Traditional wired power transmission
systems usually require lying of transmission wires between the
distributed units and the consumer units. This produces a lot of constraints as
the cost of the system- cost of the cables, the losses incurred in the
transmission as well as in distribution. Just imagine, only the resistance of
the transmission line results in loss of about 20-30% of the generated energy.
If you talk about DC power transmission system, even that is not
feasible as it requires a connector between the DC power supply and the device.
Imagine a system completely devoid of wires, where you can get
AC power to your homes without any wires. Where you can recharge your mobile
without having to physically plug in to the socket. Where the battery of
the pacemaker (placed inside a human heart) can be recharged without having to
replace the battery. Of course such a system is possible and that’s where the role
of Wireless Power Transmission comes.
This concept is actually not a new concept. This whole idea was
developed by Nicolas Tesla in 1893, where he developed a system of illuminating
vacuum bulbs using wireless transmission technique.
3 Types of Wireless Power Transfer Methods:
·
Inductive
Coupling: One of the most prominent methods of
transferring energy is through inductive coupling. It is basically used for
near field power transmission. It is based on the fact that when current flows
through one wire, a voltage is induced across the ends of the other wire.
The power transmission takes place through mutual inductance between the
two conductive materials. A general example is the transformer.
·
Microwave
Power Transmission: This idea was
developed by William C Brown. The whole idea involves converting the AC power
to RF power and transmitting it through space and again reconverting it to AC
power at the receiver. In this system power is generated using microwave
power sources like klystron, and this generated power is given to the
transmitting antenna via the waveguide (which protects the microwave power from
reflected power) and the tuner (which matches the impedance of the microwave
source with that of the antenna). The receiving section consists of the
receiving antenna which receives the microwave power and the Impedance matching
and filter circuit which matches the output impedance of the signal with that
of the rectifying unit. This receiving antenna along with the rectifying unit
is known as the Rectenna. The antenna used can be a dipole or a Yagi-Uda
Antenna. The receiver unit also consists of the rectifier section consisting of
schottkey diodes which is used to convert the microwave signal to DC signal.
This transmission system uses frequencies in the range of 2GHz to 6GHz.
·
Laser
Power Transmission: It
involves the use of LASER beam to transfer power in form of light energy, which
is converted to electric energy at the receiver end. The LASER gets
powered using sources like Sun or any electricity generator and accordingly
generates high intensity focused light. The beam size and shape are determined
by a set of optics and this transmitted LASER light is received by the
photovoltaic cells, which convert the light to electrical signals. It generally
uses optical fiber cables for transmission. Like in basic solar power system,
the receiver used in LASER based transmission is the array of photovoltaic cells
or solar panel which can convert the incoherent monochromatic light into
electricity.
