ABSTRACT
In this globalized era, the usage of inductive charging is widely spread. Inductive charging uses the electromagnetic field to transfer energy between two objects. A charging station sends energy through inductive coupling to an electrical device, which stores the energy in the batteries. Since there is a small gap between the two coils, inductive charging is one kind of short-distance wireless energy transfer. Induction chargers typically uses an induction coil to create time varying electromagnetic field within a charging base station, and another induction coil which is attached with the portable device receives power from the electromagnetic field and stores the energy in the battery. Through a rectifier, the two induction coils in proximity combine to form an electrical transformer.
1.0 INTRODUCTION
Process of electrically charging small battery-powered devices such as smartphones, electric toothbrush and PDAs or even larger objects such as robots and electric cars and equipment without the need for a wired electrical power connection is called inductive charging or commonly known as wireless charging. It enables the transfer of electrical charge wirelessly from a charging device or node to the recipient device. It uses electromagnetic waves to transfer energy and charge devices and it requires the device to be placed on a conductive charging pad/equipment. This pad must be connected directly to a wall socket.
Wireless charging has been around since the late 19th century, when electricity pioneer Nikola Tesla demonstrated magnetic resonant coupling which is the ability to transmit electricity through the air by creating a magnetic field between two circuits, a transmitter and a receiver. Nikola Tesla was a Serbian-American inventor, electrical engineer, physicist, and futurist.
2.0 CONTENTS
2.1 PHYSIC CONCEPTS
2.1.1 FARADAY’S LAW IN TRANSFORMER
Inductive charging used the principle of transformer that transfer electrical energy. A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors which is the transformer’s coils. Current flow in the primary coil. A varying current in the first or primary winding creates a varying magnetic flux in the transformer’s core and thus a varying magnetic field through the secondary winding. Magnetic Flux is essentially a measure of the magnetic field running through a loop of wire. The changing of magnetic flux induced a varying electromotive force (EMF) which causes electrons to move or voltage to form a current. Changing the area of the loop of wire induced a current, too, and so did changing the angle between the loop and the magnetic field. This is called Faraday’s Law of magnetic induction.
If a circuit contains N tightly wound loops and the magnetic flux through each loop changes by the amount ∆ B during the interval ∆t, the average electromotive force (EMF) induced in the circuit during change in time, ∆t is
Figure 1.0
2.1.2 RESONANT INDUCTIVE COUPLING
Resonant inductive coupling has key implications in solving the main problem associated with non-resonant inductive coupling for wireless energy transfer specifically, the dependence of efficiency on transmission distance. A varying current in the first or primary winding creates a varying magnetic flux in the transformer’s core and thus a varying magnetic field through the secondary winding. The changing of magnetic flux induced a varying electromotive force (EMF) or voltage that will produce current. The range is negligible because most of the magnetic field misses the secondary. Even over relatively small distances the induction method is inefficient and wastes much of the transmitted energy. The application of resonance improves the situation somewhat. When resonant coupling is used the transmitter and receiver inductors are tuned to a mutual frequency and power transfer occurs over multiple cycles. In this way significant power may be transmitted over a distance of up to a few times the size of the transmitter. Unlike the multiple-layer windings typical of non-resonant transformers, such transmitting and receiving coils are usually single layer solenoids or flat spirals with series capacitors, which, in combination, allow the receiving element to be tuned to the transmitter frequency and reduce losses.
During the process, a magnetic loop antenna which is copper coil is used to create an oscillating magnetic field, which can create a current in one or more receiver antennas. If the appropriate capacitance is added so that the loops resonate at the mutual frequency, the amount of induced current in the receivers increases. It enables power transmission at greater distances between transmitter and receiver and increases efficiency. Coil size also affects the distance of power transfer. The bigger the coil, or the more coils there are, the greater the distance a charge can travel.
2.2 HARDWARE IN INDUCTIVE CHARGERS
2.2.1 TRANSMITTER
Figure 3.1
Power supply is given to the primary coil. It acts as the Transmitter. Copper coil is wound into number of turns as per the requirement. when the power is supplied to Transmitter the coil energizes and results in the magnetic coupling. Hence the power is transferred.
2.2.2 RECEIVER COIL
Figure 3.2
Receiver coil is similar to that of transformer primary coil. The secondary receiver coils are similar designs to the primary sending coils. Running the secondary at the same resonant frequency as the primary ensures that the secondary has a low impedance at the transmitter’s frequency and that the energy is optimally absorbed. To remove energy from the secondary coil, different methods can be used, the AC can be used directly or rectified and a regulator circuit can be used to generate DC voltage.
2.2.3 AC TO DC CONVERTER
Figure 3.3
This converter will convert the 120 V AC from the power outlet to a 9 V DC voltage across the input of the frequency oscillator. This converter is basically a rectifier circuit composed a diode network and a capacitor.
2.2.4 FREQUENCY OSCILLATOR
The frequency oscillator is the device that will create the magnetic field that will allow the transmitter and receiver coils to exchange energy. This device will be composed of components such as resistors, inductors and capacitors.
2.3 INDUCTIVE CHARGING PROCESS
As AC current flow through the transmission coil, it will produce magnetic flux. In the receiver device, a coil of the same the type is embedded into the charging circuit. The alternating magnetic field is picked up by the receiving coil and a current is induced. The AC power is passed through a power rectifier and stabilizer to convert into DC power. Both the transmitter and receiver have electrical resonant frequencies designed to be the same.
2.4 APPLICATION
Inductive charging is used by certain brands to easy the users. Examples of companies which is known using wireless charging are Braun Company, Tesla Company, Apple Inc. and Motorola Inc.
Specifically, Braun Company uses inductive charging in their rechargeable toothbrushes, Oral-B since the early 1990s. Next, Tesla Company produces cars which uses inductive chargers such as Tesla model S. Also, the well-known Steve Jobs introduced Apple Watch, and the latest iPhones, 8 and X, using wireless charging. Surprisingly, the world No.1 furniture brand, Ikea invented a series of wireless charging home appliances that support the Qi standard.
2.5 ADVANTAGES AND DISADVANTAGES OF INDUCTIVE CHARGING
One of the advantages is ease of use which is placing the phone on or near a charging pad or surface without having to worry about the alignment or movement of the device from bumps or vibration. Several portable devices can also be charged from one pad or surface. If all the devices could be charged wirelessly, one universal charging pad can accommodate all the devices at a time. This means that, less money spent on buying different cables for different devices. It also creates safe charging zones almost anywhere. There can be no safety risk in terms of heating or emissions, so the technology can be safely used at a public place or even at home. It is also environmentally friendly which makes several markets and cultures demand for environmentally friendly solutions that also do not consume excessive power.
It is less efficient than wired charging. For example, a phone charged on a wireless charging pad will take longer to reach full charge compared to a phone plugged directly into an electrical socket. Next is the less flexibility when charging. Electronic devices being charged wirelessly have to be left in one place or the charging process will be interrupted (the induction coils need to be extremely close together for the system to work). A phone being charged using the traditional charging cable can still be picked up and used, even if only within a meter or so of the plug socket. Next, inductive charging also requires drive electronics and coils that increase manufacturing complexity and cost.
2.5 SAFETY ISSUES RELATED TO INDUCTIVE CHARGING
Inductive charging is actually very safe to use. The electromagnetic field generated by the transmitters are very small and weak in power, only operating over short distances. Inductive charging has been used in many applications, such as your electric toothbrush, medical devices and more. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has found no evidence of adverse effects on human health when exposed to inductive charging.
In some ways, wireless charging is actually safer than plugging in a device. Wireless charging transmits power without contact with exposed electrical connectors. This reduces failure and possibility of electric shocks and allows for electrical devices to be used in more environments. For example, electric toothbrushes can be used in bathrooms as the electrical components can be fully encased in plastic and protected. Medical devices can be charged without invasive procedures.
3.0 CONCLUSION
Inductive charging is an advanced innovation of wired chargers using Faraday’s Law, which induced an EMF to produce current that will be used to charge the devices. This technology provides wide range of benefits to users but at the same time there’s cons of this innovation.
Aside from Faraday’s Law, it also uses resonant inductive coupling to improve the distance problem between pad and devices.
4.0 ISLAMISATION
From Surah Al Mujadalah verse 11,
“Allah will raise those who believe
d among you and those who were given knowledge by degrees.”
Creatures are all the household of God, and He loves best those who most benefit the members of His household and make them happy. So, in relation with inductive charging, inventing wireless charging, for those who have extra knowledge may presenting new technologies that would help people and make their lives easier is considered, according to Islam, as an act of worship and as a way of gaining His pleasure.
5.0 BIBILIOGRAPHY
1. Nizam,B.(2013).Inductive Charging Technique. International Journal of Engineering Trends and Technology (IJETT), 4(4), pp.1054-1059.
2. Nor Sabirin Mohamed. (n.d.). Pre-University physics. 2nd ed. Malaysia: Thomson Learning.
3. Serway, R. and Vuille, C. (2015). College physics. 11th ed. Canada: Cencage Technology Edition.
4. Ware, R. (2018). What is Inductive Charging?. [online] Lifewire. Available at: https://www.lifewire.com/what-is-inductive-charging-575296
5. Woodford, C. (2018). How wireless induction chargers work. [online] Explain that Stuff. Available at: http://www.explainthatstuff.com/inductionchargers.html
6. YouTube. (2018). Induction – An Introduction: Crash Course Physics #34. [online] Available at: https://www.youtube.com/watch?v=pQp6bmJPU_0