Wireless power transfer(WPT) is the transmission of electrical power from a power source to a consuming device withoutusing discrete manmade conductors.
Researchers have developed severaltechniques for moving electricity over long distance without wires. Some existonly as theories or prototypes but others are already in use. This paperprovides the techniques used for wireless power transmission. It is a genericterm that refers to a number of different power transmission technologies thatuse time varying electromagnetic fields.
Wireless transmission isuseful to power electrical devices in case where interconnecting wires areinconvenient, hazardous, or are not possible. For example the life of WSN isits node which consist of several device controllers, memory, sensors, actuators,transceivers and battery and battery. The transceiver can operate in fourstates, i.
e 1) Transmit 2) Receive 3) Idle and 4) Sleep. The major energyproblem of a transmitter of a node is its receiving in idle state, as in thisstate it is always being ready to receive, consuming great amount of power. However, the batter has a very short lifetimeand moreover in some developments owing to both practically and economicallyinfeasible or may involve significant resists to human life. That is why energyharvesting for WSN in replacement of battery is the only and unique solution.In wireless power transfer, a transmitter device source, such as the mainspower line, transmits power by electromagnetic fields across an interveningspace to one or more receiver devices, where it is converted back to electricpower and utilized.
In communication the goal is the transmission ofinformation, so the amount of power reaching the receiver is unimportant aslong as it is enough that signal to noise ratio is high enough that theinformation can be received intelligibly. In wireless communicationtechnologies, generally, only tiny amounts of power reach the receiver. Bycontrast, in wireless power, the amount of power received is the importantthing, so the efficiency (fraction of transmitted power that is received) isthe more significant parameter.