Description
Wireless power transfer is a novel technology and the theory is based on magnetic resonant circuit. The energy can be transferred via magnetic resonant circuit using non-radiative near field. The self-resonance coils were designed according to parallel resonant circuit configuration and operated in a strongly coupled regime. The energy transfer technique involved the concept of near field where the distance of transmission is a few times the diameter of the antenna and a quarter of the wavelength of the transmitted signal. The near field energy itself is non-radiative. The advantage of using non-radiative field is the fact that the power not taken by the receiving coil is returned to the sending unit, instead of being radiated into the surrounding and getting wasted. Though with such a design the power transfer has a limited range, and the range will be smaller for smaller receiving coils. A theoretical and analytical model is proposed and implemented in this project.
TABLE OF CONTENTS
TITLE PAGE
APPROVAL PAGE
DEDICATION
ACKNOWLEDGEMENT
ABSTRACT
TABLE OF CONTENT
CHAPTER ONE
- INTRODUCTION
- Background of the project
- Problem statement
- Aim and objectives of the project
- Scope of the project
- Significance of the project
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 Magnetic Resonant Coupling
2.1.1 Magnetic Field
2.1.2 Magnetic Coupling
2.1.3 Resonant frequency
2.1.4 Magnetic Resonant Coupling
2.2 Optimization of Wireless Power Transfer System
2.2.3 Impedance Matching
2.3 Power Transfer Efficiency Analysis
2.4 High Quality Factor Coil Designing
2.5 Advantages of an Air Core Coil
2.6 Advantages of Copper as Conductor Material
2.7 Q factor of a Single layer Air Core Coil
CHAPTER THREE
3.0 DESIGN METHODOLOGY
3.1 Block of Wireless Power Transfer System
3.2 Description of System blocks
3.3 Components description
3.4 Oscillator Circuit Operation
3.4.1 Oscillator Components
3.5 Implementation of Wireless Power Transfer System
3.6 Theoretical Model
CHAPTER FOUR
4.0 RESULT ANALYSIS
4.1 Performance and Analysis
4.2 Efficiency and Evaluation of Power Losses
4.3 Analysis
4.4 Discussions
4.5 Problems and Solutions
4.6 Cost of the project
CHAPTER FIVE
5.1 Summary
5.2 Conclusion
5.2 Recommendations
REFERENCES
CHAPTER ONE
1.0 INTRODUCTION
Power is very important to modern systems. From the smallest sensors, bionic implants, deliver power means other than classical wires or transmission lines. Wireless transmission is useful in cases where instantaneous or continuous energy transfer is needed but interconnecting wires are inconvenient, hazardous, or impossible [1]. In the case of biological implants, there must be a battery or energy storage element present that can receive and hold energy. This element takes up valuable space inside a person body. In the case of satellites, UAVs and oil platforms, solar panels, fuel cells, or combustion engines are currently used to supply power. Solar panels take up a great deal of weight and bulk in terms of energy density and must have a tracking system to maximize exposure to the sun. Fuel cells and combustion cells needs fuel and maintenance to be delivered on site [2].
Wireless Power Transmission (WPT) is the efficient transmission of electric power from one point to another through vacuum or an atmosphere without the use of wire or any other substance. This can be used for applications where either an instantaneous amount or a continuous delivery of energy is needed, but where conventional wires are unaffordable, inconvenient, expensive, hazardous, unwanted [3]. The power can be transmitted using Inductive coupling for short range, Resonant Induction for mid-range and Electromagnetic wave power transfer. WPT is a technology that can transport power to locations, which are otherwise not possible or impractical to reach [3].
1.1 BACKGROUND OF THE STUDY
Late scientist Nikola Tesla was the one who first conceived the idea Wireless Power Transmission and demonstrated “the transmission of electrical energy without wires” [3].
That depends upon electrical conductivity as early as 1891. In 1893, Tesla demonstrated the illumination of vacuum bulbs without using wires for power transmission at the World Columbian Exposition in Chicago. The Wardenclyffe tower was designed and constructed by Tesla mainly for wireless transmission of electrical power rather than telegraphy [4].
Schemes for wireless power transmission attempted by Nikola Tesla, required large scale construction of 200 ft tall masts. It also produced undesirably and sometimes dangerously high voltages that approached 10, 00, 00,000V. Later attempts at wireless power led to the development of microwave power transmission, but its line-of-sight requirements meant that any practical power source needed to be high in the sky. Previous proposed projects included large power platforms as well as microwave-beaming satellites. Both Tesla’s devices and the later microwave power were forms of radiative power transfer. Radiative power transfer, which is used in wireless communication, is not particularly suitable for power transmission due to its low efficiency and radiative loss due to its omni-directional nature [4].
After the Race of wireless power transmission started with Dr. Nikola Tesla, now there is tremendous interest in wireless devices and gadgets in 21st Century, with the compactness of such devices created a need for cord-less charging systems and power supply [5].
1.3 STATEMENT OF THE PROBLEM
Low power devices commonly have an energy storage element like a battery or a capacitor to provide energy for their different electronic circuits. In order to be recharged, the energy storage element must be cable connected to a voltage regulator and the main power supply. Regulator, wiring and conductors as well as the energy storage itself, especially in case of a battery, are often sources of error. The need of wiring, connectors or even batteries in electronic equipment can be eliminated by wireless energy transmission. It is the ideal solution when little board space is available and low costs are of paramount importance because the costs of the charger can be eliminated from the total cost.
1.4 OBJECTIVES OF THIS WORK
The objectives of this project is given below-
- To design and construct a method to transmit wireless electrical power through space.
- The system will work by using resonant coils to transmit power from AC line to a resistive load.
- To investigate various geometrical and physical form factors that was evaluated in order to increase coupling between transmitter and receiver.
- To maximize power transfer by using resonant coupling.
1.5 SCOPE OF THIS STUDY
The scope of this study covers wireless power transmission via magnetic resonant circuit. Based on this system the induced electromagnetic force (EMF) in the receiving coil has been experimentally tested. The primary design is involved of a source with bridge rectifier. The second set-up is designed with a transmitter circuit. And the third set-up is involved with the receiving coil. We also have used an intermediate coil in between the transmitter coil and receiver coil. We have achieved significant improvements in terms of power transfer efficiency by using this intermediate coil.
1.6 SIGNIFICANCE OF THE STUDY
Working on this topic will serve as a means of eliminating the need for physical cords and cables, making it more convenient for users. You can place your device on a charging pad, and it starts charging without the hassle of plugging and unplugging cables.
The study will serve as a means of reducing wear and tear. Since no physical connectors are involved, charging ports and cables have less wear and tear. This can extend the lifespan of devices, especially those with delicate or frequently used charging ports.
In terms of Safety, wireless power transfer systems are designed with safety in mind. They often include temperature monitoring and foreign object detection to prevent overheating or damage. This can reduce the risk of electrical accidents or fires.
CHAPTER FIVE
5.0 Summary, conclusion and recommendation
5.0 Summary
Magnetic coupling is an old and well understood method in the field of wireless power transfer. But as the magnetic field decay very quickly, magnetic field is effective only at a very short distance. By applying resonance with in magnetic coupling, the power transfer at a greater distance can be obtained.
Resonant based power delivery is an alternative wireless power transfer technique which is used for high power transfer efficiently.
Apart from losses due to non-ideal characteristics of the inductor and capacitor, radiation loss and ohmic loss; the total power transmitted might not be received because of the loading effect of the receiver which causes the system to “de-tune” from resonance and weakening the coupling factor. Also wave attenuation occurs when it passes through a lossy dielectric medium (free space, air). If the effect of the losses can be minimized then the efficiency of the overall system can be improved to desired levels.
In order to transmit power wirelessly via magnetic resonant coupling all these components has to be used. The design of the transmitter and receiver circuit depends on these components. The overall efficiency of the experiment should be decreased if any one of these components was not be used.
The theoretical model and circuit implementation of the wireless power transfer system was designed based on the concept of magnetic resonant coupling. Various optimization factors were also considered while designing the whole system. Due to generalized approach, presented wireless power transfer system can be optimized for new design constraints or for different applications.
5.2 Conclusion
The goal of this project was to design and implement a wireless power transfer system via magnetic resonant coupling. After analyzing the whole system step by step for optimization, a system was designed and implemented. Experimental results showed that significant improvements in terms of power-transfer efficiency have been achieved. Measured results are in good agreement with the theoretical models.
We have described and demonstrated that magnetic resonant coupling can be used to deliver power wirelessly from a source coil to a load coil with an intermediate coil placed between the source and load coil and with capacitors at the coil terminals providing a simple means to match resonant frequencies for the coils. This mechanism is a potentially robust means for delivering wireless power to a receiver from a source coil.
We have used an intermediate coil in our project. It is placed in between the transmitter coil and receiver coil. The intermediate coil receives power from the transmitter coil. The distance is increased by using this coil. It consists of capacitor, inductor and a receiver load (LED or Bulb). We have got output voltage 2.2 volts and maximum distance covered is 91cm by using a LED as the load of the intermediate coil. We also have got output voltage 10 volts and maximum distance covered is 41cm by using a 3 watt bulb as the load of the intermediate coil. Intermediate coil makes the power transfer more efficient.
We have achieved that the prototype of the system was successful at transferring a significant amount of power wirelessly up to a certain range. This method can be made commercially feasible if the non-ideal conditions are taken care by substitution with external components. This work lays the foundation for wireless power technology to be implemented in commercial product, for instance charging the battery of the laptops, cell phone, PDA and all kinds of portable devices or supplying power to personal computers, lamps, sensors and other product wirelessly.
5.3 Suggestions for future work
Our circuit is just a trivial representation of the wireless power transfer concept. Suggestions for the future works are given below-
- To transmit the power to a greater distance a high power radio frequency amplifier connected with an oscillator is needed. But the construction of the bulky RF power amplifier requires much time and patience.
- High power vacuum tube transistor amplifier with high current will make the system more efficient.
- The receiver coil can also be fabricated on a PCB board in order to attach with electronic
- A layer of silver coat can also be applied over the conductor material in order to decrease the surface resistance and increase the conductivity.
Further effort on this same project can yield some real solutions that can solve the problem we faced. The knowledge of this project will help those who want to design a wireless power transmission.
