Future Transformer Development Trend-Planar Transformer

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Future Transformer Development Trend-Planar Transformer [Copy link]

The development of micro transformers is the demand of today's electronic and information technology. The miniaturization of transformers is an inevitable trend in the development of transformer technology. At present, the planar transformer with ferrite as the core is small in size and high in power density, which is the mainstream of micro transformers. Thin film transformers with micro-manufacturing technology are in the development stage, but their promotion and application are still individual cases. With the rapid development of electronic technology, ferrite planar transformers will still play a major role in high-power module power supplies. Application of planar transformer technology In just over 10 years since its advent, planar transformers have been widely used in communications, notebook computers, automotive electronics, digital cameras and digital televisions. For example, DC-DC converters with a power range of 560W made of planar transformers have been used in plug-in card-type on-board power supplies in telecommunications systems. The special electrical and mechanical environment in automobiles puts forward more stringent requirements on transformer design and process. DC-DC converters used in planar transformers for xenon arc lamp ballasts have been used in mid-range cars. Secondly, planar transformers for broadband transmission applications also show good development prospects. In addition, the product varieties of planar transformers have involved various aspects of conventional ferrite core transformers such as power transformers, bandwidth transformers and impedance matching transformers. Due to its good consistency and small size, it is particularly suitable for use in electronic equipment with small internal space and strict requirements on energy saving and heat dissipation. The application of planar transformers in fields such as national defense, aviation, and aerospace, which have extremely high requirements on weight and stability, will also open up a new situation for the miniaturization of systems. In short, miniaturized and planarized inductor ferrite components will arouse more interest in people's applications. It is believed that in some high-tech fields, planar transformers will soon replace traditional transformers and gradually realize large-scale production.

Structural principle of planar transformers Planar transformers usually have two or more cylindrical cores of the same size. Now, we will take the planar transformer with two magnetic cores as an example to introduce its structure, as shown in Figure 1. The two corners of each magnetic core column on the diagonal line are connected with copper sheets, and the copper sheets are close to the inner wall of the magnetic core when passing through the magnetic core column. The two magnetic cores are placed side by side, and the adjacent two corners are welded with copper sheets. The copper sheets on the two corners on the outer side of one magnetic core are welded together with a piece of copper sheets. This is the center of the secondary coil of the planar transformer. If a tap is drawn here, it is the center tap of the secondary coil; the copper sheets on the two corners on the outer side of the other magnetic core are the two ends of the secondary coil of the planar transformer. This basically constitutes the main part of a planar transformer. Its secondary coil has only one turn and can have a center tap. A complete planar transformer also has a preset energy storage inductor, one end of which is often connected to the center tap, and there is a fixed copper plate on the top and bottom, which sandwiches the magnetic core and the filter inductor in the middle, and serves as the two poles of the rectifier power supply and the heat sink.

Planar transformers are made of copper leadframes and flat continuous copper spirals, replacing the magnetic copper wire wound on conventional ferrite cores. The spirals are etched on a thin sheet of dielectric material coated with copper foil, and then stacked on a flat high-frequency ferrite core to form the transformer magnetic circuit. The core material is then bonded with small-particle epoxy resin to minimize core losses, and the high-temperature resistant (130) insulation material in the spiral stack ensures high insulation between windings. Advantages of planar transformer classification Classification of planar transformers: Planar transformers can be divided into four types according to different design and manufacturing processes: printed circuit (PCB) type, thick film type, thin film type, and submicron type. Compared with conventional transformers, the core size of planar transformers is greatly reduced, especially the height. This feature is quite attractive in power supply equipment where space is strictly limited, so it can become the preferred magnetic component in many power supply equipment. The structural advantages of planar transformers also bring many advantages to its electrical characteristics: high power density, high efficiency, low leakage inductance, good heat dissipation, low cost, etc. Application of planar transformers In just over 10 years since its advent, planar transformers have been widely used in communications, notebook computers, automotive electronics, digital cameras and digital televisions. For example, DC-DC converters with a power range of 5 to 60W made of planar transformers have been used in plug-in card-type on-board power supplies in telecommunications systems. Due to the special electrical and mechanical environment in automobiles, more stringent requirements are placed on transformer design and technology. Planar transformers are used in DC-DC converters for xenon arc lamp ballasts and have been used in mid-range cars. Secondly, planar transformers for broadband transmission applications also show good development prospects. In addition, the product varieties of planar transformers have involved various aspects of conventional ferrite core transformers, such as power transformers, bandwidth transformers and impedance matching transformers. Due to its good consistency and small size, it is particularly suitable for use in electronic equipment with small internal space and strict requirements on energy saving and heat dissipation. In the fields of national defense, aviation, aerospace, etc., which have extremely high requirements on weight and stability, the application of planar transformers will also open up a new situation for the miniaturization of systems.