Efficient Wireless Power Transfer Through Magnetic Resonance Coupling

Imagine that you do not need to connect electrical equipment to the wall. In this case, you can charge a laptop or cell phone easily and seamlessly simply by placing it in the room. This is the ability of many experimental wireless power equipments that will adapt to domestic use in the future. Today, the main methods of energy transmission are wires and batteries. Wired connections are probably the most common. In this energy transfer method, energy is supplied from the power plant to the household.

Wireless charging is based on the principle of magnetic resonance or inductive power transfer (IPT). By using a coil to induce an electromagnetic field, it is possible to achieve a process of transferring current between two objects. Therefore, to understand the concept behind wireless charging, you need to be familiar with the terms related to it. Energy transmission from the charger to the portable device is carried out by mutual induction and managed by Faraday's induction rules.

The disadvantage of transmitting power over a very short distance is overcome by other resonant wireless power technologies that are considered loosely coupled solutions. With this technology, we can transmit power over long distances (many times larger than inductive coupling). Resonance technology works at higher frequencies than inductive coupling. In addition, another advantage of resonant technology is that it can charge multiple devices at 22 W. Magnetic resonance coupling usually hits in the megahertz spectrum, and the quality factor is usually very high. As the charging range becomes wider, the high quality factor reduces the sharp decline in coupling efficiency, thereby lowering the charging efficiency.

In the early stages of magnetic resonance ('MR') there was a standard permissible output of 5 W and 5 W, but recently it has increased to 50 W. Transmitter coil with very high Q (quality factor). Thus, air fuel provides greater flexibility in the physical placement of the transmitter to the receiver. The above wireless charging standard applies to both inductive and resonant technologies. Inductive technology is a type of compliance that the Qi standard mainly uses during charging. This technology uses tightly coupled coils and uses low frequency resonant tanks to transmit power only for very short distances. The power transmission distance is 10 mm or less. Initially, Qi standard appeared in the consumer market in 2009. The electric power required at that time was considered to be very low (about 5 W).