Transformers have long been essential components in power supply systems, with the primary goal of reducing size, increasing power density, and achieving modular design. Although high-frequency conversion technology has been introduced to eliminate the need for bulky power-line frequency transformers, high-frequency transformers using ferrite cores are still required. While these ferrite-core transformers are smaller than their traditional counterparts, they still fall short of meeting modern modular requirements. They remain too large, generate significant heat, and exhibit non-negligible leakage inductance. As a result, researchers, engineers, and scholars have been actively exploring solutions to overcome these limitations. The development of high-frequency flat-panel transformers marks a major breakthrough in transformer technology. These transformers not only significantly reduce size but also offer low internal temperature rise, minimal leakage inductance, and efficiency as high as 99.6%. Moreover, their cost is about half that of conventional transformers with similar power ratings. They are suitable for various converter topologies, including single-ended forward, flyback, half-bridge, full-bridge, and push-pull configurations, especially for low-voltage, high-current applications. This makes them ideal for use in modern computer power supplies.
One of the key challenges in high-frequency operation of conventional transformers is **leakage inductance**. In an ideal transformer, all magnetic flux from the primary winding should pass through the secondary without any loss. However, in reality, some flux remains uncoupled, creating an inductance known as leakage inductance. This stored energy can cause noise when the transformer is turned off, resulting in high-frequency voltage spikes. The amplitude of these spikes is proportional to the product of the leakage inductance and the rate of change of current:
|Uspike| = Lleak × di/dt.
As operating frequency increases, the rate of current change also rises, making leakage inductance more problematic. This leads to higher EMI and potential damage to switching devices. To mitigate this, buffer circuits are often added, which increase losses and reduce overall efficiency.
Another issue is **inter-winding capacitance**, which becomes significant in multi-layer windings. The potential difference between layers creates parasitic capacitance, leading to increased losses during high-frequency charging and discharging cycles.
Additionally, **skin effect** and **proximity effect** further complicate high-frequency operation. Skin effect causes current to concentrate on the surface of conductors, increasing resistance, while proximity effect results in uneven current distribution due to magnetic field interactions. Together, these effects contribute to higher losses and thermal issues.
Conventional transformers also suffer from **local hot spots**, particularly in the core, which limits their suitability for high-density power systems. To reduce thermal stress, designers often lower the magnetic flux density, which increases the transformer's size and reduces its power density.
In contrast, **flat-panel transformers** address many of these issues. Unlike conventional transformers, which typically have multiple primary windings around a single core, flat-panel transformers use a single or few turns on the primary side, paired with multiple cores and secondary windings arranged in a compact module. This design enables tight coupling, significantly reducing leakage inductance—measured at just 2.0 nH in a 30A model. This makes them ideal for fast-switching circuits, where minimizing losses and component stress is critical.
Flat-panel transformers also exhibit superior frequency performance, operating efficiently between 100 kHz and 500 kHz. Their design allows for direct mounting on a heatsink or baseplate, ensuring excellent thermal management and eliminating hot spots. With a large surface area and compact form factor, they provide a reliable solution for high-power density applications. Overall, flat-panel transformers represent a significant advancement in power electronics, offering improved performance, efficiency, and reliability compared to traditional designs.
Air Pressure Type Heat Shrink Tubing For Fibre Optic Connector Box
Air pressure type heat shrink tubing for fibre optic connector box
Air pressure type heat shrink tubing for fibre optic connector box,Heat-shrink tube,Heat shrinkable tubing,thermal contraction pipe,Shrink tube
Mianyang Dongyao New Material Co. , https://www.mydyxc.com