Inductors are like resistors and conductors which are designed to carry out some important function. Its structure is coil-like, the coil is insulated wires which are looped around the core. inductors are used in electrical circuit. It is mostly used to decrease the electrical spike, store energy and release it back to the circuit.
What is aninductor?
Inductor is a passive component used in power electronics circuit. It stores energy in the form of electromagnet when voltage is applied to it. Inductors hinder or oppose any change in the current flowing in it. Whenever the current change in inductor it acquires the change are loose the charge to balance the current passing through it. Inductor is also known as reactor, coil and chock.
When voltage is applied to the inductor, the magnetic field is induced in it which cause inductance. Inductance means the ratio of voltage to the rate of change of current. Inductance is determined from several factors like.
Shape of the coil
Number of turns of the wire.
Space between the turns
The core size.
Permeability of the materials from which the core made.
The SI unit of inductance is henry (H), and when inductance measured in magnetic circuit, it is equal to weber/ampere. Its symbol is L.
Inductor is different from the capacitor. Capacitor store energy in the form of electrical energy while inductor store energy in the form of magnetic energy.
Inductor changes its polarity while discharging means the inductor polarity is opposite to the polarity of inductor in charging.
An advantage of using ferromagnetic materials is it offer high permeability which help in increasing the magnetic field. The inductors with low frequency, the core of such inductors is made from steel which is laminated to help decrease eddy current. Soft ferrite materials are used to construct core for audio frequency device.
Inductors are coming in many shapes, some inductors are used to change the inductance, while some inductors are used to block high frequencies the core of such inductor are made from ferrite bead on wire.
Planner inductors are made from plane core. Small value inductors are made from aluminum and its shape is spiral coil pattern and this inductor are used in integrated circuit.
There are shielded type inductors which is used in power regulation system, lighting and low frequency devices. These inductors are partially or fully shielded.
Different types of inductors
Inductors are classified in many types depending on the types of materials used.
The iron core inductor is one in the types of inductors. the core of iron core inductor is made from the iron, these are low space inductors which have high power and high inductance. These inductors are limited in high frequency. Iron core inductors are used in audio equipment.
The Air core inductor is one of type in the types of inductors. the air core inductor are low inductance inductors. It has no core so there is zero core loss, but a greater number of turns are required as compared to inductors which have core. Generally ceramic inductors are referring as air core inductors.
The iron powder inductor is one of type in the types of inductors. the iron powder core inductor is iron oxide. They are made from very fine insulating particle of pure iron powder. Due to air gap in it high, magnetic flux can be store in it. Its permeability is very less which is below 100. This type of inductor is used in switching power supplies.
Ferrite core inductor is one of type in the types of inductors. The core of this type of inductor are made from the ferrite materials. The ferrite materials composition is XFe2o4, here x is the transition materials.
Ferrite are classified into two types of soft ferrite and hard ferrite.
Soft Ferrite: soft ferrite are the materials that can reverse its polarity without any external voltage or energy is applied
Hard Ferrite: Hard ferrite cannot change its polarity because these are permanent magnets. Even if the magnetic field is removed it will not change its polarity.
This type of inductor is used to block high frequency AC current and pass low frequency current or allow DC current to pass. Choke is used to oppose the changes in current. Chokes consist of coil of insulating wire wound around the core. Choke does not require high Q factor construction technique which aim is to reduce the resistance in the inductors.
The coil of the inductor is used to store energy. The function of the inductor depends upon the frequency of the current passing across the inductor. Low frequency signal will pass Easly while high frequency signal is passing less Easly, it is used to block AC signal and pass DC signals.
Inductor store energy in the form of magnetic energy. The current flow through in the coil which produce magnetic field.
Inductor in parallel
When two terminals of inductor are connected to the other two terminal other inductor then the connection are called parallel. In parallel connection the effective inductance are decreases. Inductors which are in parallel form are like capacitors in series.
Consider the example below.
Inductor in Parallel (amppowergy)
In this example the current flow each inductor is zero. The current depends upon the value of inductance, the voltage across each conductor will be same. The total current is the sum of each brance current to calculate the current use kirchaffs current law.
IT=I1+I2+I3
VOLTAGE across the inductor as
V=L di/dt
We can it as
Vab= LTOTAL × dit/dt
VAB= LTOTAL × d (I1 + I2 + I3) /dt
We can further write it as
vAB = LTotal x dl1 / dt + LTotal x dl2 / dt + LTotal x dl3 / dt
That is,
vAB = LTotal ( V / L1 + V / L2 + V / L3 )
To simplify the equation
1 / LTotal = 1 / L1 + 1 / L2 + 1 / L3
Indictors in series
When inductor is connected together like chain in a straight like as positive connected to negative and negative is connecting to positive, or they are connected end to end. When inductor is connected in series their effective inductance are increases as like resistor. Inductors are in series as like capacitors are in parallel. To calculate total inductance, add every inductance that as the total inductance is equal to the sum of the whole inductance.
Consider the connection below
Inductor in Series (amppowergy)
In this figure three inductor are connected in series, the current flowing in each inductor is same while the voltage is different that as the voltage depends upon the inductance value. According to kirchoffs law the total voltage drops is the sum of the voltage drops across each inductor. That as
VT = V1 + V2 +V3
The voltage across each inductor as
V = L di / dt
We can write,
LTotal dl / dt = L1 x dl1 / dt + L2 x dl2 / dt + L3 x dl3 / dt
but
I = I1 = I2 = I3
therefore,
L dl / dt = L1 x dl / dt + L2 x dl / dt + L3 x dl / dt
LTotal = L1 + L2 + L3
Energy store in the inductor
When the current passes through the inductor an emf is induce in it, this called back emf and this back emf is opposes the flow of current in the inductor. Now to establish current in the inductor work needs to be done which will be against of this emf.
Consider the time interval is dt.
And the work done is dW
dW = Pdt
dW= – Eidt
dW= iL di / dt x dt
dW= Lidi
To find the work done integration will use.
W = 0∫ILidi = ½ LI2
Energy store in inductor can be find from the below equation.
The opposition offered by the inductor is called inductive reactance. The symbol of inductive reactance is XL. inductive reactance opposes the change in current.
Equation for inductive reactance,
XL = VL / IL = Lω
From the equation, inductive reactance is proportional to frequency.
Frequency vs Reactance plot is given below:
frequently asked question FAQs
Q1: what is the value of the power factor for a pure inductor?
Ans: for pure inductor the power factor value is zero.
Q2 what is self-induction?
Ans: when an emf is induce in a coil due to current change in the coil itself is called self-induction.
Q3: what is mutual induction?
Ans: when the current change in one coil and the emf induce in the other coil is known as mutual inductance.
Q4: how emf induce in the circuit?
Ans: when voltage is applied to the circuit, the current pass through the coil which produce magnetic flux. when there is any change comes in that flux the emf is induce in the circuit.
