Wireless charging of moving objects comes in sight
The technology developed by electrical engineering professor Shanhui Fan and his team could have the potential not only to make time-consuming charging stops with e-cars unnecessary but also to untether robotics in manufacturing, Fan said. Not to mention wireless charging of smaller devices such as smartphones or even medical implants.
The group further developed an existing technology developed at the Massachusetts Institute of Technology (MIT). This technology transmits electricity over distances of several feet to s stationary object. The Stanford team was able to transmit electricity to a moving object – in this case an LED lamp. The problem: The energy transmitted amounted to one milliwatt; electric cars however requires tens of kilowatts. The team is now working to eliminate this power gap.
Today’s available electric cars need to periodically take a break for recharging their batteries – in most cases a matter of several hours. This drawback is one of the reasons why electric mobility has yet failed to conquer the markets. The wireless charging system under development by the Stanford team is based on a series of coils embedded in the road. Similar work is in progress at several other universities. Other wireless charging technologies such as the one developed by Qualcomm are approaching commercial deployment. However, these technologies are providing that the cars is standing while being charged.
Like other wireless energy transfer technologies, the approach from Shanhui Fan is based on inductive coupling of coils. If both the sending and receiving coil are tuned to the same resonance frequency, the efficiency is greatly increased. However, the resonance approach requires to be tuned manually as the object moves. To avoid this challenge, the researchers replaced the RF source in the transmitter with a voltage amplifier with a feedback resistor. This system, the researchers claim, automatically figures out the right frequency for different distances without the need for human interference. Adding the amplifier greatly increases the efficiency of the power transfer despite changing orientation of the receiving coil, the researchers claim. At the same time, it does away with the need for continuously tuning the circuit. The group used an off-the-shelf amplifier with a rather low power efficiency of just 10 %. With custom-made amplifiers, the efficiency could be increased to more than 90%, the group claims.
The technology which already has been patented has been introduced in the June edition of magazine Nature.
More information: TomKat Center for Sustainable Energy
Related articles:
Heart pump wireless charging system promises to reduce infections
Industry agrees on wireless charging standard for cars
Wireless charging transmitter coil for Qi wireless charging pads
If you enjoyed this article, you will like the following ones: don't miss them by subscribing to :
