On Tuesday, May 31, 2022 the IEEE PSES Chicago Chapter hosted a virtual meeting via Teams on Tuesday rather than the usual Wednesday meeting time for the chapter. The tech topic for the meeting was “Consumer facing EV charging infrastructure Equipment Today and the Near Future”. Despite the change of day for the meeting, it was well attended.
The presenter was Mr. Joseph Bablo, the Principal Engineer Manager for Energy Storage and e-Mobility and is responsible for standards and categories for automotive equipment and associated technologies at UL Solutions. Joe serves as the technical representative for all UL EV charging standards as well as IEC committees for EV charging. Joe is also the chair of Code Making Panel 12 for the National Electrical Code, NFPA 70. Joe is a Distinguished Member of Technical Staff for the William Henry Merrill Society of UL with over 26 years at UL.
The presentation began with an overview of the legacy EV charging equipment with the UL standards that apply for each. These standards include UL 2202, the Standard for Electric Vehicle (EV) Charging System Equipment; UL 2594, the Standard for Electric Vehicle Supply Equipment; UL 2251, the Standard for Plugs, Receptacles, and Couplers for Electric Vehicles and UL 2231, the Standard for Personnel Protection Systems for Electric Vehicle (EV) Supply Circuits. The scope of these standards as follows:
- UL 2022: More complex EV charging equipment where voltage conversion is part of product and the charger provides the protection for the output.
- UL 2594: Simple EV charging equipment where the vehicle controls the charging event and the primary protection is located in the building installation.
- UL 2231: The personal protective equipment built into the charging transfer equipment between the EV charger and the vehicle.
- UL 2251: Covers the plugs and receptacles for EV charging.
The legacy systems are conductive systems where the charging energy is transferred between the EV charger and the vehicle through a wire and plug/connector assembly. The output from these charger systems is either AC (either UL 2202 or UL 2594) or DC (UL 2202).
The presentation also covered advances and innovations for EV charging. One of these innovations is charging using an automatic connection (e.g. a pantograph system that makes contact with the battery), which was started for buses and trucks but is also being considered for passenger vehicles as well. For fleet vehicles such as buses, this system can be installed at bus stops or at the depot. This type of system uses and automated mechanism to connect the charger to the vehicle. An automatic EV charging connection eliminates the need to lift or manipulate cable assemblies as well as the need to leave the vehicle in order to connect. These automated systems are more complicated due to their automated nature.
Another innovation under development is megawatt charging. Megawatt chargers will have a much higher output rating of 1500 Vdc, 3000 A, and are primarily aimed at truck and bus charging. However, megawatt charging may expand in the future to other use cases. This type of charging requires different charge protocols and configurations, and is intended for charging only by skilled personnel and not the general public. Research and testing for megawatt charging is ongoing to assist in identifying and addressing potential hazards. This research and testing will help to inform the standards development, which is currently under way. There are some pilot programs with megawatt level charging already under way within Europe, and EV Megawatt chargers are projected to be commercially available in 2023.
In addition to various EV charging technologies, there is also consideration of bi-directional power transfer which deals with the exporting of power from an EV for use off board the vehicle. There are many different use cases exist, including V2G (vehicle to grid), V2P (vehicle to premise) and V2L (vehicle to load. The standard developed to address bi-direction power transfer from vehicles is UL 9741, Electric Vehicle Power Export Equipment (EVPE), covers the equipment used for this power transfer from the vehicle.
Finally, the last method of EV charging presented was wireless power transfer type charging. With this type of charging, there is no conductive connection during the charging. There was a standard developed in 2011, UL 2750, Outline for Wireless Power Transfer Equipment for Electric Vehicles to address wireless charging before there were actually commercially available systems. There is also SAE J2954, Wireless Power Transfer for Light-Duty Plug-in/Electric Vehicles and Alignment Methodology. Interoperability is a key issue for all vehicles using this charging method. There are concerns with the vehicle alignment during charging and with exposing living things and nonliving objects to high levels of electromagnetic energy inadvertently. Foreign object detection and living object detection need to be built into the system to prevent exposure to the electromagnetic fields. The safe operation is critical and SAE J2954 is working on the vehicle side of these safety concerns, and UL 2750 is addressing these issues and currently moving towards becoming a consensus standard. Currently, there are systems that are certified at this time and there are other vehicles that are adding this feature. There are also larger vehicles such as buses using this charging method that are being piloted in California.
The presentation concluded noting that the future of EV charging is based upon the understanding that it will continue to grow and evolve for vehicle charging, and that it is moving into other areas including electric aircraft whether drone or passenger aircraft and electric boats and ferries. The EV charging concept for these various other applications is not different from vehicle charging, but the power level and connection means may be different. There is a need for charging and increased speed of charging, and new innovations in EV charging are continuing to be developed.