Charging multiple electric vehicles using single charger

Abstract

A direct current (DC) charging system for an electric vehicle may include a DC charger having a DC charger charging port. The system may also include a plurality of low power access points (LPAPs), each LPAP having a first daisy chain port, a second daisy chain port, and an LPAP charging port. The plurality of LPAPs are connected in series to a DC charger charging port of the DC charger using the first daisy chain port and the second daisy chain port. Each of the plurality of LPAPs is configured to transfer energy from the DC charger to the electric vehicle using the LPAP charging port. The system may also include a plurality of electric vehicles. Each of the plurality of electric vehicles is connected to an LPAP charging port of one of the plurality of LPAPs to charge the plurality of electric vehicles.

Description

Technical Field

[0001] This disclosure relates to systems and methods for charging electric vehicles. Background Technology

[0002] Electric Vehicle Power Supply Equipment (EVSE) has been developed for charging electric vehicles, including AC EVSE and DC EVSE. AC EVSE can reduce development and construction costs because it does not require AC-DC conversion (i.e., rectification). However, vehicles compatible with AC EVSE must integrate onboard AC-DC conversion, which can increase weight and resource usage. DC EVSE can offer higher efficiency than AC EVSE and can reduce the weight and resource usage required for onboard power electronics. However, because DC EVSE must perform AC-DC conversion, it can increase development and construction costs compared to AC EVSE. Therefore, it is advantageous to utilize current and future EVSE infrastructure most efficiently. However, current AC and DC EVSE, as well as industry-standard vehicle-to-EVSE communication protocols, are designed to connect to a single electric vehicle simultaneously.

[0003] Therefore, while current electric vehicle charging systems and methods have achieved their intended purpose, a new and improved system and method for DC charging of electric vehicles is still needed. Summary of the Invention

[0004] According to several aspects, a direct current (DC) charging system for electric vehicles is provided. The system may include a DC charger having a DC charger charging port. The system may also include multiple low-power access points (LPAPs), each LPAP having a first daisy-chain port, a second daisy-chain port, and an LPAP charging port. The multiple LPAPs are connected in series to the DC charger charging port of the DC charger via the first and second daisy-chain ports. Each of the multiple LPAPs is configured to transfer energy from the DC charger to the electric vehicle using the LPAP charging port. The system may also include multiple electric vehicles. Each of the multiple electric vehicles is connected to the LPAP charging port of one of the multiple LPAPs to charge the multiple electric vehicles.

[0005] In another aspect of this disclosure, the system may further include an LPAP controller that is electrically in communication with each of the plurality of LPAPs. The LPAP controller is programmed to determine the battery voltage of each of the plurality of electric vehicles. The LPAP controller is also programmed to control the DC charger and one or more of the plurality of LPAPs to charge one or more of the plurality of electric vehicles at least in part based on the battery voltage of each of the plurality of electric vehicles.

[0006] In another aspect of this disclosure, the LPAP controller is also programmed to identify the lowest battery voltage among a plurality of electric vehicles. The LPAP controller is also programmed to control the DC charger and one or more of the plurality of LPAPs to charge one or more of the plurality of electric vehicles having the lowest battery voltage. The LPAP controller is also programmed to periodically reassess the battery voltage of each of the plurality of electric vehicles, identify the lowest battery voltage, and control the DC charger and one or more of the plurality of LPAPs to charge one or more of the plurality of electric vehicles having the lowest battery voltage.

[0007] In another aspect of this disclosure, at least one of the plurality of LPAPs may further include an electronically controllable switch configured to connect a first daisy-chain port to an LPAP charging port. The electronically controllable switch is configured to be controlled by an LPAP controller.

[0008] In another aspect of this disclosure, in order to control the DC charger and one or more of the plurality of LPAPs, the LPAP controller is also programmed to command the DC charger to provide a first output voltage at the DC charger charging port. The first output voltage is determined at least in part based on the lowest battery voltage. The LPAP controller is also programmed to control electronically controllable switches of one or more of the plurality of LPAPs to charge one or more of the plurality of electric vehicles having the lowest battery voltage.

[0009] In another aspect of this disclosure, in order to control the DC charger and one or more of the plurality of LPAPs, the LPAP controller is also programmed to command the DC charger to limit the current at the DC charger charging port to a first output current. The first output current is determined at least in part based on the maximum charging current of one or more of the plurality of electric vehicles having the lowest battery voltage.

[0010] In another aspect of this disclosure, the LPAP controller is also programmed to identify the highest battery voltage among the plurality of electric vehicles. The LPAP controller is also programmed to control the DC charger and one or more of the plurality of LPAPs to charge the plurality of electric vehicles at least partially based on the highest battery voltage. The LPAP controller is also programmed to periodically re-evaluate the battery voltage of each of the plurality of electric vehicles, identify the highest battery voltage, and control the DC charger and one or more of the plurality of LPAPs to charge the plurality of electric vehicles at least partially based on the highest battery voltage.

[0011] In another aspect of this disclosure, each of the plurality of LPAPs may further include a DC-DC converter connected between the first daisy-chain port and the LPAP charging port. The DC-DC converter is configured to be controlled by the LPAP controller.

[0012] In another aspect of this disclosure, in order to control the DC charger and one or more of the plurality of LPAPs, the LPAP controller is also programmed to command the DC charger to provide a second output voltage at the DC charger charging port. The second output voltage is determined at least in part based on the highest battery voltage. In order to control the DC charger and one or more of the plurality of LPAPs, the LPAP controller is also programmed to control the DC-DC converter of each of the plurality of LPAPs to charge each of the plurality of electric vehicles at least in part based on the battery voltage of each of the plurality of electric vehicles.

[0013] In another aspect of this disclosure, in order to control the DC-DC converter of each of the plurality of LPAPs, the LPAP controller is also programmed to determine a plurality of voltage differences between the second output voltage and the battery voltage of each of the plurality of electric vehicles. In order to control the DC-DC converter of each of the plurality of LPAPs, the LPAP controller is also programmed to control the DC-DC converter of each of the plurality of LPAPs based at least in part on one of the plurality of voltage differences.

[0014] According to several aspects, a direct current (DC) charging system for an electric vehicle is provided. The system may include a DC charger having a DC charger charging port. The system may also include a first low-power access point (LPAP) having a first daisy-chain port, a second daisy-chain port, a charging port, and a first LPAP controller. The first daisy-chain port of the first LPAP is connected to the charging port of the DC charger. The system may also include a second low-power access point (LPAP) having a second daisy-chain port, a second daisy-chain port, a charging port, and a second LPAP controller. The first daisy-chain port of the second LPAP is connected to the second daisy-chain port. The second LPAP controller is in electrical communication with the first LPAP controller. The first and second LPAP controllers are programmed to determine the battery voltages of a first electric vehicle connected to the first LPAP charging port and a second electric vehicle connected to the second LPAP charging port. The first and second LPAP controllers are also programmed to control the DC charger, the first LPAP, and the second LPAP to charge one or more of the first electric vehicle and the second electric vehicle, at least in part, based on the battery voltages of the first and second electric vehicles.

[0015] In another aspect of this disclosure, the first LPAP may further include a first electronically controllable switch configured to connect a first daisy-chain port of the first LPAP to a first LPAP charging port. The first electronically controllable switch is configured to be controlled by a first LPAP controller. The second LPAP may further include a second electronically controllable switch configured to connect a first daisy-chain port of the second LPAP to a second LPAP charging port. The second electronically controllable switch is configured to be controlled by a second LPAP controller.

[0016] In another aspect of this disclosure, the first LPAP controller and the second LPAP controller are also programmed to identify the lowest battery voltage in the first electric vehicle and the second electric vehicle. The first LPAP controller and the second LPAP controller are also programmed to control the DC charger, the first electronically controllable switch of the first LPAP, and the second electronically controllable switch of the second LPAP to charge one or more of the following vehicles having the lowest battery voltage: the first electric vehicle and the second electric vehicle. The first LPAP controller and the second LPAP controller are also programmed to periodically reassess the battery voltages of the first electric vehicle and the second electric vehicle, identify the lowest battery voltage, and control the DC charger, the first electronically controllable switch of the first LPAP, and the second electronically controllable switch of the second LPAP to charge one or more of the following vehicles having the lowest battery voltage: the first electric vehicle and the second electric vehicle.

[0017] In another aspect of this disclosure, for controlling the DC charger, the first electronically controllable switch of the first LPAP and the second electronically controllable switch of the second LPAP, the first LPAP controller, and the second LPAP controller are further programmed to command the DC charger to provide a first output voltage at the charging port of the DC charger using the first LPAP controller. The first output voltage is determined at least in part based on a minimum battery voltage. For controlling the DC charger, the first electronically controllable switch of the first LPAP and the second electronically controllable switch of the second LPAP, the first LPAP controller, and the second LPAP controller are further programmed to control the first electronically controllable switch of the first LPAP and the second electronically controllable switch of the second LPAP to charge one or more of the following vehicles having a minimum battery voltage: a first electric vehicle and a second electric vehicle.

[0018] In another aspect of this disclosure, the first LPAP may further include a first DC-DC converter connected between the first daisy-chain port of the first LPAP and the first LPAP charging port. The first DC-DC converter is configured to be controlled by a first LPAP controller. The second LPAP may further include a second DC-DC converter connected between the first daisy-chain port of the second LPAP and the second LPAP charging port. The second DC-DC converter is configured to be controlled by a second LPAP controller.

[0019] In another aspect of this disclosure, the first LPAP controller and the second LPAP controller are also programmed to identify the highest battery voltage in the first electric vehicle and the second electric vehicle. The first LPAP controller and the second LPAP controller are also programmed to control the DC charger, the first DC-DC converter of the first LPAP, and the second DC-DC converter of the second LPAP to charge one or more of the following vehicles at least partially based on the highest battery voltage: the first electric vehicle and the second electric vehicle. The first LPAP controller and the second LPAP controller are also programmed to periodically re-evaluate the battery voltages of the first electric vehicle and the second electric vehicle, identify the highest battery voltage, and control the DC charger, the first DC-DC converter of the first LPAP, and the second DC-DC converter of the second LPAP to charge one or more of the following vehicles at least partially based on the highest battery voltage: the first electric vehicle and the second electric vehicle.

[0020] In another aspect of this disclosure, in order to control the DC charger, the first DC-DC converter of the first LPAP and the second DC-DC converter of the second LPAP, the first LPAP controller and the second LPAP controller are further programmed to use the first LPAP controller to command the DC charger to provide a second output voltage at the charging port of the DC charger. The second output voltage is determined at least in part based on the highest battery voltage. In order to control the DC charger, the first DC-DC converter of the first LPAP and the second DC-DC converter of the second LPAP, the first LPAP controller and the second LPAP controller are further programmed to determine a first voltage difference between the second output voltage and the battery voltage of the first electric vehicle. In order to control the DC charger, the first DC-DC converter of the first LPAP and the second DC-DC converter of the second LPAP, the first LPAP controller and the second LPAP controller are further programmed to determine a second voltage difference between the second output voltage and the battery voltage of the second electric vehicle. In order to control the DC charger, the first DC-DC converter of the first LPAP and the second DC-DC converter of the second LPAP, the first LPAP controller and the second LPAP controller are further programmed to control the first DC-DC converter of the first LPAP at least in part based on the first voltage difference. In order to control the DC charger, the first DC-DC converter of the first LPAP and the second DC-DC converter of the second LPAP, the first LPAP controller and the second LPAP controller are also programmed to control the second DC-DC converter of the second LPAP at least in part based on the second voltage difference.

[0021] According to several aspects, a direct current (DC) charging method for electric vehicles is provided. The method may include determining the battery voltage of each of a plurality of electric vehicles. Each of the plurality of electric vehicles is connected to one of a plurality of low-power access points (LPAPs). The plurality of LPAPs are connected in series to a DC charger. The method may further include controlling the DC charger and one or more of the plurality of LPAPs to charge one or more of the plurality of electric vehicles, at least in part based on the battery voltage of each of the plurality of electric vehicles.

[0022] In another aspect of this disclosure, the method may further include identifying the lowest battery voltage among a plurality of electric vehicles. The method may also include commanding a DC charger to provide a first output voltage. The first output voltage is determined at least in part based on the lowest battery voltage. The method may further include controlling an electronically controllable switch of one or more of the plurality of LPAPs to charge one or more of the plurality of electric vehicles having the lowest battery voltage. The method may further include periodically reassessing the battery voltage of each of the plurality of electric vehicles, identifying the lowest battery voltage, commanding the DC charger, and controlling the electronically controllable switch of one or more of the plurality of LPAPs to charge one or more of the plurality of electric vehicles having the lowest battery voltage.

[0023] In another aspect of this disclosure, the method may further include identifying the highest battery voltage among a plurality of electric vehicles. The method may further include commanding a DC charger to provide a second output voltage. The second output voltage is determined at least in part based on the highest battery voltage. The method may further include controlling a DC-DC converter of each of the plurality of LPAPs to charge each of the plurality of electric vehicles at least in part based on the battery voltage of each of the plurality of electric vehicles. Controlling the DC-DC converter of each of the plurality of LPAPs may further include determining a plurality of voltage differences between the second output voltage and the battery voltage of each of the plurality of electric vehicles. The method may further include controlling the DC-DC converter of each of the plurality of LPAPs at least in part based on one of the plurality of voltage differences. The method may further include periodically re-evaluating the battery voltage of each of the plurality of electric vehicles, identifying the highest battery voltage, commanding the DC charger, and controlling the DC-DC converter of each of the plurality of LPAPs to charge each of the plurality of electric vehicles.

[0024] Further areas of application will become apparent from the description provided herein. It should be understood that these descriptions and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0025] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0026] Figure 1 This is a schematic diagram of a system for direct current (DC) charging of an electric vehicle according to an exemplary embodiment;

[0027] Figure 2 This is a schematic diagram of multiple low-power access points (LPAPs) shown together with a DC charger according to an exemplary embodiment;

[0028] Figure 3 This is a flowchart of a first method for DC charging of an electric vehicle according to an exemplary embodiment; and

[0029] Figure 4 This is a flowchart of a second method for DC charging of an electric vehicle according to an exemplary embodiment. Detailed Implementation

[0030] The following description is merely exemplary in nature and is not intended to limit this disclosure, its application, or its uses.

[0031] In all aspects of this disclosure, as consumer use of electric vehicles increases, the demand for effective charging infrastructure also increases. The installation and maintenance of electric vehicle power supply units (EVSEs) are typically complex and resource-intensive. Furthermore, EVSEs are generally designed to charge only one electric vehicle at a time. Therefore, this disclosure provides a novel and improved system and method for direct current (DC) charging of electric vehicles, which allows a single EVSE unit to power multiple vehicles.

[0032] refer to Figure 1 The diagram illustrates a direct current (DC) charging system for electric vehicles and is generally indicated by reference numeral 10. System 10 is shown as having an exemplary plurality of vehicles 12. Although a plurality of passenger vehicles are shown, it should be understood that the plurality of vehicles 12 may include various types of vehicles without departing from the scope of this disclosure. System 10 typically includes a DC charger 14 and a plurality of low power access points (LPAPs) 16.

[0033] In exemplary embodiments, the plurality of vehicles 12 includes electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, etc. In the exemplary embodiments discussed in this disclosure, the plurality of vehicles 12 includes a first vehicle 12a and a second vehicle 12b. It should be understood that the plurality of vehicles 12 can generally include any number of vehicles. Although passenger cars are discussed in this disclosure, it should be understood that the plurality of vehicles 12 may also include additional types of electric vehicles, such as electric motorcycles, electric off-road vehicles, electric boats, electric aircraft, electric recreational vehicles, electric trucks, electric public transportation vehicles (e.g., buses, trains, etc.) and / or additional motors.

[0034] Each of the plurality of vehicles 12 has a vehicle electrical system (not shown), which includes at least a vehicle battery, a battery management system (BMS), and a vehicle charging port 18. In some examples, the vehicle electrical system also includes additional power electronic devices, such as a rectifier for implementing AC charging, a DC-DC converter for implementing variable voltage DC charging, etc.

[0035] The vehicle battery stores and provides electrical energy in direct current (DC) form to propel each of the plurality of vehicles 12. In an exemplary embodiment, the vehicle battery includes a plurality of battery cells (e.g., lithium-ion battery cells) connected in series and / or parallel to provide increased voltage and / or current carrying capacity. In a non-limiting example, the plurality of battery cells are housed in a housing configured to protect the plurality of battery cells from mechanical vibration, water intrusion, and dust intrusion. The housing is also configured to provide temperature regulation (e.g., using a liquid cooling system, a resistance heating system, etc.).

[0036] A Battery Management System (BMS) is used to monitor and manage a vehicle's battery to ensure its safe operation, optimal performance, and lifespan. In a non-limiting example, a BMS includes voltage sensors, current sensors, temperature sensors, a balancing circuit, contactors, and a battery control unit (BCU). Voltage sensors measure the voltage of the individual battery cells within the vehicle battery. Current sensors measure the current flowing into and out of the vehicle battery. Temperature sensors monitor thermal conditions. The balancing circuit ensures that all batteries maintain the same state of charge. Contactors control the current between the vehicle battery and electrical loads, such as a traction motor.

[0037] The Battery Control Unit (BCU) is used to collect data from sensors and control contactors and balancing circuits to manage the charging, discharging, and balancing processes. In a non-limiting example, the BCU is a controller that includes a processor (not shown), non-transitory memory (not shown), and interfaces (e.g., general-purpose input / output (GPIO) pins, a serial interface, an analog-to-digital converter, etc.) (not shown). The non-transitory memory contains program instructions that, when executed by the processor, command the BCU to collect data from sensors and control the contactors and balancing circuits through the interfaces. In a non-limiting example, the program instructions also allow determining battery characteristics, such as state of charge (SOC), state of health (SOH), etc., based on the data collected from the sensors.

[0038] In an exemplary embodiment, the BMS regulates the charging current and voltage during the charging process to prevent overcharging, overheating, and other conditions that could damage the battery cells. In a non-limiting example, the BMS communicates with the Electric Vehicle Power Supply (EVSE) connected to the vehicle's charging port 18 to control charging parameters such as charging voltage, charging current, charging power, and charging rate. The BMS ensures that the charging process occurs within applicable temperature and voltage limits by dynamically adjusting the charging parameters based on real-time data from sensors.

[0039] The vehicle charging port 18 is used to establish a connection between the vehicle electrical system and the EVSE for charging the vehicle battery. Generally, the vehicle charging port 18 includes multiple pins for establishing electrical communication with the EVSE. Within the scope of this disclosure, electrical communication includes the transfer of power and / or energy between electrical devices (e.g., using wired and / or wireless power transmission technologies) and the transfer of information and / or data between electrical devices (e.g., using CAN networks, FLEXRAY networks, local area networks (e.g., WiFi, Ethernet, etc.), Serial Peripheral Interface (SPI) networks, etc.).

[0040] In an exemplary embodiment, the vehicle charging port 18 includes two or more conductive pins, at least one protective ground pin, and at least one communication pin. The two or more conductive pins are used to transfer power between the EVSE and the vehicle battery to charge the vehicle battery and / or to supply power from the vehicle battery to the grid. The protective ground pin provides a protective ground connection.

[0041] At least one communication pin allows the BMS to communicate with the EVSE to control charging parameters, as described above. In an exemplary embodiment, the at least one communication pin includes a proximity pilot (PP) pin and a control pilot (CP) pin. The PP pin is primarily used to detect the connection between the vehicle charging port 18 and the EVSE. The CP pin is used to transmit charging parameters between the BMS and the EVSE. In a non-limiting example, after the EVSE is detected using the PP pin, the BMS controls the resistance between the CP pin and the protective ground pin to indicate the charging status (e.g., standby, vehicle detected, ready (charging), error, etc.).

[0042] Upon detecting continuity between the CP pin and the protective ground pin, the EVSE transmits a variable pulse width modulation (PWM) square wave signal via the CP pin. The duty cycle of the PWM square wave represents the maximum charging current available to the EVSE. In some embodiments, the duty cycle of the PWM square wave is also used to indicate additional information or provide commands. In a non-limiting example, the EVSE may request a high-frequency digital communication protocol (e.g., as specified in International Organization for Standardization (ISO) 15118, Society of Automotive Engineers (SAE) J2931 / 4, and / or German Association for Standardization (DIN) 70121) by providing a specific duty cycle (e.g., 5%). Subsequently, the EVSE and BMS can switch to the high-frequency digital communication protocol, thereby allowing the transmission of additional information and charging parameters.

[0043] It should be understood that the above description of the vehicle charging port 18, including the configuration and function of multiple pins, is merely exemplary in nature. Any electric vehicle charging connector capable of transmitting energy and establishing communication between the EVSE and the vehicle's electrical system is within the scope of this disclosure. In a non-limiting example, the vehicle charging port 18 is implemented according to specifications such as SAE J1772, SAE J3400, etc. In a non-limiting example, communication between the EVSE and the vehicle's electrical system is implemented according to specifications such as International Electrotechnical Commission (IEC) 61851, ISO 15118, DIN 70121, SAE J2847 / 2, SAE J2931 / 4, etc.

[0044] DC charger 14 is an EVSE for charging an electric vehicle (e.g., one of a plurality of vehicles 12). In an exemplary embodiment, DC charger 14 includes a rectifier (not shown) connected to an AC power source (e.g., a utility grid, a portable generator, or other power source), a power control unit (not shown), a DC charger charging port 20, and a charging control unit (CCU) 22. Figure 2 ).

[0045] A rectifier is used to convert alternating current (AC) power to direct current (DC) power. In an exemplary embodiment, the rectifier is a full-wave bridge rectifier. In a non-limiting example, the full-wave bridge rectifier includes four diodes arranged in a bridge configuration. These diodes are arranged such that during each half-cycle of the AC input, two diodes are conducting while the other two are not conducting, thereby allowing current to flow in a single direction. This produces a pulsating DC output, which can then be further smoothed by capacitors or other filtering components to provide a stable DC voltage for the power control unit. The rectifier is in electrical communication with the AC power supply and the power control unit.

[0046] The power control unit controls the DC power output to the connected electric vehicle. In an exemplary embodiment, the power control unit includes one or more electronically controllable switches and one or more DC-DC converters. The one or more electronically controllable switches control the current flow between the DC charger 14 and the connected electric vehicle. In a non-limiting example, the one or more electronically controllable switches are transistors, relays, contactors, etc. The one or more DC-DC converters control the voltage and current supplied to the connected electric vehicle. The power control unit is in electrical communication with the rectifier, the DC charger charging port 20, and the CCU 22.

[0047] The DC charger charging port 20 is used to establish a connection between the DC charger 14 and the vehicle charging port 18 for charging the vehicle battery. Generally, the DC charger charging port 20 includes multiple pins for establishing electrical communication with corresponding pins in the vehicle charging port 18 via a charging cable. In an exemplary embodiment, the DC charger charging port 20 includes two or more conductive pins, at least one protective ground pin, and at least one communication pin. The two or more conductive pins are used to transfer power between the DC charger 14 and the vehicle charging port 18 to charge the vehicle battery and / or supply power from the vehicle battery to the grid. The protective ground pin provides a protective ground connection. The function of the at least one communication pin and exemplary communication modes between the DC charger 14 and the connected electric vehicle have been discussed above with reference to the vehicle charging port 18.

[0048] It should be understood that the above description of the DC charger charging port 20, including the configuration and function of the various pins, is merely exemplary in nature. Any electrical connector capable of transmitting energy and establishing communication between the DC charger 14 and the electric vehicle is within the scope of this disclosure. In a non-limiting example, the DC charger charging port 20 is implemented according to specifications such as SAE J1772, SAE J3400, etc. In a non-limiting example, communication between the DC charger 14 and the connected electric vehicle is implemented according to specifications such as IEC 61851, ISO 15118, DIN 70121, SAE J2847 / 2, SAE J2931 / 4, etc., as described above.

[0049] The CCU is used to control the operation of the DC charger 14. The CCU 22 includes at least one processor 24. Figure 2 ) and non-transitory computer-readable storage devices or media 26 ( Figure 2Processor 24 may be a custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among several processors associated with CCU 22, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, a combination thereof, or generally a device for executing instructions.

[0050] Computer-readable storage device or medium 26 may include volatile and non-volatile storage devices such as read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is persistent or non-volatile memory that can be used to store various operational variables when processor 24 is powered off. Computer-readable storage device or medium 26 may be implemented using multiple storage devices, such as programmable read-only memory (PROM), electrical PROM (EPROM), electrically erasable PROM (EEPROM), flash memory, or other electrical, magnetic, optical, or combined memory devices capable of storing data, some of which represents executable instructions used by CCU 22 to control the power control unit (i.e., control the operation of one or more electronically controlled switches and one or more DC-DC converters) and to communicate with the connected electric vehicle, as discussed above with reference to vehicle charging port 18. In a non-limiting example, CCU 22 is programmed to communicate with the connected electric vehicle according to specifications such as IEC 61851, ISO 15118, DIN 70121, SAE J2847 / 2, SAE J2931 / 4, etc., as described above. CCU 22 electrically communicates with the DC charger charging port 20 to send data to / receive data from the connected electric vehicle. CCU 22 also electrically communicates with the power control unit to control charging parameters (e.g., current and voltage limits) according to instructions received from the connected electric vehicle.

[0051] Multiple low-power access points (LPAPs) 16 are used to allow multiple electric vehicles (e.g., multiple electric vehicles) to connect to a single DC EVSE (e.g., DC charger 14) and to transfer energy between the single DC EVSE and the multiple electric vehicles. In an exemplary embodiment, the multiple LPAPs 16 include a first LPAP 16a and a second LPAP 16b. For clarity, the multiple LPAPs 16 will be discussed primarily with respect to the first LPAP 16a and the second LPAP 16b. However, it should be understood that the multiple LPAPs 16 can include any number of LPAPs, and the following disclosure, including the disclosure of the structure and function of the first LPAP 16a and the second LPAP 16b, is applicable to systems including any number of LPAPs.

[0052] refer to Figure 2An exemplary embodiment of a plurality of LPAPs 16 is shown together with a DC charger 14. In the exemplary embodiment, a first LPAP 16a includes a first LPAP first daisy-chain port 28a, a first LPAP second daisy-chain port 30a, a first LPAP charging port 32a, a first LPAP power electronics module 34a, and a first LPAP controller 36a.

[0053] The first LPAP first daisy-chain port 28a and the first LPAP second daisy-chain port 30a are used for interconnection between multiple LPAPs 16 and for connection of multiple LPAPs 16 to the DC charger 14. The first LPAP first daisy-chain port 28a and the first LPAP second daisy-chain port 30a can be implemented using any electrical connector that provides a current-carrying conductor and a communication conductor for communication with the DC charger 14. In a non-limiting example, the first LPAP first daisy-chain port 28a and the first LPAP second daisy-chain port 30a are implemented according to specifications such as SAE J1772, SAE J3400, etc. In an exemplary embodiment, the first LPAP first daisy-chain port 28a and the first LPAP second daisy-chain port 30a are also used for communication between LPAP controllers. In a non-limiting example, the first LPAP first daisy-chain port 28a and the first LPAP second daisy-chain port 30a include one or more additional communication pins dedicated to communication between LPAP controllers.

[0054] In an exemplary embodiment, the first LPAP 16a is connected in series with a plurality of LPAPs 16 (i.e., the second LPAP 16b) and the DC charger 14 using a first LPAP first daisy-chain port 28a and a first LPAP second daisy-chain port 30a. In an exemplary embodiment, the first LPAP 16a includes a low-impedance connection between the first LPAP first daisy-chain port 28a and the first LPAP second daisy-chain port 30a, such that the plurality of LPAPs 16 are effectively connected in parallel to the DC charger 14. In a non-limiting example, the first LPAP first daisy-chain port 28a is connected to the DC charger charging port 20 using a charging cable. The first LPAP second daisy-chain port 30a is connected to the second LPAP 16b using a charging cable.

[0055] The first LPAP charging port 32a is used to connect an electric vehicle (e.g., the first vehicle 12a) to the first LPAP 16a. The first LPAP charging port 32a can be implemented using any electrical connector that provides a current-carrying conductor and a communication conductor for communication with the vehicle charging port 18. In a non-limiting example, the first LPAP charging port 32a is implemented according to specifications such as SAE J1772, SAE J3400, etc. The first LPAP charging port 32a is connected to the vehicle charging port 18 of the first vehicle 12a using a charging cable. Figure 1 ).

[0056] The first LPAP power electronics module 34a is used to control the current flow between the first LPAP daisy-chain port 28a and the first LPAP charging port 32a. In a first exemplary embodiment, the first LPAP power electronics module 34a is an electronically controllable switch (e.g., one or more transistors, relays, contactors, etc.). The electronically controllable switch is configured to be controlled by a first LPAP controller 36a, as will be discussed in more detail below. In a second exemplary embodiment, the first LPAP power electronics module 34a is a DC-DC converter (e.g., a buck converter, a boost converter, a buck-boost converter, a flyback converter, etc.). The DC-DC converter is configured to be controlled by the first LPAP controller 36a, as will be discussed in more detail below.

[0057] The first LPAP controller 36a is used to control the first LPAP power electronics module 34a, communicate with the first vehicle 12a, and communicate with the DC charger 14. In an exemplary embodiment, the first LPAP controller 36a is structurally and functionally similar to the CCU 22 discussed above, having a processor (not shown) and non-transitory memory (not shown). In an exemplary embodiment, the first LPAP controller 36a executes a first method 100a and / or a second method 100b for DC charging of an electric vehicle, as will be discussed in more detail below. In a non-limiting example, because the first LPAP 16a is directly connected to the DC charger 14, the first LPAP controller 36a is designated as the master LPAP controller and communicates with the DC charger 14 on behalf of each of the plurality of LPAPs 16. In an exemplary embodiment, the first LPAP controller 36a is also configured to communicate with additional LPAP controllers. In a non-limiting example, the first LPAP controller 36a uses dedicated LPAP communication pins for communication between LPAP controllers.

[0058] In an exemplary embodiment, the second LPAP 16b includes a second LPAP first daisy-chain port 28b, a second LPAP second daisy-chain port 30b, a second LPAP charging port 32b, a second LPAP power electronics module 34b, and a second LPAP controller 36b.

[0059] The second LPAP first daisy-chain port 28b and the second LPAP second daisy-chain port 30b are used for interconnection between multiple LPAPs 16 and for connection of multiple LPAPs 16 to the DC charger 14. The second LPAP first daisy-chain port 28b and the second LPAP second daisy-chain port 30b can be implemented using any electrical connector that provides a current-carrying conductor and a communication conductor for communication with the DC charger 14. In a non-limiting example, the second LPAP first daisy-chain port 28b and the second LPAP second daisy-chain port 30b are implemented according to specifications such as SAE J1772, SAE J3400, etc. In an exemplary embodiment, the second LPAP first daisy-chain port 28b and the second LPAP second daisy-chain port 30b are also used for communication between LPAP controllers. In a non-limiting example, the second LPAP first daisy-chain port 28b and the second LPAP second daisy-chain port 30b include one or more additional communication pins dedicated to communication between LPAP controllers.

[0060] In an exemplary embodiment, the second LPAP 16b is connected in series with a plurality of LPAPs 16 (i.e., the first LPAP 16a) and the DC charger 14 using a second LPAP first daisy-chain port 28b and a second LPAP second daisy-chain port 30b. In an exemplary embodiment, the second LPAP 16b includes a low-impedance connection between the second LPAP first daisy-chain port 28b and the second LPAP second daisy-chain port 30b, such that the plurality of LPAPs 16 are effectively connected in parallel to the DC charger 14. In a non-limiting example, the second LPAP first daisy-chain port 28b is connected to the first LPAP second daisy-chain port 30a using a charging cable. The second LPAP second daisy-chain port 30b can be connected to a third LPAP (not shown) using a charging cable.

[0061] The second LPAP charging port 32b is used to connect an electric vehicle (e.g., the second vehicle 12b) to the second LPAP 16b. The second LPAP charging port 32b can be implemented using any electrical connector that provides current-carrying and communication conductors for communication with the vehicle charging port 18. In a non-limiting example, the second LPAP charging port 32b is implemented according to specifications such as SAE J1772, SAE J3400, etc. The second LPAP charging port 32b is connected to the vehicle charging port 18 of the second vehicle 12b using a charging cable. Figure 1 ).

[0062] The second LPAP power electronics module 34b is used to control the current between the first daisy-chain port 28b of the second LPAP and the charging port 32b of the second LPAP. In a first exemplary embodiment, the second LPAP power electronics module 34b is an electronically controllable switch (e.g., one or more transistors, relays, contactors, etc.). The electronically controllable switch is configured to be controlled by the second LPAP controller 36b, as will be discussed in more detail below. In a second exemplary embodiment, the second LPAP power electronics module 34b is a DC-DC converter (e.g., a buck converter, a boost converter, a buck-boost converter, a flyback converter, etc.). The DC-DC converter is configured to be controlled by the second LPAP controller 36b, as will be discussed in more detail below.

[0063] The second LPAP controller 36b is used to control the second LPAP power electronics module 34b, communicate with the second vehicle 12b, and communicate with the first LPAP 16a. In an exemplary embodiment, the second LPAP controller 36b is structurally and functionally similar to the CCU 22 discussed above, having a processor (not shown) and non-transitory memory (not shown). In an exemplary embodiment, the second LPAP controller 36b performs a first method 100a and / or a second method 100b for DC charging of the electric vehicle, as will be discussed in more detail below. In a non-limiting example, the second LPAP controller 36b is designated as an auxiliary LPAP controller and relays communication to the DC charger 14 via the first LPAP controller 36a. In an exemplary embodiment, the second LPAP controller 36b is also configured to communicate with an additional LPAP controller. In a non-limiting example, the second LPAP controller 36b uses dedicated LPAP communication pins for communication between LPAP controllers.

[0064] It should be understood that each of the plurality of LPAPs 16 is similar or identical in structure and function, allowing system 10 to be modularly expanded to include any number of LPAPs. In the above embodiments, each of the plurality of LPAPs 16 includes a separate LPAP controller that operates in cooperation with other LPAP controllers to perform the first method 100a and / or the second method 100b. In another exemplary embodiment, system 10 includes a single centralized LPAP controller that communicates wirelessly and / or wiredly with each of the plurality of LPAPs. In a non-limiting example, the centralized LPAP controller is implemented as a separate module or unit that communicates electrically with each of the plurality of LPAPs. In another non-limiting example, the centralized LPAP controller is integrated into the DC charger 14. In a non-limiting example, the function of the centralized LPAP controller is performed by the CCU 22 of the DC charger 14. It should be understood that any control mode for the plurality of LPAPs 16, including independent LPAP controllers (i.e., the first LPAP controller 36a and the second LPAP controller 36b) and / or one or more centralized LPAP controllers, is within the scope of this disclosure.

[0065] refer to Figure 3 A flowchart of a first method 100a for DC charging of an electric vehicle is shown. The first method 100a uses an embodiment of an electronically controlled switch for the LPAP power electronics module (i.e., the first LPAP power electronics module 34a and the second LPAP power electronics module 34b, or any number of LPAP power electronics modules) of each of a plurality of LPAPs 16. In an exemplary embodiment, the first method 100a is performed by an independent LPAP controller (i.e., the first LPAP controller 36a and the second LPAP controller 36b, or any number of LPAP controllers) or one or more centralized LPAP controllers. For clarity, the first method 100a will be discussed in relation to a plurality of LPAPs 16. It should be understood that the following disclosure also applies to one or more centralized LPAP controllers. In a non-limiting example, when the first method 100a is performed by an independent LPAP controller (i.e., the first LPAP controller 36a and the second LPAP controller 36b), the independent LPAP controllers communicate with each other to exchange information while performing the first method 100a. The first method 100a begins at block 302 and proceeds to blocks 304 and 306.

[0066] At block 304, a plurality of LPAPs 16 determine the battery voltage of each of the plurality of vehicles 12. In an exemplary embodiment, a first LPAP controller 36a determines the battery voltage of a first vehicle 12a and a second LPAP controller 36b determines the battery voltage of a second vehicle 12b. In a non-limiting example, to determine the battery voltage, the plurality of LPAPs 16 communicate with the BMS of the vehicle electrical system of each of the plurality of vehicles 12. For example, the first LPAP controller 36a communicates with the BMS of the first vehicle 12a using a connection between a first LPAP charging port 32a and a vehicle charging port 18 of the first vehicle 12a. The second LPAP controller 36b communicates with the BMS of the second vehicle 12b using a connection between a second LPAP charging port 32b and a vehicle charging port 18 of the second vehicle 12b. Following block 304, the first method 100a proceeds to block 308, as will be discussed in more detail below.

[0067] At block 306, a plurality of LPAPs 16 determine charging parameter constraints for each of the plurality of vehicles 12. Within the scope of this disclosure, charging parameter constraints include, for example, minimum / maximum charging voltage, minimum / maximum charging current, minimum / maximum charging power, minimum / maximum charging rate, etc. In an exemplary embodiment, a first LPAP controller 36a determines the charging parameter constraints for a first vehicle 12a, and a second LPAP controller 36b determines the charging parameter constraints for a second vehicle 12b. In a non-limiting example, to determine the charging parameter constraints, the plurality of LPAPs 16 communicate with the BMS of the vehicle electrical system of each of the plurality of vehicles 12.

[0068] For example, the first LPAP controller 36a uses the connection between the first LPAP charging port 32a and the vehicle charging port 18 of the first vehicle 12a to communicate with the BMS of the first vehicle 12a. The second LPAP controller 36b uses the connection between the second LPAP charging port 32b and the vehicle charging port 18 of the second vehicle 12b to communicate with the BMS of the second vehicle 12b. After block 306, the first method 100a proceeds to block 308.

[0069] At block 308, the plurality of LPAPs 16 identify the lowest battery voltage in the plurality of vehicles 12. In an exemplary embodiment, the lowest battery voltage is determined by comparing the battery voltage determined at block 304. In a non-limiting example, the plurality of LPAPs 16 communicate with each other to compare the battery voltage determined at block 304. After block 308, the first method 100a proceeds to block 310.

[0070] At block 310, a plurality of LPAPs 16 command the DC charger 14 to provide a first output voltage at the DC charger charging port 20. In an exemplary embodiment, a first LPAP controller 36a is designated as the master LPAP controller and communicates with the DC charger 14 on behalf of each of the plurality of LPAPs 16. In an exemplary embodiment, the first output voltage is determined at least in part based on a minimum battery voltage determined at block 308. In a non-limiting example, the first output voltage is determined to be greater than or equal to the minimum battery voltage. In another exemplary embodiment, the first output voltage is determined at least in part based on the minimum battery voltage determined at block 308 and charging parameter constraints determined at block 306. In a non-limiting example, the first output voltage is determined such that one or more of the plurality of vehicles 12 having the minimum battery voltage do not exceed their maximum charging current.

[0071] In an exemplary embodiment, at block 310, the plurality of LPAPs 16 further instruct the DC charger 14 to limit the current supplied at the DC charger charging port 20 to a first output current. In an exemplary embodiment, the first output current is less than or equal to the maximum charging current of one or more of the plurality of vehicles 12 having the lowest battery voltage and the lowest maximum charging current. Following block 310, the first method 100a proceeds to blocks 312 and 314.

[0072] At block 312, a plurality of LPAPs 16 control an electronically controllable switch of one or more of the plurality of LPAPs 16 to charge one or more of the plurality of vehicles 12 having the lowest battery voltage. In a non-limiting example, if a first vehicle 12a, as determined at block 308, has the lowest battery voltage, a first LPAP controller 36a closes an electronically controllable switch of a first LPAP power electronics module 34a to connect the first vehicle 12a to a DC charger 14. In another non-limiting example, if a second vehicle 12b has the lowest battery voltage determined at block 308, a second LPAP controller 36b closes an electronically controllable switch of a second LPAP power electronics module 34b to connect the second vehicle 12b to a DC charger 14. In another non-limiting example, if both the first vehicle 12a and the second vehicle 12b have a minimum battery voltage determined at block 308 (e.g., within a predetermined tolerance, such as 5%), the first LPAP controller 36a closes the electronically controllable switch of the first LPAP power electronics module 34a and the second LPAP controller 36b closes the electronically controllable switch of the second LPAP power electronics module 34b, such that the first vehicle 12a and the second vehicle 12b are simultaneously connected to the DC charger 14. After block 312, the first method 100a continues into the standby state at block 316.

[0073] At block 314, a plurality of LPAPs 16 control an electronically controllable switch of one or more of the plurality of LPAPs 16 to terminate charging of one or more of the plurality of vehicles 12 having a battery voltage greater than a minimum battery voltage (e.g., at least a predetermined threshold, e.g., 10 percent). In an exemplary embodiment, charging is terminated by opening the electronically controllable switch after appropriate communication with one or more of the plurality of vehicles 12. After block 314, the first method 100a continues into a standby state at block 316.

[0074] In an exemplary embodiment, throughout the first method 100a, the first LPAP controller 36a simulates an electric vehicle during communication with the DC charger 14 (e.g., using the communication protocols and techniques discussed above). Therefore, the DC charger 14 operates as if connected to a single electric vehicle and provides charging power to the first LPAP first daisy-chain port 28a based on data transmitted between the first LPAP controller 36a and the DC charger 14. Furthermore, throughout the first method 100a, multiple LPAPs 16 simulate EVSEs during communication with multiple vehicles 12 (e.g., using the communication protocols and techniques discussed above).

[0075] Multiple LPAPs 16 also intercept and act upon any communications from multiple vehicles 12 that are directed to the DC charger 14. For example, if the first vehicle 12a sends a signal requesting termination of charging (e.g., when the first vehicle 12a has reached its maximum charging state), the first LPAP controller 36a intercepts the signal and activates the electronically controllable switch of the first LPAP power electronics module 34a without affecting the charging process of the second vehicle 12b. For example, if the second vehicle 12b sends a signal requesting a change in charging voltage, the second LPAP controller 36b intercepts the signal and relays it to the first LPAP controller 36a. The first LPAP controller 36a then communicates with the DC charger 14 to adjust the charging voltage.

[0076] In an exemplary embodiment, the plurality of LPAPs 16 repeatedly exit standby state 316 and restart the first method 100a at block 302 to periodically reassess the battery voltage of each of the plurality of vehicles 12, identify the lowest battery voltage, and control the DC charger 14 and one or more of the plurality of LPAPs 16 to charge one or more of the plurality of vehicles 12 with the lowest battery voltage. In a non-limiting example, the plurality of LPAPs 16 exit standby state 316 and restart the first method 100a based on a timer, for example, every three hundred milliseconds.

[0077] refer to Figure 4A flowchart of a second method 100b for DC charging of an electric vehicle is shown. The second method 100b includes embodiments of DC-DC converters in the LPAP power electronics modules (i.e., the first LPAP power electronics module 34a and the second LPAP power electronics module 34b, or any number of LPAP power electronics modules) of each of a plurality of LPAPs 16. In an exemplary embodiment, the second method 100b is performed by independent LPAP controllers (i.e., the first LPAP controller 36a and the second LPAP controller 36b, or any number of LPAP controllers) or one or more centralized LPAP controllers. For clarity, the second method 100b will be discussed in relation to a plurality of LPAPs 16. It should be understood that the following disclosure also applies to one or more centralized LPAP controllers. In a non-limiting example, when the second method 100b is performed by independent LPAP controllers (i.e., the first LPAP controller 36a and the second LPAP controller 36b), the independent LPAP controllers communicate with each other to exchange information while performing the second method 100b. The second method 100b begins at box 402 and proceeds to boxes 404 and 406.

[0078] At block 404, a plurality of LPAPs 16 determine the battery voltage of each of the plurality of vehicles 12. In an exemplary embodiment, a first LPAP controller 36a determines the battery voltage of a first vehicle 12a and a second LPAP controller 36b determines the battery voltage of a second vehicle 12b. In a non-limiting example, to determine the battery voltage, the plurality of LPAPs 16 communicate with the BMS of the vehicle electrical system of each of the plurality of vehicles 12. For example, the first LPAP controller 36a communicates with the BMS of the first vehicle 12a using a connection between a first LPAP charging port 32a and a vehicle charging port 18 of the first vehicle 12a. The second LPAP controller 36b communicates with the BMS of the second vehicle 12b using a connection between a second LPAP charging port 32b and a vehicle charging port 18 of the second vehicle 12b. Following block 404, a second method 100b proceeds to block 408, as will be discussed in more detail below.

[0079] At block 406, a plurality of LPAPs 16 determine charging parameter constraints for each of the plurality of vehicles 12. Within the scope of this disclosure, charging parameter constraints include, for example, minimum / maximum charging voltage, minimum / maximum charging current, minimum / maximum charging power, minimum / maximum charging rate, etc. In an exemplary embodiment, a first LPAP controller 36a determines the charging parameter constraints for a first vehicle 12a, and a second LPAP controller 36b determines the charging parameter constraints for a second vehicle 12b. In a non-limiting example, to determine the charging parameter constraints, the plurality of LPAPs 16 communicate with the BMS of the vehicle electrical system of each of the plurality of vehicles 12.

[0080] For example, the first LPAP controller 36a uses the connection between the first LPAP charging port 32a and the vehicle charging port 18 of the first vehicle 12a to communicate with the BMS of the first vehicle 12a. The second LPAP controller 36b uses the connection between the second LPAP charging port 32b and the vehicle charging port 18 of the second vehicle 12b to communicate with the BMS of the second vehicle 12b. After block 406, the second method 100b proceeds to block 408.

[0081] At block 408, the plurality of LPAPs 16 identify the highest battery voltage among the plurality of vehicles 12. In an exemplary embodiment, the highest battery voltage is determined by comparing the battery voltage determined at block 404. In a non-limiting example, the plurality of LPAPs 16 communicate with each other to compare the battery voltage determined at block 404. Following block 408, a second method 100b proceeds to block 410.

[0082] At block 410, the plurality of LPAPs 16 command the DC charger 14 to provide a second output voltage at the DC charger charging port 20. In an exemplary embodiment, a first LPAP controller 36a is designated as the master LPAP controller and communicates with the DC charger 14 on behalf of each of the plurality of LPAPs 16. In an exemplary embodiment, the second output voltage is determined at least in part based on the highest battery voltage determined at block 408. In a non-limiting example, the second output voltage is determined to be greater than or equal to the highest battery voltage.

[0083] In an exemplary embodiment, at block 410, the plurality of LPAPs 16 further instruct the DC charger 14 to limit the current supplied at the DC charger charging port 20 to a second output current. In an exemplary embodiment, the second output current is equal to the sum of the maximum charging currents of each of one or more of the plurality of vehicles 12. Following block 410, the second method 100b proceeds to block 412.

[0084] At block 412, a plurality of LPAPs 16 control the DC-DC converter of each of the plurality of LPAPs 16 to charge each of the plurality of vehicles 12. In an exemplary embodiment, the DC-DC converter of each of the plurality of LPAPs 16 is controlled at least in part based on the battery voltage of each of the plurality of vehicles 12. In another exemplary embodiment, the DC-DC converter of each of the plurality of LPAPs 16 is controlled at least in part based on the battery voltage of each of the plurality of vehicles 12 and a second output voltage. In a non-limiting example, the plurality of LPAPs 16 determine a plurality of voltage differences between the second output voltage and the battery voltage of each of the plurality of vehicles 12. The plurality of LPAPs 16 then control the DC-DC converter of each of the plurality of LPAPs 16 at least in part based on one of the plurality of voltage differences.

[0085] In a non-limiting example, the duty cycle of the DC-DC converter of the first LPAP power electronics module 34a is controlled such that the voltage supplied at the first LPAP charging port 32a matches the battery voltage of the first vehicle 12a (e.g., within a predetermined tolerance, such as 5%). In a non-limiting example, the duty cycle of the DC-DC converter of the second LPAP power electronics module 34b is controlled such that the voltage supplied at the second LPAP charging port 32b matches the battery voltage of the second vehicle 12b (e.g., within a predetermined tolerance, such as 5%). After block 412, the second method 100b continues into the standby state at block 414.

[0086] In an exemplary embodiment, throughout the second method 100b, the first LPAP controller 36a simulates an electric vehicle during communication with the DC charger 14 (e.g., using the communication protocols and techniques discussed above). Therefore, the DC charger 14 operates as if connected to a single electric vehicle and provides charging power to the first LPAP first daisy-chain port 28a based on data transmitted between the first LPAP controller 36a and the DC charger 14. Furthermore, throughout the second method 100b, multiple LPAPs 16 simulate EVSEs during communication with multiple vehicles 12 (e.g., using the communication protocols and techniques discussed above).

[0087] Multiple LPAPs 16 also intercept and act upon any communications from the multiple vehicles 12 directed to the DC charger 14. For example, if the first vehicle 12a sends a signal requesting termination of charging (e.g., when the first vehicle 12a has reached its maximum charging state), the first LPAP controller 36a intercepts the signal and disables the DC-DC converter of the first LPAP power electronics module 34a without affecting the charging process of the second vehicle 12b. For example, if the second vehicle 12b sends a signal requesting a change in charging voltage, the second LPAP controller 36b intercepts the signal and adjusts the operation of the DC-DC converter of the second LPAP power electronics module 34b. If necessary, the second LPAP controller 36b relays the signal to the first LPAP controller 36a. The first LPAP controller 36a then communicates with the DC charger 14 to adjust the charging voltage.

[0088] In an exemplary embodiment, the plurality of LPAPs 16 repeatedly exit standby state 414 and restart the second method 100b at block 402 to periodically reassess the battery voltage of each of the plurality of vehicles 12, identify the highest battery voltage, and control the DC charger 14 and one or more of the plurality of LPAPs 16 to charge the plurality of vehicles 12 based at least in part on the highest battery voltage. In a non-limiting example, the plurality of LPAPs 16 exit standby state 414 and restart the second method 100b based on a timer, for example, every three hundred milliseconds.

[0089] The system 10, first method 100a, and second method 100b disclosed herein offer several advantages. System 10 can be used to charge a large number of electric vehicles using only a single DC EVSE. For example, multiple portable LPAPs can be temporarily installed during events or holidays to provide enhanced charging capacity. Furthermore, when used in conjunction with a portable generator, LPAPs can be used to charge multiple electric vehicles in remote areas. Additionally, system 10, first method 100a, and second method 100b are compatible with existing EVSEs without requiring hardware or software modifications, as multiple LPAPs 16 work collaboratively to simulate a single electric vehicle using industry-standard communication protocols.

[0090] The descriptions in this disclosure are merely exemplary in nature, and variations thereof that do not depart from the spirit and scope of this disclosure are intended to fall within its scope. Such variations should not be considered as departing from the spirit and scope of this disclosure.

Claims

1. A DC charging system for electric vehicles, comprising: DC charger with DC charger charging port; Multiple low-power access points (LPAPs), each LPAP having a first daisy-chain port, a second daisy-chain port, and an LPAP charging port, wherein the multiple LPAPs are connected in series to the DC charger charging port of the DC charger via the first daisy-chain port and the second daisy-chain port, and wherein each of the multiple LPAPs is configured to transfer energy from the DC charger to an electric vehicle via the LPAP charging port; and A plurality of electric vehicles, wherein each of the plurality of electric vehicles is connected to the charging port of one of the plurality of LPAPs for charging the plurality of electric vehicles.

2. The system according to claim 1, further comprising: An LPAP controller, electrically communicating with each of the plurality of LPAPs, wherein the LPAP controller is programmed to: Determine the battery voltage of each of the plurality of electric vehicles; and Control the DC charger and one or more of the plurality of LPAPs to charge one or more of the plurality of electric vehicles at least in part based on the battery voltage of each of the plurality of electric vehicles.

3. The system according to claim 2, wherein the LPAP controller is further programmed to: Identify the lowest battery voltage among the plurality of electric vehicles; Controlling the DC charger and one or more of the plurality of LPAPs to charge one or more of the plurality of electric vehicles having the lowest battery voltage; and The battery voltage of each of the plurality of electric vehicles is periodically reassessed, the lowest battery voltage is identified, and the DC charger and one or more of the plurality of LPAPs are controlled to charge one or more of the plurality of electric vehicles having the lowest battery voltage.

4. The system according to claim 3, wherein, At least one of the plurality of LPAPs also includes: An electronically controllable switch is configured to connect the first daisy-chain port to the LPAP charging port, wherein the electronically controllable switch is configured to be controlled by the LPAP controller.

5. The system of claim 4, wherein, in order to control the DC charger and one or more of the plurality of LPAPs, the LPAP controller is further programmed to: The command instructs the DC charger to provide a first output voltage at the DC charger charging port, wherein, The first output voltage is determined at least in part based on the lowest battery voltage; as well as The electronically controllable switch of one or more of the plurality of LPAPs is controlled to charge one or more of the plurality of electric vehicles having the lowest battery voltage.

6. The system according to claim 5, wherein, In order to control the DC charger and one or more of the plurality of LPAPs, the LPAP controller is further programmed to: The DC charger is instructed to limit the current at its charging port to a first output current, wherein the first output current is determined at least in part based on the maximum charging current of one or more of the plurality of electric vehicles having the lowest battery voltage.

7. The system according to claim 2, wherein, The LPAP controller is also programmed to: Identify the highest battery voltage among the plurality of electric vehicles; Control the DC charger and one or more of the plurality of LPAPs to charge the plurality of electric vehicles at least in part based on the highest battery voltage; as well as The battery voltage of each of the plurality of electric vehicles is periodically reassessed, the highest battery voltage is identified, and the DC charger and one or more of the plurality of LPAPs are controlled to charge the plurality of electric vehicles at least in part based on the highest battery voltage.

8. The system according to claim 7, wherein, Each of the plurality of LPAPs also includes: A DC-DC converter is connected between the first daisy-chain port and the LPAP charging port, wherein the DC-DC converter is configured to be controlled by the LPAP controller.

9. The system according to claim 8, wherein, In order to control the DC charger and one or more of the plurality of LPAPs, the LPAP controller is further programmed to: The DC charger is instructed to provide a second output voltage at the DC charger charging port, wherein the second output voltage is determined at least in part based on the highest battery voltage; and The DC-DC converter of each of the plurality of LPAPs is controlled to charge each of the plurality of electric vehicles at least in part based on the battery voltage of each of the plurality of electric vehicles.

10. The system according to claim 9, wherein, In order to control the DC-DC converter of each of the plurality of LPAPs, the LPAP controller is further programmed to: Determine a plurality of voltage differences between the second output voltage and the battery voltage of each of the plurality of electric vehicles; as well as The DC-DC converter of each of the plurality of LPAPs is controlled at least in part based on one of the plurality of voltage differences.

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