In this blog post, we will look at the principles and possibilities of wireless power transmission technology, focusing on magnetic induction and magnetic resonance.
Wireless power transmission is less efficient than wired power transmission, which connects devices directly to a power source, but it offers the advantage of allowing electronic devices to be moved and used freely. Wireless power transmission is a technology that uses electromagnetism to transmit and utilize electricity wirelessly. There are two main types of wireless power transmission: magnetic induction and magnetic resonance.
Magnetic induction is similar to the principle of a transformer. A transformer has a coil wrapped around a square iron core, and when an alternating current with alternating polarity is sent to the primary coil, it creates a magnetic field in the primary coil, as if a magnet were moving. This magnetic field generates a current in the secondary coil, which is called induced current. Transformers have iron cores that can efficiently transmit the energy of magnetic fields, but the magnetic induction method transmits power wirelessly without iron cores.
This magnetic induction method has the advantage of very high power transmission efficiency of over 90%. However, there is a problem in that the power transmission efficiency drops sharply when the transmitter, which corresponds to the primary coil, and the receiver, which corresponds to the secondary coil, are separated by more than a few centimeters or when the centers of the transmitter and receiver are not aligned. In the case of mobile phones, the distance problem is solved by placing the mobile phone on a charging pad, and wireless charging is made possible by placing coils throughout the charging pad to increase the transmission efficiency between the transmitting and receiving parts. However, since mobile phones use direct current, a rectifier is required before the charging stage to convert the alternating current induced from the primary coil to the secondary coil into direct current.
In addition, since the magnetic induction method has high power transmission efficiency, the possibility of interference from electromagnetic waves must also be considered. If other electronic devices in the surrounding environment are sensitive to electromagnetic waves, interference may occur, and electromagnetic wave shielding technology is important to prevent this. This will ensure that wireless power transmission systems operate more reliably.
The second transmission method is magnetic resonance. Resonance is a physical phenomenon in which, when one of various tuning forks is struck, the tuning forks with the same natural frequency vibrate together. The primary coil and resonator are designed to cause resonance in the magnetic field to create a resonance frequency. The principle of the magnetic resonance method is to design the secondary coil and resonator so that the resonance frequency is transmitted.
Due to these characteristics, unlike the magnetic induction method, the magnetic resonance method has the advantage of enabling power transmission over short distances of several meters. If this method is commercialized, it will be possible to use or charge various electronic products that resonate with the transmitter without connecting a power source. However, the coil size in the experimental stage is too large to be applied to general consumer electronics, so it is necessary to miniaturize the coil. Therefore, research is needed to solve this problem.
In addition, standardization of frequency bands and related specifications is essential for the commercialization of magnetic resonance technology. Since interference may occur when various devices use the same frequency band, specifications must be established in accordance with international standards to ensure that multiple devices operate smoothly. Such standardization efforts are underway worldwide, and wireless power transmission technology is advancing as a result.
In addition, the commercialization of wireless power transmission systems using magnetic resonance could bring about major changes in electric vehicle charging. Currently, electric vehicles are charged by connecting cables at charging stations, but with wireless power transmission technology, wireless charging pads can be installed in parking spaces, enabling charging simply by parking the vehicle. This will provide great convenience to electric vehicle users and have a positive impact on the spread of electric vehicles.
Wireless power transmission technology has great potential for application in various fields, and much research and development is expected to continue in the future. This will make our lives more convenient and efficient.
