The Stanford University research team is conducting research on wireless power transmission technology using magnetism in order to realize the wireless charging technology for a battery vehicle in operation. This wireless power transmission technology can be the key to solving the charging problem of various electronic devices such as robots and unmanned aerial vehicles as well as electric vehicles.
Wireless charging pads for smartphones have already spread to some extent. Thanks to this, it is not uncommon to leave a smartphone in a specific location for an hour or two. In addition, smartphones can open a web browser and check emails or play videos even when they are fixed at a specific location.
However, electric vehicles are quite inconvenient because if the vehicle is left in a charger that supplies fuel for driving for 1-2 hours, it cannot be driven at all during that time. The research team is conceiving a highway that can charge batteries anytime, anywhere by wirelessly transmitting power to electric vehicles and is developing technology for realization.
From the perspective of electric vehicles, the research team that envisioned this high-speed highway has succeeded in constructing a system for wireless power transmission to moving objects. However, since this system is only in the prototype stage, it is inefficient and may not function properly outside of the laboratory’s equipped environment.
The technology for transmitting wireless power to the fuselage is still in the early stages of development, but a paper has been published in the electronic journal Nature Electronics. If the technology for transmitting wireless power to the dongchae is developed smoothly, in the near future, a scaffolding for wireless charging of a moving robot will become feasible, and in this case, there is no need to stop the factory or warehouse business by charging the robot.
The research team said that it is an important step to develop a practical and efficient system for wirelessly charging batteries even when cars and robots move at high speeds. Charging a moving car needs to increase the transmission power, but this will not cause serious obstacles. Wireless charging of a robot in motion means that the existing system is within a sufficiently practical range. The research team argues that the technology for transmitting wireless power to the fuselage is insufficient to charge electric vehicles, but is sufficient to charge robots.
In the case of general wireless power transmission technology, some wireless power supply methods exist. Among them, the most promising is the method of transmitting power by resonating the receiving and transmitting self-coil. However, with this method, if the power source and the reception distance change even a little, the resonant frequency changes and the power transmission efficiency decreases.
The research team developed a wireless charger in 2017 that can transmit power even when the distance between the receiver and the sender changes. To charge this wireless charger and battery, an amplifier and feedback resistor are integrated so that the system can adjust the operating frequency when the distance between moving objects changes. This way, the charger side can sequentially change the resonant frequency so that the body can also be charged wirelessly. However, since it was only in the early stages of development, the amplifier for changing the operating frequency consumed a lot of power, so that only 10% of the power flowing through the system could be wirelessly transmitted.
The research team published an upgraded version of the technology that transmits wireless power to the fuselage in a paper in April. The latest version has improved wireless transmission efficiency from 10% to 92%. It is said that the amplifier, which was the key to improving the transmission efficiency, was changed to a switch amplifier that is more efficient. The switch amplifier itself is not new, but it is difficult to handle and performs highly efficient amplification only under precise conditions. Therefore, the research team said that they spent several years designing the circuit configuration of the fuselage wireless power transfer technology to work properly while using the switch amplifier.
The wireless charger made as a result of the research can wirelessly transmit 10W of power at a distance of 0.91m. As it is a prototype for theoretical verification, the transmittable power is 10W. It’s not enough to charge an electric vehicle. However, the research team argues that there are basically no obstacles in expanding the system to transmit the hundreds of kW power required by electric vehicles.
In addition, the latest version of the technology transmits power to a fast-moving receiver, which is enough to charge the car battery while driving. The power transfer takes only a few milliseconds.
The research team says that wireless chargers will not pose a health hazard, and that even powerful wireless chargers capable of charging electric vehicles will end up generating magnetic fields within the limits of existing safety guidelines. Related information can be found here .