Patent Application
20240317103
This application generally relates to improvements to charging stations generally and, more particularly, to improvements in energy management and charge transfer between multiple charging stations at a charging site interconnected by a battery bus.
Charging stations for electric vehicles (EVs), referred to below also as “EV Supply Equipment” (EVSEs), “EV chargers,” or simply as “chargers,” provide electric power to EVs, including plug-in hybrid vehicles, that can operate without the use or with limited use of hydrocarbon-based fuels. Installation of conventional charging stations typically requires improvements to infrastructure including upgrades to electrical service and construction of suitable housing. The costs, planning, and time required to install these charging systems can be a deterrent to potential commercial or residential operators. To reduce the installation and operating requirements associated with traditional charging stations, some EV chargers include batteries to store energy received from a power source (such as an electric utility power grid) over an extended time interval. More particularly, a battery-based EV charger incorporates a stationary battery as an energy buffer, storing energy received from an AC grid for example, to prevent the direct supply of DC charging power.
At charging sites having multiple charging stations, different chargers can have different states of charge (SOCs) due to different rates of utilization or other reasons. For example, drivers frequently park and charge at the chargers nearest a location of interest (e.g., an entrance to a business), resulting in higher rates of battery discharging for such chargers. Because the batteries of the chargers are discharged during vehicle charging at a faster rate than they are charged from a power source such as the AC grid, the batteries of the more frequently used chargers may be depleted more quickly than the batteries of charging stations that are less frequently used.
Multiple decentralized batteries of respective electric vehicle (EV) charging stations, or simply “chargers,” are disposed at a common site and are interconnected via a bus to effectively operate as one large charger with multiple ports for independently charging multiple EVs. The bus can be implemented as a high-voltage DC (HVDC) bus. Because the voltages at the respective batteries of the chargers can be at different levels, at least some of the chargers include a switching component configured to connect the battery of the charger directly to the bus in one operational state, and connect the battery of the charger to the bus via a DC-to-DC converter in a second operational state. The DC-to-DC in the second operational state operates to transfer energy from the battery of the charger to the one or more batteries of the peer chargers via the bus or from the one or more batteries of the peer chargers to the battery of the charger via the bus, depending on whether the voltage across the battery of the charger is higher or lower than the voltage across the bus. The switching component can include for example power sharing or paralleling contactors and a rebalancing contactor. The chargers further can communicate via wireless or wires communication links to coordinate the respective battery management systems (BMSs) and, in some implementations, receive commands from a virtual BMS that controls multiple chargers at the site. These techniques allow a site to provide the same charging capability at all EV charging ports of the site.
An example embodiment of these techniques is a charger for an electric vehicle. The charger comprises a battery system; a high-voltage direct current (HVDC) bus configured to connect the charger to an external battery system; a DC-to-DC converter; and a switching component configured to (i) in a first operational state, connect the battery system to the HVDC bus directly so as to provide a parallel electric connection to the external battery system, and (ii) in a second operational state, connect the battery system to the HVDC bus via the DC-to-DC converter to align a voltage across the battery system with a voltage across the HVDC bus.
Another example embodiment of these techniques is a charging system comprising a first charger including (i) a first battery system, (ii) a DC-to-DC converter, (iii) at least one port configured to removeably receive connectors of electric vehicles, and (iv) a switching component; a second charger including (i) a second battery system, and (ii) at least one port configured to removeably receive connectors of electric vehicles; and a high-voltage direct current (HVDC) bus coupled to the first charger and a second charger. The switching component is configured to connect the first battery system to the HVDC bus via the DC-to-DC converter to align a voltage across the first battery system with a voltage across the second battery system.
Yet another example embodiment of these techniques is a method implemented in a charger for an electric vehicle. The method includes determining whether a voltage VBAT across a battery system of charger differs from a voltage VHVDC across a high-voltage DC bus to which the charger is connected by at least a threshold amount; when VBAT differs from VHVDC by at least the threshold amount, transferring power between the battery system and the bus to reach a substantial alignment between VBAT and VHVDC; and when VBAT does not differ from VHVDC by at least the threshold amount, connecting the battery system to the bus in parallel.
A battery-equipped charger for an electric vehicle (EV) is configured to connect to a battery bus, also referred to below as a high-voltage direct current (HVDC) bus or simply “bus,” to form a unified battery system for EV charging. The charger can use a DC-to-DC converter to transfer energy to or from the battery of the charger to one or more remote batteries connected to the HVDC bus. The techniques of this disclosure solve the problem of ensuring availability of reliable power at each of the charging stations at a multi-charger site.
The techniques discussed below include interconnecting decentralized batteries within charging stations and establishing a unified battery system for independent EV charging. In some cases, this approach leverages the site infrastructure instead of relying on individual batteries, enabling energy sharing among multiple chargers in a networked environment. EV charge ports according connect to, and draw energy from, a single unified system.
Although described below as relating to EVs, it should be understood that the techniques of this disclosure may apply also to plug-in hybrid vehicles or other wholly or partially battery-powered devices that may be charged by a high-voltage or high-power charging station.
The AC power from the site meter 22 is provided as an input AC electric power to the respective input ports 102A-D of the EV charging systems 100A-D via one or more wired AC connections. In some embodiments, the input AC electric power is received at each of the input ports 102A-D as a 120V or 240V single-phase or three-phase AC power supply. As discussed elsewhere herein, each of the EV charging systems 100A-D converts and stores such input AC electric power to DC power stored in batteries of respective energy storage modules 114A-D, from which charging currents may be provided to vehicles via vehicle couplings 132A-D of the EV charging systems 100A-D. The EV charging systems 100A-D are controlled by respective system controllers 120A-D, which monitor operating data of the respective EV charging systems 100A-D and control charging and discharging of the energy storage modules 114A-D.
In some embodiments, the DC power may be stored in the energy storage modules 114A-D over an interval of time in order to provide charging current to EVs via respective vehicle couplings 132A-D at a faster rate than the input AC electric power is received by the EV charging systems 100A-D. While this has significant advantages in reducing the electrical infrastructure requirements for the charging site 10, some of the EV charging systems 100A-D may be used more than others. For example, EV charging systems 100C and 100D may experience greater use due to closer proximity to a destination (e.g., by being located in a parking lot at locations nearer an entrance to a commercial building). As illustrated, vehicles 140C and 140D may be connected to EV charging systems 100C and 100D by vehicle couplings 132C and 132D, respectively, in order to receive charging currents from energy stored in the energy storage modules 114C and 114D, while no vehicles are charging at EV charging systems 100A and 100B. Thus, the batteries of EV charging systems 100C and 100D will discharge faster than those of EV charging systems 100A and 100B, resulting in a charge imbalance among the energy storage modules 114A-D. To address such an imbalance, energy may be transferred from EV charging systems 100A and 100B to EV charging systems 100C and 100D via the DC bus 101.
The DC bus 101 provides a direct DC power connection between the EV charging systems 100A-D to enable charge transfers among the energy storage modules 114A-D. Each of the EV charging systems 100A-D includes an inter-charger connection (not shown) that provides a bidirectional DC connection to the DC bus 101, and thereby to each of the other EV charging systems 100A-D. Through such inter-charger connections, the EV charging systems 100A-D are enabled to receive and to provide DC current at various times as part of charge transfers, which may be used to perform charge balancing between the energy storage modules 114A-D. In some embodiments, one or more external batteries 30 are also connected to the DC bus 101 to store energy received from the EV charging systems 100A-D and provide the stored energy at a later time, as needed. Such external batteries 30 may include controllers (not shown) to control charging and discharging, or the external batteries 30 may be controlled by the system controllers 120A-D of the EV charging systems 100A-D or by a centralized management system 150. Similarly, in various embodiments, charge transfers may be determined and controlled by the system controllers 120A-D of the EV charging systems 100A-D or by a centralized management system 150. To facilitate such control decisions, each of the system controllers 120A-D is connected via wired or wireless communication connections with the other system controllers 120A-D and/or with the centralized management system 150 to exchange electronic messages or signals.
The centralized management system 150 may communicate with each of the EV charging systems 100A-D in order to monitor operating data regarding the EV charging systems 100A-D and to determine and control charge transfers as needed. The centralized management system 150 may be located at the charging site 10 or at a location remote from the charging site 10. When remote from the charging site 10, the centralized management system 150 may be communicatively connected to the EV charging systems 100A-D via a network 40, which may be a proprietary network, a secure public internet, a virtual private network, or some other type of network, such as dedicated access lines, plain ordinary telephone lines, satellite links, cellular data networks, or combinations of these. In various embodiments, the EV charging systems 100A-D may be communicatively connected with the network 40 directly or via a local router 42. In some embodiments in which the centralized management system 150 is located at the charging site 10, the centralized management system 150 may be combined with or incorporated within any of the EV charging systems 100A-D. In still further embodiments, the centralized management system 150 may be configured as a local cloud or server group distributed across the system controllers 120A-D of the EV charging systems 100A-D in order to provide robust control in the event of a network disruption.
In some embodiments, the centralized management system 150 may also communicate with remote EV charging systems that are deployed in locations remote from the charging site 10, which locations may be separated by large geographic distances. For example, the centralized management system 150 may communicate with EV charging systems 100 located in different parking facilities, on different floors of the same parking structure, or in different cities. Such centralized management system 150 may comprise one or more servers configured to receive operating data from and to send data and/or control commands to each of the EV charging systems 100A-D. To facilitate communication, the centralized management system 150 may be communicatively connected to the system controllers 120A-D of the EV charging systems 100A-D via an electronic communication link with a communication interface module (not shown) within each of the EV charging systems 100A-D.
The centralized management system 150 may group or relate EV charging systems according to their location, their intended function, availability, operating status, and capabilities. The centralized management system 150 may remotely configure and control the EV charging systems, including the EV charging systems 100A-D. The centralized management system 150 may remotely enforce regulations or requirements governing the operation of the EV charging systems 100A-D. The centralized management system 150 may remotely interact with users of the EV charging systems 100A-D. The centralized management system 150 may remotely manage billing, maintenance, and error detection for each of the EV charging systems 100A-D. For example, error conditions resulting in manual disconnection of a vehicle from any of the EV charging systems 100A-D may be reported by such EV charging system to the centralized management system 150 for analysis. The centralized management system 150 may also communicate with mobile communication devices of users of the EV charging systems 100A-D, such as mobile communication devices or other computing devices used by operators of the EV charging systems 100A-D to enable the operator to self-configure the EV charging systems 100A-D, charge pricing, language localization, currency localization, and so on. Operation of the centralized management system 150 in relation to charge transfers between the EV charging systems 100A-D is further described elsewhere herein.
The EV charging system 100 includes a power input module 110 having one or more circuits configurable to transform, condition, or otherwise modify power received from an input port 102 or 104 to provide conditioned power to a power conversion module 112. The input power received at input ports 102 or 104 may be received from an electric power grid 20, a local power generator (e.g., a solar panel or a wind turbine), or any other power source. In some embodiments, input AC power is received at an AC input port 102, while input DC power is received at a DC input port 104 (e.g., from photovoltaic cells or other types of DC power sources). The DC input port 104 may be connected to one or more of an inverter module 106 or a power conditioning module 108 for the input DC power. In further embodiments, DC current received via DC input port 104 is converted to an AC current by an inverter module 106, and the AC current is then provided to power input module 110. The power input module 110 may combine AC or DC current received from multiple sources. Similarly, the power input module 110 may direct AC or DC current received from multiple sources to individual circuits or sections of the power conversion module 112. In some embodiments, the power input module 110 may include a rectifier to convert AC current received at an input port 102 or 104 into DC current to be provided to the power conversion module 112. In further embodiments, DC current received via DC input port 104 may instead be provided to a power conditioning module 108 that may include voltage level converting circuits, filters, and other conditioning circuits to provide a charging current to the energy storage module 114.
The power conversion module 112 includes some combination of one or more AC-to-DC, DC-to-DC, and/or DC-to-AC converters for efficient conversion of AC or DC input power received from a power utility or other source at input port 102 or 104 via the power input module 110 to a DC energy storage current 126 provided to the energy storage module 114, which stores the power until needed to provide a charging current 116 to a vehicle 140. In some embodiments, the power conversion module 112 includes an AC-to-DC conversion circuit that generates a DC energy storage current 126 that is provided to an energy storage module 114. Alternatively, the power input module 110 may include an AC-to-DC conversion circuit to generate a DC current from an input AC electric power. In further embodiments, the energy storage module 114 includes high-capacity batteries that have a storage capacity greater than a multiple of the storage capacity in the EVs to be charged (e.g., three times, five times, or ten times an expected vehicle battery capacity). The storage capacity of the energy storage module 114 may be configured based on the expected average charge per charging event, which may depend upon factors such as the types of vehicles charged, the depletion level of the vehicle batteries when charging starts, and the duration of each charging event. For example, a retail parking site may have more charging events of shorter duration, while a commuter train parking lot may have fewer charging events of longer duration. In various embodiments, the storage capacity of the energy storage module 114 may be configured based on maximum expected charging offset by power received from an electric utility. In some embodiments, the storage capacity of each of the energy storage modules 114 of the EV charging systems 100 and any external batteries 30 at a charging site 10 may be configured to ensure a total charge stored at the charging site 10 is sufficient for an expected maximum load due to vehicle charging. In further embodiments, the power received from an electric utility may be limited to power available during low-demand times, such as off-peak or low-priced periods of the day. The power input module 110 may be configured to block or disconnect inflows of power during peak or high-priced periods of the day. In some embodiments, the power input module 110 may be configured to enable power reception during peak periods to ensure continued operation of the EV charging system 100 when power levels in the energy storage module 114 are unexpectedly low.
In some embodiments, the power conversion module 112 may include one or more DC-to-DC conversion circuits that receive DC current 128 at a first voltage level from the energy storage module 114 and drive a charging current 116 to a vehicle 140 through a vehicle coupling 132 to supply a vehicle 140 with the charging current 116 via a vehicle charge port 142. The vehicle coupling 132 serves as an electrical interconnect between the EV charging system 100 and the vehicle 140. In various embodiments, such vehicle coupling 132 comprises a charging head and/or a charging cable. For example, the vehicle coupling 132 may comprise a charging cable having a standard-compliant plug for connection with a vehicle charge port 142 of vehicles 140. The vehicle coupling 132 may include both a power connection for carrying the charging current 116 and a communication connection for carrying electronic communication between the charge controller 130 and the vehicle 140. In some embodiments, the EV charging system 100 may comprise multiple vehicle couplings 132, and the power conversion module 112 may include a corresponding number of DC-to-DC conversion circuits specific to each of the multiple couplings. According to some embodiments, the power conversion module 112 may be further configured to receive a reverse current 118 from a vehicle 140 via the vehicle coupling 132, which reverse current 118 may be used to provide a DC energy storage current 126 to add energy to the energy storage module 114. In some examples, the power conversion module 112 includes one or more inverters that convert the DC current 128 to an AC current that can be provided as the charging current 116.
A charge controller 130 controls the charging current 116 and/or reverse current 118 through each vehicle coupling 132. To control charging or discharging of the vehicle 140, the charge controller 130 comprises one or more logic circuits (e.g., general or special-purpose processors) configured to execute charging control logic to manage charging sessions with vehicle 140. Thus, the charge controller 130 is configured to communicate with the system controller 120 to control the power conversion module 112 to provide the charging current 116 to the vehicle 140 or to receive the reverse current 118 from the vehicle 140 via the vehicle coupling 132. In some instances, the charge controller 130 may include power control circuits that further modify or control the voltage level of the charging current 116 passed through the vehicle coupling 132 to the vehicle 140. The charge controller 130 also communicates via the vehicle coupling 132 with a vehicle charge controller 144 within the vehicle 140 to manage vehicle charging. Thus, the charge controller 130 communicates with the vehicle charge controller 144 to establish, control, and terminate charging sessions according to EV charging protocols (e.g., CCS or CHaDEMO). The charge controller 130 may be communicatively connected with the vehicle coupling 132 to provide output signals 134 to the vehicle charge controller 144 and to receive input signals 136 from the vehicle charge controller 144.
A system controller 120 is configured to control operations of the EV charging system 100 by implementing control logic using one or more general or special-purpose processors. The system controller 120 is configured to monitor and control power levels received by the power input module 110, power levels output through the charging current 116, energy levels in the energy storage module 114, and charge received from or output to the DC bus 101 via the DC bus connection 160. The system controller 120 is further configured to communicate with and control each of the one or more charge controllers 130, as well as controlling the power conversion module 112. For example, the system controller 120 is configured to control the power conversion module 112 and the charge controller to supply a charging current 116 to the vehicle coupling 132 in response to instructions from the charge controller 130. As discussed further herein, the system controller 120 is also configured to control (either separately or in coordination with the centralized management system 150) charge transfers to manage energy levels of the EV charging system 100 in relation to additional EV charging systems 100′ and 100″ at the charging site 10.
The system controller 120 controls charge transfers by determining occurrence of a triggering condition for a charge transfer and controlling a response to such triggering condition in order to provide or receive DC power via a direct connection with one or more additional EV charging systems 100′ or 100″ provided by the DC bus 101. Thus, the system controller 120 controls receiving DC input from and providing DC output to the DC bus 101 via a DC bus connection 160 of the EV charging system 100 in order to effect charge transfers at the charging site 10. The DC bus connection 160 serves as an inter-charger connection of the EV charging system 100 and is configured to connect the EV charging system 100 to the DC bus 101 at the charging site 10 as a direct connection for the exchange of DC power between the EV charging system 100 and additional EV charging systems 100′ and 100″ (e.g., other EV charging systems of the EV charging systems 100A-D) at the charging site 10, as well as with any external batteries 30 at the site 10 (as illustrated in
The system controller 120 is also configured to communicate with other various system components 138 of the EV charging system 100 (e.g., other controllers or sensors coupled to the energy storage module 114 or other components of the EV charging system 100) in order to receive operating data and to control operation of the system via operation of such system components 138. For example, the system controller 120 may monitor temperatures within the EV charging system 100 using the system components 138 and may be further configured to mitigate increases in temperature through active cooling or power reductions using the same or different system components 138. Likewise, the system controller 120 communicates with a user interface module 122 (e.g., a touchscreen display) and a communication interface module 124 (e.g., a network interface controller) to provide information and receive control commands. Each communication interface module 124 may be configured to send and receive electronic messages via wired or wireless data connections, which may include portions of one or more digital communication networks.
The system controller 120 is configured to communicate with the components of the EV charging system 100, including power input module 110, power conversion module 112, the user interface module 122, the communication interface module 124, the charge controller 130, and the system components 138 over one or more data communication links. The system controller 120 may also be configured to communicate with external devices, including a vehicle 140 via the vehicle coupling 132, one or more additional EV charging systems 100′ and 100″ via the centralized management system 150, one or more external batteries 30, or a site meter 22. The system controller 120 may manage, implement or support one or more data communication protocols used to control communication over the various communication links, including wireless communication or communication via a local router 42. The data communication protocols may be defined by industry standards bodies or may be proprietary protocols.
The user interface module 122 is configured to present information related to the operation of the EV charging system 100 to a user and to receive user input. The user interface module 122 may include or be coupled to a display with capabilities that reflect intended use of the EV charging system 100. In one example, a touchscreen may be provided to present details of charging status and user instructions, including instructions describing the method of connecting and disconnecting a vehicle 140. The user interface module 122 may include or be coupled to a touchscreen that interacts with the system controller 120 to provide additional information or advertising. The system controller 120 may include or be coupled to a wireless communication interface that can be used to deliver a wide variety of content to users of the EV charging system 100, including advertisements, news, point-of-sale content for products/services that can be purchased through the user interface module 122. The display system may be customized to match commercial branding of the operator, to accommodate language options and for other purposes. The user interface module 122 may include or be connected to various input components, including touchscreen displays, physical input mechanisms, identity card readers, touchless credit card readers, and other components that interact through direct connections or wireless communications. The user interface module 122 may further support user authentication protocols and may include or be coupled to biometric input devices such as fingerprint scanners, iris scanners, facial recognition systems and the like.
In some embodiments, the energy storage module 114 is provisioned with a large battery pack, and the system controller 120 executes software to manage input received from a power source to the battery pack based upon demand level data (e.g., demand or load data from an electric power grid 20 or site meter 22), such that power is drawn from the power source to charge the battery pack at low-load time periods and to avoid drawing power from the grid during peak-load hours. The software may be further configured to manage power output to provide full, fast charging power in accordance with usage generated by monitoring patterns of usage by the EV charging system 100. The use of historical information can avoid situations in which the battery pack becomes fully discharged or depleted beyond a minimum energy threshold. For example, charging may be limited at a first time based upon a predicted later demand at a second time, which later demand may be predicted using historical information. This may spread limited charging capacity more evenly among vehicle throughout the course of a day or in other situations in which battery pack capacity is expected to be insufficient to fully charge all EVs over a time interval, taking account of the ability to add charge to the energy storage module 114.
In further embodiments, the system controller 120 executes software (either separately or in coordination with the centralized management system 150) to manage energy draw and use by controlling charging and discharging over time among multiple EV charging systems 100 at the charging site 10. Thus, the charge drawn from the power source may be limited or avoided during peak-load hours by charge transfer between the EV charging system 100 and one or more additional EV charging systems 100′ and 100″ via the DC bus 101 at the charging site 10, effectively pooling the energy stored in the batteries of all of the charging systems at the charging site 10. As noted above, in some embodiments, the charging site 10 may include one or more external batteries 30 connected to the DC bus 101. In such embodiments, the systems controller 120 and/or the centralized management system 150 may further manage energy inflow and outflow at the charging site 10 by controlling selective charging and discharging such batteries at appropriate time periods to avoid or reduce total power draw of the charging site 10 from the power source during peak-demand or other high-demand times by charging the batteries of the EV charging systems 100 and the external batteries 30 during low-demand times. In some such embodiments, such energy management enables the EV charging system 100 to continue charging vehicles 140 even when the power source is disconnected or unavailable (e.g., when a local power grid is down). As discussed further elsewhere herein, the systems controllers 120 of the EV charging systems 100 and/or the centralized management system 150 may further manage site-wide energy use by controlling charge transfers based upon differential charge levels or discharge levels associated with differential utilization of the various EV charging system 100 at the charging site 10 in order to effect charge balancing or to ensure sufficient charge availability for charging vehicle 140 at one or more of the EV charging systems 100.
In some embodiments, the EV charging system 100 may be configured with two or more vehicle couplings 132 to enable concurrent charging of multiple vehicles 140. The system controller 120 may be configured by a user via the user interface module 122 to support multiple modes of operation and may define procedures for charge transfer or power distribution that preserve energy levels in the energy storage module 114 when multiple vehicles 140 are being concurrently charged. Charge transfers may be used to transfer power from EV charging systems 100 that have available power or are not being used to charge a vehicle 140 to EV charging systems 100 that are charging one or more vehicles 140. Distribution of power may be configured to enable fast charging of one or more vehicles 140 at the expense of other vehicles 140. In this regard, the vehicle couplings 132 may be prioritized or the system controller 120 may be capable of identifying and prioritizing connected vehicles 140. In some instances, the system controller 120 may be configured to automatically control the respective charge controllers 130 to split available power between two vehicles 140 after the second vehicle 140 is connected. The available power may be evenly split between two vehicles 140 or may be split according to priorities or capabilities. In some examples, the system controller 120 may conduct arbitration or negotiation between connected vehicles 140 to determine a split of charging capacity. A vehicle 140 may request a charging power level at any given moment based on temperature, battery charge level, and other characteristics of the vehicle 140 and its environment and to achieve maximum charge rate and minimum charging time for the current circumstances.
As illustrated, a vehicle 140 may be charged by connecting the vehicle 140 to the EV charging system 100 via a vehicle coupling 132. This may include plugging a charging cable of the EV charging system 100 into a vehicle charge port 142 of the vehicle 140. The vehicle charge port 142 is configured to receive the charging current 116 through the vehicle coupling 132 and provide such received current to a vehicle power management module 146. The vehicle charge port 142 is further configured to provide an electronic communication connection between the vehicle coupling 132 and a vehicle charge controller 144, which controls charging of the vehicle 140. The vehicle power management module 146 is controlled by the vehicle charge controller 144 to provide power to each of one or more batteries 148 of the vehicle 140 in order to charge such battery 148. In some instances, the vehicle charge port 142 includes a locking mechanism to engage and retain a portion of the vehicle coupling 132 in place during charging sessions. For example, for safety reasons, the vehicle charge controller 144 may control a locking mechanism of the vehicle charge port 142 to lock a plug of a charging cable in the vehicle charge port 142 while a charging session is active.
As discussed elsewhere herein, the EV charging systems 200A-D are configured and controlled by the system controllers 120A-D and/or the centralized management system 150 to transfer charge via local AC circuit 201 or 203 as needed to improve the balance of energy storage and energy demand at each of the EV charging systems 200A-D. To achieve such energy transfers, the DC power provided by one or more of the energy storage modules 114A-D is converted to an AC current by an inverter (not shown) and provided to the local AC circuit 201 or 203 in order to transfer energy to one or more other energy storage modules 114A-D. The respective system controllers 120A-D of the donor EV charging systems 200A-D may be configured to control the phase of the AC output power to the local AC circuit 201 or 203 to match that of the input AC electric power from the site meter 22 or of other donor EV charging systems 200A-D. As noted above, the input AC electric power may be received at each of the input ports 102A-D as a 120V or 240V single-phase or three-phase AC power supply. In various embodiments, the AC output power at input ports 102A-D or input ports 204A-D may be provided according to the same or different voltage and phase combinations.
In some embodiments, the local AC circuit 201 and/or 203 also connects one or more external battery systems 230 to the EV charging systems 200A-D in order to increase the storage capacity at the charging site 10. Such external battery systems 230 may receive input AC power from the electric power grid 20 via local AC circuit 201 and/or from the EV charging systems 200A-D via local AC circuit 203 in order to charge one or more batteries (not shown) of the external battery systems 230. Such external battery systems 230 may include various components (not shown), including controllers and bidirectional inverters or separate rectifiers and inverters in order to convert the input AC power into DC power for storage and later convert the stored DC power into output AC power for charge transfers to one or more of the EV charging systems 200A-D.
The bidirectional inverter 210 is configured to alternatively operate in an inverter mode or in a rectifier mode at various times as controlled by the system controller 120. In the rectifier mode, the bidirectional inverter 210 converts an input AC current from a power source (e.g., the electric power grid 20 or an additional EV charging system 200′ via a local AC circuit 201 or 203) into a DC current to provide to the energy storage module 114 via the power conversion module 112. In the inverter mode, the bidirectional inverter 210 convers a DC current from the energy storage module 114 via the power conversion module 112 into an output AC current to the local AC circuit 201 or 203 via an input port 102 or 204. Thus, when a triggering condition occurs to cause the EV charging system 200 to provide an AC output power to the local AC circuit 201 or 203 to transfer charge to an additional EV charging system 200′ at the charging site 10 (e.g., to enable the additional EV charging system 200′ to charge a vehicle 140′), the bidirectional inverter operates in the inverter mode to convert a DC current from the power conversion module 112 into the AC output power and provide such AC output power to the local AC circuit 201 or 203 via an input port 102 or 204. In some embodiments, a plurality of separate components may instead be configured to perform such functionality of the bidirectional inverter 210, such as by including one or more inverters and rectifiers in the EV charging system 200. In further embodiments, part or all of the functionality of the bidirectional inverter 210 may be incorporated into the power conversion module 112, or part or all of the functionality of the power conversion module 112 may be incorporated into the bidirectional inverter 210.
In the illustrated example, the controller 400 may be implemented with a bus architecture, represented generally by the bus 410. The bus 410 may include any number of interconnecting buses and bridges depending on the specific application of the controller 400 and the overall design constraints. The bus 410 links together various circuits including the one or more processors 404 and storage 406. Storage 406 may include memory devices and mass storage devices, any of which may be referred to herein as computer-readable media. The bus 410 may also link various other circuits, such as timing sources, timers, peripherals, voltage regulators, and power management circuits. A bus interface 408 may provide an interface between the bus 410 and one or more line interface circuits 412, which may include a line interface transceiver circuit 412a and a radio frequency (RF) transceiver circuit 412b. A line interface transceiver circuit 412a may be provided for each networking technology supported by the controller. In some instances, multiple networking technologies may share some or all of the circuitry or processing modules found in a line interface circuit 412, such as line interface transceiver circuit 412a for wired communication and RF transceiver circuit 412b for wireless communication. Each line interface circuit 412 provides a means for communicating with various other devices over a transmission medium. In some embodiments, a user interface 418 (e.g., touchscreen display, keypad, speaker, or microphone) may also be provided, and may be communicatively coupled to the bus 410 directly or through the bus interface 408.
A processor 404 may be responsible for managing the bus 410 and for general processing that may include the execution of software stored in a computer-readable medium that may include the storage 406. In this respect, the processor 404 of the controller 400 may be used to implement any of the methods, functions, and techniques disclosed herein. The storage 406 may be used for storing data that is manipulated by the processor 404 when executing software, and the software may be configured to implement any of the methods disclosed herein.
One or more processors 404 in the controller 400 may execute software. Software may include instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, algorithms, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside in computer-readable form in the storage 406 or in an external computer readable medium. The external computer-readable medium and/or storage 406 may include a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk, a smart card, a flash memory device (e.g., a “flash drive,” a card, a stick, or a key drive), a random access memory (RAM), a read only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. Portions of the computer-readable medium or the storage 406 may reside in the controller 400 or external to the controller 400. The computer-readable medium and/or storage 406 may be embodied in a computer program product. By way of example, a computer program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.
The storage 406 may maintain software maintained or organized in loadable code segments, modules, applications, programs, etc., which may be referred to herein as software modules 416. Each of the software modules 416 may include instructions and data that, when installed or loaded on the controller 400 and executed by the one or more processors 404, contribute to a run-time image 414 that controls the operation of the one or more processors 404. When executed, certain instructions may cause the controller 400 to perform functions in accordance with certain methods, algorithms, and processes described herein.
Some of the software modules 416 may be loaded during initialization of the controller 400, and these software modules 416 may configure the controller 400 to enable performance of the various functions disclosed herein. For example, some software modules 416 may configure internal devices or logic circuits 422 of the processor 404, and may manage access to external devices such as line interface circuits 412, the bus interface 408, the user interface 418, timers, mathematical coprocessors, etc. The software modules 416 may include a control program or an operating system that interacts with interrupt handlers and device drivers to control access to various resources provided by the controller 400. The resources may include memory, processing time, access to the line interface circuits 412, the user interface 418, etc.
One or more processors 404 of the controller 400 may be multifunctional, whereby some of the software modules 416 are loaded and configured to perform different functions or different instances of the same function. For example, the one or more processors 404 may additionally be adapted to manage background tasks initiated in response to inputs from the user interface 418, the line interface circuits 412, and device drivers. To support the performance of multiple functions, the one or more processors 404 may be configured to provide a multitasking environment, whereby each of a plurality of functions is implemented as a set of tasks serviced by the one or more processors 404 as needed or desired. In one example, the multitasking environment may be implemented using a timesharing program 420 that passes control of a processor 404 between different tasks, whereby each task returns control of the one or more processors 404 to the timesharing program 420 upon completion of any outstanding operations or in response to an input such as an interrupt. When a task has control of the one or more processors 404, the processing circuit is effectively specialized for the purposes addressed by the function associated with the controlling task. The timesharing program 420 may include an operating system, a main loop that transfers control on a round-robin basis, a function that allocates control of the one or more processors 404 in accordance with a prioritization of the functions, or an interrupt-driven main loop that responds to external events by providing control of the one or more processors 404 to a handling function.
Referring to
In this example implementation, the battery 530, the AC-to-DC converter (or inverter) 531, and the DC-to-DC converters 532, 534 are interconnected via a battery bus 540, operating as a central hub. The battery bus 540 also can be understood as a DC link of the charger 500A.
The EV charger 500A can include battery contactors 550 configured to open or close a circuit including the battery 530 and the battery bus 540; inverter contactors 551 configured to open or close a circuit including the inverter 531 and the battery bus 540; port 1 contactors 562 configured to open or close a circuit including the EV charging port 512 and the DC-to-DC converter 532; port 2 contactors 564 configured to open or close a circuit including the EV charging port 514 and the DC-to-DC converter 534; DC link contactors 572 configured to open or close a circuit including the DC-to-DC converter 532 and the HVDC bus 540; and DC link contactors 574 configured to open or close a circuit including the DC-to-DC converter 534 and the battery bus 540.
The contactors 550, 551, 552, 554, 562, and 564 collectively define a switching component 570. The switching component 570 can operate as a part of a control system of the EV charger 500A, which can also include voltage and/or current sensors, insulation monitoring devices, HVDC fuses to protect against short circuits on the battery bus 540.
The architecture of
When multiple instances of the EV charger 502A are present at a site, each charger operates independently of the others. In particular, the EV charging ports of each charger are linked to a single respective stationary charger battery, and the charging capability of a charger depends on the SOC of the corresponding battery. Consequently, EVs arriving at the site may see different power levels at different chargers.
Now referring to
The EV charger 500B is generally similar to the EV charger 500A, but the EV charger 500B also includes a rebalancing contactor 580 and power sharing or paralleling contactors 582A-B. The battery bus 540 extends to an HVDC bus or DC link 542, via which the EV charger 500B is connected to a peer EV charger, as discussed below with reference to
In an example implementation, the EV charger 500B supports a 3″ conduit to land DC link wiring; the EV charger 500B supports up to four conductors (2 IN, 2 OUT), and the conductors are sized so as to support a continuous current of 320 Amps at 800 VDC with a maximum allowable voltage drop of 1V; and wires are landed at bus bars using ring terminals with a 5/16″ stud.
When the rebalancing contactor 580 is open, the battery 530 is connected to the DC-to-DC converter 534 so as to provide power at EV charging port 514. Further, when the rebalancing contactor 580 is open, and the power sharing contactors 582A and 582B are closed, the battery 530 is connected in parallel to the HVDC bus 542. When the rebalancing contactor 580 is closed, and the power sharing contactors 582B is open, the DC-to-DC converter 534 does not provide power at EV charging port 514. Instead, the battery 530 is connected to the HVDC bus 542 via the DC-to-DC converter 534, which operates to substantially align the voltage across the battery 530 with the voltage across the HVDC bus 542.
Although the EV charger 500B is illustrated in
Now referring to
In an example configuration 600A, the rebalancing contactor (labeled as contactor C3) of the EV charger 602 is closed, the rebalancing contactor of the EV charger 604 is open, and the rebalancing contactor of the EV charger 606 is open. One of the paralleling contactors (labeled as contactor C1) of the EV charger 602 is closed, but the other paralleling contactor (labeled as contactor C2) of the EV charger 602 is open. The paralleling contactors of the EV chargers 604 and 606 are closed. Thus, in the example configuration 600A, the battery 632 of the EV charger 604 is going through a rebalancing procedure to align with the voltage across the HVDC bus 610, and accordingly with the voltage across the batteries 634, 636 of the EV chargers 604, 606, respectively. More specifically, the DC-DC converter of the EV charger 602 adjusts the voltage across the battery 632 to the match the voltage across the HVDC bus 610. During the procedure, the paralleling contactor C2 remains open, and the rebalancing contactor remains closed.
During the rebalancing procedure, the EV chargers 604 maintains availability of the EV charging port of the DC-to-DC converter that operates independently of the rebalancing contactor (e.g., the DC-to-DC converter 532 of
In an example scenario, the EV charger 602 is a new charger introduced to the site that already includes the EV chargers 604 and 606, after a new installation or service. The battery 632 of the EV charger 602 is at a different voltage level than the batteries 634 and 636. The rebalancing procedure aligns the voltage across the battery 632 with the rest of the site.
As a more specific example, the unified battery system of
With continued reference to
In an example scenario, a unified battery system that includes only two EV charges (such the EV chargers 500B, 602, 604, or 606) interconnected via a DC link (such as the HVDC bus 542 or 610) has a voltage of 770V across the DC link, which can be the 80% SOC level, and which in turn can correspond to 251.2 kWh. When a new EV charger with a voltage of 720V (or the 60% SOC level corresponding to 94.2 kWh) is connected to the DC link, the updated parameters for the DC link become the following: (i) the energy is 345.4 kWh for the unified battery system, or 115.13 kWh for the induvial batteries, (ii) the SOC is 73.33%, and (iii) the voltage is 748V. Thus, the unified battery system must transfer 20.93 kWh of energy from the DC link to the battery of the new EV charger. Assuming the charge current limit (CCL) of the battery of the new EV charger corresponds to 50 Kw, the total time required for equalization in this example is 20.93 kWh/50 KW, which is approximately 25 minutes.
After all the batteries of the EV chargers 602, 604, and 606 are connected in parallel via the DC link 710 to form the unified battery system, the induvial BMSs of the EV chargers can collectively implement, or provide data to, a unified virtual BMS. The unified virtual BMS can utilize data collected from the individual BMSs to implement decision-making processes related to the unified battery system. For example, the unified virtual BMS can determine the discharge current limit (DCL) as the minimum discharge current limit among all the batteries connected to the DC Link 710. Similarly, the unified virtual BMS can determine the charge current limit (CCL) as the minimum charge current limit of the individual EV charges. The unified virtual BMS can apply similar principles to managed faults observed at the individual EV chargers.
Referring to
Next,
At block 802, the BMS determines voltage VHVDC across the HVDC bus or the DC link. As discussed above, the EV chargers can be equipped with various sensors, or a sensor can operate on the HVDC bus externally to all the EV chargers (e.g., on the DC link 610 or 710). At block 804, the BMS determines voltage VBAT across the battery of an EV charger. Next, at block 810, the BMS determines whether VHVDC and VBAT differ by at least a threshold amount, which for example can be a configuration parameter expressed in terms of voltage (e.g., 5V, 10V, 15V) or a percentage (e.g., 1%, 2%, 5%).
When the VHVDC and VBAT differ by at least a threshold amount, the flow proceeds to block 820, where the BMS causes the rebalancing contactor (e.g., the contactor 580 of
At optional block 824, the BMS stops providing charge at an EV charging port of the DC-to-DC converter involved in the rebalancing procedure (e.g., the DC-to-DC converter 534). At optional block 826, the BMS continues providing charge at an EV charging port of the DC-to-DC converter that is not involved in the rebalancing procedure (e.g., the DC-to-DC converter 532). At block 828, the BMS continues monitoring the difference between VHVDC and VBAT, until these voltages reach a substantial alignment (e.g., until these voltages are within a certain threshold distance, expressed in terms of Volts or a percentage).
The flow then proceeds to block 840. Further, when the BMS at block 810 determines that VHVDC and VBAT do not differ by at least a threshold amount, the flow proceeds from block 810 to block 840. At block 840, the BMS causes the rebalancing contactor to open, and the paralleling or power sharing contactor to close, so that the battery connects to the HVDC bus in parallel and directly, without the DC-to-DC converter. The BMS also can resume supplying charge at the EV charging port of the DC-to-DC converter used during the rebalancing procedure.
Next,
To appreciate the effects of the DLC of the unified battery system, an example scenario can be considered in which a unified battery system includes three EV charges connected in parallel, with a DC Link voltage of 700V. If the individual DCL for each charger is 110 A for example, the aggregated DCL is determined as the minimum of DCL1, DCL2, and DCL3, multiplied by the number of chargers. In this case, this product is 330 A. The maximum power that can be sourced from the DC Link for EV charging is thus 330 A×700V=231 kW.
However, if DCL1 from one the chargers drops down to 95A, the overall aggregated DCL drops to the minimum of 95A, 110A, and 110A multiplied by the number of chargers (in this example, three), which is equal to 285 A. The maximum power that can be sourced from the DC link for EV charging is thus 285 A×700V=199.5 kW. This is a reduction in the maximum power output.
Thus, if the DCL becomes excessively low and significantly restricts power output (see block 1010), the unified virtual BMS may determine that it is advantageous to disconnect the corresponding charger from the DC link (see block 1020).
Further, to appreciate the effects of the CCL of the unified battery system, an example scenario can be considered in which a unified BMS includes three EV chargers connected in parallel with a DC Link voltage of 700V. The individual CCL for each charger is 70 A, and the aggregated CCL is determined as the minimum of CCL1, CCL2, and CCL3, multiplied by the number of chargers, which in this example is 210 A. The maximum power that can be provided to charge up the DC link for EV charging is 210 A×700V=147 kW.
However, if CCL1 from one the chargers drops to 45 A, the overall aggregated CCL drops to the minimum of 45 A, 80 A, and 80 A multiplied by 3, which equals 135 A. The maximum power that can be sourced from the DC Link for EV charging is 135 A×700V=94.5 kW. This is a reduction in the rate of charge and an increase in the overall charge time for the unified battery system.
Thus, if the CCL becomes excessively low and significantly restricts power input (see block 1010), the unified virtual BMS may determine that it is advantageous to disconnect the corresponding charger from the DC link (see block 1020).
Although the preceding text sets forth a detailed description of numerous different embodiments, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment, as describing every possible embodiment would be impractical, if not impossible. One could implement numerous alternate embodiments, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims.
It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based upon any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term be limited, by implication or otherwise, to that single meaning. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”
Throughout this specification, plural instances may implement components, operations, or structures described as a single instance. Although individual operations of one or more methods are illustrated and described as separate operations, one or more of the individual operations may be performed concurrently, and nothing requires that the operations be performed in the order illustrated. Structures and functionality presented as separate components in example configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements fall within the scope of the subject matter herein. Unless specifically stated otherwise, the term “some” refers to one or more. Likewise, use of the “a” or “an” are employed to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of the description. This description, and the claims that follow, should be read to include one or at least one and the singular also includes the plural unless the context clearly indicates otherwise.
Upon reading this disclosure, those of skill in the art will appreciate still additional alternative structural and functional designs for the systems and a methods disclosed herein. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those skilled in the art, may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims.
This application claims priority to and the benefit of the filing date of provisional U.S. Patent Application No. 63/454,019, titled “Sharing Power Battery Among Multiple Charging Stations,” filed on Mar. 22, 2023. The entire contents of this provisional application are hereby expressly incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63454019 | Mar 2023 | US |
