• Latest
  • Trending

Functionality of Transformer

Resistors and Thermistors for EVs; Vishay Webinar

Resistors and Thermistors for EVs; Vishay Webinar

Researchers Believe that Antiferroelectric Superlattice Materials Can Yield in Next Gen of High Energy Capacitors

Researchers Believe that Antiferroelectric Superlattice Materials Can Yield in Next Gen of High Energy Capacitors

Stackpole Releases Automotive Anti-Sulfur Thick Film Chip Resistors

Stackpole Releases Automotive Anti-Sulfur Thick Film Chip Resistors

Card Edge Connectors For Automotive Applications

Card Edge Connectors For Automotive Applications

Polymer Families

Polymer Families

Polymer Processing

Polymer Processing

Polymer Materials

Polymer Materials

ZIF Contacts Selection Guide; WE Webinar

ZIF Contacts Selection Guide; WE Webinar

Thermistor-Based Temperature Sensing System Optimization and Evaluation

Thermistor-Based Temperature Sensing System Optimization and Evaluation

Axial Aluminum Electrolytic Capacitors’ ESL and its Measurement

Axial Aluminum Electrolytic Capacitors’ ESL and its Measurement

  • Home
  • ABC of CLR
    • All
    • ABC of Capacitors
    • ABC of Inductors
    • ABC of Resistors
    • Mounting Guidelines

    RF Inductors and Filters

    Power transformers

    Telecom transformers

    LAN transformers

    Transformer Calculation and Applications

    Power Inductors 2 (cont.)

    Power inductors

    Current compensated chokes

    Coil with ferrite

    Trending Tags

      • ABC of Capacitors
      • ABC of Inductors
      • ABC of Resistors
      • Mounting Guidelines
    • e-Symposium
    • EPCI Membership
    • About
    No Result
    View All Result
    European Passive Components Institute
    • Home
    • ABC of CLR
      • All
      • ABC of Capacitors
      • ABC of Inductors
      • ABC of Resistors
      • Mounting Guidelines

      RF Inductors and Filters

      Power transformers

      Telecom transformers

      LAN transformers

      Transformer Calculation and Applications

      Power Inductors 2 (cont.)

      Power inductors

      Current compensated chokes

      Coil with ferrite

      Trending Tags

        • ABC of Capacitors
        • ABC of Inductors
        • ABC of Resistors
        • Mounting Guidelines
      • e-Symposium
      • EPCI Membership
      • About
      No Result
      View All Result
      European Passive Components Institute
      No Result
      View All Result
      Home ABC of CLR

      Functionality of Transformer

      February 11, 2022
      Reading Time: 6 mins read
      35 1
      A A

      L.1.8 Differentiating EMC ferrite ↔ inductor

      The terminology used in this handbook clearly distinguishes between inductors and EMC ferrites in regard to the quality of the inductor:

      EMC ferrites are based on Ni-Zn materials. This material has good quality factors (Q < 3) above approx. 20 MHz – i.e. trimmed for high losses. These originate in the core material and serve to absorb EMC interference. The inductance of these components is purposely kept low.

      Inductors however should show high quality factors, i.e. operate as loss-free as possible and buffer energy in the magnetic field. Also, they require stable inductance values over a wide frequency range. The distinction emphasized is reflected in the layout of the relevant manufacturer catalogue.

      1.9 Functionality of a transformer

      A transformer consists of at least two windings, with the winding turns NP on the primary side and NS on the secondary side. For the sake of simplicity, we will look at
      an ideal transformer with a turns ratio of 1 : 1.

      In a first step, we will look at a transformer with an open secondary winding NS (Figure 1.32). A UP voltage pulse is created at winding NP. Due to the inductance of the
      winding, this pulse generates a linearly progressive current IP. The following applies:

      Fig. 1.32: Principle of a transformer with zero load. This ideal transformer is wound as a bifilar so as to ignore parasitic effects.

      Winding NS also wraps around this magnetic flux. Changing the magnetic flux creates voltage.


      If you solve both equations after changing the voltage and then equate them, you will get the following for the voltage transformation:


      Current does not flow in winding NS because the winding is open. If we now connect winding NS to a load resistor RL (Figure 1.33), the voltage induced in NS generates a current flow through the load resistor:

      Fig. 1.33: The same transformer but with a load

      The primary current now consists of the transformed secondary current and the linearly progressive magnetisation current that is already available without load.

      IS* Secondary current transformed on the primary side

      As no power can be generated, the transformed power is the same as the primary power put into the system. If the magnetisation current is disregarded, the following applies:


      Currents are thus transformed in the reversed direction as voltage. The following also applies:


      Resistances are thus transformed with the transformation ratio squared. This also applies to inductances, capacitances and impedances. So the magnetising current is not transferred to the secondary side. It is required to generate the magnetic field. The aim of the transformer design must therefore be to keep the magnetizing current as small as possible.

      There are two possibilities here:

      • Insertion of a highly permeable core to increase the primary inductance. This causes the magnetizing current to rise less steeply and is therefore smaller (Figure 1.34).

      Fig. 1.34: Magnetizing current of a transformer with and without a highly permeable core

      • Shorter voltage pulses with higher frequency are generated, as the rise in current stops at the end of the voltage pulse and starts again at the original point for the
        next pulse (Figure 1.35).


      Fig. 1.35: Magnetizing current for a transformer at different driving frequencies

      Parasitic effects
      In reality, there are other factors that affect the behavior of transformers. The most important ones are:

      • Leakage inductance
      • Coupling capacitance (capacitance between windings)
      • Winding capacitance (capacitance within a winding)

      Leakage inductance
      Looking at two windings, we see that the entire flux is not coupled to the other winding. A part of the streamlines of the magnetic field closes outside of the other winding. This part of the inductance is called “leakage inductance.” To understand how to minimize leakage inductance, you must know the parameters that influence it.

      If you look at a long concentric coil (Figure 1.36), its inductance results from:


      lW Length of the coil
      N Winding turns
      A Cross section of the coil

      Fig. 1.36: Long solenoid

      If a second winding is wound on top of it (Figure 1.37), the leakage inductance results from (1.48)

      Fig. 1.37: Long solenoid with second winding

      Where A here is the surface between the two windings. It can be calculated using:

      MLT Mean length of turn
      Hins Distance between the windings (isolation)
      H1, H2 Winding height of windings 1 and 2

      The leakage inductance is thus independent of core material and air gap. To minimize leakage inductance you must either increase the length of the coil (broad windings) or reduce the distance between the windings (e.g. bifilar wind).

      Figure 1.38 shows various more or less ideal winding constructions. With existing geometry the most commonly used means is a sandwich construction (Figure 1.38d), in which the secondary winding is wound between the primary winding that is divided into two halves. This doubles the length of the winding.


      Fig. 1.38: Different winding structures

      Coupling capacitance

      You can picture the coupling capacitance between the two windings as plate capacitor between the two windings. From this it follows that you can reduce this capacitance either by increasing the distance or reducing the surface. Both directly increase leakage inductance.

      Winding capacitance

      Each winding builds up winding capacitance because they are isolated from each other and rest on different potential. This capacitance increases with the number of layers that are required within a winding. It can be reduced by means of various winding technologies, e.g. Z-wind (wire is returned after each layer).


      ABC of CLR: Chapter L Inductors

      Functionality of Transformer 

      EPCI licensed content by: Würth Elektronik eiSos, Trilogy of Magnetics, handbook printouts can be ordered here.

      Creative Commons License

      This page content is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

      see the previous page:

      Inductance, Impedance and Losses

      < Page 6 >

      see the next page:

      Equivalent Circuits and Simulation Models – Circuit Types

      Previous Post

      Electrostatic Capacitors Constructional Solutions

      Next Post

      Non-Wirewound Resistors – Metal Film, Foil and Metal Oxide

      Related Posts

      ABC of CLR

      RF Inductors and Filters

      704
      ABC of CLR

      Power transformers

      576
      ABC of CLR

      Telecom transformers

      467

      Categories

      • ABC of CLR
        • ABC of Capacitors
        • ABC of Inductors
        • ABC of Resistors
        • Mounting Guidelines
      • e-Symposium
        • ESA SPCD
        • PCNS
      • EPCI news
      • news collection

      Popular Posts

      • Transformer: Parasitic parameters and equivalent circuit

        928 shares
        Share 371 Tweet 232
      • Transformer Calculation and Applications

        538 shares
        Share 215 Tweet 135
      • Simulation with LTspice

        399 shares
        Share 160 Tweet 100
      • Introduction to Ceramic Capacitors

        346 shares
        Share 138 Tweet 87
      • Insulation Resistance, DCL Leakage Current and Voltage Breakdown

        311 shares
        Share 124 Tweet 78

      EPCI Membership

      join passive components community

      proud member of:

      © Copyright 2022 European Passive Components Institute

      No Result
      View All Result
      • Home
      • ABC of CLR
        • ABC of Capacitors
        • ABC of Inductors
        • ABC of Resistors
        • Mounting Guidelines
      • e-Symposium
      • EPCI Membership
      • About

      Welcome Back!

      Login to your account below

      Forgotten Password?

      Retrieve your password

      Please enter your username or email address to reset your password.

      Log In
      This website uses cookies. By continuing to use this website you are giving consent to cookies being used. Visit our Privacy and Cookie Policy.