• Latest
  • Trending
  • All
  • Capacitors
  • Resistors
  • Inductors
  • Filters
  • Fuses
  • Non-linear Passives
  • Applications
  • Integrated Passives
  • Oscillators
  • Passive Sensors
  • New Technologies
  • Aerospace & Defence
  • Automotive
  • Industrial
  • Market & Supply Chain
  • Medical
  • RF & Microwave
  • Telecommunication

Storage Chokes and Power Inductors

18.2.2022

Vishay NTC Thermistor LTspice Simulation for PID Optimization; Vishay Webinar

21.5.2022

Coverlay – More than a Flexible Soldermask Substitute; WE Webinar

19.5.2022

Stackpole Presents High Current Metal Shunt Resistors

19.5.2022

Coilcraft Introduced Ultra-Low Loss Shielded Power Inductors

19.5.2022
  • Home
  • Privacy Policy
  • EPCI Advertisement & Membership
  • About
No Result
View All Result
NEWSLETTER
Passive Components Blog
  • Home
  • NewsFilter
    • All
    • Aerospace & Defence
    • Antenna
    • Applications
    • Automotive
    • Capacitors
    • Filters
    • Fuses
    • Inductors
    • Industrial
    • Integrated Passives
    • Market & Supply Chain
    • Medical
    • New Materials & Supply
    • New Technologies
    • Non-linear Passives
    • Oscillators
    • Passive Sensors
    • Resistors
    • RF & Microwave
    • Telecommunication

    Vishay NTC Thermistor LTspice Simulation for PID Optimization; Vishay Webinar

    Stackpole Presents High Current Metal Shunt Resistors

    Coilcraft Introduced Ultra-Low Loss Shielded Power Inductors

    Panasonic Releases SMD Automotive Power Choke Coil

    GAM Introduces Tantalum and Niobium Powders for Cold Spray Applications

    Skeleton Curved Graphene Scientists Named as European Inventor Award 2022 Finalists

    Flexible Cable Supercapacitor Application in EVs and HEVs

    Snubber Capacitor Selection for SiC-Based Switching Converters

    Vishay Releases High Precision Compact Thin Film Wraparound Chip Resistor 

    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
    • Filter videos
    • Fuse videos
    • Inductor videos
    • Non-linear passives videos
    • Oscillator videos
    • Passive sensors videos
    • Resistor videos
    • Sensors

    Vishay NTC Thermistor LTspice Simulation for PID Optimization; Vishay Webinar

    Coverlay – More than a Flexible Soldermask Substitute; WE Webinar

    Soldering THT Components by SMD Reflow Assembly; WE Webinar

    Strain Gage Resistive Sensor Simulation; Vishay Video

    EMC Filters Explained – from Component to Design; WE Webinar

    How to Avoid EMI Noise on Data Cable by Isolated Power Module; WE askLorandt Video

    Introduction to Wireless Power Transfer; WE Webinar

    How to Pass Conducted Emissions Using Line Filters; WE Webinar

    EMI Debugging of a Low Power Buck Converter; WE Webinar

    Trending Tags

    • Capacitors explained
    • Inductors explained
    • Resistors explained
    • Filters explained
    • Application Video Guidelines
    • EMC
    • New Products
    • Ripple Current
    • Simulation
    • Tantalum vs Ceramic
  • Knowledge Blog
  • Preferred Suppliers
  • Who is Who
  • Events
  • Home
  • NewsFilter
    • All
    • Aerospace & Defence
    • Antenna
    • Applications
    • Automotive
    • Capacitors
    • Filters
    • Fuses
    • Inductors
    • Industrial
    • Integrated Passives
    • Market & Supply Chain
    • Medical
    • New Materials & Supply
    • New Technologies
    • Non-linear Passives
    • Oscillators
    • Passive Sensors
    • Resistors
    • RF & Microwave
    • Telecommunication

    Vishay NTC Thermistor LTspice Simulation for PID Optimization; Vishay Webinar

    Stackpole Presents High Current Metal Shunt Resistors

    Coilcraft Introduced Ultra-Low Loss Shielded Power Inductors

    Panasonic Releases SMD Automotive Power Choke Coil

    GAM Introduces Tantalum and Niobium Powders for Cold Spray Applications

    Skeleton Curved Graphene Scientists Named as European Inventor Award 2022 Finalists

    Flexible Cable Supercapacitor Application in EVs and HEVs

    Snubber Capacitor Selection for SiC-Based Switching Converters

    Vishay Releases High Precision Compact Thin Film Wraparound Chip Resistor 

    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
    • Filter videos
    • Fuse videos
    • Inductor videos
    • Non-linear passives videos
    • Oscillator videos
    • Passive sensors videos
    • Resistor videos
    • Sensors

    Vishay NTC Thermistor LTspice Simulation for PID Optimization; Vishay Webinar

    Coverlay – More than a Flexible Soldermask Substitute; WE Webinar

    Soldering THT Components by SMD Reflow Assembly; WE Webinar

    Strain Gage Resistive Sensor Simulation; Vishay Video

    EMC Filters Explained – from Component to Design; WE Webinar

    How to Avoid EMI Noise on Data Cable by Isolated Power Module; WE askLorandt Video

    Introduction to Wireless Power Transfer; WE Webinar

    How to Pass Conducted Emissions Using Line Filters; WE Webinar

    EMI Debugging of a Low Power Buck Converter; WE Webinar

    Trending Tags

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

Storage Chokes and Power Inductors

18.2.2022
Reading Time: 31 mins read
0 0
0
SHARES
299
VIEWS

Switched-mode power supplies are becoming ever more widespread. The semiconductor manufacturers have made their contribution, offering a wide range these integrated circuits with simplified circuit design. Care must be taken in the selection of the appropriate power inductor storage choke to fully utilize the advantages of switching regulators.

This article is split in two chapters:

RelatedPosts

Filters and RF Inductors

SMD Inductors

Transformer Calculation, Losses and Applications

  1. calculation of power inductors
  2. example of high current inductor types
Jump to section

1. Power Inductors Calculations

  • 1. Power Inductors Calculations
  • 2. High Current Inductor Types

The selection of cores and windings of storage chokes are optimized for use in switching converters and DC-DC converters.

Leading manufacturers of storage chokes following recommendations from various switching converter IC manufacturers, e.g. National Semiconductor, Linear Technology, STMicroelectronics, Texas Instruments, Exar, Diodes, MPS, ON Semiconductor, Semtech, Maxim and a special customized solutions can be found in their reference design guidelines.

Figure 1. Toroidal storage choke (WE-SI and WE-GI)

Toroidal Core Types

Toroidal storage chokes are ideal from the EMC perspective: The magnetic field lines mainly pass through the core. The stray field and associated coupling in neighboring conductor tracks or components remain small.

In the field of switching converters, storage chokes serve to buffer electrical energy and, at the same time, to smooth the output current. The energy stored in the core in this process is:

energy stored in storage choke inductor eq. 1.

To enable high energy storage and to minimize the resulting core losses, the toroidal core volume is divided into many electrically isolated regions. The iron powder used in our storage chokes therefore has three-dimensional, uniformly distributed, microscopic air gaps, which prevent eddy-current losses.

The disadvantage of reduced permeability is balanced by greater maximum energy storage and lower losses. Furthermore, these cores are extremely well suited for use in applications with high DC premagnetization.

Data book specifications

Open-circuit inductance L0:

If the inductor is operated without DC premagnetization or with only a small AC current, the open-circuit inductance L0 results.This value may be measured with sufficiently sensitive inductance measuring equipment for small AC voltages e.g. 0.1–0.5 V and a fixed measuring frequency between 1 kHz and 100 kHz, depending on the inductance value.

Figure 2. Inductance with DC premagnetization; IN = 1 A; LN = 100 µH

Inductance rating LN:

In addition to the small AC voltage amplitude, the specified DC current is superimposed and the resulting inductance measured.

Current rating IN:

The DC current, for which the inductance and wire thickness are specified and whose specifications are optimized. As shown in graph on Figure 2., inductance only saturates with a much larger current.

DC resistance DCR:

The windings resistance value is measured with an ohmmeter at an ambient temperature of +25 °C.The test current for resistance measurement is a small DC current, which does not lead to a significant temperature increase in the wire. As values in the milliohm range are measured here, a 4-wire measurement must be made to minimize measurement errors.

Magnetic field energy E:

The energy, for which the core data and windings of the coil is optimized. This is specified in microjoules.The following simple and practically proven formulae can be used for dimensioning a storage choke. A brief extract from the extensive core material program and the following table should provide an overview of the choke dimensioning process. Depending on the application, further specifications from the core material data spectrum may be necessary.

Table 1. Materials and their applications (source: Würth Elektronik)

Iron core material data:

The table 1. shows an overview of the most commonly used materials and their applications.

Operating temperature:

The operating temperature of the iron powder core may be from –55 °C to +125 °C. Prolonged core operation above +75 °C however results in increased losses.

Insulation voltage:

The protective coating of the toroidal core uniquely identifies the core material and serves to protect against environmental effects and provides electrical isolation from the windings. Epoxy resin coatings are used and an insulation dielectric strength of 500 VDC is achieved as standard. Higher insulation voltages can also be offered.

AL value: For every size of core an AL value is specified to simply calculate the winding turns for the required choke; the tolerance is ±10%.
The standard means of measuring the AL value is at B = 1 mT and f = 10 kHz.

Figure 3. Effective permeability with DC premagnetization
Table 2. Specifications of iron powder cores (source: Würth Elektronik)
  • da = outer diameter
  • di = inner diameter
  • h = height
  • l = effective magnetic length
  • A = effective magnetic cross-sectional area
  • V = effective magnetic volume l
  • W = winding wire length for 1 turn
Table 3. Wire table (source: Würth Elektronik)

Storage Choke Calculation:

The following demonstrates how a storage choke can be calculated for a switching converter application:
Example: switching converter (step-down controller – storage choke)

Requirements:

Inductance rating LN = 100 µH Current rating (DC) IN = 1 A Peak current through the inductance Imax = 1.5 A Ripple current = 20% of Imax = 0.3 A (see Chapter III/Applications) Switching frequency f = 52 kHz

A maximum AC flux density BAC = 0.05 T is recommended for iron powder cores (to ensure low core losses). Also the inductance should be selected so the ripple current does not exceed 20%–30% of the maximum current.

Step 1 : Choice of the core material and the necessary core volume (V). As the switching frequency is just 50 kHz, we firstly select the material 3W7538 with µr = 75.

inductor core volume calculation eq. [2]

Selected core: 3W7538, as switching frequency < 70 kHz; core no. 13 da = 12.7 mm; di = 7.7 mm; h = 4.83 mm

Magnetic data: l = 3.19 cm; A = 0.112 cm2; V = 0.358 cm3 AL value: 33 nH/N2

Step 2: Required winding turns

inductor winding turns calculation eq. [3]
  • L in nH
  • AL value in nH/N2

The final number of winding turns must be increased as a result of current dependent permeability. The correction factor for the AL value is determined from the “effective permeability against DC premagnetization” graph (see Figure 3.).

inductor current dependent permeability eq. [4]

At H = 1724 A/m on the graph in Figure 3. → Effective permeability with DC premagnetization = 80% of the initial permeability.

To be certain that the full inductance rating of 100µH exists with a DC current of 1A, the final number of winding turns is calculated as:

compensated inductor winding turns calculation eq. [5]

Step 3: Determination of the DC resistance

The wire diameter can be ascertained from the relevant wire tables for the required current of 1A, e.g. AWG 22 (d = 0.6 mm). This limits the self-heating of the wire to less than +10°C.

The DC resistance of the windings is given by:

inductor DC resistance eq. calculation [6]

Step 4: Check for max. AC field flux density

inductor AC field flux density calculation [7]
  • Inductance rating L in H
  • Ripple current ΔI in A
  • Core cross-sectional area A in cm2
  • Winding turns N
  • Peak voltage of the choke Us in V (during “t”)
  • Duration of peak voltage t in s

Step 5: Calculation of core losses

The losses in the core material may be calculated from the following formula:

inductor core loss calculation [8]
  • Frequency f in Hz
  • AC field flux density B in mT
  • Core losses PC in mW/cm3

For our examples this leads to:

The total core losses of the selected core are:

The losses in the windings equal:

The total losses of the storage choke are low at around 370mW and the choke calculated is well suited for the application.

Jump to section

1. Power Inductors Calculations

  • 1. Power Inductors Calculations
  • 2. High Current Inductor Types
Page 1 of 2
Previous 12 Next

Related Posts

Applications e-Blog

Vishay NTC Thermistor LTspice Simulation for PID Optimization; Vishay Webinar

21.5.2022
29
Applications e-Blog

Coverlay – More than a Flexible Soldermask Substitute; WE Webinar

19.5.2022
9
Aerospace & Defence

Coilcraft Introduced Ultra-Low Loss Shielded Power Inductors

19.5.2022
13

Popular Posts

  • Dielectric Constant and its Effects on the Properties of a Capacitor

    7 shares
    Share 7 Tweet 0
  • Capacitor Selection for Coupling and Decoupling Applications

    28 shares
    Share 28 Tweet 0
  • Understanding High-Precision Resistor Temperature Coefficient of Resistance

    0 shares
    Share 0 Tweet 0
  • Why Low ESR Matters in Capacitor Design

    0 shares
    Share 0 Tweet 0
  • How to Choose the Right Inductor for DC-DC Buck Applications

    0 shares
    Share 0 Tweet 0

Newsletter Subscription

 

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

© 2021 EPCI - Premium Passive Components Educational and Information Site

No Result
View All Result
  • Home
  • News
  • Video
  • Knowledge Blog
  • Preferred Suppliers
  • Events

© 2021 EPCI - Premium Passive Components Educational and Information Site

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.