PREMO, a Spanish manufacturer of inductive components for the automotive market, has announced a new series of compact secondary coils for wireless charging, the WC-RX-Series, that boast high efficiency and durability.
In Wireless Power Transfer (WPT) systems for EVs, the secondary coils (also known as the receiver antenna) are installed on the vehicle, while the primary coils are installed on the floor. When the EV is parked in the correct spot, electricity flows from the primary coils to the secondary coils, allowing the vehicle to charge.
WPT is convenient, but conventional ferrite cores found in high-frequency transformers are too fragile for EV applications. Over the past three years, PREMO sought to create a technology than can support EV WPT in the range of 90 kHz. It sourced €1 million in public and private funding and gathered a team of scientists from various universities and research institutes to join its own team of materials scientists.
The result, PREMO’s WC-Rx-Series, provides high-efficiency power transfer (above 95%) by combining and optimizing the coil (composed of Litz wire) with a flexible-core configuration that avoids air gaps and reduces heating areas. The magnetic core itself combines Flex-Ferrite blocks with PBM (Soft-Polymer Bonding Magnetic).
PREMO says the secondary coil boasts a high Q-factor and high reliability. The 7.7 kW model see a 94.5% efficiency, 20% K-factor, and 12 uH mutual inductance. Samples of the 7 to 11 kW models will be available by the end of 2019. Samples of the 22 kW model will be available by Q1 2020.