include an AC generator electrically coupled to the controller and mechanically coupled to the rotor. In at least one embodiment, the generator can be configured to supply AC power to the controller. In at least one embodiment, the AC generator can be a synchronous AC generator.

[0092] In at least one embodiment, the rotor can be supported by at least one high-temperature superconducting magnetic bearing. For example, the rotor can be supported axially by one high-temperature superconducting magnetic bearing at the upper end and / or by another high-temperature superconducting magnetic bearing at the lower end. In at least one embodiment, the flywheel is supported by at least one magnetic levitation bearing. For example, the flywheel can be supported from below by a repulsive-mode permanent magnet levitation bearing and / or from above by an attractive-mode permanent magnet levitation bearing.

[0093] In at least one embodiment, the controller can be configured to receive AC power from a power source at a first level and supply DC power to a load at a second level. In at least one embodiment, the second level can be higher than the first level. In at least one embodiment, the controller can be configured to add power from the flywheel to the AC power received from the power source to supply DC power to the load at the second level. In at least one embodiment, the controller can be configured to limit the AC power received from the power source to the first level.

[0094] In at least one embodiment, a system for storing input power and providing output power, such as for use with electric vehicle charging, can include a controller, a line-start synchronous AC motor, a flywheel, a synchronous AC generator, or any combination thereof. In at least one embodiment, the controller can be electrically coupled to an AC power source and / or a load. In at least one embodiment, the controller can convert AC power to DC power for delivery to the load at a first level.

[0095] In at least one embodiment, a line-start synchronous AC motor can be electrically coupled to an AC power source. In at least one embodiment, the motor can have a first rotor and / or can receive AC power from the power source at a second level. In at least one embodiment, the second level can be lower than the first level. In at least one embodiment, a controller can limit the AC power received from the power source to the second level. In at least one embodiment, a flywheel can be mechanically coupled to the first rotor external to the motor.

[0096] In at least one embodiment, a synchronous AC generator can have a second rotor mechanically coupled to the flywheel. In at least one embodiment, the generator can be electrically coupled to a controller to supply power to a load. In at least one embodiment, the load can be an electric vehicle. In at least one embodiment, the generator can supply AC power to the controller.

[0097] Other and further embodiments that utilize one or more aspects of the present disclosure can be devised without departing from the spirit of the applicants' disclosure. For example, the devices, systems, and methods can be implemented for numerous different types and sizes in numerous different industries. Further, various methods, and embodiments of the devices, systems, and methods can be included in combinations with each other to generate variations of the disclosed methods and embodiments. Consideration of a single element can include a plurality of elements and vice versa. The order of steps can occur in a variety of orders unless otherwise limited. The various steps described herein can be combined with other steps, inserted into the described steps, and / or divided into multiple steps. Similarly, elements can be functionally described and embodied as separate components or can be combined into components having multiple functions.

[0098] The present invention is described in the context of preferred and other embodiments, and not all embodiments of the invention are described. Obvious modifications and variations to the described embodiments are available to those skilled in the art who benefit from this disclosure. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived by the applicants. Rather, in accordance with patent law, the applicants intend to fully protect all such modifications and improvements that fall within the scope or realm of the equivalents of the following claims.

Claims

1. A system for storing input power and providing output power, comprising: A controller configured to be electrically coupled to an AC power source and a load, the controller being configured to convert AC power to DC power for delivery to the load; At least one flywheel energy storage system configured to mechanically store power received from the power source, each flywheel energy storage system comprising: A flywheel mechanically coupled to a rotor; An AC motor electrically coupled to the controller and mechanically coupled to the rotor, the motor being configured to receive AC power from the power source; Including; System.

2. The system according to claim 1, wherein the motor is a line-start synchronous reluctance motor.

3. The system according to claim 1, wherein the motor is further configured to supply AC power to the controller.

4. The system according to claim 1, wherein each flywheel energy storage system further includes an AC generator electrically coupled to the controller and mechanically coupled to the rotor, the generator being configured to supply AC power to the controller.

5. The system according to claim 1, wherein the rotor is supported by at least one high-temperature superconducting magnetic bearing.

6. The system according to claim 1, wherein the flywheel is supported by at least one magnetic levitation bearing.

7. The system according to claim 1, wherein the controller is configured to receive AC power from the power source at a first level and supply DC power to the load at a second level, the second level being higher than the first level.

8. The system according to claim 7, wherein the controller is configured to add power from the flywheel to the AC power received from the power source to supply DC power to the load at the second level.

9. The system according to claim 7, wherein the controller is configured to limit the AC power received from the power source to the first level.

10. The system according to claim 1, wherein the load is an electric vehicle.

11. A system for storing input power and providing output power, comprising: A controller configured to be electrically coupled to an AC power source and a load, the controller configured to convert AC power to DC power for delivery to the load, and a controller; An AC motor electrically coupled to the controller, the motor having a rotor and configured to receive AC power from the power source through the controller; A flywheel mechanically coupled to the rotor external to the motor, the flywheel configured to mechanically store power received from the power source through the motor; A system comprising.

12. The system according to claim 11, wherein the motor is a line-start synchronous motor.

13. The system according to claim 11, wherein the motor is configured to receive AC power from the controller and supply AC power to the controller.

14. The system according to claim 11, wherein the controller is configured to receive AC power from the power source at a first level and supply DC power to the load at a second level, the second level being higher than the first level.

15. The system according to claim 14, wherein the controller is configured to add power from the flywheel to the AC power received from the power source to supply DC power to the load at the second level.

16. The system according to claim 14, wherein the controller is configured to limit the AC power received from the power source to a first level.

17. The system according to claim 11, wherein the load is an electric vehicle.

18. A system for storing input power and providing output power, A controller configured to be electrically coupled to an AC power source and a load, the controller configured to convert AC power to DC power for delivery to the load at a first level, and a controller; A line-start synchronous AC motor configured to be electrically coupled to the AC power source, the motor having a first rotor and configured to receive AC power from the power source at a second level, the second level being lower than the first level; A flywheel mechanically coupled to the first rotor external to the motor; A synchronous AC generator having a second rotor mechanically coupled to a flywheel, the generator being configured to be electrically coupled to a controller for supplying power to a load and configured to supply AC power to the controller, and the generator comprising a system. **Claim 19** The system according to claim 18, wherein the controller is configured to limit the AC power received from the power source to a second level. **Claim 20** The system according to claim 18, wherein the load is an electric vehicle.

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