* Product Parameters
Operating frequency:10kHz-500KHz Operating temperature:-40℃ to +125℃ Storage temperature:-25℃ to +85℃ Storage humidity:30 to 95%
* Features In terms of structure, the EE4 transformerStandardized, low-cost, easy to wind and install; large window area, convenient for safety design. In terms of power, it has a moderate power range, wide applicability, adjustable air gap, flexible design, high saturation flux, and can reduce the number of turns. For thermal management, its large surface area provides good natural heat dissipation.
* Typical application areas
* Product Standards UL, RoHS, 3C,CQC
* Size Specifications 
Type | Structure
Tурe | Dimension（mm） | Pin Row （mm） | Row Pitch（mm） | OD Pin（mm） | note | A | B | C | Pin | E | F | EE40-001 | Vertical | 41.0 | 28.0 | 34.0 | 6+6 | 5.0 | 22.6 | Φ0.80 |
| EE40-002 | Horizontal | 41.0 | 32.0 | 28.5 | 7+7 | 5.0 | 25.8 | Φ0.80 |
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*The above are commonly used skeleton styles for the company.,Other styles are not included.,Inquiries are welcome. Our company can customize various specifications according to customer requirements.High-frequency transformer.
EE40 Transformer Electrical Performance Analysis The EE40 transformer (external span A=40mm) belongs to the ultra-high-power high-frequency transformer category. Compared to high-power models like the EE33 and EE35, its core's effective cross-sectional area (Ae) and window area (Aw) achieve a significant leap, reaching industrial top-tier standards in power handling capability, thermal stability, and insulation reliability. Its core electrical performance is determined by core material selection, winding process design, topology scheme matching, and heat dissipation system configuration, making it suitable for 500–1000W ultra-high-power supply scenarios. The following analysis covers core parameters, performance influencing factors, typical applications, and optimization directions. I. Core Electrical Performance Parameters (Baseline Conditions: 100kHz, LLC Resonant Topology) Parameter Category | Key Indicators | Typical Value / Range | Explanation | Basic Electromagnetic Parameters | Inductance (L) | 15mH–200mH | Determined by core AL value, turns, and air gap; tolerance ±0.3% to ±1%; high air gap adjustment precision, suitable for ultra-high-power resonant topologies. | Leakage Inductance (Lk) | 0.05%–0.3% of L | Under same process, leakage inductance is far lower than medium and small power cores, significantly reducing voltage spikes and simplifying EMI filter design. | DC Resistance (DCR) | Primary: 0.01–0.4Ω; Secondary: 0.003–0.15Ω | Extra-large window area allows for large wire diameter or multiple parallel strands, achieving industry-leading copper loss control. | Loss & Efficiency | Core Loss (Pc) | 2000–4000mW | Increases with frequency/flux density; N97 material's high-frequency loss is over 40% lower than N87, with excellent high-temperature resistance. | Copper Loss (Pcu) | 2500–5000mW | Affected by current density/winding process; Litz wire effectively suppresses skin effect above 200kHz. | Efficiency (η) | 97%–99.5% | Higher efficiency than EE35 at equivalent power; full-load efficiency in LLC topology can exceed 99%. | Safety & Insulation | Isolation Withstand Voltage | Primary-Secondary: 15–20kV AC/1min | Bobbin barrier height ≥25mm, creepage distance ≥20mm, meeting medical Class A and heavy-duty industrial equipment safety standards. | Insulation Resistance | ≥20000MΩ (500VDC) | Excellent moisture and salt spray resistance, suitable for outdoor and high-humidity industrial environments. | Thermal Performance & Endurance | Operating Frequency | 5kHz–500kHz | Saturation risk is negligible at low frequencies, high-frequency loss is controllable, covering scenarios from power frequency critical points to high-frequency switching supplies. | Output Power | 500–1000W | 600W with natural convection; up to 1000W with water cooling + finned heatsink. | Operating Temperature | -40℃~+280℃ | Compatible with HC (250℃) and NH (280℃) insulation systems; full-load temperature rise ≤75℃. |
II. Key Factors Affecting Performance 1. Core Characteristics: Core Support for Ultra-High-Power Handling Advantage of external span A=40mm: Effective cross-sectional area (Ae) increases by approximately 60% compared to EE35, geometrically enhancing flux handling capability, making core saturation risk under high-current conditions virtually zero. The significantly larger window area (Aw) can accommodate large-diameter windings, multi-layer insulation structures, and shielding layers simultaneously, meeting design needs for high inductance, low copper loss, and high insulation. Air Gap Design: Optimal air gap range is 1.5–4.0mm.
Forward Topology: Requires a very small and uniform air gap (1.5–2.5mm) to ensure fast core reset.
Flyback Topology: The air gap can be increased (3.0–4.0mm) to significantly boost saturation current and short-term overload capability.
LLC Resonant Topology: Requires high-precision air gap grinding to ensure high matching between magnetizing inductance and resonant parameters, reducing resonant circulating current loss.
Material Selection:
N97: Suitable for high-frequency, ultra-high-power scenarios (50–500kHz), offering low loss, high permeability, and high-temperature resistance. Preferred for industrial inverters and large energy storage power stations.
3C94: Suitable for 200–500kHz, offering balanced cost-effectiveness, ideal for consumer electronics ultra-high-power adapters.
N27: Suitable for high-temperature (>200℃) industrial scenarios, with higher Curie temperature and stronger thermal stability.
2. Winding Design: Key to Losses and Stability Turns Ratio & Wire Gauge: The turns ratio determines the voltage conversion ratio. For 500–1000W supplies, primary wire diameter is recommended at 2.0–4.0mm, secondary at 3.5–5.0mm. For high output current, the secondary uses 20–30 parallel strands of 1.5mm wire to maximize suppression of skin and proximity effects. Winding Technique: Using interleaved winding (e.g., primary-secondary-primary-secondary) plus a six-layer copper foil shield can control leakage inductance to within 0.1% of the main inductance. A five-layer insulation barrier of Nomex paper + polyimide film + epoxy board + insulating adhesive + ceramic insulating sheet between primary and secondary meets high isolation withstand voltage requirements. For high-frequency operation, use Litz wire with strand diameters of 0.3–0.4mm, reducing high-frequency copper loss by 50–60%. Insulation Design: Inter-layer insulation thickness ≥0.5mm, primary-secondary creepage distance ≥20mm, meeting safety standards like UL60601-1 (Medical Class A) and UL508C (industrial control equipment), suitable for high-reliability, ultra-high-power scenarios. 3. Topology Matching: Core to Efficiency and Reliability
LLC Resonant Topology: Suitable for 800–1000W high-efficiency power supplies, efficiency can exceed 99%. The low leakage inductance of EE40 reduces resonant loss and improves system dynamic response, making it the preferred topology for large energy storage power stations, charging piles, and server power supplies.
Forward Topology: Suitable for 500–800W low-ripple power supplies, requiring an active clamp + synchronous rectification + current sharing circuit. The large Ae reduces flux density, decreasing core loss, suitable for precision industrial control power supplies and large medical equipment power supplies.
Flyback Topology: Suitable for 500–600W cost-effective solutions. Compared to EE35, it can use fewer turns and larger wire diameter, further reducing copper loss. Short-term overload capability can reach 300% of rated load.
4. Operating Conditions: Ensuring Long-term Stable Operation
Frequency: Core loss is proportional to the square of frequency. When frequency exceeds 300kHz, prioritize low-loss materials like N97 or 3C94. When frequency is below 10kHz, flux density should be further reduced to avoid core saturation.
Temperature: High temperature reduces permeability and increases losses. Ensure core operating temperature does not exceed the Curie temperature (~240℃ for N97). Using a combined cooling system of thermal grease + aluminum finned heatsink + water cooling can reduce temperature rise by 50–60℃.
Load Rate: Optimal efficiency typically occurs at 85–95% load. Under light load (<20%), optimize winding distributed capacitance to reduce standby loss to below 150mW.
III. Performance Optimization Suggestions
Material Optimization: Use N97 instead of 3C94 for high-frequency, ultra-high-power scenarios; choose N27 for high-temperature industrial scenarios; PC44 can be used for cost-sensitive consumer electronics.
Winding Optimization: Mandate the use of Litz wire for frequencies ≥200kHz. Employ interleaved winding + six-layer copper foil shielding to control leakage inductance within 0.05%.
Thermal Optimization: Apply high thermal conductivity coating on the core surface and attach a large-area finned heatsink + water cooling pipes. Design an independent circulating air duct to improve heat dissipation efficiency.
Parameter Matching: For LLC topology, prioritize magnetizing inductance accuracy (tolerance ±0.3%). For Forward topology, reduce the air gap and match active clamp parameters. For Flyback topology, increase the air gap to enhance saturation resistance.
Summary of Core Characteristics of EE40 Transformer The EE40 transformer is a classic medium-power magnetic component with distinctive characteristics that require careful trade-offs in engineering design. I. Main Advantages and Characteristics High Cost-Effectiveness and Popularity
Mature Structure: The E-E core assembly features a simple structure, high levels of standardized mold-based production, and low manufacturing cost.
Complete Accessories: Standardized bobbins and core clips (clippers) are readily available, facilitating automated winding, assembly, heat dissipation, and electrical insulation.
Excellent Thermal Management Capability
Large Surface Area: The core is flat with substantial exposed surface area, which is conducive to heat dissipation through radiation and convection.
Easy Thermal Conduction: The core can easily make contact with heat sinks, or thermal gaps can be filled with thermal adhesive, simplifying and enhancing the effectiveness of thermal management design.
High Design Flexibility
Adjustable Air Gap: The effective permeability (AL value) can be precisely adjusted by grinding the center leg or inserting an air gap material. This prevents magnetic saturation and allows for flexible design of the desired inductance, making it highly suitable for energy-storage transformers like those in flyback converters.
Convenient Manufacturing and Maintenance
Easy Winding: Pin-type bobbins are suitable for both manual and machine winding. Multi-section bobbins facilitate the layout of multiple windings, insulation, and taps.
Easy Installation: Standard pins allow for direct soldering onto PCBs, providing good mechanical stability.
II. Inherent Limitations and Disadvantages Relatively High Leakage Inductance (Structural Disadvantage)
Cause: Primary and secondary windings can typically only be layered on the bobbin, making it physically challenging to achieve highly interleaved windings. This results in magnetic coupling that is less tight compared to toroidal or PQ-type cores.
Consequence: Higher voltage spikes are generated during switch turn-off, necessitating the design of snubber circuits (e.g., RCD, clamp circuits) to protect the power switching transistors. This increases losses and component costs.
Challenges in Electromagnetic Interference (EMI) Control
Cause: Higher leakage inductance implies greater magnetic field leakage. Furthermore, its flat structure makes its windings act like a "magnetic dipole" antenna.
Consequence: Conducted and radiated EMI are relatively more difficult to manage. Typically, more comprehensive shielding (e.g., adding copper foil, using enclosures) and filtering measures are required.
Limited Power Density
Cause: Its rectangular window has a lower copper fill factor, and the ratio of its center leg's cross-sectional area to volume is lower compared to circular cores like PQ or RM types, which are specifically optimized for high-frequency operation.
Consequence: For the same physical volume, the maximum power handling capability or peak efficiency of an EE40 transformer is generally lower than that of the aforementioned alternatives, making it less compact.
EE40 Transformer Applications Leveraging its core advantages of ultra-high power coverage (500–1000W), ultra-high efficiency, and top-tier insulation stability, the EE40 transformer is widely used in high-power scenarios including industrial heavy-duty equipment, energy storage & charging, medical electronics, and commercial lighting. Specific applications are as follows: Industrial Heavy-Duty Power Systems
800–1000W industrial frequency converters, high-power servo drives, and CNC machine tool main power supplies, capable of stable operation in an ultra-wide temperature environment of -40℃ to +280℃. 15–20kV high isolation withstand voltage protects against industrial high-power electrical interference, ensuring long-term reliable equipment operation.
Large industrial control cabinet power supplies and automated production line power modules, where low leakage inductance characteristics reduce voltage spikes, adapting to complex industrial electromagnetic environments.
Energy Storage & Charging Pile Equipment
1000W-class portable power stations and RV/camper power supply systems, supporting 220V AC output. High-efficiency characteristics extend the runtime of energy storage batteries; coupled with water-cooling solutions, they can meet the demand for prolonged full-load outdoor operation.
DC charging pile core modules (500–1000W) and high-power automotive inverters, which tolerate automotive vibration and voltage fluctuations, adapting to voltage conversion for 12V/24V automotive power systems and energy storage battery systems.
Large Medical Electronic Equipment
Main power supplies for large medical equipment such as CT scanners, MRI machines, and hemodialysis systems, meeting UL60601 Medical Class A safety standards. High insulation resistance (≥20000MΩ) and low leakage current design ensure electrical safety for patients and medical personnel.
Power supply units for large ventilators and biochemical analyzers, providing stable voltage output to prevent instrument data deviation, suitable for the continuous, uninterrupted operation required by medical equipment.
Commercial & Outdoor High-Power Lighting
800–1000W LED sports venue lighting, high-mast streetlights, and port/wharf lighting driver power supplies, supporting a high power factor (PF≥0.998) and low harmonic distortion (THD≤1%), complying with national energy-saving lighting standards.
Power supply modules for outdoor large-scale advertising displays and landscape lighting projects, featuring moisture and salt spray resistance to withstand harsh outdoor environments, and wide-temperature capability to tolerate day-night temperature swings and extreme weather.
High-End Consumer Electronics Power Supply Equipment
1000W high-power laptop adapters and specialized power supplies for gaming PCs. Low-loss characteristics reduce device heat generation, improving overall system stability; compact design balances high-power needs with portability requirements.
Home energy storage inverters and high-power household backup power supplies, suitable for home emergency power scenarios, supporting short-term power supply for high-power home appliances like refrigerators and air conditioners.
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