87750391-Wireless-Battery-Charger-Ppt.ppt

PRESENTED BY 

Sowmya 12QE1A0414 ECE

stract

This report covers the basis and design of the wireless battery charger. The wireless charger will convert the RF/ microwave signal at 900 MH  fre!"ency into a #$ signal% and then store the power into into an AAA battery. The pro&ect is divided into ' parts( transmitter% transmitter% antenna% and charging circ"it. A complete disc"ssion of the specifications of the battery charger is provided after data meas"rements. This report also incl"des component list and other )ey information.

Portable electronic devices are very popular these days. As the usage of portable electronic devices is increasing, increasing, it demands for a longer battery life. li fe.  Batteries need to recharged or replaced periodically.   To  To overcome overcome this, concept concept of wireless wireless battery charging was developed.  So there is a need to make a proto-type device that converts microwave signal to ! power. 

A battery charger is a device used to put energy into rechargeable battery by forcing electric current through it.  The charging charging protocol protocol depends depends on the si"e and type of the battery being charged Some charges might be having temperature or voltage control sensors to ad#ust the charging current and cut o$ at the end of charge •

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%ig&'(verall wireless battery batt ery charger system

 This design includes includes a power transmitter.  Transmitter  Transmitter consists consists of an oscillator ampli)er and an antenna. At a pre-determined fre*uency i.e., +", oscillations are generated.  These signals are are ampli)ed ampli)ed before transmission. •

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%ig./ + " 0ideo7Audio 0ideo7Aud io Transmitter ransmi tter

Power'

&/0 !, + mA

(utput Power'

1 2atts

(perating %re*uency'

+ "

!onnector Type'

SA 3 %emale

(utput 4mpedance'

5 6

 Table.&  Table.& The speci)cation of the transmitter

 To  To charge charge a battery, battery, high power power ! signal signal is re*uir re*uired. ed.   To  To choose appropriate appropriate antenna, antenna, two factors factors are are to be taken into consideration' &. 4mpedance of antenna /. 8ain of antenna 

4mpedance of the antenna should match with the output impedance of the power transmitter.  igher antenna gains yields to a better gain result, but also increases si"e and cost of the antenna.   Taking  Taking the above above design speci)cation into consideration yagi antennas are best suited. 

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Figure 3: A picture of the 9 dBi gain Yagi antenna

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It is a directio directional nal antenna consisting of a driven element (typically dipole) and additional parasitic elements(usually elements(usua lly reectors and one or more directors) Reector element is slightly longer than the driven dipole whereas directors are little bit shorter short er.. This design achieves a very substantial increase in antenna’s directionality and gain compared to simple dipole Highly directional antenna’s such as yagi uda antennas are commonly referred to as beam antennas due to there higher gain.

Block diagram of a receiver is as shown in the )gure ) gure •

4t consists of receiving antenna, recti)er circuit circuit and load9AAA load9AA A battery: •

;eceiver main purpose is to charge AAA battery. •

Simple battery charging theory is to run current through the battery, and apply the voltage di$erence between the terminals to the battery to reverse the chemical process. •

A full wave recti)er is used due to its simplicity and e