1 Special conditions of mobile base stations and requirements for communication power supply equipment
With the rapid development of mobile communications, the number of mobile base stations is constantly increasing, and gradually develop from cities to remote villages. Mobile base stations scattered in every corner of people's lives have special working conditions compared with general communication equipment rooms. These special working conditions put forward higher requirements for the communication power supply module equipment used in mobile base stations. Mainly manifested in the following aspects:
1) The power supply quality of mobile base stations powered by rural power grids cannot be guaranteed. Therefore, it is required that the communication power supply power module can adapt to a wide grid voltage fluctuation, generally more than ± 30%. In addition, the operating overvoltage and lightning overvoltage of the mobile base station power grid are serious, and the communication power supply module should have reliable overvoltage and lightning protection measures.
2) Many mobile base stations often have moisture, high temperature, dust, etc. in the early stage of equipment operation, so the communication power supply is required to have measures against moisture, high temperature, and dust.
3) The number of mobile base stations is large and unattended. Therefore, it is required that the communication power supply is easy to maintain and operate, and has remote monitoring and strong fault diagnosis functions.
4) In order to ensure smooth communication, the communication power supply of the mobile base station should have the function of lack of phase operation.
2 Reliability, maintainability and availability solutions of mobile base station communication power supply module system
Regarding the specific requirements of mobile base stations for communication power supply module equipment, the reliability, maintainability and availability solutions of the mobile base station communication power supply system are as follows:
2.1 Reliability design of mobile base station communication power supply module system
The reliability design of the communication power supply system of the mobile base station is mainly used to solve the excessively high requirements of the mobile power station's special environment on the communication power supply system. The reliability solution is as follows:
1) Increase the allowable AC input voltage fluctuation range of the power supply module to ± 30%, which can improve the adaptability of the power supply system to the power grid.
2) The power module adopts natural cooling mode. Natural cooling (compared with air cooling) can fundamentally avoid the risk of damage to the power system reliability due to fan damage and the risk of requiring a large area of ​​fan replacement after a few years of operation.
3) The mobile station base station communication module power supply system is equipped with a comprehensive overvoltage protection circuit, and the lightning overvoltage protection and non-lightning overvoltage protection are integrated to ensure that when the lightning overvoltage and non-lightning overvoltage occurs, the mobile station communication power supply can be effective protection of. The principle circuit of the integrated overvoltage protection for the mobile power supply of the base station is shown in Figure 1.
4) The fault isolation design of the mobile base station communication power supply is an important method to improve the reliability of the power supply system. This design isolates the power supply monitoring fault from the power supply module fault; isolates the faulty power supply module from the normal power supply module. The module power supply system can continue to supply power even when the power supply monitoring fails and some power supply modules fail.
2.2 The maintainability design of mobile base station communication power system
The purpose of the maintainability design of the communication power supply system of the mobile base station is to make the fault maintenance of the communication power supply system as simple as possible. Mainly manifested in the convenience of power module replacement, system failure diagnosis, etc. The maintainability solution is as follows:
1) The installation mode of the power module adopts the live plug-in mode, and the power module can be arbitrarily inserted and removed in any state. To this end, a power module dynamic identification circuit is designed, which can ensure that the work of the current sharing circuit of the system is not affected during the insertion and removal of the power module. The dynamic identification and control circuit of the charged plug-in current-sharing bus is shown in Figure 2.
The potential at point A in the circuit follows the potential change of the current sharing bus. When the normal load changes, the potential change on the current sharing bus is small. The potential at the output point B of the dynamic recognition control circuit of the live plug-in current plug is low, and the current sharing relay remains in the same state; when the current sharing bus potential When the change is large, the output point B of the dynamic plug-in current sharing bus dynamic recognition control circuit is high, the current sharing relay is powered off, the current sharing line of the module power output is disconnected from the system current sharing bus, and the module operation is not affected by the The impact of sudden changes in the stream bus. When the system returns to normal, the output of the dynamic identification and control circuit of the charged plug-in current sharing bus returns to a low level, the current sharing relay draws in, and the system operates normally. The live plugging and unplugging of the power supply module can make the maintenance time of the power supply system the shortest and the maintenance difficulty the lowest.
2) The fault diagnosis function for monitoring the power supply system of the mobile base station provides convenience for the maintenance of the power supply system. The fault diagnosis software can provide accurate fault diagnosis and fault location for the internal faults of the power supply module and the input and output faults of the power supply system, and remotely transmit the fault information of the power supply system to the duty room of the switching center to provide accurate maintenance for the power supply system Information service.
2.3 Usability design of mobile base station communication power system
The purpose of usability design of the communication power supply system of the mobile base station is to adapt the communication power supply system to the requirements of the special working conditions of the mobile base station. The availability solutions for mobile base station communication power systems mainly include the following aspects:
1) On-load characteristics of the power module The special working condition of the mobile base station is that the power supply equipment is often in the no-load state when the power system is installed and debugged, and the power supply equipment is in the light-load state during normal operation. In order to improve the usability of the communication power supply system, the circuit topology and control circuit of the power supply module have been improved so that the power supply system can run for a long time under no-load condition. The no-load loss of the 48V / 50A power module is less than 20W. The efficiency is improved.
2) The lack of phase operation characteristics of the power supply module The power supply quality of the mobile base station cannot be guaranteed. Sometimes the input power supply will lack one phase. For a three-phase input high-frequency switching power supply module, under normal circumstances, it should be protected immediately and the module should be turned off. But this puts higher requirements on the power maintenance time. For this reason, the phase loss operation function is added in the design of the power module. When the input power is missing one phase, the power module should continue to operate while providing a phase failure alarm, and can carry a load of less than 50%. The lack of phase and non-stop provides a reliable guarantee for the smooth communication of mobile base stations.
3) The battery of the power system realizes the intelligent management of the power monitoring unit and the power module, and divides the balanced charging of the battery into two stages: constant current and constant voltage. The average floating charging voltage of the battery is set according to the specific parameters of the battery. The average floating charging voltage of the battery is automatically compensated and adjusted by the monitoring according to the ambient temperature of the battery, so that the battery can maintain a full capacity under various environmental temperatures.
3 Conclusion
The special working environment and working conditions of the mobile base station determine the special requirements for the mobile power supply system of the mobile base station. Combining the practice and lessons of providing module power supply for mobile base stations, the reliability, maintainability and availability solutions of mobile base station communication power supply system are proposed. This solution has been implemented in our products and verified in specific applications. Practice has shown that the live plug-in characteristics of the module, the no-load operation characteristics, the allowable input voltage fluctuation range, the fault diagnosis function, and the natural cooling method are very necessary for the mobile base station power system.
As a mobile multi-purpose platform, tablet computers also provide many possibilities for mobile teaching. The touch-based learning & entertainment teaching platform allows children to efficiently improve their academic performance in a relaxed and pleasant atmosphere. Such tablet computers generally integrate two learning sections of various courses and systematic learning functions. Generally, it includes multi-disciplinary high-quality teaching resources. The education tablet has the following main functions: it has the functions of touch screen input, text editing, picture editing, data storage, data management, wired and wireless Internet access that ordinary tablet computers have; Management functions, search methods support manual search, query by keyword, query by time; text and pictures can be scanned and converted into documents to save.
Education Tablet,learning tablet,leaning machine,New learning tablet
Jingjiang Gisen Technology Co.,Ltd , https://www.gisengroup.com