With the rapid development of electronic information technology and the increasing demand of users for various services, the traditional telecommunication network, Internet and cable TV networks that were originally designed and operated independently are moving toward integration. "Three networks integration" has become an important part of social development. Trend. The characteristics of these changes have gradually changed the operators of the original business, and put forward new requirements for network equipment.
The tremendous development of the information industry has brought huge market opportunities and challenges to the power market, and at the same time put forward some new demands on the power supply. For example, a variety of physical devices are put together, there is the need for electromagnetic compatibility and the requirements of the room area and load-bearing capacity; the variety of network equipment makes the load of the power supply become larger, the type of load becomes more, and the power efficiency and type are required; The number of base stations is increasing, and higher requirements are placed on the reliability and ease of maintenance of the power supply to meet the unattended needs. The difference in power supply environment also puts new demands on the application environment of the power supply, such as stronger grid adaptability and environmental adaptability. Outdoor power supply is a typical representative of this demand. Power is the heart of the entire information network, and new networks require more reliable power. In addition, with the globalization trend of operators, power supply equipment also needs to meet the special requirements of products in different markets around the world.
The development of global communication power technology has the following major trends: (1) High efficiency, high power density, wide use environment temperature, with the increasing number of operators' equipment, increased power consumption, and tight room area and other objective factors. High efficiency, high power density, and wide ambient temperature requirements are imposed on power products.
Continuous development, emergence and application of new high-performance devices such as insulated gate bipolar transistors (IGBT), power field effect transistors (MOSFET), smart IGBT power modules (IPM), MOS gated thyristors (MCT), electrostatic induction transistors (SIT), over recovery diodes, non-inductive capacitors, non-inductive resistors, new magnetic materials and transformers, EMI filters, etc. The application of these new devices can increase the switching frequency of the communication power supply, reduce the size of the power supply, and increase the power density of the power supply.
In communication power, switching technology is an important technology to improve power efficiency. Typical examples of soft switching technology and quasi-resonant technology are circuit topology such as resonant conversion, phase shift resonance, zero-switch PWM, and zero-transition PWM. With the deep research of soft-switching topology theory and the popularization of applications, the loss and noise generated by the voltage drop/rise and the current rise/fall waveform overlap in the power-on and power-off of the power device in the hard-switching mode are greatly reduced. Zero voltage / zero current switching is achieved, reducing losses and improving the efficiency of the power system.
In order to better adapt to the environment and improve product reliability, the communication power supply for 220Vac operation can generally work at 120-290Vac, and the environmental adaptability is also improved from the traditional 45 °C to 60 °C, or even 75 °C.
(2) Networked intelligent monitoring and management With the development of the network, huge network equipment requires a lot of manpower and material resources to invest in the management and maintenance of equipment, such as: the environment in which communication facilities are more and more complex, sparsely populated, traffic Inconvenience increases the difficulty of maintenance. This puts new demands on the monitoring and management of power equipment.
The centralized decentralized monitoring system of the communication power system needs to monitor the state quantity and control quantity in the system, and can also fully manage the battery; the control data can be directly transmitted on the Internet, so that maintenance personnel can query, control, etc. through the Internet. maintenance work. The friendly human-machine interface makes it easy for maintenance personnel to get the information they need. Such as various protection, alarm and data information storage, processing, printing and other functions; maintenance planning, asset management and other work.
(3) The development of digital control digital technology has gradually demonstrated the advantages that traditional analog technology can not achieve, such as: the use of full digital control technology, effectively reducing the size of the power supply reduces costs, greatly improving the reliability of the device and the user Adaptability. DSP sampling is used for signal sampling, processing, control (including voltage and current loops, etc.) and communication of the entire power supply, and optimized and stable control parameters can be obtained. More flexible control methods can be used to optimize the output of the power supply under various voltages and temperatures, such as derating protection and PFC digital control of harmonics. Using DSP technology, simpler and more stable communication and current sharing can be achieved, and good EMC specifications can be obtained. More intelligent, such as a flexible combination of LED alarm indications, can communicate without monitoring. Reduce the number of components, increase module specifications, and increase power density. Eliminate the discreteness and temperature drift of the analog control technology to ensure that each module achieves the optimal index and improves the reliability of the power supply. The module is more intelligent and easy to use and maintain.
(4) Safety, protection, and EMC Considering the complicated operating environment of the equipment, the power supply equipment must meet the relevant safety, protection, and lightning protection standards to ensure reliable operation of the power supply.
Security is the most important indicator of power equipment; commercial equipment needs to pass relevant safety certifications, such as UL, CSA, VDE, CCC, etc. Lightning protection design is an indispensable link to ensure the reliable operation of the communication power system. For communication equipment, the sources of lightning overvoltage mainly include induced overvoltage, lightning intrusion wave and counterattack overvoltage. In general, communication power supplies must adopt lightning protection principles of system protection, probabilistic protection, and multi-level protection. Communication power systems generally require a three-level lightning protection system.
The moisture-proof, salt-proof and anti-fungal designs are called three-proof design. Corrosion-resistant materials are usually used in engineering, and the surface of the electronic equipment is covered with a metal or non-metal protective film by plating, coating or chemical treatment to isolate it from the surrounding medium, thereby achieving the purpose of protection, generally in the printing plate. Three anti-paint; structurally sealed or semi-sealed to isolate the external environment. Good EMC indicators enable different electronic devices to work together; at the same time, the user's electromagnetic environment is cleaner and the electromagnetic environment is protected from the user. Generally accepted standards are: EN55022, EN 300 386:2001,; CFR 47 Part 15; Telcordia GR-1089 [NA requirement].
(5) One of the indicators of environmental protection and environmental protection is that the current harmonics of the communication power supply meet the requirements. Reducing the input harmonics of the power supply can not only improve the load characteristics of the power supply to the power grid, but also reduce the serious pollution to the power grid and reduce the harmonic interference to other network equipment. Another important aspect is that the materials are recyclable and environmentally friendly. This aspect requires products to meet the WEEE/ROHS directive.
The WEEE/ROHS Directive consists of two parts, namely ROHS that recycles and reuses WEEE and limits the use of hazardous substances. The main purpose of implementing the WEEE Directive is to prevent and treat electrical and electronic waste (WEEE), and to achieve reuse, recycling and other forms of recycling of these wastes to reduce waste disposal. At the same time, we also strive to improve the environmental behavior of all operators involved in the life cycle of electrical and electronic equipment, such as producers, distributors, consumers, especially those directly involved in the disposal of waste electrical and electronic equipment.
The goal of the ROHS Directive is to align the laws of Member States on the restrictions on the use of hazardous substances in electrical and electronic equipment, and to help protect human health and waste electrical and electronic equipment from environmentally desirable recycling and disposal. Since July 1, 2006, new electronic and electrical equipment placed on the market does not contain lead, mercury, cadmium, hexavalent chromium, polybrominated diphenyl ether (PBDE) or polybrominated biphenyl (PBB).
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