The global shift toward electric vehicles (EVs) has placed unprecedented demands on charging infrastructure. As charging piles move toward higher power density and faster charging speeds (Level 3 DC Fast Charging), the selection of magnetic components—specifically Nanocrystalline Cores—becomes a critical factor in determining system efficiency, thermal management, and EMI performance.
In this technical guide, we will analyze the key parameters engineers must consider when selecting nanocrystalline cores for EV charging applications.
High Saturation Induction (Bs): Typically 1.25 T, nearly three times that of MnZn ferrites (0.45 T). This allows for a significant reduction in core volume.
High Permeability (μ): Provides superior impedance at lower frequencies, making it idealfor Common Mode Chokes (CMC)to filter grid-side noise.
Excellent Thermal Stability: With a Curie temperature (Tc) above 560℃, its magnetic properties remain stable even in the harsh thermal environments of a 30kW or 60kW power module.
EV charging piles typically operate at switching frequencies between 20 kHz and 100 kHz.
The Goal: Minimize core loss to prevent overheating.
The Selection: Look for nanocrystalline ribbons with a thickness of 18-25μm. Thinner ribbons reduce eddy current losses. When reviewing data sheets, ensure the Pcu curve at 20 kHz/0.2T is within your thermal budget.
The charging pile generates significant electromagnetic interference (EMI).
High Permeability (80,000 to 150,000μ): Choose this for low-frequency noise suppression (150 kHz-30 MHz).
The Tip: For high-power DC chargers (>120 kW), ensure the core has a high "Saturation Current" capability. You don't want the CMC to saturate during a surge, losing its filtering ability.
The environment inside a charging station can reach 70°C to 80°C ambient.
Casing: Choose PBT or PPS plastic cases that can withstand 155°C (Class F) or higher.
Fixing: Ensure the core is fixed with high-grade silicone oil or specialized epoxy to prevent magnetostriction noise (humming) and to protect the brittle ribbon from mechanical stress.
|
Component Type |
Core Material Focus |
Recommended Core Shape |
|
Input EMI Filter |
High μ, High Bs |
Toroidal (Ring) Core |
|
Main Transformer |
Low Loss, High Bs |
Oval or Rectangular Stacked Core |
|
PFC Inductor |
High Saturation, DC Bias stability |
Gapped Nanocrystalline Core |
One common mistake in EV pile design is ignoring the DC Bias characteristic. In many charging scenarios, the magnetic core must handle a composite signal (AC + DC).
Pro Tip: When selecting a core for an output filter or a transformer, always request the B-H curve under high temperature (100 °C). Nanocrystalline cores maintain a much flatter B-H loop compared to ferrites, but you must ensure the operating point doesn't drift into the saturation region during a peak load.
Choosing the right nanocrystalline core is a balance between magnetic performance, space constraints, and cost. For EV charging pile manufacturers, the core is not just a component; it is the heart of the power conversion efficiency.
At BIDRAGON, we specialize in customized nanocrystalline solutions for the EVSE (Electric Vehicle Supply Equipment) industry. From high-permeability ribbons to finished toroidal cores with specialized coatings, we provide the data-backed reliability your project requires.