Fujitsu Laboratories Limited today announced the development of wireless recharging technology that enables the design of magnetic resonance-based wireless charging systems that can simultaneously recharge various types of portable electronic devices.
This technology not only promises more compact and more efficient power transmitters and receivers, it also offers the ability to design charging systems in 1/150th the time currently required. In addition to dramatically shortening development times, this technology paves the way to integrating compact wireless charging functions into mobile phones and enabling multiple portable devices to be charged simultaneously without any restrictions on their position with respect to the charger.
What Fujitsu Laboratories has done is to develop technology that dramatically shortens the time required to design transmitters and receivers for magnetic resonance charging systems and, in addition, enables accurate tuning of resonant conditions in the design phase, even for compact transmitters and receivers that are prone to influences from nearby metallic and magnetic objects.
The new technology has the following characteristics:
1. A magnetic field analysis simulator which analyzes the coil model and a specialized circuit simulator which analyzes the resonance conditions, including the capacitor model, are combined, making it possible to quickly and accurately design wireless charging systems for multiple transmitters and receivers at once using a variety of coil sizes.
2. The design of the wireless charging system can be automated to precisely match the desired resonance requirements, based on an assessment function which maximizes the charging efficiency.
Together, these two technologies represent the world’s first practical magnetic resonance design simulator which enables rapid and precise designs for transmitters and receivers according to the desired resonance requirements.
This analysis and design technology was used to design a compact, slim power receiver, and to manufacture prototype mobile phones with built-in wireless charging (shown above). The prototype mobile phones can charge anywhere within the power-transmitter’s range, regardless of their position in reference to the transmitter, with 85% efficiency.
The above figure shows how charging performance varies with changes in the size of the transmitter’s coil in an analysis of the simultaneous charging of multiple devices, where a single transmitter was transmitting to three receivers. This analysis, which found the optimal coil size for efficiently charging three devices, took roughly 10 minutes, or 1/150th the time it had taken before. Even with multiple transmitters and receivers, the design time is dramatically reduced.
The figure above shows the charging of multiple devices at a distance from the charger to demonstrate that this technology effectively handles multiple receivers in any position relative to the transmitter.
Future Development Plans
Fujitsu plans to continue using this analysis and design technology in research and development on wireless charging systems for mobile phones and other portable devices, and plans to bring products using it to market in 2012. The company is also looking at applying the results of this work to fields other than portable electronics, including power transmission between circuit boards or computer chips, and providing mobile charging systems for electric cars.