Wisdom News on July 29, according to the US media Tech Xplore, recently, researchers at Aalto University in Finland designed a new type of wireless charging system that can charge multiple devices at the same time.
The researchers designed the antenna coil, the core part of the transmitter in the wireless charging system, to realize that the wireless charging system does not need to locate the charging device first, and can charge directly. It can also automatically adjust the charging direction when the device moves.
The research paper titled “Self-tuning Omnidirectional Wireless Power Transfer using Double Toroidal Helix Coils” was published on July 21 in IEEE Transactions on Industrial Electronics.
1. The original wireless charging first detects the charging equipment and its location
People everywhere can rely on mobile phones and tablets to keep in touch, but these devices still need to be charged through plugs, sockets and charging pads.
Researchers all over the world are working on free-position wireless charging, which can free smart devices from the limitations of charging cables. At present, the most common wireless charging solutions include some complex control and detection functions.
For example, the energy transmitter of a charging system usually needs to detect the required charging device and its location before determining the direction of sending energy to the device. This function is generally implemented by a camera or sensor, which will increase the volume and cost of the transmitter.
Researchers at Aalto University have newly designed an omnidirectional wireless energy transmission system (WPT) based on a special double helix coil, which eliminates the need to install a camera or sensor on the transmitter by creating power transmission channels in all directions. When the device to be charged is moving, the wireless charging system automatically adjusts the charging channel.
Mobile phones, laptops, and other newly equipped devices with wireless charging receivers can receive energy while charging their batteries or directly powering applications on the device, without the need to contact the device with the charging system or place the device in a specific location.
2. Wound the coil in a special way to generate 2 kinds of magnetic fields
Prasad Jayathurathnage, a postdoctoral researcher at Aalto University, explained: “The difference with this transmitter is that it is self-tuning, which means you don’t need complicated electronic devices to connect to the receiver embedded in the device. Because it can self-tune. By adjusting the charging channel, you can also freely move those devices that need to be charged within the charging range that the wireless charging system can reach.”
The research team achieved the above effects by designing the coil antenna used in the transmitter. Coil antennas are wound on the torus, and their structure is a double helix structure. They will generate two electromagnetic fields: one is circular and is confined within the torus; the other is polar and distributed outside the torus.
The strength of these two electromagnetic fields can be enhanced by adjusting the shape of the coil.
The wireless charging system transfers energy through electromagnetic fields. However, the receiver and transmitter need to be coupled and paired.
The electromagnetic field coupling coefficient is determined by the researchers. Regardless of the location and direction of the receiver, high efficiency can be guaranteed and it can be automatically tuned.
This depends on the topological structure of the charging system. The realization of self-regulation needs to minimize the coupling between the transmitter and the receiver, and then use the repeater to adjust the charging direction. There is a strong coupling between the relay and the repeater.
The system includes three pairs of orthogonal transmitter and repeater combinations to ensure omnidirectional charging.
3. The transmission efficiency is as high as 90% within 20cm
At present, the energy transmission efficiency of this kind of transmitter is 90% within a distance of 20cm, and it can also work at longer distances, but the energy transmission efficiency is low. In principle, the range of the peak distance that the transmitter energy transmission can maintain will be expanded with the continuous improvement of technology.
Jayathurathnage said: “Currently, the maximum distance that can maintain 90% efficiency depends on the size of the transmitter and receiver. With the right engineering technology, we can make the transmitter and receiver smaller.”
Although the research team has proven this design concept, safety tests are still needed to confirm that the electromagnetic field generated by the transmitter is not harmful to the human body. Obviously, because the technology relies on magnetic fields, the electric field, which is considered to be the main cause of potentially harmful effects, is at a minimum.
Once the design is considered safe and then applied to the product, it will be convenient for many people.
Jayathurathnage pointed out: “True wireless charging means more personal freedom, so that people don’t have to worry about where to charge their phones, and they don’t have to worry about forgetting to plug them in.”
The research team has applied for a patent for the transmitter and has also developed wireless charging equipment that may be used in the industrial field through the Finnish Parkzia project.
Conclusion: Wireless charging facilitates people’s lives
The purpose of wireless charging is to let smart devices get rid of the limitation of charging lines and reduce the impact of insufficient power when people use smart devices.