Electronic transformer: common progress with upstream and downstream enterprises

Jiang Deqing, Secretary General of the Electronic Transformer Technology Department of the Components Branch of the Chinese Institute of Electronics (Excerpted from Big Bit Blog)

In the past 30 years, almost all kinds of electronic products are developing in the direction of high frequency, high efficiency, low loss and high cost performance, making the living space of traditional EI and C-type magnetic core electronic transformers narrower and smaller. Therefore, under the circumstance that the traditional type still accounts for a large proportion of the electronic transformer production in mainland my country, it is necessary to increase the pace of its upgrading in the spirit of reform and innovation, otherwise, the electronic transformer industry in the mainland will continue to grow for a long time. in a "working" position.

Going through three levels of renewal

In a sense, my country's electronic transformer industry is undergoing three levels of upgrading: the first level is the innovation of three-dimensional transformers (that is, traditional ordinary transformers) to planar transformers. The volume and weight of planar transformers are higher than those of traditional transformers. It has been reduced by 80%, and a product series of 5W-20kW/20kHz～2MHz has been formed, and the typical value of its efficiency can reach 98%. The second level update is the mass production of chip transformers. The height of the chip transformer is further reduced, and the flattening is basically realized. They are suitable for the requirements of low-voltage high-current power supplies with currents above 100A. Its structure generally uses one primary winding with multiple magnetic cores instead of the traditional one with multiple windings. The primary windings of multiple magnetic cores are connected in series to meet the requirements of step-down and isolation, and the internal temperature rise is lower than that of the planar transformer, which is only about 10 °C; it can be installed on PCBs and other substrates with a higher rated temperature. The third level update is the successful development and design of thin-film transformers. Due to the thin film structure, the low height is better achieved, generally less than 1mm, and the operating frequency exceeds 1MHz, reaching 10MHz to 100MHz. Thin-film transformers can be manufactured by integrated circuit technology, so the cost is not higher than that of chip transformers. Thin-film transformers are the development direction of widely used DC switching power supply transformers.

Everyone has noticed that at present, the development from traditional ordinary three-dimensional transformers to planar transformers, chip transformers and thin-film transformers is just a process of development and progress, each of which has its own application range and market positioning, not one type completely replaces the other. kind. For example, the current use and output of ordinary electronic transformers are still large; planar transformers have formed series and batches and are being promoted and used; chip electronic transformers are still in small batch trial production of a small number of varieties; thin film transformers are still under development. research stage.

Make progress together with upstream and downstream products

First of all, soft magnetic materials are upgraded to high-end products and gradually developed on a large scale

The development and production of high-end components requires the support of high-end raw materials. The main raw material that affects the performance indicators of electronic transformers is magnetic materials. Therefore, the electronic transformer inductor industry is very concerned about the development of soft magnetic materials, especially its high-end materials. In recent years, my country's soft magnetic material industry has made great progress. Some large and medium-sized soft magnetic enterprises have entered the world's advanced ranks. The total output of soft magnetic materials and medium and low-grade soft magnetic products have an absolute advantage in the international market. Soft magnetic products have also begun to form international competitiveness. It can be said that the entire soft magnetic industry has begun to change from big to strong.

The development and progress of upstream raw material products have provided a good foundation for the upgrading of the electronic transformer industry and products.

Secondly, the domestic complete machine industry and products are undergoing transformation and upgrading, which will definitely drive the market and technological development of the electronic transformer industry and products.

The technology and products of electronic transformers continue to expand with the development of the whole product, which provides a market and technical space for their own development, such as various electronic computers and their peripheral equipment, wired and wireless and mobile communication equipment, automobiles Electronic equipment, medical electronic equipment and instruments have broad market and technological development space, and some emerging industries and technologies such as high-definition TV, liquid crystal products, digital products, etc. have formed a rapid development trend. These industrial fields are inseparable from various power sources. Therefore, there is no doubt that the electronic transformer technology and market have the same development potential as them.

Product upgrades put forward new requirements

From the perspective of use, the design of electronic products is becoming more and more personalized and diversified, with many categories, varieties and models. The design and manufacture of electronic transformers must adapt to this trend and principle. At present, the design and manufacture of electronic transformers must pay attention to the following requirements:

First, structural design, the general trend is small, thin and light, suitable for SMT installation requirements. For electronic transformer designers, small, thin and light is the most difficult of the three passive components. In order to meet the requirements of miniaturization indicators, the preferred measure is to increase the operating frequency of the power supply, and the current operating frequency is above 20kHz to 100MHz. Selecting a high operating frequency is accompanied by an increase in high-frequency loss and electromagnetic noise, which requires the use of new high-end magnetic materials and anti-electromagnetic interference devices to overcome, which will complicate the design of electronic transformers and power supplies.

Second, the design of electronic transformers should put work efficiency and production efficiency in an important position. Improving the working efficiency and production efficiency of electronic transformers is the specific implementation of environmental protection and energy saving. In the design of electronic transformers, the required working efficiency is: the efficiency of low-power DC switching power supply below 100W is > 85%; the working efficiency of medium and high-power DC switching power supply should be greater than 90%. The loss of electronic transformers and inductors accounts for about 15% of the power supply, so the working efficiency of electronic transformers is required to be > 95% to 98%. The no-load loss and no-load current of the electronic transformer are the main factors for the standby loss of electronic equipment. Therefore, the no-load loss of the electronic transformer is required to be preferably less than 2%. The design of improving the working efficiency of electronic transformers must also solve the problems of less heat and faster heat dissipation.

Third, as with any other product, cost is an issue that electronic transformer design must face. In addition to adapting to the requirements of modern electronic equipment in terms of low loss, small size, high efficiency, stability and reliability, the low price is a necessary condition for market competition. To reduce transformer cost, design is the foundation. The use of raw materials and the structure of the design play a leading role in the cost. Process equipment and process design, online testing equipment and route design, etc. should all be based on the lowest cost.

Fourth, maximize the use of standard parts. At present, the standardization rate of traditional transformer design is relatively high, while in the design of planar, chip and thin-film electronic transformers, it is more inclined to the technical and installation requirements of the whole product, and there is no strict requirement for the standardization rate. To improve the standardization rate of design, we must do a good job in two aspects. One is to speed up the formulation of industry standards, and the other is to make good use of existing standard parts and design methods.

Fifth, when the price of some materials (such as copper) has risen and maintained at a high price, look for some lower-priced materials to replace, such as copper-clad aluminum wires instead of copper wires.