The equipment is operating normally, yet EMC test results consistently exceed the limits? The issue may lie in the selection of the common-mode inductor.

When dealing with high‑current, high‑frequency switching power supplies, common‑mode inductors must not only suppress interference but also meet requirements for operating current, temperature rise, withstand voltage, noise‑frequency range, and mounting space. An improper selection can lead to inadequate filtering performance, excessive device temperature rise, or a physical form factor that cannot be accommodated.

Common-mode inductors primarily consist of a magnetic core, windings, and a base. Common winding configurations include:

Segmented winding: The two sets of windings are arranged separately, resulting in improved insulation and dielectric strength.

Parallel winding structure: The two winding groups are wound synchronously, resulting in high coupling and low leakage inductance; however, the inter-winding distributed capacitance may also increase, necessitating a comprehensive design that takes the target frequency band into account.

Common core materials used in common-mode inductors include:

Manganese-zinc ferrite: It has a high permeability and is suitable for suppressing low- to mid-frequency noise.

Nickel-zinc ferrite: It has a higher resistivity, making it more suitable for suppressing mid- to high-frequency noise.

Nanocrystals: It features high permeability and wide‑band characteristics, making it suitable for applications with stringent requirements for compact size, current handling, and broadband suppression.

Note: Core materials should be selected based on a comprehensive assessment of the target noise frequency band, operating current, temperature rise, and product dimensions.

Note: The images are for illustrative purposes only.
 

In new‑energy vehicles, electric compressors and PTC heaters typically operate under high‑current conditions, elevated temperatures, and complex electromagnetic environments. During high‑speed switching of power devices, common‑mode noise can be generated via the power supply lines, parasitic capacitances, and wiring harnesses, potentially degrading the performance of control circuits and communication interfaces and increasing the complexity of whole‑vehicle EMC testing and remediation.

For vehicle thermal management systems requiring high current and low losses , high voltage resistance and In response to the demand for miniaturization, Lika Electric Control has developed a custom common-mode inductor. ACM2825-151N。

This series employs a square magnetic core, resulting in higher leakage inductance and effectively reducing the risk of circuit self-resonance.
 

It can be used for common-mode noise suppression in high-current power circuits such as vehicle air-conditioning controllers, electric compressors, and PTC heating controls.

When selecting a common-mode inductor, you should not rely solely on its inductance value; you must also take into account the operating current, noise frequency range, temperature rise, voltage rating, and available mounting space.

When standard products fail to meet specific requirements, Lika Power Control can provide common-mode inductor selection, design, and customization services tailored to the customer’s circuitry and application needs.

Lika’s products cover the vast majority of thermal management applications, offering high reliability—validated through environmental testing, vibration tests, and temperature‑rise assessments under extreme high‑ and low‑temperature conditions.