More Hardware En Route to Support Qi2 Wireless Charging Standard

In a big boost for wireless charging, the Wireless Power Consortium (WPC) released the Qi2 charging standard for wireless charging in January 2023. This announcement builds on the original Qi standard and promises more efficient charging with new hardware.

 

Qi2 products feature several characteristics that improve charging performance, such as automatic alignment, device communication, and improved power delivery. Image used courtesy of Infineon

 

The Qi standard has given consumers a way to wirelessly charge devices, removing the need for physical ports on many devices. The standard, however, has proven imperfect and impractical; users must align their devices just so on charging pads in order for effective charging to take place. Further, new charging mechanisms, such as Apple's MagSafe technology, outperform the standard.

Developers like Infineon are now releasing new hardware to improve the efficiency and speed of Qi2. This article takes a look at some of the new hardware features behind Qi2 and provides examples of how this hardware can provide faster and more efficient wireless charging.

 

The Issue of Leaking Fields

The Qi standard relies on electromagnetic induction and mutual inductance to transfer power wirelessly. At the charger, a controller generates an alternating magnetic field using a coil. This alternating magnetic field passes through a second coil on the device and induces a voltage that charges the device.

In addition to the two coils and drivers, digital controllers communicate and detect that the two devices are compatible to prevent wasted power. As the two coils move further away, the efficiency continues to drop.

 

Misaligned coils in wireless charging not only waste power but also heat up the device, creating issues for battery health management. Image used courtesy of ACS Energy Letters. (Click on image to enlarge)

 

Beyond conduction losses, one source of the Qi standard's inefficiency is the lack of forced alignment. Since users may orient a device at various angles and positions for charging, some areas will have considerably lower efficiency than others due to leaking fields. The Qi2 standard hopes to remedy this challenge.

 

Qi2 Targets Coil Alignment for Efficiency

As part of the Qi2 standard, the WPC is adopting a magnetic power profile (MPP) technique, a method similar to MagSafe technology, where magnets are used to align the transmitter and receiver, removing user error and improving efficiency. This efficiency can translate directly to faster charging since more power can be delivered to the device instead of being wasted. The Qi2 standard supports up to 15 W power transfer, allowing various devices to quickly charge. 

Hardware developers are already making way for these improvements, with one example being a reference solution from Infineon. Infineon's recently announced Qi2 solution leverages a WLC1 controller to provide alternating field and MPP signal conditioning. This solution provides 15 W of power through a custom coil with a permanent magnet ring.

 

Infineon's reference solution gives designers turnkey performance with the Qi2 standard, allowing for rapid integration with existing devices. Image used courtesy of Infineon

 

At 43 mm in diameter, the solution showcases the strengths of the new Qi2 standard, allowing users and designers to move the focus away from physical connectors that often break to a more robust long-term solution.

 

More Charging Options Amid Miniaturization

Though the Qi2 standard is not likely to replace every wired charger available, especially in power-hungry cases, designers may benefit from this option when prototyping new miniaturized technology. This is especially true for IoT designers, who may feel that wired charging paradigms limit the potential for dense integration. While the cell phone market is the primary target for this charging standard, developers can also use Qi2 to quickly charge sensors without needing to plug in.