Current status of electromagnetic compatibility improvement of domestic communication switching power supply
Since the drafting of yd/t983 standard, domestic communication power supply manufacturers have started the research of electromagnetic compatibility. Due to the high cost of electromagnetic compatibility test equipment, test site construction, and the need for experienced R & D personnel, many manufacturers do not have their own laboratory, the electromagnetic compatibility of the research has caused some difficulties. yd/t983 standard, the immunity indexes selected from foreign standards in the lower level. In addition to lightning surge, esd and eft indicators, other immunity indicators are relatively easy to meet the requirements. Electromagnetic interference indicators, such as conducted and radiated interference indicators, are difficult to meet the requirements of the standard, which is the hotspot of the current electromagnetic compatibility research, and only a very few domestic manufacturers can fully meet the requirements of the relevant standards.
ZTE Corporation has established its own electromagnetic compatibility laboratory, and is committed to electromagnetic compatibility research at the early stage of communication switching power supply research and development. The front stage of the communication switching power supply adopts the most advanced active power factor correction technology and lossless absorption circuit, and the rear stage DC/DC adopts zero-voltage-zero-current (zvzcs) phase-shifted resonance soft-switching technology or double-tube positive excitation lossless absorption soft-switching technology, and through the professional power supply input/output filter design and lightning-proof design, as well as the safety of the whole machine, the anti-static design of the digital interface circuit, and the design of anti-fast transient pulse group, the whole machine is protected by the EMC requirements of relevant standards. Through professional power supply input and output filter design and lightning protection design, as well as the safety of the whole machine, anti-static design of the digital interface circuit and anti-rapid transient pulse group design, and the electromagnetic shielding design of the whole machine structure, not only make the internal electromagnetic environment of the whole machine is good, stable, and improve the reliability, but also make the communication switching power supply to the outside of the current harmonics, electric undulation and flickering, conductive interference and radiated interference to meet or exceed the requirements of the cispr22 standard of class A. The input AC power line is able to withstand at least ±6kv (1.2/50μs and 8/20μs combined wave) surge voltage interference, and the DC power line is able to withstand at least ±2kv surge voltage; the entire external machine is able to withstand at least ±8kv electrostatic discharge (esd) interference, at least ±4kv electric fast transient pulse group (eft), as well as 3v/m high-frequency electromagnetic field interference, the 300a/m industrial frequency magnetic field interference. Wide range of AC input voltage, so that the switching power supply can work normally after the disturbance of voltage drop, voltage transient and short-term interruption of voltage of the whole machine. The interference voltages of power grids from all over the country have been verified and analysed on the ZTE switching power supply.
The electromagnetic compatibility indexes of ZTE series switching power supply have fully met and exceeded the indexes of all items stipulated in yd/t983-1998 Electromagnetic Compatibility Requirements and Measurement Methods for Communication Switching Power Supply Equipment, and some of the products have passed the ce certification and all the electromagnetic compatibility indexes in the fcc certification, which is a real environmentally friendly switching power supply for communication, especially suitable for mobile base stations, programme stations, and other power supply applications. Especially suitable for mobile base station, programme control switching equipment, ip telephone, cable TV and other data communication transmission equipment, as well as railways, hydropower, thermal power stations and other strong electromagnetic field interference occasions.
