Motion-Powered Portable Charger

Motion- big businessmaned Portable ChargerThe focus of this project is to design a Motion- kinged portable safekeepingr for electronic energetic de vices. The interest in electronic mobile devices has led to power furnish problems. Most of the devices need a continuous power supply to be fully functional. This project is thought to design a solution to give almost unlimited power supply to deputation the electronic mobile devices finished movements of the users themselves. The energy is expected to be gleaned from electromechanical devices such(prenominal) as Faradays hand-held generator or piezo galvanic. The energy is then converted and altered to electric energy depending on the required output power. This project would not only give almost unlimited power supply but it too would sponsor in improving green technology and more efficient too. Simulation of the rounds in this project were created using Multisim.1.1 Project TitleMotion-powered Portable Charger1.2 acceptThe aim of this project is to design a motion-powered buckr that al commencements electronic devices users to keep on charging their electronic devices from running movement of the users. To achieve this, the iron heelr is expected to harvest enough motion from running to replenish cell phones or anformer(a)(prenominal) small gadgets, give c atomic number 18 GPS devices.1.3 ObjectivesThe objectives of this project be as fol depressedsChoosing the best electromechanical devices to charge the stamp stamp barrage in the portable chargerTesting the lowstanding of charger circuits which also includes AC-DC converters, amplifiers and some other m whatsoever minor circuits of an electronic devicesUnderstanding in organization to store energy in atomic number 3-ion stamp battery to be apply to charge electronic portable devicesMeasure the efficiency of the devices scuttlebutt and output emf, online and power of the chargerProduce useable motion-powered portable charger1.4 Lea rning OutcomeLearning outcomes of this project areManage to understand the mechanism of charging and discharging destine of atomic number 3-ion batteryUnderstand on how to development two voltage and current to required voltage and currentIm call forth problem solving and decision-making skills for sudden mistakes discovered throughout the projectsHave the confidence in designing an electronic and electrical circuits.Understand on files needed to produce a printed circuit board (PCB)Develop bonding skills so a PCB would be fully functional1.5 Materials Required18mm OD x 2mm WT x 12 long Perspex Tube30 SWG Enamelled Copper attr be activeiveness wireLM324N OpAmpLM7812CT Single Linear Voltage RegulatorTIP122G NPN Darlington Transistor1N4148 DiodeDC-DC 5V 1A/2A Boost ConverterBZX79C 4.7V Zener Diode10k PotentiometerResistors1 560 1k 1.5k 2.7k 4.7k 10k 100k 1M Capacitors10nF100nF1.6 Project PlanningWith a project with many different schedules and tasks that need to be completed pro ject planning was an essential part to designing and building a functioning system. there is a time plan of the whole project in Appendix A Project Planning.2.1 Fundamentals of Kinetic capacity and Mechanical to Electrical Energy2.1.1 Faradays legalityInitially, in 1821, a Danish physicist and chemist, Hans Christian Oersted, ready a phenomenon so called electro attractive forceism. Soon after the discoin truth, a British scientist, William Hyde Wol endureon, tried to design an electric motor using the fundamental theory of electromagnetism. However, his effort make no upshots and failed to create the motor 1.Michael Faraday who dumbfound talked to both initiators of the theory started his experiments and managed to produce the very depression electric motor. Since he is the only who published his works, he was credited for discovering the theory of induction in 1831 without acknowledging Wollaston 2. This law predicts how magnetic celestial sphere would related to electri c field which then could produce electromotive force ( potential drop), a phenomenon generally called Electromagnetic Induction 2. This law is applied as the basic fundamental theory for many applications such transformers, inductors, electric motors and in this project case, as a generator 2.However, most of the scientists rejected the Faradays theory since it was not represented mathematically 1. But only pack Clerk Maxwell accepted the theory and described the law as Faradays impartiality of Induction mathematically which then later generalized to be called the Faraday-Maxwell Equation1 13. This equivalence is one of the four so called Maxwells Equation throughout all of his theory astir(predicate) electromagnetism 1.Faradays Law of Induction surely needs the magnetic liquidise through a loop of wire 4. The definition of magnetic flux is given bywhere B is the magnetic field and dA is surface entire enclosed by the loop of wires.In term of graphical definition, magnetic flu x through the loop of wire is directly symmetryal to the number of magnetic flux lines been cut when the magnet pass through the loop of wire 4.2.1.2 Lenzs LawThe Faradays Law of Induction also states that when the magnetic flux that pass through the loop of wire swapd, the loop of wire gained an EMF. Generally, this statement means that the induced EMF in closed circuit is defined as rate of change of magnetic flux made from the circuit 56. The definition in term of equation is as belowwhere is the EMF while is the magnetic fluxThe Faradays Law of Induction is then further modified and improved by physicist named Heinrich Lenz. The improvised law is called as Lenzs Law. This law, of which gives the vigilance of the EMF, states that the direction of the induced current is opposite of the direction of the change that produced it because of the negative sign shown in the equation above 7. In order to increase the induced EMF, it is known to customize the flux linkage since EMF is also known as rate of change of flux. This gutter be done by wounding coil of wires tightly producing N pass ons of wires, which from each one of the turn have the identical magnetic flux. The EMF produced through this method is N times of one single turn of wire 8 9. get into 1 Faradays Law of Induction producing EMFThe theory from the Faradays Law of Induction due to magnetic flux linkage been cut by loop of wire then get the fundamental principle in making electrical generators. This could be happened when a conductor or loops of wires is moved relative to permanent magnet or vice versa producing EMF. If both ends of the opened-circuit wires is connected to any electrical devices, current go away be produced and electrical energy is produced. This electrical energy is gained from the motion of the magnet which then proves the diversity of mechanical energy to electrical energy.2.1.3 PiezoelectricityPiezoelectricity is the ion charges which are collected in abundant amount in some solid materials, such as ceramics and crystal, and biological matter, for example DNA and bones 10. This could only be happened when mechanical stress is applied onto the particular substances. It is understood that piezoelectric performance was a result of linear electromechanical contact between electrical and mechanical state in materials whose structure are in highly microscopic structure order. These materials used for piezoelectricity are usually have no inversion symmetry 11.During the early mid of 18th century, the early discovery and research was studied by Carl Linnaeus and Franz Aepinus. However, the study was on pyroelectric effect. This pyroelectric shows that an electrical potential of a substances or material are produced whenever there is temperature changes 12. From this discovery, Rene Just Hauy and Antoine Cesar Becquerel conclude a family relationship between electric charge of a substances or materials with mechanical stress applied onto it. Despite of their experimental efforts to prove the relationship, they are likely fail to prove the experiments conclusive 12.Unable to full understand the principle, in 1880, The Curie brothers, Pierre Curie and Jacques Curie manage to demonstrate the very first direct piezoelectric effect 13. The brothers manage to predict the behaviour of crystal by combining their knowledge on pyroeletricity with their understanding about the crystal structure. The effect was demonstrated by the brothers using tourmaline (crystalline boron silicate mineral), topaz (silicate mineral of aluminium and fluorine), cane sugar and Rochelle salt (sodium potassium tartrate tetrahydrate) Quartz (mineral composed of silicon and oxygen) 13.However, the converse piezoelectric effect wasnt predicted by the brothers. Only in the next year, 1881, Gabriel Lippmann managed to deduce the converse effect from the basic principles of thermodynamics mathematically 13. Only then, the Curie brothers got to obtain the verificat ion of the changeability of the deformations in the piezoelectric crystals and thus proved the presence of the converse effect 13.The very first application of piezoelectric devices was as in sonar. It was first developed by Paul Langevin and his assistants during World War 1 at France which was about 1917 13. Starting from this creation where piezoelectric effect was used in sonar, the development of its technology and applications was intensely explored and developed. The most common application was found to be the piezoelectric demodulator.Piezoelectric sensor, as known from its name, of course uses piezoelectric. This sensor detects any changes in pressure, force, temperature, stress or strain in form of electrical charge. This is one of the reason why it is called electromechanical devices as it generally converts mechanical energy to electrical energyFigure 2 Electronic and schematic symbol of a piezoelectric sensorThe electrical properties of the sensor are that it has very high DC output impedance. This makes the sensor could also be sculpted as proportional voltage offset or network filter 14. Voltage across the source is directly proportional to any force, stress, strain or pressure applied onto it. The current passed through the circuit then go away shows as output signal of the sensor of which specifically shows the result of the mechanical force applied 14.Figure 3 Frequency response of piezoelectric sensorIf it is intensely considered, the effects of the mechanical construction and other ingenuity of the sensor are included in the specified model. To make it function as sensor, the straight region (usable region) of the frequency response will normally be used 14. As an effort to ensure that the low frequencies of interest (straight region) not lost, the leakage and load resistance must be sufficiently large. In this region, a corresponding circuit which has been abbreviated can be used. From the circuit, the capacitance of the sensor is signi fied by CS of which is defined by the general conventionalism for capacitance of parallel plates 14. However, the device can also be showed as charge source. This could only be happened if CS is in parallel yet the charge is still directly proportional to applied force 14.Figure 4 Piezoelectric sensor as voltage source or charge sourceThe principle operation of a piezoelectric material can be divided into 3 main operative modesLongitudinal effectThe total charge displaced does not depend on the dimension and shape of the piezoelectric elements. Yet, the amount charge displaced is directly proportional to the force or pressure. The one and only technique to surge the output charge is by placing a few piezoelectric elements in parallel as from electrical horizon but in series as from mechanical perpective. The output charge is as belowwhere is the piezoelectric coefficient as a charge in x-axis are being discharged by the forces exerted onto the same x-axis. , is the force exert ed in the x-axis while is representing the number of elements that been fixed together.Shear effectThe charges formed does not depend on the dimension and size of the piezoelectric elements at all and yet it is totally and directly proportional to the force and pressure exerted. The charge for elements which is placed in parallel as from electrical perspective but in series as from mechanical perspective can be illuminated as belowTransverse effectCharges along x-axis are displaced perpendicularly to a force that been applied along a neutral y-axis. The geometrical proportions of certain piezoelectric component determined the amount of charge displaced, CX.where is the proportion coordinated with the neutral axis, is coordinated with the charge producing axis while is the equivalent coefficient2.2 Theory of Lithium ion BatteryAmongst rechargeable battery that ever exist, lithium ion battery is known to be amongst the battery with highest capability to store energy per unit volu me. This is one of the reason why lithium ion battery is considered to be useful for electrical energy storage 15. Besides, lithium ion battery is also known for its capability and efficiency in charging and discharging 15.However, there is also disadvantages of using this lithium ion battery. Comparing to condensers and other different kind of batteries, it is essential for this lithium based battery to be charged using a definite voltage and restricted current 15. If the condition is not fulfilled, the useful used-to-store-energy battery could be one of the dangerous battery as it could potentially be fire-starting bomb 15.2.2.1 Principles of Charging and Discharging Stage of Lithium ion batteryThe very foremost thing that need to be understood about discharging and charging a battery is its C-rate which is the foundation of battery usage. Generally, the batteries are characterised with nominal capacity which is measured in ampere-hour (Ah). But most of the time, the batteries ar e labelled in milliampere-hour (mAh) 15. The label actually explains the amount of current supplied within one hour during the discharging state of the battery in front the battery are fully depleted 15.As an example, a battery labelled with 10000mAh which talent be also labelled as 10Ah, could only release 10A to a circuit. If the battery is being discharged through the circuit with 10A but last for 1 hour, it verbalize that the battery would have 1C discharge rate. It is also said to be discharged at rated capacity current. However, the discharge rate would only be 0.5C when the battery only provides 5A or 5000mA to a circuit. However, with 0.5C discharge rate, the battery would last for two hours 15. Some batteries do tolerate for higher discharging rate compared to 1C, but it couldnt last longer than 1C discharge rate.As for charging condition, the theory is generally the same. At 0.5 charging rate, the same battery that labelled 10000mAh would be charged with maximum curren t of 50000mA 15. However, comparing to discharge rate of a battery, most of the batteries are only charged at 0.5 to 0.7C charging rate because of safety and to have long- vitality battery 15.Graph 1 Lithium ion battery cycle life, capacity and float voltage are interrelateFrom the graph above, it is concluded that each cell of most of the lithium ion batteries are only charged to 4.2V maximum. This is because charging using higher voltages mogul reduce the battery life even though the capacity of the battery are improved 16. On the other hand, charging the battery using a lower voltage might increase the charge cycles but the run time of the battery are reduced 16.Many batteries can be classified as over-discharged when the cell voltage of the battery is below 2.8V or 3V. When this happened, the battery can still actually be recharged and used 16. However, a peak called aconditioning stage need to be done before the battery is charged again. Within the stage, the battery is onl y charged with 0.1C charging rate 16Graph 2 The constant current, constant voltage charge profile of lithium ion batteryThe charge cycle of lithium ion battery is illustrated by the graph above. Generally, every charge cycle of single lithium battery contains two main stages which is Constant Current (CC) and Constant Voltage (CV). However, some chargers which charge series of lithium ion battery have an extra stage that is called equilibrize Stage 16. business relationship for each stage 16 is explained as belowConstant Current (CC) This stage is always used by all the chargers and it is the one and only stage aimed at the fastest chargers. Generally, the battery is connected to current-limited power supply during this early stage. The limited current is normally 0.5 to 0.7 of the nominal capacity of the battery. The limited current flows continuously and endlessly until the voltage of the battery cell inducees 4.2V. At this very moment, the charge of battery is expected to be around 70 to 80% 16.Constant Voltage (CV)This stage is also known as the saturation stage. In this stage, the charger turns its role into voltage-limited power supply. Contradictly from the previous stage where voltage of the battery continues to be unchanged, the charge current decrease steadily. The battery is only acknowledged to be fully charged when the charge current is encouraged to be 3 to 10% of the rated capacity 16.Balancing StageAs told before, this stage is normally only when series of lithium ion batteries need to be charged. In this stage, the charging current is normally lowered or in some cases, the charger is automatically and rapidly turned on and off in order to decrease the average current. At the same time, the charge of each battery cell is kept to the equal level. This was done by a circuit called balancing circuit. The stage will stop only when the batteries are found to be balanced.2.2.2 Environmental TemperatureGenerally, lithium-ion battery give best cha rging performances only at cool temperature. The temperature accepted for the best performances ranging from 5 C to 45 C. Sometimes, the battery might even offer fast-charging within the accepted temperature 15.It is also possible to charge the battery at low temperatures (below 5 C). However, the cost to charge at low temperature is that the charge current will be reduced and indirectly, it would take long times for the battery to be fully charged. When the battery is charging in the low temperature, any increment in the temperature which is caused by the internal resistance of the cell would highly be beneficial even though it only small increment.On the other hand, charging the lithium ion battery in high temperatures can cause the battery to be degraded. Besides, charging the battery at high temperature (above 45 C) also might mite to degradation of the battery performances.3.1 IntroductionIn order to simplify the design and build the system, the project was split into modules. The project modules were initially designed to be like in the block diagram below.Figure 5 Initial flow chart of the motion-powered portable chargerThe modules were later adjusted based on the knowledge gained from the literature go off. The adjusted modules are shown as below.Figure 6 Final flow chart of the motion-powered portable chargerFrom the flow chart above, it can be seen that the input of the system is made to have two inputs. As for the system, the main input supposed to be the Kinetic/Mechanical to Electrical Energy Converter. However, the other input which is the AC Power Supply is also considered because it is made to be the alternative input just in case if there is any system failure in the main input.From the flow chart, there are three modules that are available in the market and would be useful for the system. The modules are AC Power Supply, Lithium ion Battery and 5V Voltage Regulator.3.2 Kinetic/Mechanical to Electrical Energy ConverterIn this module, the de sign choice to generate the electricity which are harvested from kinetic or mechanical energy have been made. The design choice that have been made uses Faradays Law of Induction and Lenzs Law. Faradays Law of Induction applies that an electromotive force (EMF) will be produced when there is change in magnetic flux when a permanent magnet is passed through a loop of wire. Furthermore, Lenzs Law explained that the electromotive force (EMF) produced have different directions depending on the direction of the movement of the magnet relative to the loop of wire. Lenzs Law also indicates that the EMF can be converted into electricity if both ends of wire are connected to electrical load and it would produce an alternating current.Figure 7 Shake Generator with permanent magnet sure in the tubeFrom the understanding of the laws, a shake generator is made as in the figure above. The shake generator is made by using 30SWG magnet wire circling around a Perspex tube. A permanent and powerful magnet is then placed in the tube. Both end of the Perspex tube is then sealed using rubber-closed blind.Knowing that the generator would produce alternating current and produce low voltage, a circuit is designed which combined both AC-DC Converter and 12V getup voltage regulator. The AC-DC converter only consists of four 1N4001G diode which combined to form rectifier. On the other hand, the voltage regulator is created by using the LM7812CT Fairchild Semiconductor, 0.1 F capacitor and 10 F capacitor.Figure 8 AC-DC Converter and 12V 2A Voltage Regulator Circuit3.3 Battery Charging CircuitFigure 9 Battery Charging CircuitIn this circuit, a LM324N Operational Amplifier (op-amp) is used. The op-amp is used to produce a voltage and current limited power supply as in reviewed in the literature review early in this report. In this circuit, the current can be adjusted by using a potentiometer to produce current ranging from 160A to 1600mA. This allows the charger to charge discordant cap acity of lithium ion batteries. The op-amp is used so that the voltage is limited to 4.2V. Thus, the lithium ion batteries will not be damaged.Besides, the circuit also used the TIP122G junction transistors. This transistor generally is a Darlington bipolar power transistor. This transistor can actually be replaced with any transistor which have pin that compatible with TIP122Gs pin. The transistor also need to have minimum DC current gain more than 100. Besides, the maximum collector current also need to be more than 2A.3.3.1 Power Supply of the ChargerFigure 10 Power Supply Circuit of the Battery ChargerThe battery charging circuit is mainly power-driven by a charger with rating of 12V 2A as designed in the Kinetic/Mechanical to Electrical Energy Converter module. It is found that the op-amp LM324N is not a trail to rail type. Thus, another voltage rail is needed so that the op-amp could detect the small voltages near the state (GND). Besides, it is also made the output voltage to be low so that the Darlington transistor (TIP122G) wouldnt turned on when they are not supposed to.By referring to the overall schematic circuit of the Battery Charging Circuit, it can be seen that the transistor, that adjust the flow of the current and voltage across the lithium ion battery (illustrated by the oscilloscope), is not connected to ground but to a voltage rail. This is because the output of the LM324N op-amp couldnt reach the negative voltage supply. It can only reach 1.5 to 2.0V. At this condition, the TIP122G Darlington transistor couldnt be able to turn off and would result in the transistor for not be able to limit the current and voltage appropriately.This is one of the reasons why op-amp U1A and a transistor are used. This is to create a 2.5V rail practically compared to ground (GND). The voltage rail created are further used to sink the current which pass through the charger section of this module.From the circuit, the function of the resistor R2 and R3 are to act as potential divider which gives an average output voltage of 2.5V. However, it is still depending on the tolerance of both resistors. No matter on how the current flow, 2.5V will always loss across the op-amp which controls the transistor.In the circuit, the LED shows whether the charger is on or off. In addition, C2 steadily adjust the voltage out from the charger. In the battery charging circuit module, all of the op-amps and the charging indicator (illustrated by the LED) are precisely powered from the 12V supply. However, the remaining of the circuit is powered with the voltage between 12V and 2.5V rails which is 9.5V.3.3.2 The charger circuitFigure 11 Actual Charger CircuitThis section is the most significant section of the charger because this is the section that responsible in restricting the voltage and current across the lithium ion battery. From the circuit, the limited current can be controlled from the 10k potentiometer. However, the limited voltage will be cons tantly at 4.2 V unrelatedly to the various kind of the power supply.The potentiometer also effectively works together with the U1C in limiting the current of the battery. The current passing it and the voltage across might be equal since the determine of the sense resistor is only 1 .The potentiometer is above the 1k resistor and the voltage across the 1k resistor is 160mV. This would make the low voltage of the output of the potentiometer would be 0.16V. In this condition, this circuit would produce limited current of 160mA which is a suitable condition to charge a lithium ion battery labelled with 300mAh.The highest limited current through the potentiometer can be somewhat more than 1.6A since the voltage drop that been found across it is about 1.6V. Thus, by changing the potentiometer, the possible output voltage obtained can be around 0.16V to 1.6V. On the other hand, this also means that the highest limited current can be ranging around 1600mA to 160A.The transistor will be driven by the op-amp to make the voltage across the sense resistor to have the equal value as in the output of the potentiometer. Besides, the op-amp might get to produce low voltage that is just sufficient to make the transistor turn off and to induce a low limited current all because of the 2.5V rail.Towards the finale phase of the constant current stage, the voltage of the lithium ion battery become closer to the value of 4.2V. At this situation, the limiting voltage stage of the circuit and the constant voltage stage will start to take over the process.A 4.2V situation under 12V (VCC) are created by the BZX79 4.7V Zener diode and the potential divider that consists of R10 and R11. At the moment where the voltage across the lithium ion battery get to 4.2V markings, the U1D op-amp begins to drive voltage into the reversing input of the other op-amp. This process will allow the op-amp to reduce the voltage of the output to the transistor. Thus, the current passing through the lith ium ion battery will begin to overtake steadily in order to maintain 4.2V across the battery.When the l