The transformer core (also known as the magnetic core) is the central magnetic circuit component of a transformer. Its material selection directly affects the transformer's efficiency, losses, and applicable scenarios. Based on operating frequency, power requirements, and cost factors, core materials can be categorized into the following types:   1. Traditional Silicon Steel Sheets (Fe-Si Alloy):​​ Composition: Cold-rolled steel sheets with silicon content ranging from 0.8% to 4.8% , typically with a thickness of  0.35mm or thinner​. Characteristics: High saturation magnetic induction (Bs≈1.6–1.7T), suitable for high-power scenarios at power frequencies (50/60 Hz). Laminated stacking: Insulating coatings are applied between layers to reduce eddy current losses. However, losses increase significantly at high frequencies​. Applications: Primarily used in power transformers and motor cores for low-frequency, high-power electrical equipment.   2. Ferrite Core​ Composition: Manganese-zinc (MnZn) or nickel-zinc (NiZn) ferrite, classified as sintered magnetic metal oxides. Characteristics: High resistivity: Significantly reduces eddy current losses at high frequencies, suitable for a ​frequency range of 1 kHz——1 MHz​ . Low saturation flux density (Bs ≈<0.5T), weak DC bias capability, and prone to magnetic saturation. Applications: Widely used in electronic devices such as switch-mode power supplies (SMPS)​, ​high-frequency transformers, and inductors.   3. Metal Magnetic Powder Cores Types: Iron powder cores Iron-silicon-aluminum powder cores (FeSiAl) High-flux powder cores (HighFlux) Molybdenum permalloy powder cores (MPP) . Characteristics: Strong anti-saturation capability: Reduces eddy currents through insulation-coated dispersed magnetic particles, making it suitable for DC superposition scenarios . Medium permeability (μe≈10—125) with a frequency range of 10 kHz - 100 kHz​ . Applications: Widely used in medium-to-high-frequency power devices such as: ​PFC inductors (Power Factor Correction) ​Filter inductors.   4. Novel Alloy Materials​ Amorphous Alloys​ Composition: Iron-based (e.g., Fe₈₀B₁₀Si₁₀) or cobalt-based amorphous ribbons, characterized by disordered atomic arrangement​ . ​Advantages: ​Ultra-low core losses (only 1/5 of silicon steel), enabling significant energy savings . Limitation: Significant magnetostriction (resulting in higher operating noise) . ​Applications: Energy-efficient distribution transformers.   Nanocrystalline Alloys​ ​Structure: ​Nano-scale crystalline grains (<50 nm) embedded in an amorphous matrix . ​Advantages: ​High permeability & low losses (superior to ferrites at 50 kHz) . ​Strong harmonic resistance and excellent thermal stability (operating range: -40–120°C) . ​Applications: ​High-frequency transformers and PV inverters​ . ​EV electric drive systems (e.g., integrated OBC/DC-DC modules）   Key Factors in Material Selection​ ​Operating Frequency​ ​Low Frequency (≤1 kHz) : ​Silicon Steel or Amorphous Alloys (e.g., Fe₈₀B₁₀Si₁₀). High Frequency (>10 kHz) : ​Ferrite Cores (MnZn/NiZn) or Nanocrystalline Alloys.   Loss Requirements​ ​Lowest Core Loss: ​Amorphous/Nanocrystalline Alloys. High-Frequency Loss Optimization: ​Ferrites.   Cost and Process ​Cost-Effectiveness & Maturity: ​Silicon Steel. High Initial Cost with Long-Term ROI: ​Amorphous/Nanocrystalline Alloys.​