DNP Develops Coil for Wireless Charging of EV

With a low profile and light weight, also cuts leakage magnetic field

Dai Nippon Printing Co., Ltd. (DNP) has developed a sheet-type coil for wireless charging of electric vehicles (EV). The newly developed coil maintains a low profile and light weight, and has been made compatible with high power transmission by reducing the leakage magnetic field.


Amidst the transition to EV seen on a worldwide basis, wireless technology capable of charging EV through non-contact methods has come under the spotlight. There are great expectations for the early deployment of wireless charging given that it increases the ease of the charging process by removing the need to connect cables and maintains a high affinity with the EV autonomous driving.

DNP is pushing ahead with the development of the coils that form the core component of the wireless charging systems, using photolithography technology that the Company has worked with over a period of many years. The sheet-type coil newly developed on this occasion maintains a lower profile and lighter weight than standard general coils based on litz wire. In addition, the leakage magnetic field has been reduced during charging, and the new product is also compatible with high power transmission.

[Sheet Coil Features]

The newly developed sheet-type coil developed by DNP is composed of a coil sheet and a ferrite sheet, and is compatible with the dual wireless charging systems, i.e., both the transmitting and receiving sides.

Low Profile and Light Weight

Coils including ferrite sheets have a maximum thickness of about 3 mm and a weight of about 1 kg in the case of J2954 WPT2 / Z2-compliant receiving coil as specified by the Society of Automotive Engineers (SAE) International. SAE International is a US-based non-profit organization with approximately 127,000 mobility specialist members who engage in the development of auto and aerospace standards. Compared to similar specification coil including ferrites and based on standard litz wire, with thickness and weight of approximately 12mm and 4kg respectively, according to DNP in-house calculations, the newly developed coil makes for a significant reduction in both.

Reduces the leakage magnetic field enabling high power transmission

As a result of optimizing the coil pattern and applying high-resolution photolithography technology, the resultant structure makes it difficult for the magnetic field to leak beyond the coil. Consequently, leakage magnetic field that affects the human body and devices including pacemakers, has been reduced, enabling high power transmission.

Magnetic Field Simulation Results During EV Wireless Charging When Using DNP Developed Coil

[Looking Ahead]

DNP will provide the newly developed sheet-type coil for wireless charging of EV mainly to domestic and foreign automobile manufacturers and infrastructure industries, such as parking lot developers, aiming for sales of 5.0 billion yen per annum in 2025, when EVs are expected to spread.

In addition, by applying and developing this coil technology, expansion to other applications is also contemplated, such as charging while the vehicle is in motion, which is undergoing R&D in various nations as a future technology. Uses with drones are also contemplated.

* Product prices, specifications and service contents mentioned in this news release are current as of the date of publication. They may be changed at any time without notice.

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