Advantages of different types of power inductors

2023-11-03

This time, we will explore various types of power inductors. Let’s take a look at the advantages and technologies behind each structure.

Winding Ferrite

Winding ferrite involves coiling copper wire in a spiral around a ferrite core. Many of Murata's winding ferrite offerings feature a coating of magnetic resin on the copper wire, which serves to diminish leakage flux, enhance inductance performance, and boost durability. Given the high magnetic permeability of ferrite material, winding ferrite is particularly beneficial for applications requiring high inductance. This technology is widely used in various products such as smartphones, TVs, hard disk drives, and more.

Multilayer Ferrite

Multilayer ferrite inductors consist of alternating layers of magnetic material and inner electrodes that are laminated and sintered together. This structure allows for a more compact and low-profile design compared to winding structures. While the use of winding Metal Alloy has grown to meet demands for smaller sizes and lower inductance, the properties of multilayer ferrite are particularly valuable in applications that require both a small footprint and high inductance along with high voltage.

Winding Metal Alloy inductors

They are created by bonding coiled wire and resin-coated metallic magnetic powder using thermocompression. This technique is adaptable for use in high-current applications across a variety of product sizes, from large to small. Although metal magnetic materials exhibit lower magnetic permeability compared to the ferrite materials mentioned below, they offer superior DC superposition characteristics, making them well-suited for high-current applications. With the recent trend towards high-speed switching in DC-DC converters, there is a growing requirement for low inductance, positioning Winding Metal Alloy as a predominant choice in much of the market.

Additionally, the excellent temperature characteristics of these materials compared to ferrite provide a significant benefit. Since changes in magnetic permeability due to ambient temperature are minimal, they can uphold stable DC superposition characteristics even under high temperature conditions. The broad array of target markets for these materials includes automobiles, smartphones, hard disk drives, and more.

Comparative analysis of power inductor performance

When evaluating the performance of power inductors, the key aspects to consider include 1) inductance value, 2) DC superposition characteristic, 3) temperature characteristic, 4) voltage endurance, and 5) leakage flux. Understanding these elements is crucial for choosing the right power inductor structure that meets the necessary performance requirements.

1)Inductance value

The available range of inductance values depends on the inductor’s design. Winding ferrite inductors can achieve a broad spectrum of inductance values, starting from those with high magnetic permeability, reaching inductance levels of 10 µH or higher. In contrast, multilayer ferrite inductors, which are more compact than winding ferrite types, typically offer lower inductance values of up to 10 µH. Similarly, Winding Metal Alloy is recognized for its lower inductance values, also generally 10 µH or less, which are influenced by the properties of the materials used.

2) DC superposition characteristic

In high-current applications, such as digital circuits, it's crucial to use a power inductor whose inductance remains stable under high current loads. This is often referred to as having a robust DC superposition characteristic. Stability in inductance ensures that ripple currents do not fluctuate, thereby maintaining consistent circuit performance. Winding Metal Alloy inductors are particularly effective in this regard because they are less prone to magnetic saturation compared to ferrite materials, thus offering superior DC superposition properties.

3)Temperature characteristic

When power inductors operate at high temperatures, such as within an automobile's power supply circuit, temperature characteristics become crucial. Magnetic materials exhibit a property where their magnetic permeability varies with temperature. However, metal magnetic materials experience less variation in magnetic permeability due to temperature changes compared to ferrite materials, demonstrating superior performance in this respect.

For winding Metal Alloy, there are negligible variations in both inductance value and DC superposition characteristics across temperatures. Figure 1-17 illustrates the DC superposition characteristics of winding Metal Alloy compared to ferrite materials over a range of ambient temperatures from 25°C to 125°C. It is evident that the performance of winding Metal Alloy remains consistent between 25°C and 125°C.

4) Voltage endurance

In circuits such as LED drivers or other voltage-boosting applications, and in power supply circuits with a high step-down voltage ratio, the voltage endurance of power inductors is critical. In the case of winding Metal Alloy, insulation is achieved by encapsulating the metal magnetic powder in an insulating resin. However, this insulation is generally less effective compared to that provided by winding ferrite. Therefore, despite its many superior attributes, it is crucial to verify the performance of winding Metal Alloy in scenarios that demand high voltage endurance.

5) Leakage flux

Leakage flux from an inductor can interfere with nearby circuits, resulting in noise that may cause signal degradation or malfunctions, especially in power supply circuits where component spacing is limited. The amount of leakage flux significantly depends on the inductor's structure. The closed magnetic circuit designs of winding Metal Alloy and multilayer ferrite are beneficial in minimizing this issue. These configurations allow both winding Metal Alloy and multilayer ferrite to effectively reduce external leakage flux while achieving the same level of inductance, as depicted in Figure 1-18. Comparative data on leakage flux by structure is presented in Figure 1-19, which illustrates that winding Metal Alloy and multilayer ferrite manage to keep leakage flux at lower levels compared to winding ferrite.

When selecting a power inductor, it's important to compare various performance attributes to find the best match for your specific application. Please refer to the provided comparison table, which summarizes key performance aspects such as inductance value, DC superposition characteristics, temperature stability, voltage endurance, and leakage flux. This table will help guide you in choosing the power inductor that aligns optimally with your application's requirements, ensuring efficient and reliable operation.

Hongda Capacitors offers wind range of inductors, which includes Wire Wound, Molding Type, Coil Type, Multilayer Ceramic Type, Multilayer Ferrite Type, and Winding Type inductors. Welcome to share your parameter with us to get best offer. Thank you.