SAE Publishes J2954 RP for Wireless Charging to 11 kW

SAE International published SAE J2954 Recommended Practice (RP), providing the first worldwide specification for wireless power transfer (WPT) for electric vehicles up to 11 kW power levels (WPT 3). Following the previous Technical Information Report J2954, with power levels up to WPT 2 (7.7 kW), 11 kW wireless charging is a big step towards commercialization for electric vehicles.

The RP also provides a standardized test stand (first up to WPT 2 power levels) which gives both electric vehicle manufacturers and infrastructure companies a means for testing performance and validation of products and new developments. The J2954 standard test stand is based on the circular topology but also provides a way to demonstrate compatibility to other topologies such as the “double D” design.

Inductive WPT systems have two main components; a Ground Assembly (GA) unit and a Vehicle Assembly (VA) unit. The GA contains a grid-connected Power Factor Correction (PFC) converter, followed by a DC-AC inverter, a filter and impedance matching network (IMN) connected to the GA coil. The VA consists of the VA coil connected to an IMN and filter, a rectifier and an optional impedance converter that produces suitable voltages and currents to the connected battery. During charging, the magnetic energy created by the GA Coil is coupled to the VA Coil.

The Recommended Practice establishes a new methodology using magnetic triangulation for vehicle alignment to assist manual as well as autonomous parking. Coupled with communications, SAE J2954 can assist EV drivers seamlessly to park their vehicles, to establish payment and to charge without customer interaction.

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