High frequency electronic test transformer will go from here

The development direction of high-frequency electronic test transformers, the biggest characteristic of high-frequency electronic test transformers is high frequency. From the working principle of the transformer, increasing the operating frequency can reduce the transformer. The development direction of high-frequency electronic test transformers, the biggest characteristic of high-frequency electronic test transformers is high frequency. From the working principle of the transformer, increasing the operating frequency can reduce the volume and weight of the transformer, that is, achieving a short and thin, thereby increasing the transmission power per unit volume (or weight), that is, high power density. These are the inherent characteristics of the high-frequency electronic transformer itself and the direct result, and can not simply be high-frequency, short and thin, high power density, as the development direction of high-frequency electronic transformers. From the aspects of the overall structure of the high-frequency electronic transformer, core material and structure, and coil material and structure, some suggestions on the direction of development are proposed.

1. The overall structure adapts to the increasingly thin and light electronic devices. One of the main development directions of high-frequency electronic transformers is to develop from three-dimensional structures to planar structures, slice structures, and thin-film structures, thereby forming a new high-frequency electronic transformer from generation to generation. : Planar transformers, chip transformers, thin film transformers.

The development of the overall structure of the transformer not only forms a new magnetic core structure and coil structure, but also adopts new materials, and it also brings new directions for development in design aspects and production processes. In terms of design, in addition to studying the distribution of electromagnetic fields of various new structures, how to achieve optimal optimization design, we must also study various problems of multi-layer structures. In the production process, various new processing methods should be studied to ensure the consistency of performance and to realize the mechanization and automation of the processing technology.

In MHz-class high-frequency electronic transformers, more and more applications use hollow transformers. The structure, design method, manufacturing process and application characteristics of the hollow transformer are also the research and development direction. In addition, the research of high-frequency electronic transformers such as piezoelectric transformers is also a development direction. After nearly a decade of research and development, piezoelectric transformers have been practically applied in some fields.

The use of computers for optimization and specific design of the overall structure scheme is one of the major development directions of various electronic devices. Of course, it is also a major development direction of high-frequency electronic transformers. This can shorten design time, reduce material usage, shorten production cycles, and reduce costs.

2. Magnetic core materials and structural cores are the most critical components in high-frequency electronic transformers that use soft magnetic materials and work on the principle of electromagnetic induction. The main development direction of magnetic core materials is to reduce losses, widen the temperature range used and reduce costs. The main development direction of the magnetic core structure is how to form planar magnetic cores, chip magnetic cores, and thin film magnetic cores with the best shape and size (parameters for electromagnetic performance, heat dissipation, usage, and cost).

Nowadays, all kinds of soft magnetic materials are constantly being improved and developed to compete with the market of high-frequency electronic transformers.

Soft ferrites are the main core materials used in high-frequency electronic transformers. The development direction is to develop new varieties with better performance and new processes that reduce costs. In terms of new material varieties, Japan's TDK Corporation developed a wide-temperature, low-loss material PC95 in 2003, with losses of less than 350mW/cm3 (at 100kHz x 200mT) in the 25°C to 120°C temperature range. The loss is minimal at 80°C and is 280 mW/cm3.

Bs is 540mT at 25°C and 420mT at 100°C. Also developed a high temperature and high saturation magnetic dense material PE33, Curie point Tc> 290 °C, at 100 °C, Bs is 450mT. Under conditions of 100°C and 100kHz×200mT, Pc≤1100mW/cm3, FDK Corporation of Japan, EPCOS Corporation of Germany, and Ferrocube Company also developed similar high-temperature and high-saturation magnetically dense materials.

High permeability materials also have many new varieties, such as TDK's pulse transformer H5C5, μi is about 30,000. Anti-electromagnetic interference inductor HS10, while having good frequency characteristics and impedance characteristics, still has a high permeability at 500kHz, although the initial permeability is not high, only about 10,000. High permeability high saturation magnetic dense material DN50, Bs is 550mT at 25°C, Bs is 380mT at 100°C, μi is about 5200, Curie temperature Tc≥210°C.

In the new process, self-propagating high-temperature synthesis (SHS) is a research hotspot in recent years. The principle is to use the chemical energy inside the reactants to synthesize the material. The entire process is extremely simple, low energy consumption, high production efficiency and product purity, no pollution to the environment, has been successfully synthesized Mg, MgZn, MnZn, NiZn ferrite, is to achieve industrialization.
Spark Plasma Sintering (SPS) can successfully fabricate multi-layer magnetic cores of MnZn ferrite and permalloy composite soft magnetic materials. It also has high-frequency low-loss characteristics of MnZn ferrites and high permeability of permalloy. With high saturated magnetic density, this composite soft-magnetic material core will significantly improve the performance of high-frequency electronic transformers. Other processes such as self-combustion synthesis, rapid combustion synthesis, hydrothermal synthesis, novel hydrothermal synthesis, mechanical alloying, microwave sintering, etc., have all undergone extensive research in recent years, all in line with the development direction of improving performance and reducing costs. . Due to the low saturation magnetic flux density of soft ferrites, in the higher frequency range of 20kHz to 100kHz, the advantage of cost performance is not as obvious as the high frequency range above 100kHz, and other soft magnetic materials are higher in the range of 20kHz to 100kHz. In the frequency range, fierce competition with ferrite occurs.

All kinds of soft magnetic materials have their own characteristics. Therefore, how to make full use of the advantages of various soft magnetic materials in specific high-frequency electronic transformer products in order to achieve a better performance-cost ratio is the use of high-frequency electronic transformers soft The development direction of magnetic materials.

Silicon steel is characterized by high saturation magnetic density, stable performance, and low price. In recent years, it has developed a series of high-frequency silicon steels, including ultra-thin silicon steel, 6.5% silicon steel, gradient silicon steel, and chromium-containing silicon steel. In particular, chromium-containing silicon steels have been used in electronic transformers at 25 kHz and 70 kHz. Now the operating frequency of silicon steel has reached 325kHz.

High-permeability permalloy is characterized by high magnetic permeability and good environmental adaptability, but it is expensive. In recent years, permalloy ultra-thin belts have been developed, and the operating frequency has exceeded 1 MHz. The special requirements of the place and military equipment Used in.

Cobalt-based amorphous alloys are the most expensive material for high-frequency loss in existing soft magnetic materials, and they are expensive. However, they are used at high frequencies above 200 kHz. The weight of the magnetic core is small, and the price factor is not prominent. It is currently at 200 kHz and 1 MHz. High frequency electronic transformers are used in large quantities.

Soft magnetic composite materials have now become a major development direction for magnetic core materials for high-frequency electronic transformers. Compared with conventional soft ferrites and soft magnetic alloys, magnetic metal particles or thin films can be distributed on non-conductors and other materials. In this way, the high-frequency losses are significantly reduced and the operating frequency is increased. At the same time, its processing technology can be processed into a powder core by hot-pressing, or it can be injected into a complex-shaped magnetic core using current plastic engineering technology. It has a small density, light weight, high production efficiency, low cost, and product reproducibility. With good consistency and other characteristics. Different proportions can also be used to change the magnetic properties. Examples of composite materials consisting of soft ferrite and permalloy have been introduced above. Soft magnetic composite powder cores with an operating frequency of 10 kHz or more have been developed, and soft magnetic ferrites can be replaced in high-frequency filter inductors.

According to the development requirements of the overall structure of high-frequency electronic transformers, the development direction of magnetic core structures is planar magnetic cores, chip magnetic cores, and thin-film magnetic cores. Previously, planar magnetic cores were modified with the original soft magnetic ferrite core. Now there are various low-profile ferrite magnetic cores that are specially used for planar transformers. In the future, it may also develop a variety of low-grade soft magnetic composite cores. In addition to the planar magnetic core, the magnetic core of the chip transformer has a chip core manufactured by the co-firing method. Thin-film magnetic cores and magnetic materials are currently one of the most active development directions of high-frequency electronic transformers, and will become the main magnetic core materials and structures of high-frequency electronic transformers above MHz, and it is possible to reduce the height of thin film electronic transformers to 1 mm or less. Load in various cards. Several centers in China have been vigorously researched. Now it is hoped that the material development, electronic transformer manufacturing and application units can be united to transform the thin film soft magnetic material developed in China into a high frequency electronic transformer magnetic core in electronic information products as soon as possible to form a domestic thin film transformer with independent intellectual property rights.

3. Coil material and structure With the development of the overall structure of high-frequency electronic transformers, the main development direction of the coil structure is planar coils, chip coils and thin film coils, which also include multilayer structures. There are also some new developments in the selection of materials for various coil structures.

The three-dimensional structure of the high-frequency transformer coils, wire materials due to the skin effect and proximity effect, the use of multiple strands (Ritz wire), sometimes using flat copper wire and copper tape. Insulation materials are made of high heat-resistant grades to increase the allowable temperature rise and reduce the coil volume. Double and triple insulated conductors can be used to reduce coil size. As an example, recently, domestically developed C-level insulated magnet wires coated with mica swimming on copper wires using nanotechnology have been applied in industrial frequency motors and transformers, and have achieved good results, and are estimated to be also in high-frequency electronic transformers. Will be applied.

Plane structure coils, the use of copper wire, most of the use of single-layer and multi-layer printed circuit board manufacturing, but also use a certain pattern of copper foil, a plurality of folded. Insulation materials generally use Class B materials.

Film structure coils, copper, silver, and gold films are used for the wires to form patterns such as combs, spirals, and field shapes. Insulation materials use H and C grade materials. There are also multi-layer structures, either a combination of several multilayer coils, or several overlapping coils and several cores. In short, thin-film transformers are high-frequency electronic transformers that are being vigorously developed. Many structures are not fixed, and perhaps many new coil structures will emerge.