Small & flat transformers remain the trend

by Vianie Li & Cecile de Veyra

Passive components come in smaller configurations, driven by miniaturization in various electronics, yet must exhibit the opposite in performance as applications become more complex in functionality.

In power transformers, compact and flat types represent this trend for their low profile. Compared to conventional units, they use thin magnetic cores, resulting in designs especially suitable for power supplies with a limited board space. Despite their size, however, these components do not have reliability issues, displaying characteristics of high power density and efficiency, and low current leakage.

In China, flat power transformers have grown in popularity based on orders received from domestic and overseas customers, according to manufacturers interviewed by Global Sources.

Shenzhen Yamaxi, a national high-tech enterprise, offers an EFD series, which is based on a magnetic core with a high initial permeability and saturation flux density. The core is designed in a special geometric shape said to effectively reduce core loss. These transformers, with wide voltage and frequency ranges, low power loss and temperature rise, and high efficiency, are for LED power supplies, displays and TVs, and other electrical equipment.

Widely available transformers in China are for household appliances, mobile electronics, communications and medical equipment, and automotive applications. They come in single- and three-phase versions.

Categorized by power, there are mini-power types that are below 25VA, low-power in the range of 25VA to 0.5kVA, medium-power 0.5 to 10kVA and high-power over 10kVA. By geometry, the common options include toroidal, EI, EE, EP, EFD, RM, R, C, PQ, EPC and pot-core kinds. Based on mounting, there are horizontal, vertical and SMD styles.

Other typical specifications, depending on requirements, are an output voltage ranging from 0.5 to 5,000V, output current of 0.01 to 100A and operating frequency of up to 500kHz.

These power transformers can be customized for any application. They are made using ferrite cores, coils, insulation materials and cases obtained domestically or from overseas suppliers as required.

Chinese manufacturers state that their products have the same quality as imported ones, being based on relevant safety standards such as CB, CE, CQC, UL and VDE, as well in compliance with RoHS. They also offer them at prices that are about 30 percent lower than typically quoted by foreign companies.

Diverse supplier base

China’s power transformer manufacturing sector consists of hundreds of suppliers and includes industry leaders from Europe, the US, Japan and the Taiwan region.

While homegrown enterprises are the majority, most are operating on a small or medium scale, with the exception of a few such as Baoding Tianwei Baodian and TBEA. Foreign companies, including ABB, Siemens and Toshiba, dominate the Chinese market with a combined share of 20 to 30 percent.

Many factories are in the coastal provinces of Guangdong, Zhejiang and Jiangsu, although there are others in Hubei, Sichuan and other inland locations. These areas are expected to continue attracting domestic and overseas suppliers in the coming years for their comprehensive supply chain and economic infrastructure.