Wireless Power TransmissionUsing Microwaves Abstract: Various new technologies are beingdeveloped for transmitting power through wireless systems and one of the waysto transmit electricity without wire is through the microwave transmission.
Theprocess of transmitting the power by using microwaves is called as Microwave PowerTransmission(MPT). This will cause reduction in the transmission anddistribution losses. Rectenna is a device used to convert the microwaves intopower for the MPT system. This paper will give the idea about impact on humanbeings, advantages, disadvantages, & applications of wireless powertransmission.Keywords: Wireless power transmission (WPT),Microwave power transmission (MPT), Wireless Sensor network(WSN). Introduction: Wireless power transfer (WPT) is thetransmission of electrical power from a power source to a consuming devicewithout using discrete manmade conductors.
For transmitting over long distancewithout using wires researchers have developed several techniques for movingelectricity. There are some exists only as theories or prototypes but othersare already in use. This paper provides the techniques used for wireless powertransmission. It is a generic term that refers to a number of different powertransmission technologies that use time varying electromagnetic fields. Wireless transmission is useful topower electrical devices in case where interconnecting wires are inconvenient,hazardous, or are not possible. For example the life of WSN is its node whichconsist of several device controllers, memory, sensors, actuators, transceiversand battery and battery. The transceiver can operate in four states, i.e 1)Transmit 2) Receive 3) Idle and 4) Sleep.
The major energy problem of atransmitter of a node is its receiving in idle state, as in this state it isalways 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.MICROWAVEREGION Figure 1.1 Microwave Region of ElectromagneticSpectrumThe figure 1.1 shows that themicrowaves are the radio signal which has the wavelength array of 1 mm to 1meter and the frequency is 3000 MHZ to 300 GHZ. Microwaves contain wavelengththat preserves is calculated in centimeters microwaves are good quality fortransmitting information from one place to another place because microwaveenergy be able to penetrate haze, snow, clouds, light rain, and smoke.
Microwave radiation is still connected with an energy level that is typicallynontoxic except for people with pacemakers.EXISTING METHOD Possible methods of wireless transmission ofelectrical power A.Inductive coupling B.Laser C.
Radio frequencyD.Microwave A.Inductive coupling In this whentransmitting coil is excited then it generates flux and when receiver coilreceives this flux a potential difference is developed across its terminal.This is the basic model and its efficiency is very poor hence cannot be usedfor large distance transmission.B.
LaserIt is a devicewhich emits light based on the stimulated emission of electromagneticradiation. Power can be transmitted by means of converting electricity keen onlaser beam. But in this laser radiation is hazardous and conversion betweenelectricity and light is ineffective.
C.Radio frequencyRadio frequencysignals to direct current electrical current powered from either aninternational or ambient power sources. PROPOSEDMETHOD:The figure 1.2 shows that the purposeful block diagramof WPT consists of two sections: transmitting section and receiving section.
In thetransmission section, the microwave power source generates microwave powerwhich is prohibited by the electronic control circuits. The waveguidecirculator protects the microwave resource from the reflected power, which isconnected through the co-ax waveguide adaptor. The tuner contests the impedancebetween the microwave source and transmitting antenna. Then, based on thesignal broadcast direction, the attenuated signals are separated by thedirectional coupler.
The transmitting antenna emits the power frequentlythrough open space to the receiving antenna. In thereceiving element, the receiving antenna receives the transmitted power andconverts the microwave power into DC power. The impedance matching circuit andfilter is provided for locating the harvest impedance of a signal source whichis equivalent to rectifying circuit. This circuit consists of Schottky barrierdiodes which convert the received microwave power keen on DC power.
Working: A rectenna is arectifying circuit, a special type of antenna that is used to convert microwaveenergy into DC current. It’s elements are usually arranged in a mesh pattern,to provide a distinct appearance from most antennae. We can construct simple rectenna by using aSchottky diode placed between antenna dipoles.
The diode (a uni directiondevice) rectifies the current induced in the antenna by the microwaves signals.Rectenna is highly efficient for converting microwave energy into electricity.In laboratory environments, efficiencies above 90% have been observed.Scientists also tried to convert electricity into microwave energy usinginverse rectenna, but efficiencies are very low.
only in the area of 1%. Withthe advent of nanotechnology and MEMS the size of rectenna elements can bebrought down to molecular level. A rectenna contains a mesh of dipoles and amesh of diodes for absorbing microwave energy from a transmitter and convertingit into electric current.
RECTENNADESIGNIn emergent this design, the PBG antenna, DGS LPF, andrectifier circuits were every first fabricated, designed, and characterizedalone. The rectenna isa passive element which consist of antenna, rectifying circuit with a low passfilter between the antenna and rectifying diode.Schottky Brrier diodes(GaAs-W, Si, GaAs) are usually used in therectifying circuit due to the fast reverse recoery time and lower forwardvoltage drop and good RF characteristics.The rectenna efficieny for variousdiodes at different frequency is shown in table 1.1. Frequency (GHz) Schottky Diode Measured Efficiency (%) Calculated Efficiency (%) 2.45 GaAs-W 92.
5 90.5 5.8 Si 82 78.5 8.5 GaAs 62.5 66.2 Table 1.1 Rectenna Efficieny For Various Diodes at Different Frequency Figure 1.
3 Rectenna Design The figure 1.3 shows the rectenna used in the project.Rectenna has divided two copper plates with Schottky diode which acts as aresistor between two plates. Likewise, we have positioned 10 setups in parallelsuch that we have placed 10 resistors in parallel which intone act as theconductor with high absorption power since resistors in parallel act as aconductor. RESULTSTable 1. 2 Distance Covered Vs Voltage S.
No Distance(cm) Voltage(volts) 1 35 32 2 50 30 3 65 22 4 80 18 5 100 8 In table 1.2 we have presented thewireless power transmission which displays that increase in distance leads todecrease in voltage. This decrease in voltage is due to distortion of microwavesin the air medium.
Figure 1.8 Distance Vs Voltage Curve In figure 1.8, the graph is drawn betweenthe distance and voltage. If the rectenna is nearer to the transmitter, thevoltage level absorbed by the rectenna is high up to 32V.If the distance isincreased between the transmitter and receiver, the Voltage level decreased. VI.ADVANTAGES AND DISADVANTAGEA.ADVANTAGES1.
Entirely eradicate the existing high-powertransmission line towers, cables etc…2. The transmission and distributioncost become less3. Hence, the efficiency of this methodis very much higher than wired transmission.
4. The power failure as a result ofshort circuit and fault of cables would never be present.5. The power can be transmitted to theplaces where the wired transmission is not a feasible.6. Capability to charge vehicles such asindustrial vehicles and golf carts. 7.
Substantiateand alter to loads B.DISADVANTAGE 1. Production and development is still underprocess.2. It does not give sufficientenergy to charge enormous vehicles and types of equipment.3. Transmitting distance is unreliable4.
Heat energy is lost during the transmission.5. Intervention of microwaves with apresent signal. VII.APPLICATIONS1.
Used in cordlesstools, automatic wireless charging for mobile robots and instrument thiseliminates complex mechanism.2. Easy and neatInstallation – there is no cable running here and there, just start up thewireless device.3.
Mobility -within the wireless range user device can be moved easily.4. The ability of our technology to transferpower efficiently, safely and over distance can improve products by making themmore reliable, convenient, and environmentally friendly. VIII.CONCLUSION Wireless Power Transmission (WPT) wassuccessfully achieved up to the distance of 1 meter and beyond with the help ofthe high power rectenna and proposed with higher lumens.
It is difficult tofind inductors and capacitors that are capable of working at higher powerlevels. However, safety is needed to be concern for the further extension ofthe project and modification is required for higher end design. Configurationon the cost factor and design constraints, including noise factor are to beconsidered and suggested to concern for the further development.