Contents - Akademi Sains Malaysia
Contents - Akademi Sains Malaysia
Contents - Akademi Sains Malaysia
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ASM Science Journal, Volume 7(1), 2013and we only focused on the behavior of certain parametersat different physical characteristics of the coil structure.RESULTS AND DISCUSSIONThe output of a fluxgate is actually induced voltage atsensing coils and given as:V ind = NA dBdt (1)The complexity of Equation 1 is increased to takeinto account the magnetizing and demagnetizing of themagnetic core (Ripka 2001). Equation 1 then becomes:V ind = NA µ o H o(1 – D) dµ(t){1 + D[µ(t) – 1]} 2 dt (2)where, H o is outside of the core magnetic field while D isthe demagnetizing factor.However, in this study, magnetic core is excluded toreduce the complexity. With the exclusion, the structuredesign of the three-dimensional coils resembles thesolenoid. Hence, basic equations related to the inducedvoltage of the solenoid can be applied.Based on Faraday's law of induction, induced voltage,V ind can be determine as follows:V ind = – N dFdt (3)and also,V ind = – L dIdt (4)where, L is the inductance, with current, I and number ofturns, N. Magnetic flux is denoted as Ф. It can be seenthat, the induced voltage is directly proportional to theinductance, and number of turns.Magnetic energy in a coil is given as:E m = LI22 (5)Physical characteristics of the three-dimensionalcoil structure are: width of the coil; distance betweensuccessive coils; and gap between the top and bottomcoils. Simulations were done based on the three physicalcharacteristics of the coils.Width of CoilIn this part, only the width of the coil is varied andparameters such as inductance and magnetic flux densityare determined. Table 2 summarizes simulation settings forthis part.The resulting plot between inductance, magnetic energyand magnetic flux density against varying width of coil isshown in Figure 3. It can be seen that inductance decreasesas the width of the coil increases.There is an obvious explanation. As the width of the coilincreases, the cross-section of the coil also increases. Thisleads to higher conductivity, less resistance and inductance.Magnetic energy is half the values of inductance whenTable 1. Simulation process steps.StepStep 1Step 2Step 3Step 4Step 5ProcessGeometry modelingThickness: 20 µmInitial width: 50 µmInitial distance: 50Initial gap: 40 µmModule and application settingAC/DC moduleMagnetostatic applicationPhysics settingsSub-domainBoundaryMeshSolve30