Wireless Electricity Transfer: Startup Company from MIT

The above claim is no where near what Nikola Tesla dreamed of a century ago because Witricity(short for Wireless Electricity) have come up with techniques to send power wirelessly over only a few meters. This is different from capturing ambient radiowave energy as reported earlier, because the mode of transmission involves magnetic induction, similar to an (electric) transformer. In a transformer, there are two coils, a transmitting primary and a receiving secondary, coupled together magnetically. The magnetic coupling is made stronger through the help of an iron/steel core.

In Witricity’s devices, the two coils do not have a common solid core and are separated by a short distance, but they are finely tuned to achieve resonance and also both coils are made to closely match the resonant frequency. Thus, maximum power transfer can occur as per what is known simply as the maximum power transfer theorem. Thus, the coils can transmit magnetic energy over a quarter wavelength of the transmitter, which may be between 1 to 10 meters (3 to 33 feet) depending on the frequency of the devices.

This is significant as it allows this method to be implemented for charging electric vehicles. For example, a public bus can be charged at stops by a wireless charger as the passengers are getting on/off or as it waits at traffic lights. The charger can be mounted at the bus depot. The driver parks the bus and leaves and the batteries are charged overnight wirelessly. They driver does not have to worry about misalignment or plugging in cables. This concept can also be used for charging flashlights and electronic devices.

Wireless charging stations, such as the Powermat for electronic devices, also work on the principle of magnetic inductive charging. But the Witricity devices which utilize resonance are more effective over longer distances and much more efficient.

Witricity was started by a group of MIT physicists and engineers in 2007. It has also received funding from Toyota Motor Corp in April 2011.

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About propulsiontech

Propulsion technologist, aerospace engineer
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