Abstract: To develop concept of transmitting power without using wires i.e., transmitting power as microwaves from one place to another is in order to reduce the transmission and distribution losses. In previous project they had designed the variable frequency power source at the range of 10 kHz to 15 kHz. But the power transmits only 10cm and high power loss during transmission. The MPT method works in the course of convert microwave into power by means of using unique devices called a rectenna. This paper center of attention to overcome the problem of previous year project effort output power that is emitted from the magnetron in the form of microwaves and these microwaves can be received in using rectenna and we achieved about 40cm power transmission.
Keywords: Wireless power transmission (WPT),
Microwave power transmission (MPT), Wireless Sensor network (WSN).
In progression to transport electrical power is have to be transformed into an appropriate energy form. For wireless transmission, this has to be a form that can shift through the air 1. Microwave frequencies hold this ability. The microwave band is distinct as electromagnetic energy ranging from approximately 1 GHz to 1000 GHz in frequency but older observe includes poorer frequencies. Most general applications are within the 1 to 40 GHz range.
It consists of two essential parts:
· Absorption antenna that captures the waves
· Electrical power to microwave power conversion
The machinery which includes a microwave source a transmitting antenna and a receiving antenna. The
Combination of receiving and converting unit is known as rectenna. The rectenna is a rectifying antenna that is used to directly convert microwave energy into direct current electricity 2. This is an antenna which includes an interlock of dipoles and diodes for absorbing microwave energy from a transmitter and converting it keen on electric power.
Figure 1.1 Microwave Region of Electromagnetic Spectrum
The figure 1.1 shows that the microwaves are the radio signal which has the wavelength array of 1 mm to 1 meter and the frequency is 3000 MHZ to 300 GHZ. Microwaves contain wavelength that preserves is calculated in centimeters microwaves are good quality for transmitting information from one place to another place because microwave energy be able to penetrate haze, snow, clouds, light rain, and smoke. Microwave radiation is still connected with an energy level that is typically nontoxic except for people with pacemakers 3.
B.WIRELESS POWER TRANSMISSION
WPT is defined as the power transmitted from one point to another point without the use of the physical conductor. The power is transmitted with the use of vacuum or an atmosphere, i.e. without the use of wire or any additional material.
For example, the life of WSN is its node which consists of a number of device memory, sensors, controllers, actuators, transceivers, and battery 4.
The transceiver can function in four states,
The most important energy problem of a transmitter of a node is its receiving in an idle state, as in this condition it is always being prepared to receive, consuming a large quantity of power 5.
Possible methods of wireless transmission of electrical power 6.
A. Inductive coupling
C. Radio frequency
A. Inductive coupling
In this when transmitting coil is excited then it generates flux and when receiver coil receives this flux a potential difference is developed across its terminal. This is the basic model and its efficiency is very poor hence cannot be used for large distance transmission.
It is a device which emits light based on the stimulated emission of electromagnetic radiation. Power can be transmitted by means of converting electricity keen on laser beam. But in this laser radiation is hazardous and conversion between electricity and light is ineffective.
C. Radio frequency
Radio frequency signals to direct current electrical current powered from either an international or ambient power sources.
III. PROPOSED METHOD (Microwave)
Figure 1.2 Block Diagram of Proposed Method
The figure 1.2 shows that the purposeful block diagram of WPT consists of two sections: transmitting section and receiving section. In the transmission section, the microwave power source generates microwave power which is prohibited by the electronic control circuits. The waveguide circulator protects the microwave resource from the reflected power, which is connected through the co-ax waveguide adaptor. The tuner contests the impedance between the microwave source and transmitting antenna. Then, based on the signal broadcast direction, the attenuated signals are separated by the directional coupler. The transmitting antenna emits the power frequently through open space to the receiving antenna.
In the receiving element, the receiving antenna receives the transmitted power and converts the microwave power into DC power. The impedance matching circuit and filter is provided for locating the harvest impedance of a signal source which is equivalent to rectifying circuit. This circuit consists of Schottky barrier diodes which convert the received microwave power keen on DC power.
In emergent this design, the PBG antenna, DGS LPF, and rectifier circuits were every first fabricated, designed, and characterized alone.
Table 1.1 Rectenna Efficieny For Various Diodes at Different Frequency
The rectenna is a passive element which consist of antenna, rectifying circuit with a low pass filter between the antenna and rectifying diode.Schottky Brrier diodes(GaAs-W, Si, GaAs) are usually used in the rectifying circuit due to the fast reverse recoery time and lower forward voltage drop and good RF characteristics.The rectenna efficieny for various diodes at different frequency is shown in table 1.1.
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 a resistor between two plates. Likewise, we have positioned 10 setups in parallel such that we have placed 10 resistors in parallel which intone act as the conductor with high absorption power since resistors in parallel act as a conductor.
V. RESULTS AND OBSERVATION
A. Stage 1
Initially, the circuit has been connected and a project was made to run. Firstly an incandescent lamp is used which needs high power but the magnetron emits only less radiation because it is in open condition and therefore the lamp does not glow.
Figure 1.4 Initial Stage Without Waveguide Circulator
B. Stage 2
In order to make the radiation high ,the entire setup is placed in a closed container which makes the electron to move faster. Therefore, the incandescent lamp into enclosed surface like micro oven and this increase the radiation level in micro oven, the lamp glows.
Figure 1.5 Entire Setup Inside the Micro Oven
C. Stage 3
Finally, waveguide circulator is used as an enclosed surface to send the radiations in a particular direction at certain distance. So, the high watts incandescent lamp is replaced by the low watts CFL lamp and the output has been obtained as shown in figure. Figure 1.6 Using Waveguide Circulator
Table 1. 2 Distance Covered Vs Voltage
Figure 1.8 Distance Vs Voltage Curve
In table 1.2 we have presented the wireless power transmission with distance and voltage in which when the distance increases the voltage get decreased. This is shown in figure 1.8.
VI.ADVANTAGES AND DISADVANTAGE
1. Entirely eradicate the existing high-power transmission line towers, cables etc…
2. The transmission and distribution cost become less
3. Hence, the efficiency of this method is very much higher than wired transmission.
4. The power failure as a result of short circuit and fault of cables would never be present.
5. The power can be transmitted to the places where the wired transmission is not a feasible.
6. Capability to charge vehicles such as industrial vehicles and golf carts.
7. Substantiate and alter to loads
1. Still under production and development.
2. It does not give sufficient energy to charge enormous vehicles and types of equipment.
3. Transmitting distance is unreliable
4. Heat loss takes place.
5. Intervention of microwaves with a present signal.
Ø Used in cordless tools, automatic wireless charging for mobile robots and instrument this eliminates complex mechanism.
Ø Easy and neat Installation – there is no cable running here and there, just start up the wireless device.
Ø Mobility – within the wireless range user device can be moved easily.
Ø The ability of our technology to transfer power efficiently, safely and over distance can improve products by making them more reliable, convenient, and environmentally friendly.
Wireless Power Transmission (WPT) was successfully achieved up to the distance of 1 meter and beyond with the help of the high power rectenna and proposed with higher lumens. It is difficult to find inductors and capacitors that are capable of working at higher power levels. However, safety is needed to be concern for the further extension of the project and modification is required for higher end design. Configuration on the cost factor and design constraints, including noise factor are to be considered and suggested to concern for the further development.
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