Current status of electromagnetic compatibility improvement of domestic communication switching power supplies
Since the YD/T983 standard was drafted, domestic communication power supply manufacturers have begun research on electromagnetic compatibility. Since the construction of electromagnetic compatibility testing instruments and test sites is very expensive and requires experienced R&D personnel, many manufacturers do not have their own laboratories, which causes certain difficulties in electromagnetic compatibility research. In the yd/t983 standard, the immunity index adopts the lower level in foreign standards. Except for lightning surge, esd and eft indicators, other immunity indicators are relatively easy to meet the requirements. Electromagnetic interference indicators, such as conducted interference and radiation interference indicators, are currently a hot topic in electromagnetic compatibility research because it is difficult to meet the requirements of the standards. Only a handful of domestic manufacturers can fully meet the requirements of relevant standards.
ZTE has established its own electromagnetic compatibility laboratory and has been committed to electromagnetic compatibility research in the early stages of research and development of communication switching power supplies. The front stage of its communication switching power supply uses 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 shift resonance soft switching technology or dual-tube forward lossless absorption soft switching. Technology, through professional power input and output filter design and lightning protection design, as well as the safety of the entire machine, anti-static design of digital interface circuits and anti-fast transient pulse group design, and appropriate electromagnetic shielding design for the entire machine structure, It not only makes the electromagnetic environment inside the whole machine good, the operation is stable, and the reliability is improved, but also the external current harmonics, electrical fluctuations and flickers, conduction interference and radiation interference of the communication switching power supply meet or exceed the Class A requirements stipulated in the cispr22 standard. The input AC power line can withstand at least ±6kv (combined wave of 1.2/50μs and 8/20μs) surge voltage interference, the DC power line can withstand at least ±2kv surge voltage; the outside of the machine can withstand at least ±8kv electrostatic discharge (esd) interference, electrical fast transient pulse group (eft) of at least ±4kv, as well as high-frequency electromagnetic field interference of 3v/m, and power frequency magnetic field interference of 300a/m. The wide AC input voltage range enables the switching power supply to operate normally after disturbances such as voltage drops, voltage transients, and short-term voltage interruptions of the entire machine. The power grid interference voltages professionally collected from all over the country have been verified and analyzed on ZTE switching power supplies.
