Quels paramètres doivent être pris en compte dans le choix des inductances de puissance ?

2022-09-28
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1. Nominale inductance évaluer

Measure the inductance évaluer at a frequency of 100KHz. The test frequency is not fixed, and the test frequency of the nominal inductance évaluer of different products is also different, and the manufacturer will indicate it in the product catalog.

2. Fréquence d'auto-résonance

Selon la fréquence à laquelle l'inductance et capacité parasite resonate, the critical frequency that acts as an inductor. The impedance of an ideal inductor increases as the frequency increases. However, due to the existence of capacité parasite and parasitic resistance, the actual inductance is inductive at a certain frequency, and capacitive when it exceeds a certain frequency. On the contrary, the impedance decreases with the increase of frequency. This frequency is the critical frequency.

3. Résistance CC

The resistance when applying direct current is mainly the resistance of the winding. Due to this impedance évaluer, power loss occurs due to heat generation, so the smaller the DC impedance, the less the loss. However, there is a trade-off relationship between reducing Rdc, DC superposition characteristics, and size reduction. It is sufficient to select a product with a smaller Rdc from among the above-mentioned inductors that satisfy the necessary characteristics such as inductance and rated current.

4. Courant nominal

The rated current specifies the upper limit of the current évaluer, and when the passing DC current exceeds this évaluer, the quality cannot be guaranteed. There are two rated currents for power inductors, one is the allowable current for DC overlap, and the other is the allowable current for temperature rise. Each has important meanings, and technical specifications are often recorded separately. If only one rated current is specified, it is generally specified according to the smaller of the DC overlap and the temperature rise.

5. Courant admissible de chevauchement CC

When a current flows through an inductor, the magnetic saturation of the magnetic material occurs, and the inductance decreases. This characteristic is called the DC superposition characteristic. The DC superimposed allowable current, also known as the saturation allowable current, specifies the current évaluer when the inductance decreases by a certain percentage relative to the initial characteristics of the non-superimposed current, generally by 10% to 30%, depending on the product specification.

6. Courant admissible pour l'élévation de température

The rated current is specified with the heating of the components as the index. Use beyond this range will cause damage to the components or failure of the components. Generally, it is specified according to the current évaluer at which the temperature rises by 20~40°C (depending on the product specification) when a DC current is applied.

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