Due to the superior magnetic properties of nanocrystalline materials compared to traditional ferrite materials, they have significantly advanced the development of high-power wireless charging for mobile phones. With the advancement of technology, nanocrystalline materials will also promote the development of wireless charging technology for new energy vehicles in the future.
Principle of Wireless Charging
There are various principles of wireless charging, with electromagnetic induction being the most commonly used in mobile phones.
Simply put, there is a transmitter on the base and a receiver inside the phone, both composed of coils and magnetic materials. Through the conversion of direct current, electrical energy is transformed into magnetic energy, then back into electrical energy. After processing by the phone’s wireless charging chip, the current is amplified and enhanced for phone use, achieving wireless charging. The main magnetic materials used include nanocrystalline and ferrite.
Role of Nanocrystalline Materials in Wireless Charging
Magnetic Shielding
A magnetic shielding sheet made of high-permeability materials， such as nanocrystalline materials, is usually placed behind the coil during wireless charging. This sheet provides a magnetic channel for the electromagnetic field emitted by the transmitter coil, reducing electromagnetic radiation and eddy current effects on the battery and surrounding components, thus preventing overheating and maintaining wireless charging efficiency.
Additionally, the current can be very large during high-power wireless charging, potentially causing saturation anomalies in the magnetic shielding sheet behind the coil. When saturation occurs, the electromagnetic waves emitted by the charging coil can penetrate the shielding sheet, leading to electromagnetic compatibility issues with the phone’s internal electronic components.
Improving Coupling Coefficient Between Coils
Magnetic induction wireless power transfer technology uses the principle of electromagnetic induction, where energy is transferred from the transmitter coil to the receiver coil through inductive coupling, enabling short-distance wireless power transmission similar to a transformer.
The operating frequency of magnetic induction wireless power transfer technology is generally in the tens of kHz. The higher the magnetic permeability of the nanocrystalline core, the greater the coupling coefficient, significantly improving the coupling efficiency between coils and enhancing wireless transmission efficiency.
Advantages of Nanocrystalline Materials in Wireless Charging
The inductance value of the ferrite magnetic ring decreases to 50% of its initial value under a magnetic field of 200A/m. However, the inductance value of the nanocrystalline material magnetic ring decreases slowly with the increase of the magnetic field.
When the permeability of both ferrite and nanocrystalline materials is 600 and the thickness is 0.11mm, the efficiency of nanocrystalline materials is 2.5% higher than that of ferrite.
When the efficiency of ferrite and nanocrystalline materials is the same, the thickness of nanocrystalline materials is 0.11mm, and the thickness of ferrites is 0.27mm.
Nanocrystalline materials have high Bs (saturation magnetic flux density), low loss characteristics, and excellent thermal conductivity. Under the same wireless charging conditions, the temperature rise of nanocrystalline materials is 7~8°C lower than that of ferrite.
Saturation current and charging efficiency: The high magnetic flux density significantly improves the device’s anti-saturation capability, enabling high power for the device.
High magnetic flux density nanocrystalline materials have been applied to smartphones since 2019, contributing to the development of high-power wireless charging for smartphones.
Nanocrystalline Materials Provider: Tengye
At Tengye, we’re an experienced manufacturer in China and are thrilled to be early participants in your new projects. We hope to bring our knowledge and experience to the forefront by actively engaging in your upcoming projects.
We have the know-how and deep experience in permanent magnets and mechanical design capability to assist you in designing complex magnetic assemblies to achieve specific functions. the capabilities include advanced magnetic assemblies, complex magnetic assemblies, and mechanical design capability.
Image Source: Bplus & Web & Kpontech & Mdpi
