ANL Invention Number: IN-22-026
Patent: Jason D. Harper, “Vehicle Charging System Compatible with Multiple Charging Protocols and Method,” Patent Application 18/127120 (filed April 2023), assignee Argonne National Laboratory.
What is the main problem this research addresses?
AC charging of electric vehicles can be performed in one of two ways: analog based communication and digital based communication between the EV (Electric Vehicle) and EVSE (Electric Vehicle Supply Equipment). Analog-based communication for EV charging refers to the transmission of a control signal between the charging station and electric vehicle using a continuous and non-digital electrical signal, which does not allow for the exchange of information between the EV and EVSE. Digital-based communication protocols for AC charging, such as HomePlug GreenPHY (HPGP) based communication like ISO 15118 and Single Wire CAN (SWCAN) based Tesla SAE J2411, enable continuous information exchange between the EV and EVSE.
Automotive original equipment manufacturers (OEM) have been slow to implement digital based communication for AC charging. However, the benefits of implementing digital based communication for AC charging has never been quantified or adequately explained to key industry stakeholders. Also, there is currently not an EVSE on the market that can handle these three modes of communication for charging in a single EVSE. Given the proprietary nature and industry unable to provide open access to their charging hardware and firmware, Argonne research engineers set out to develop such an EVSE.
What is Smart/Optimized Charging?
There are many stakeholders in the EV charging ecosystem with their own unique objectives including distribution utilities, site/premise owners, station owners/operators, vehicle OEMs and EV drivers. As the number of EVs charging on the grid increases, the limitation of grid capacity becomes evident. Consequently, there is a need to implement intelligent and optimized charging strategies to accommodate this growing demand on the grid. Smart/Optimized charging takes into the account the needs of all stakeholders in the ecosystem and attempts to meet those needs. One form of smart/optimized charging is charge scheduling. The ISO 15118 standard provides a means for the EV/driver and system actors to negotiate a charge schedule that meets the needs of all stakeholders. This typically is done by providing the grid constraints to an EV and the EV then negotiates a charge schedule by considering the driver’s requested departure time, energy needs and the maximum charging power of the EV.
Unfortunately, charge scheduling has not been implemented in the majority of EVs on the road today. However, Argonne research engineers believe that will change in the future and the OptiQ EVSE has been designed to leverage that capability.
The OptiQ (pronounced Optic) EVSE hardware is similar to EVSE found in the market today. The OptiQ EVSE is based on the Argonne SpEC module, which is a Linux based communication controller configured as a Supply Equipment Communication Controller and capable of high level communication. The OptiQ EVSE conforms to the SAE J1772 standard for AC EVSE and has a built-in energy meter capable of providing meter values for charge sessions. The maximum charge rate for OptiQ EVSE is dependent upon the rating of the internal AC contactor and rating of the SAE J1772 charge cord.
Where the OptiQ EVSE differs from current EVSE found in the market today is its capability of detecting and choosing the correct protocol to interface with a vehicle and attempting to perform optimized charging via charge scheduling. The OptiQ EVSE is capable of charge scheduling when paired with an OCPP 2.0.1 based smart charge scheduling application. Its firmware is capable of OCPP 1.6J and OCPP 2.0.1 based communication. The OptiQ EVSE OCPP 1.6J implementation has been self-certified utilizing the OCA 1.6J OCTT. The OCPP 2.0.1 client is currently under development.
OptiQ Modes of Operation
SAE J1772 (Analog Charging)
All U.S. based vehicles are capable of SAE J1772 based charging. This standard is an analog based standard in which no digital information is exchanged between the EV and EVSE. The protocol relies on a pulse-width modulated square wave signal generated by the EVSE to be sent to the EV via the control pilot pin of the SAE J1772 connector. The duty cycle, which is the duration of the pulse (ON time) to the total period, is measured by the EV. This duty cycle, which is a percentage, is then utilized to back-calculate the ampacity of the EVSE via a standard equation. The EV then must not pull more than the calculated ampacity of the EVSE. The EVSE is allowed to vary the duty cycle, thus varying the ampacity of the EVSE to perform controlled charging.
ISO 15118 (HLC)
ISO 15118 is an international standard that describes the high-level communication (HLC) between an EV and EVSE. ISO 15118 based communication utilizes HPGP based power line communication over the control pilot pin. ISO 15118 enables optimized charging via charge scheduling. The majority of EVs today do not have ISO 15118 AC based messaging implemented. There are two predominant versions of the ISO-15118 standard in use today: ISO-15118-2 and ISO-15118-20. The OptiQ EVSE can provide both forms of ISO-15118 communication.
Tesla SWCAN (HLC)
Argonne research engineers have reverse-engineered the Tesla CAN protocol utilized to digitally interface with Tesla EVs. Tesla EVs utilize SAE J2411 over the control pilot pin to digitally communicate with the Tesla AC EVSE. The OptiQ EVSE emulates this protocol and can monitor and control Tesla EVs digitally. A NACS connector could be added to the OptiQ EVSE to truly replicate the Tesla charging experience. As of Q4 of 2021, Tesla had a 70% market share of all light duty electric vehicles in the US representing a significant portion of the US light duty electric fleet. The ability to communicate with Tesla vehicles and integrate them into the smart grid utilizing industry standard protocols could be significant.
DIN Spoofing (HLC/Analog)
DIN Spoofing is a new technique developed by Argonne research engineers that leverages vehicles capable of DC fast charging via DIN 70121 but have not implemented HLC for AC charging. Examples of these types of vehicles include most US based EVs capable of DC charging via the SAE J1772 CCS standard. These vehicles typically utilize SAE J1772 analog based charging for AC charging. However, the OptiQ EVSE can emulate a DC based charger and digitally interface with these EVs in order to obtain the necessary information to perform charge scheduling. This DIN spoofing technique has been tested on multiple vehicles and only takes 10-20 seconds upon plugin to get the necessary info and then default back to SAE J1772 analog based charging.