Passive Components Blog
No Result
View All Result
  • Home
  • NewsFilter
    • All
    • Aerospace & Defence
    • Antenna
    • Applications
    • Automotive
    • Capacitors
    • Circuit Protection Devices
    • electro-mechanical news
    • Filters
    • Fuses
    • Inductors
    • Industrial
    • Integrated Passives
    • inter-connect news
    • Market & Supply Chain
    • Market Insights
    • Medical
    • Modelling and Simulation
    • New Materials & Supply
    • New Technologies
    • Non-linear Passives
    • Oscillators
    • Passive Sensors News
    • Resistors
    • RF & Microwave
    • Telecommunication
    • Weekly Digest

    Samsung Electro-Mechanics High Capacitance MLCCs for ADAS SoCs

    Murata Expands its Automotive Common Mode Choke Coils to 150C and High Current Capability

    Bourns Releases New Current Transformer

    Skeleton Releases GrapheneGPU to Reduce AI Energy Consumption by 44% and Boosts Power by 40%

    VINATech Expands Aluminum Capacitor Portfolio with Acquisition of Enesol

    binder Offers Wide Range of M12 Panel Mount Connectors

    Bourns Releases New Shielded Power Inductors for DDR5

    Supercapacitors Benefits in Industrial Valve Fail-Safe Control Systems

    Wk 21 Electronics Supply Chain Digest

    Trending Tags

    • Ripple Current
    • RF
    • Leakage Current
    • Tantalum vs Ceramic
    • Snubber
    • Low ESR
    • Feedthrough
    • Derating
    • Dielectric Constant
    • New Products
    • Market Reports
  • VideoFilter
    • All
    • Antenna videos
    • Capacitor videos
    • Circuit Protection Video
    • Filter videos
    • Fuse videos
    • Inductor videos
    • Inter-Connect Video
    • Non-linear passives videos
    • Oscillator videos
    • Passive sensors videos
    • Resistor videos

    Coupled Inductors Circuit Model and Examples of its Applications

    Inductor Resonances and its Impact to EMI

    Highly Reliable Flex Rigid PCBs, Würth Elektronik Webinar

    Causes of Oscillations in Flyback Converters

    How to design a 60W Flyback Transformer

    Modeling and Simulation of Leakage Inductance

    Power Inductor Considerations for AI High Power Computing – Vishay Video

    Coupled Inductors in Multiphase Boost Converters

    VPG Demonstrates Precision Resistor in Cryogenic Conditions

    Trending Tags

    • Capacitors explained
    • Inductors explained
    • Resistors explained
    • Filters explained
    • Application Video Guidelines
    • EMC
    • New Products
    • Ripple Current
    • Simulation
    • Tantalum vs Ceramic
  • Knowledge Blog
  • Suppliers
    • Who is Who
  • Events
  • Home
  • NewsFilter
    • All
    • Aerospace & Defence
    • Antenna
    • Applications
    • Automotive
    • Capacitors
    • Circuit Protection Devices
    • electro-mechanical news
    • Filters
    • Fuses
    • Inductors
    • Industrial
    • Integrated Passives
    • inter-connect news
    • Market & Supply Chain
    • Market Insights
    • Medical
    • Modelling and Simulation
    • New Materials & Supply
    • New Technologies
    • Non-linear Passives
    • Oscillators
    • Passive Sensors News
    • Resistors
    • RF & Microwave
    • Telecommunication
    • Weekly Digest

    Samsung Electro-Mechanics High Capacitance MLCCs for ADAS SoCs

    Murata Expands its Automotive Common Mode Choke Coils to 150C and High Current Capability

    Bourns Releases New Current Transformer

    Skeleton Releases GrapheneGPU to Reduce AI Energy Consumption by 44% and Boosts Power by 40%

    VINATech Expands Aluminum Capacitor Portfolio with Acquisition of Enesol

    binder Offers Wide Range of M12 Panel Mount Connectors

    Bourns Releases New Shielded Power Inductors for DDR5

    Supercapacitors Benefits in Industrial Valve Fail-Safe Control Systems

    Wk 21 Electronics Supply Chain Digest

    Trending Tags

    • Ripple Current
    • RF
    • Leakage Current
    • Tantalum vs Ceramic
    • Snubber
    • Low ESR
    • Feedthrough
    • Derating
    • Dielectric Constant
    • New Products
    • Market Reports
  • VideoFilter
    • All
    • Antenna videos
    • Capacitor videos
    • Circuit Protection Video
    • Filter videos
    • Fuse videos
    • Inductor videos
    • Inter-Connect Video
    • Non-linear passives videos
    • Oscillator videos
    • Passive sensors videos
    • Resistor videos

    Coupled Inductors Circuit Model and Examples of its Applications

    Inductor Resonances and its Impact to EMI

    Highly Reliable Flex Rigid PCBs, Würth Elektronik Webinar

    Causes of Oscillations in Flyback Converters

    How to design a 60W Flyback Transformer

    Modeling and Simulation of Leakage Inductance

    Power Inductor Considerations for AI High Power Computing – Vishay Video

    Coupled Inductors in Multiphase Boost Converters

    VPG Demonstrates Precision Resistor in Cryogenic Conditions

    Trending Tags

    • Capacitors explained
    • Inductors explained
    • Resistors explained
    • Filters explained
    • Application Video Guidelines
    • EMC
    • New Products
    • Ripple Current
    • Simulation
    • Tantalum vs Ceramic
  • Knowledge Blog
  • Suppliers
    • Who is Who
  • Events
No Result
View All Result
Passive Components Blog
No Result
View All Result

Physical Transformer Modelling in LTSpice

10.10.2023
Reading Time: 7 mins read
A A

Sotiris Zorbas, Power Εlectronics Εngineer of Frenetic in this blog explains how to build a transformer model in LTspice or Suzuka from measurements of a physical transformer.

The Transformer Model

RelatedPosts

How to design a 60W Flyback Transformer

How to Design LLC Transformer

Leakage Inductance Model; Frenetic Webinar Recording

In Figure 1, if we omit the capacitors Cp, Cs we have a power source, a Transformer model, and a load resistor. Adding the series capacitor, we have the trending CLLC topology that is currently trending in the automotive world.

Figure 1. Transformer model for a SS WPT system identical to CLLC converter

Can you believe I took this picture 7 years ago, when I was writing my thesis for the development of a complete wireless power system (WPT)? The industry back then hadn’t made the decision to move electric just yet (“thanks, Elon”). Back then, wireless power transfer was a trending topic with multiple new papers published across the globe. Mainly, the goal of the research groups was to explain the various modes of operation of WPT systems.

Figure 1 depicts the SS WPT topology because the capacitors are connected in series with Transformer. The only major difference between an SS WPT system and a CLLC Converter is the coupling factor k, not considering operation modes. You see in a WPT system, the inductors are facing each other and behave like a loosely coupled transformer.

Useful definitions and the connection to measurements

First of all:

  • LP is the primary inductance.
  • LM is the magnetizing inductance.
  • Llkp is the primary leakage inductance.

When we build an inductor and choose x turns, given the AL value of the material, we get the inductance L=x2AL.  If that is the primary winding of a Transformer, we call this inductance, primary inductance LP . Now, if the Transformer was an ideal one, then the coupling factor is equal to 1, and there are zero leakage inductances.

In the case of a real Transformer, as modelled in Figure 1, the primary “isn’t coupled” to the secondary completely, so LP is split between the leakage and the magnetizing inductance, depending on the coupling factor. The magnetizing inductance is the largest percentage of the primary inductance, responsible for power transfer, whilst the rest acts like an inductor storing energy in series.

As said:

Usually, the coupling factor k has values like 0.999, so almost all primary inductance is magnetizing inductance with a tiny percentage of it is left as leakage inductance Llkp. But in a WPT application, or in a resonant topology like LLC or CLLC, the coupling factor can take much lower values.

Also:

  • Turns ratio n is known
  • LP  is known from the AL value and turns and can be easily measured if we just measure the primary inductance with all other windings open
  • The coupling k factor is not known. If we know k, then we can calculate the primary and secondary leakage inductances and the Transformer model of Figure 1 is complete!

Do you know how to measure the k factor?

If your answer is “what do I need the k factor for, I just short the secondary and measure the leakage in the primary, which I call primary leakage”, then you’re right only if you assume the k factor is very close to unity.

When however, you design resonant Transformers you are about to commit mistakes thinking that way! Let’s look at what exactly happens if we short the secondary winding and measure from the primary side:

Figure 2. Shorting the secondary and measuring inductance at the primary side

As seen in Figure 2, we don’t measure the primary leakage, but more correctly the “lumped”/ “effective”/ “total” leakage of the transformer that way. Well, that leakage is close to the primary leakage if we assume that the secondary leakage inductance is much lower than the magnetizing inductance, thus the parallel combo value is close to zero. You see the fault in these assumptions…

Instead of assumptions, we can write the following for the equation:

So, the total inductance which I like to call Lshort is:

And after a page long of equation manipulations:

Now you can easily calculate k with this easy measurement and define all leakage inductances exactly. An example:

Figure 3. Example LLC Transformer simulation and measured values

Calculating the k factor (in an LLC- center tap the short test is done with one of the 2 secondaries):

So:

One key skill is connecting theory and practice, with knowledge about parasitic elements and assumptions made in the process, no matter of the subject.

Related

Source: Frenetic

Recent Posts

Murata Expands its Automotive Common Mode Choke Coils to 150C and High Current Capability

29.5.2025
5

Bourns Releases New Current Transformer

29.5.2025
9

Bourns Releases New Shielded Power Inductors for DDR5

29.5.2025
18

Samsung Electro-Mechanics Releases 165C Automotive 0806 Size Power Inductors

21.5.2025
27

Coupled Inductors Circuit Model and Examples of its Applications

21.5.2025
68

Würth Elektronik Introduces LTspice Models for ESD Products

21.5.2025
45

Littelfuse Gate Driver Integrates Diode and Current Limit Resistor in Compact IC

21.5.2025
20

Capacitor Ripple Current Testing: A Design Consideration

21.5.2025
62

TDK Releases 0201 High-Frequency Smallest Inductors

20.5.2025
33

Coilcraft Extends Air Core RF Inductors

20.5.2025
17

Upcoming Events

Jun 4
11:00 - 12:00 CEST

Würth Elektronik PCB Production in Asia

View Calendar

Popular Posts

  • Buck Converter Design and Calculation

    0 shares
    Share 0 Tweet 0
  • Boost Converter Design and Calculation

    0 shares
    Share 0 Tweet 0
  • LLC Resonant Converter Design and Calculation

    0 shares
    Share 0 Tweet 0
  • Flyback Converter Design and Calculation

    0 shares
    Share 0 Tweet 0
  • What is a Dielectric Constant and DF of Plastic Materials?

    4 shares
    Share 4 Tweet 0
  • Ripple Current and its Effects on the Performance of Capacitors

    3 shares
    Share 3 Tweet 0
  • Flying Capacitors Explained

    0 shares
    Share 0 Tweet 0
  • How to Design an Inductor

    0 shares
    Share 0 Tweet 0
  • SEPIC Converter Design and Calculation

    0 shares
    Share 0 Tweet 0
  • Skeleton Releases GrapheneGPU to Reduce AI Energy Consumption by 44% and Boosts Power by 40%

    0 shares
    Share 0 Tweet 0

Newsletter Subscription

 

Passive Components Blog

© EPCI - Leading Passive Components Educational and Information Site

  • Home
  • Privacy Policy
  • EPCI Membership & Advertisement
  • About

No Result
View All Result
  • Home
  • Knowledge Blog
  • Premium Suppliers

© EPCI - Leading Passive Components Educational and Information Site

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