Iec 62024-2-2008.Pdf

IEC 62024 2 Edition 1 0 2008 10 INTERNATIONAL STANDARD NORME INTERNATIONALE High frequency inductive components – Electrical characteristics and measuring methods – Part 2 Rated current of inductors f[.]

Standard atmospheric conditions for testing

Standard atmospheric conditions for testing shall be as follows (see 5.3.1 of IEC 60068-1):

– air pressure: 86 kPa to 106 kPa

In the event of dispute or where required, the measurements shall be repeated using the referee temperatures and such other conditions as given in 4.2.

General

When alternating current in which DC current is superimposed is supplied to an inductor, the inductance of the inductor decreases according to the DC current value

In standard applications, the saturation current arises from the peak current resulting from the superposition of AC on DC current, and it is measured as DC current that offsets a small signal AC current.

Establishing a standard for AC saturation limited current is impractical due to the myriad of ways AC current can be utilized in various applications Consequently, both manufacturers and users have commonly adopted DC saturation limited current as a reference point, which serves a similar purpose.

Test conditions

Unless otherwise specified in the detail specification, the test conditions shall be in accordance with Clause 4

The variation of DC saturation limited current with temperature is influenced by the magnetic material and core structure of the inductor Measuring DC saturating currents at high temperatures is often impractical for inspection, so room temperature measurements are typically used for specifications Derating curves can be created to show how DC saturation limited current changes with maximum operating temperature, allowing for correlation between room temperature and typical operating conditions In certain situations, manufacturers and users may need to establish additional specifications for high temperatures.

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.

Measurement circuit and calculation

The measuring circuit is as shown in Figure 1

I r supplied current to range resistor

Figure 1 – Inductance measurement circuit under application of DC saturation condition b) Calculation

Voltages E₁ and E₂ must be measured when the signal generator's frequency fₛ and voltage Eₛ are provided as per the detailed specifications The initial value of the inductance can then be calculated using the specified formulas.

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU. where

R x is the resistance of the specimen;

X x is the reactance of the specimen;

Z x is the impedance of the specimen;

L x is the equivalent series inductance of the specimen;

E 1 is applied voltage to specimen;

E 2 is applied voltage to range resistor (= I r R r)(E 2 can be regarded as current); θ is phase angle difference between E 1 and E 2

Attachment jig of inductor

Attachment jig of specimen shall be specified in the detail specification.

Measuring method

Before measurement, a short compensation must be performed The specimen should be connected to the circuit as illustrated in Figure 1 using the specified attachment jig If soldering is used for the connection, it must be allowed to cool sufficiently Voltages E1 and E2 are to be measured when the signal generator is set to the specified frequency $ f_s $ and voltage $ E_s $, and the initial inductance value should be calculated using the formulas provided in section 5.3 b) The DC current superimposed on the specimen must be modulated, and the inductance value measured The decrease from the initial inductance value should be calculated, and the DC saturation limited current determined by measuring the DC current at which the inductance decrease meets the specified criteria According to the detail specification, the decrease in inductance should be 10% or more.

NOTE 10 % is one of the design points typical for sharp-saturating inductors, and 30 % is one of the design points typical for soft-saturating inductors See Annex A.

Quality conformance inspection

The DC current specified in the detail specification shall be supplied to a specimen in accordance with the methods specified in 5.3 to 5.5, and then inductance shall be measured

The decrease in inductance shall be within the specified value

6 Measuring method of temperature rise limited current

General

When DC current is supplied to an inductor, the inductor generates heat by itself according to the supplied DC current value because of its DC current resistance

NOTE 1 Temperature rise results from self-heating of the inductor The sources of heating are DC copper losses,

AC copper losses and AC core losses are critical factors in determining temperature rise in specific applications This standard focuses on temperature increases caused solely by DC currents, but it is essential to also account for AC losses These AC losses are significantly influenced by the waveform, amplitude, and frequency of the current.

Setting a standard for AC temperature rise limited current is impractical due to the numerous ways AC current can be applied in various applications In DC to DC converters, AC losses are typically much smaller than DC losses Consequently, both manufacturers and users have commonly established DC temperature rise limited current as a reference point, which this standard also follows.

Test conditions

Unless otherwise specified in the detail specification, the test conditions shall be in accordance with Clause 4

Since the value of DC current resistance increases as a function of temperature, some applications require a high ambient temperature such as 85 °C, 105 °C or 125 °C for the temperature rise test

The overall power loss in an inductor arises from both DC power loss due to resistance from DC current and AC power loss from AC current in the windings, along with losses from the AC flux in the magnetic core As temperature rises, the resistance of the conductor increases, leading to higher power loss Core loss, which is solely due to AC excitation, decreases with temperature until it reaches a specific point known as the core loss minima temperature, after which it starts to increase The characteristics of the minima temperature and the extent of loss are influenced by the type and grade of the magnetic material used.

Most ferrites display distinct minima temperatures, unlike powder alloys This distinction is crucial when applying temperature rise currents in high-temperature applications, where both AC and DC power losses are significant The total loss at a specific temperature can be primarily influenced by either DC or AC loss, depending on the power loss distribution at room temperature and how each type of loss varies with temperature.

The variation of DC temperature rise limited currents with changes in ambient temperature can be predicted, but measuring these currents at elevated temperatures is often impractical Consequently, this standard typically recommends conducting measurements at room temperature.

Measurement jig

Printed-wiring board method

Printed-wiring board shall be made of epoxide woven glass (FR4) Unless otherwise specified in the detail specification, the dimensions shall be as shown in Table 1 and Figure 2

22 < I According to the detail specification a See Figure 2

Figure 2a) – Example of printed-wiring board for SMD type

Figure 2b) – Example of printed-wiring board for leaded type

Key solderable areas non-solderable areas (covered with non-solderable lacquer)

NOTE 1 a, b, c, d 1 , d 2 and p: according to the detail specification

NOTE 2 Materials of substrate: epoxide woven glass (FR4)

NOTE 3 Materials of pattern: copper

NOTE 4 Thickness of pattern: 0,035 mm ± 0,010 mm

NOTE 5 Pattern width (W): see Table 1

Figure 2 – Example of printed-wiring boards

Lead wire method

Unless otherwise specified in the detail specification, the wire diameter of lead wire to connect the inductor and the measurement circuit shall be in accordance with Table 2

Table 2 – Wire size of circuits

22 < I According to the detail specification NOTE 1 The wire size refers to MIL standard (MIL-PRF-15733)

NOTE 2 AWG is a wire diameter number of American Wire Gauge.

Measuring method and calculation

Resistance-substitution method

a) The specimen shall be connected to the circuit shown in Figure 3, by using the measurement jig specified in 6.3

The temperature rise measurement circuit utilizes the resistance substitution method After soldering the specimen, it should be allowed to cool adequately To ensure accurate measurements, the specimen must be placed inside a cubic box, approximately 20 cm on each side, which helps prevent temperature fluctuations caused by air flow Additionally, the box may feature vents at the top to avoid heat accumulation.

The specimen must be measured without direct contact to the test board When mounted on a printed-circuit board, it should also avoid direct contact with the test board Prior to supplying DC current, the resistance value of the specimen and the ambient temperature $ t_{a1} $ must be recorded DC current is then supplied from a direct power source, and once the DC voltage stabilizes, the values of DC current $ I_x $ and DC voltage are noted.

E x shall be measured by the ammeter and the voltmeter, and also ambient temperature t a2 shall be measured Then the resistance value R x shall be calculated by the following formula

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU. x x x

I x is the DC current value;

The resistance of the specimen, denoted as R x, is crucial for calculating the temperature rise value, t This value is determined using the metal's resistivity coefficient and the specimen's resistance It is essential that the absolute difference in temperature, |t a1 – t a2|, remains at 5 °C or lower.

The temperature rise value (\$t\$) is defined as the difference between the specimen's temperature when direct current (DC) is supplied (\$t_2\$) and the initial ambient temperature (\$t_{a1}\$) Additionally, it is important to consider the ambient temperature at the time of DC current application (\$t_{a2}\$).

R 1 is the resistance of winding at temperature t 1 = t a1 (Ω);

R 2 is the resistance of winding at temperature t 2 (Ω);

C is a material constant, with a value of 234.5 for copper The supplied DC current must be modulated, and the resulting temperature rise should be measured The temperature rise limited current is identified by measuring the DC current at the point when the temperature rise reaches the specified value in the detail specification, which should be set at 20 °C.

Thermo-couple method

a) The specimen shall be connected to the circuit shown in Figure 4, by using the measurement jig specified in 6.3

The temperature rise measurement circuit utilizes the thermo-couple method To ensure accurate readings, the specimen must be soldered and allowed to cool sufficiently It is essential to measure the specimen within a cubic box, approximately 20 cm on each side, to minimize temperature fluctuations caused by air flow Additionally, the box should feature vents at the top to avoid heat accumulation.

The specimen must be measured without direct contact to the test board When mounted on a printed-wiring board, this board should also avoid direct contact with the test board Additionally, the placement of the thermo-couple for accurate temperature measurement is crucial; it should be positioned where the inductor's maximum temperature is expected Optimal locations include direct contact with the specimen's surface, inside the coil, or beneath the coil before winding.

The measurement position must be clearly defined in the detail specification Prior to supplying DC current, the temperatures of the specimen (t₁) and the ambient environment (tₐ₁) should be recorded Once the DC current is applied from a power supply, the specimen's temperature will stabilize, at which point the temperatures (t₂ and tₐ₂) should be measured again The supplied DC current will be adjusted, and the temperature rise will be calculated using the specified formula.

The temperature rise value (\$t\$) is calculated using the formula \$t = t_2 - t_1 - (t_{a2} - t_{a1})\$, where \$t_1\$ is the initial temperature of the specimen, \$t_2\$ is the temperature when DC current is applied, and \$t_{a1}\$ and \$t_{a2}\$ are the initial and applied ambient temperatures, respectively The temperature rise limited current is determined by measuring the DC current at the specified temperature rise value, which should be set at 20 °C according to the detail specification.

Quality conformance inspection

The specified DC current will be supplied to the specimen following the methods outlined in sections 6.3 to 6.4, after which the temperature rise will be measured.

The temperature rise value of the specimen shall be within the specified value

The rated current for an inductor is determined by the lower value between the DC saturation limited current and the temperature rise limited current, as defined and measured according to the specified standard.

8 Information to be given in the detail specification

The following information shall be given in the detail specification.

Measuring method of DC saturation limited current

a) Frequency f s and voltage E s (see 5.3 b), 5.5 d)) b) Attachment jig (see 5.4) c) The allowable decrease in inductance (see 5.5 f))

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU. d) DC saturation limited current (see 5.6).

Measuring method of temperature rise limited current

a) Measurement jig (see 6.3) b) Measuring method (see 6.4) c) Temperature rise value (see 6.4.1 h), 6.4.2 h)) d) Measurement position (if thermo-couple method applied) (see 6.4.2 d)) e) Temperature rise limited current (see 6.5)

Example of recommended description on product specification sheets and catalogues

Both the DC saturation limited current value and the temperature rise limited current value should be described on product specification sheets and catalogues

It should be specified whether the DC saturation limited current value is determined when the allowable decrease in inductance value is at 10 % or 30 %

Sharp saturation is defined as inductance that decreases by more than 8 % for a 10 % increase in bias current, measured where bias current has already reduced the inductance by

Soft saturation refers to a condition in which the inductance decreases by less than 8% when the bias current is increased by 10% This measurement is taken after the bias current has already caused a 30% reduction in inductance compared to the unbiased state.

Sharp saturating inductors exhibit a significant decrease in inductance after reaching an inflection point, which is why they are designed to function at load currents below this critical threshold A standard specification point is typically set at 10%, as it represents a common design target However, alternative values like 20% or 30% can be established through mutual agreement between the manufacturer and the user.

Soft saturating inductors exhibit a gradual decline in inductance without a distinct inflection point They are engineered to function at load currents that can reduce inductance by 20% to 50%, or even more depending on the application A 30% reduction is commonly used as a standard specification point, representing a typical design scenario, though it is not an absolute requirement Other reduction values, such as 20%, may also be considered.

50 %, may be used by mutual agreement between manufacture and user

It should be specified whether the temperature rise limited current value is determined when the temperature rise of the inductor is at 20 °C or 40 °C

When the definition called a rated current is used, it should be the lower one of the DC saturation limited current value and the temperature rise limited current value

NOTE Unless otherwise specified in the detail specification, operating temperature is ambient temperature plus temperature rise of inductors

4.1 Conditions atmosphériques normales pour les essais 22

5 Méthode de mesure du courant continu limité en saturation 22

5.3 Circuit de mesure et calcul 23

5.4 Gabarit de fixation de la bobine d’induction 24

5.6 Contrôle de conformité de la qualité 24

6 Méthode de mesure du courant limité en échauffement 24

6.3.1 Méthode de la carte à circuit imprimé 25

6.3.2 Méthode du fil de sortie 28

6.4 Méthode de mesure et calcul 29

6.4.1 Méthode par substitution de résistance 29

6.5 Contrôle de conformité de la qualité 32

8 Informations devant figurées dans la spécification particulière 32

8.1 Méthode de mesure du courant continu limité en saturation 32

8.2 Méthode de mesure du courant limité en échauffement 32

Annexe A (informative) Exemple de description recommandée dans les fiches de spécification produits et les catalogues 33

Figure 1 – Circuit de mesure de l’inductance sous application de la condition de saturation en courant continu 23

Figure 2a) – Exemple de carte à circuit imprimé pour type de composant à montage en surface (CMS) 27

Figure 2b) – Exemple de carte à circuit imprimé pour type de composant à sortie 28

Figure 2 – Exemple de cartes à circuits imprimés 28

Figure 3 – Circuit de mesure de l’échauffement utilisant la méthode par substitution de résistance 29

Figure 4 – Circuit de mesure de l’échauffement utilisant la méthode du couple thermoélectrique 31

Tableau 2 – Taille du fil des circuits 29

COMPOSANTS INDUCTIFS À HAUTE FRÉQUENCE – CARACTÉRISTIQUES ÉLECTRIQUES ET MÉTHODES DE MESURE –

Partie 2: Courant assigné des bobines d’induction pour des convertisseurs continus-continus

The International Electrotechnical Commission (IEC) is a global standards organization that includes national electrotechnical committees Its primary goal is to promote international cooperation on standardization issues in the fields of electricity and electronics To achieve this, the IEC engages in various activities, including the publication of standards.

The International Electrotechnical Commission (IEC) develops Technical Specifications, Technical Reports, Publicly Available Specifications (PAS), and Guides, collectively referred to as "IEC Publications." The creation of these documents involves study committees, which allow participation from any national committee interested in the subject matter Additionally, international, governmental, and non-governmental organizations collaborate with the IEC in this process The IEC works closely with the International Organization for Standardization (ISO) under terms established by an agreement between the two organizations.

Official decisions or agreements of the CIS on technical matters aim to establish an international consensus on the topics under consideration, as each study committee includes representatives from the relevant national committees.

IEC publications are issued as international recommendations and are approved by the national committees of the IEC The IEC makes every reasonable effort to ensure the technical accuracy of its publications; however, it cannot be held responsible for any misuse or misinterpretation by end users.

To promote international unification, the national committees of the CIS commit to transparently implementing CIS international standards within their national and regional regulations Any discrepancies between CIS standards and corresponding national or regional standards must be clearly stated.

5) La CEI n’a fixé aucune procédure concernant le marquage comme indication d’approbation et sa responsabilité n’est pas engagée quand un matériel est déclaré conforme à l’une de ses normes

6) Tous les utilisateurs doivent s'assurer qu'ils sont en possession de la dernière édition de cette publication

The IEC and its administrators, employees, agents, including specialized experts and members of its study committees and national committees, shall not be held liable for any injuries, damages, or losses of any kind, whether direct or indirect This includes any costs, such as legal fees, arising from the publication or use of this IEC Publication or any other IEC Publication, or from the credit attributed to it.

8) L'attention est attirée sur les références Normatives citées dans cette publication L'utilisation de publications référencées est obligatoire pour une application correcte de la présente publication

Attention is drawn to the fact that some elements of this IEC publication may be subject to intellectual property rights or similar rights The IEC cannot be held responsible for failing to identify such property rights or for not indicating their existence.

La Norme internationale CEI 62024-2 a été établie par le comité d'études 51 de la CEI:

La présente version bilingue, publiée en 2009-02, correspond à la version anglaise

Le texte anglais de cette norme est issu des documents 51/937/FDIS et 51/941/RVD

Le rapport de vote 51/941/RVD donne toute information sur le vote ayant abouti à l'approbation de cette norme

La version franỗaise de cette norme n’a pas ộtộ soumise au vote

Cette publication a été rédigée selon les Directives ISO/CEI, Partie 2

Une liste de toutes les parties de la série CEI 62024, présentées sous le titre général

Composants inductifs à haute fréquence – Caractéristiques électriques et méthodes de mesure, peut être consultée sur le site web de la CEI

The committee has determined that the content of this publication will remain unchanged until the maintenance date specified on the IEC website at "http://webstore.iec.ch" in the data related to the publication in question At that time, the publication will be updated.

• remplacée par une édition révisée, ou

COMPOSANTS INDUCTIFS À HAUTE FRÉQUENCE – CARACTÉRISTIQUES ÉLECTRIQUES ET MÉTHODES DE MESURE –

Partie 2: Courant assigné des bobines d’induction pour des convertisseurs continus-continus

La présente partie de la CEI 62024 spécifie les méthodes de mesure des limites de courant continu assigné pour de petites bobines d’induction

Les méthodes de mesure normalisées pour la détermination des valeurs nominales permettent aux utilisateurs de comparer précisément les valeurs nominales courantes figurant dans les différents recueils de données fabricants

This standard applies to surface-mounted induction coils with outputs that conform to IEC 62025-1 dimensions, typically designed for a rated current of less than 22 A, although induction coils with a higher rated current may also be included.

22 A sont disponibles et s’intègrent dans les restrictions de dimensions de cette norme

Induction coils, typically measuring no more than 12 mm x 12 mm, are commonly utilized in DC-DC converters mounted on printed circuit boards (PCBs) They are essential components in electrical and telecommunications equipment, as well as in compact switching power supply units.

Les méthodes de mesure sont définies par les limites de saturation et d’échauffement induites uniquement par le courant continu

The following reference documents are essential for the application of this document For dated references, only the cited edition is applicable For undated references, the latest edition of the reference document applies, including any amendments.

CEI 60068-1, Essais d'environnement – Partie 1: Généralités et guide

The CEI 62025-1 standard outlines the non-electrical characteristics and measurement methods for high-frequency inductive components, specifically focusing on fixed inductors designed for surface mounting in electronic devices and telecommunications equipment This standard is currently available only in English.

Pour les besoins du présent document, les termes et les définitions suivants s’appliquent

3.1 courant continu limité en saturation valeur admissible de courant continu pour lequel la diminution de l’inductance se situe dans les limites de la valeur spécifiée

Conditions atmosphériques normales pour les essais

Les conditions atmosphériques normales pour les essais doivent être les suivantes (voir 5.3.1 de la CEI 60068-1):

En cas de litige ou si nécessaire, les mesures doivent être répétées en utilisant les températures de référence et les autres conditions données en 4.2.

Conditions de référence

A titre de référence, une des conditions atmosphériques normales pour les essais de référence issus du 5.2 de la CEI 60068-1 doit être sélectionnée et doit correspondre à ce qui suit:

5 Méthode de mesure du courant continu limité en saturation

Généralité

Lorsque le courant alternatif sur lequel est superposé le courant continu alimente une bobine d’induction, l’inductance de la bobine d’induction diminue selon la valeur du courant continu

In a typical application, the saturation current arises from the peak current resulting from the superposition of alternating current (AC) on direct current (DC) In this context, the saturation current is measured as a direct current that compensates for a low signal alternating current.

It is impractical to establish a standard for alternating current limited in saturation due to the infinite ways to apply alternating current in various applications Consequently, manufacturers and users typically define a limited direct current in saturation as a common reference point This standard follows the same approach.

Conditions d'essais

Sauf spécification contraire dans la spécification particulière, les conditions d’essai doivent être conformes à l’Article 4

The variation of the limited direct current in saturation, influenced by temperature, is dependent on the magnetic material and the core structure of the induction coil However, measuring saturation direct currents at high temperatures is often impractical during examinations Therefore, measurements at ambient temperature, as outlined in this standard, are typically used for specification purposes Curves indicating the reduction rate, which show the variation of limited direct current in saturation relative to the maximum operating temperature of the induction coil, can be generated These curves facilitate the correlation between the limited direct current in saturation at ambient temperature and that at operating temperatures.

Licensed to MECON Limited for internal use in Ranchi and Bangalore, supplied by Book Supply Bureau In certain cases, it may be necessary for the manufacturer and the user to agree on additional specifications for high temperatures, such as 85 °C, 105 °C, or 125 °C.

Circuit de mesure et calcul

Le circuit de mesure est illustré à la Figure 1

Alimentation en courant continu superposé

C condensateur de blocage à courant continu

Alimentations f s fréquence de la source

I r courant fourni à la gamme de résistance

Figure 1 – Circuit de mesure de l’inductance sous application de la condition de saturation en courant continu b) Calcul

The tensions E1 and E2 must be measured when the frequency fs and the tension Es of the signal generator are provided according to the specific requirements An initial value of inductance should be calculated using the following formulas.

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU. ó

R x est la résistance de l’éprouvette;

X x est la réactance de l’éprouvette;

L x est l’inductance série équivalente de l’éprouvette;

E 1 est la tension appliquée à l’éprouvette;

E 2 est la tension appliquée à la gamme de résistance (= I r R r ) (E 2 peut être considérée comme le courant); θ est la différence d’angle de phase entre E 1 et E 2

Gabarit de fixation de la bobine d’induction

Le gabarit de fixation de l’éprouvette doit être spécifié dans la spécification particulière.

Méthode de mesure

Before taking measurements, a small compensation must be made The test specimen should be connected to the circuit shown in Figure 1 using the specified mounting template in section 5.4 Once the specimen is connected by soldering, it should remain undisturbed until it has cooled sufficiently The voltages E₁ and E₂ must be measured when the signal generator's frequency fₛ and voltage Eₛ are provided according to the specific requirements, and an initial inductance value should be calculated using the formulas in section 5.3 b) The direct current superimposed on the specimen must be modulated, and the inductance value should be measured The decrease from the initial inductance value must be calculated, and the saturation-limited direct current should be determined by measuring the direct current when the inductance decrease corresponds to the value specified in the particular specification The specified decrease in inductance should be either 10% or 30%.

A 10% saturation level corresponds to a typical design point for marked induction coils, while a 30% saturation level represents a typical design point for low saturation induction coils For further details, refer to Appendix A.

Contrôle de conformité de la qualité

The specified direct current must be supplied to a test specimen according to the methods outlined in sections 5.3 to 5.5, after which the inductance should be measured The reduction in inductance must fall within the specified limits.

6 Méthode de mesure du courant limité en échauffement

Généralité

When direct current is supplied to an induction coil, the coil generates heat due to its resistance to the direct current.

The heating process is caused by the self-heating of the induction coil The sources of heat include copper losses in direct current, copper losses in alternating current, and other associated losses.

This standard, licensed to MECON Limited for internal use in Ranchi and Bangalore, focuses solely on the heating induced by direct currents In specific applications, it is essential to consider both copper losses and core losses due to alternating currents for accurate heating assessments The losses associated with alternating currents are significantly influenced by factors such as waveform, amplitude, and frequency.

It is impractical to establish a standard for alternating current limited by heating due to the infinite ways to apply it in various applications In DC-DC converters, the losses from alternating current are often significantly lower than those from direct current Consequently, manufacturers and users typically define a direct current limit based on heating as a common reference point, and this standard follows the same approach.

Conditions d'essais

Sauf spécification contraire dans la spécification particulière, les conditions d’essai doivent être conformes à l’Article 4

Etant donné que la valeur de la résistance en courant continu augmente en fonction de la température, certaines applications nécessitent une température ambiante élevée, telle que

The overall power loss in an induction coil results from both direct current (DC) resistance losses and alternating current (AC) losses due to the current in the windings and the corresponding alternating flux in the magnetic core The resistance of the conductor increases with temperature, leading to higher power losses associated with it Core losses are entirely due to AC excitation and decrease with rising temperature until reaching a minimum loss temperature, beyond which they begin to increase The minimum loss temperature and amplitude depend on the type and quality of the magnetic material, with most ferrites exhibiting distinct minimum temperatures, unlike powder alloys These factors must be considered when applying heating currents in high-temperature applications that experience significant AC power losses in addition to DC losses At any given temperature, total loss may be dominated by either DC or AC losses, depending on the distribution of power loss at ambient temperature and how each type of loss varies with temperature.

Regarding limited heating direct currents at high temperatures, the variation of the limited heating current in relation to ambient temperature changes can be predicted Additionally, measuring limited heating direct currents at elevated temperatures is typically impractical Therefore, measurements at ambient temperature, as outlined in this standard, are generally applied.

Gabarit de mesure

Méthode de la carte à circuit imprimé

The printed circuit board (PCB) must be made of epoxy fiberglass fabric (FR4) Unless otherwise specified in the particular specifications, the dimensions should adhere to those listed in Table 1 and Figure 2.

Courant assigné de la bobine d’induction

22 < I Conformément à la spécification particulière a Voir Figure 2

Figure 2a) – Exemple de carte à circuit imprimé pour type de composant à montage en surface (CMS)

Figure 2b) – Exemple de carte à circuit imprimé pour type de composant à sortie

Légende zones brasables zones non brasables (recouvertes par une laque non brasable) NOTE 1 a, b, c, d 1 , d 2 et p: conformément à la spécification particulière

NOTE 2 Matériaux du substrat: tissu de fibre verre époxyde (FR4)

NOTE 4 Epaisseur de l’impression: 0,035 mm ± 0,010 mm

NOTE 5 Largeur de l’impression (W): voir Tableau 1

Figure 2 – Exemple de cartes à circuits imprimés

Méthode du fil de sortie

Sauf spécification contraire dans la spécification particulière, le diamètre du fil de sortie destiné à connecter la bobine d'induction et le circuit de mesure doivent être conformes au

Tableau 2 – Taille du fil des circuits

Courant assigné des bobines d’induction

22 < I Conformément à la spécification particulière NOTE 1 La taille du fil se réfère à la norme MIL (MIL-PRF-15733)

NOTE 2 AWG correspond à un diamốtre de fil de l’ô American Wire Gauge ằ.

Méthode de mesure et calcul

Méthode par substitution de résistance

a) L’éprouvette doit être connectée au circuit illustré à la Figure 3, en utilisant le gabarit de mesure spécifié en 6.3

Figure 3 illustrates the measurement circuit for heating using the resistance substitution method When the specimen is connected by soldering, it should remain undisturbed until it has cooled sufficiently It is important to measure the specimen inside a cubic box approximately 20 cm on each side to prevent temperature variations caused by air circulation The box may include vents at the top to avoid heat retention inside.

The test specimen must be measured without direct contact with the test board When mounted on the printed circuit board, the specimen should not touch the test board Additionally, the resistance value of the specimen and the ambient temperature $ t_{a1} $ must be measured before applying the direct current.

Licensed to MECON Limited in Ranchi/Bangalore for internal use only, supplied by Book Supply Bureau The direct current must be supplied to the test specimen through a direct power source.

Once the DC voltage of the specimen stabilizes, the DC current $ I_x $ and the DC voltage $ E_x $ should be measured using an ammeter and a voltmeter, respectively Additionally, the ambient temperature $ t_{a2} $ must be recorded Subsequently, the resistance value $ R_x $ can be calculated using the appropriate formula.

I x est la valeur du courant continu;

The resistance of the specimen, denoted as R x, must be considered when calculating the temperature change, t, of the specimen This calculation should utilize the metal's resistivity coefficient along with the specimen's resistance It is essential that the absolute temperature difference, |t a1 – t a2|, remains at 5 °C or lower.

The variable $ t $ represents the heating value in degrees Celsius (°C), while $ t_2 $ indicates the temperature of the specimen when direct current is applied (°C) Additionally, $ t_{a1} $ denotes the initial ambient temperature (°C), and $ t_{a2} $ refers to the ambient temperature during the application of direct current (°C).

R 1 est la résistance de l’enroulement à la température t 1 = t a1 (Ω);

R 2 est la résistance de l’enroulement à la température t 2 (Ω);

The material constant for copper is C = 234.5 g It is essential to modulate the supplied direct current and measure the resulting heating The heating-limited current must be determined by measuring the direct current when the heating reaches the specified value in the particular specification The specified heating value should be either 20 °C or 40 °C.

Méthode du couple thermoélectrique

a) L’éprouvette doit être connectée au circuit illustré à la Figure 4, en utilisant le gabarit de mesure spécifié en 6.3

The measurement circuit for heating utilizes the thermoelectric couple method When the specimen is connected by soldering, it should remain undisturbed until it has cooled sufficiently It is important to measure the specimen inside a cubic box approximately 20 cm on each side to prevent temperature variations caused by air circulation The box may include vents at the top to avoid heat retention inside.

The test tube must be measured without direct contact with the test card When mounted on the printed circuit board, the board should not touch the test card It is essential to consider the correct positioning of the thermoelectric couple for temperature measurement, ideally placed where the maximum temperature of the induction coil occurs The optimal location may involve direct contact with the surface of the test tube, positioning the thermoelectric couple inside the coil, or placing it beneath the coil before winding.

The measurement position must be specified in the particular specification The temperature of the specimen, t₁, and the ambient temperature, tₐ₁, should be measured before applying the direct current The direct current must be supplied to the specimen through a continuous power supply.

Once the temperature of the test tube has stabilized, the temperature $ t_2 $ of the test tube and the ambient temperature $ t_{a2} $ must be measured again Additionally, the supplied direct current value should be modulated, and the heating value must be measured.

The equation $ (t_2 - t_a2)(t_1 - t_a1) t = - $ represents the heating value in degrees Celsius (°C), where $ t_1 $ is the initial temperature of the specimen, $ t_2 $ is the specimen's temperature when direct current is applied, $ t_{a1} $ is the initial ambient temperature, and $ t_{a2} $ is the ambient temperature during current application To determine the current limit for heating, it is essential to measure the direct current when the heating value reaches the specified limit in the particular specification The specified heating value should be either 20 °C or 40 °C.

Contrôle de conformité de la qualité

Le courant continu spécifié dans la spécification particulière doit être appliqué à une éprouvette selon les méthodes spécifiées en 6.3 et 6.4, ensuite la valeur de l'échauffement doit être mesurée

La valeur de l’échauffement de l’éprouvette doit correspondre à la valeur spécifiée

For any induction coil assigned a current characteristic, the designated current must be the lower value between the saturation-limited direct current and the heating-limited current, as defined and measured by the relevant standard.

8 Informations devant figurer dans la spécification particulière

Les informations suivantes doivent figurer dans la spécification particulière.

Méthode de mesure du courant continu limité en saturation

a) Fréquence f s et tension E s (voir 5.3 b) et 5.5 d)) b) Gabarit de fixation (voir 5.4) c) La diminution admissible de l’inductance (voir 5.5 f)) d) Courant continu limité en saturation (voir 5.6).

Méthode de mesure du courant limité en échauffement

a) Gabarit de mesure (voir 6.3) b) Méthode de mesure (voir 6.4) c) Valeur de l’échauffement (voir 6.4.1 h) et 6.4.2 h)) d) Position de mesure (s’il s’agit de l’application de la méthode du couple thermoélectrique)

(voir 6.4.2 d)) e) Courant limité en échauffement (voir 6.5)

Exemple de description recommandée dans les fiches de spécification produits et les catalogues

It is essential to include both the saturation-limited direct current value and the heating-limited direct current value in product specification sheets and catalogs.

Il convient de spécifier si la valeur du courant continu limité en saturation est déterminée lorsque la diminution admissible de la valeur de l’inductance se situe à 10 % ou 30 %

Marked saturation is defined as an inductance that decreases by more than 8% with a 10% increase in bias current, measured at a point where the bias current has already reduced the inductance by 30% compared to the inductance without bias In contrast, low saturation is characterized by an inductance that decreases by less than 8% for the same 10% increase in bias current, also measured under the condition that the bias current has reduced the inductance by 30% relative to the inductance without bias.

Saturation marked inductive coils experience a sharp drop in inductance beyond an inflection point, making them specifically designed to operate at load currents below this threshold A typical design specification uses 10% as the standard inflection point for optimal performance.

D’autres valeurs, telles que 20 % ou 30 %, peuvent être utilisées par accord mutuel entre le fabricant et l’utilisateur

Low-saturation inductance coils experience a continuous and gradual drop in inductance without a well-defined inflection point Consequently, they are specifically designed to operate under load currents that typically reduce inductance.

The typical design specification for applications ranges from 20% to 50%, with 30% often serving as a standard reference point However, this is not a mandatory design requirement Alternative values, such as 20% or 50%, can be established through mutual agreement between the manufacturer and the user.

Il convient de spécifier si la valeur du courant limité en échauffement est déterminée lorsque l’échauffement de la bobine d’induction se situe à 20 C ou 40 C

When defining an assigned current, it is important to use the lowest value between the saturation-limited direct current and the heating-limited current.

NOTE Sauf spécification contraire dans la spécification particulière, la température de fonctionnement correspond à la température ambiante plus l’échauffement des bobines d’induction

Tiêu đề	High Frequency Inductive Components – Electrical Characteristics and Measuring Methods – Part 2: Rated Current of Inductors for DC to DC Converters
Thể loại	standards
Năm xuất bản	2008
Thành phố	Geneva

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Số trang	38
Dung lượng	1,07 MB