Research And Application Of High Voltage DC Uninterrupted Power System

With the growing of information and data, the quantity and energy consumption of the base station of communication server is increased. UPS pwer supply is an important part of the base station of communication server, whose reliability and efficiency are the focus of academic and industrial research. Aiming at solving the problem of complicated structure, low efficiency, low reliability, high cost of the traditional UPS, a high voltage DC UPS was proposed. The major researchs of this paper forcuses on the high efficiency and high reliability of the high voltage DC UPS. The main contents are shown as below:1. About the circuit structure, the research use two stage structure, whick is summing up the structure of working-frequency UPS, high-frequency UPS and-48 V DC communication power supply. By using the T type three-level rectification circuit as the front-stage circuit of the power supply, the input power factor and THD of input current is improved. By using input-series and output-parallel full-bridge converter as the post-stage circuit, which applied the interleaving parallel technique, the voltage and current stress of the switching device are reduced, the switching losses and conduction losses are reduced, and the output current ripple is depressed. In order to improve power efficiency and reduce voltage spikes of switch, the energy feedback circuit is introduced, whick absorbs and feedback the peak voltage energy to the output.2. In order to meet the violent load fluctuation of the server of the communication base station, a new feed-forward control of the load current is used in both structure of this UPS, which is based on the traditionally double-close-loop control. When the load fluctuates violently, an advanced fluctuation amount of load current is superimposed to the current loop reference of control loop. It eliminates the influence on DC output when load current changes. It enables the system to quickly follow the load changes, and improve the system dynamic performance. By using a improved fixed input voltage control method, the energy feedback circuit avoid the energy of the main circuit flow through feedback circuit when this UPS starts. It also prevents reverse flowing of energy.3. Based on the above, a high voltage UPS whose power is 15kW is designed and built, and finally, the proposed architecture’s feasibility is verified by experiments. The results indicate that the maximum efficiency of the power supply is 96.3%. The recovery time is less than 200us and the fluctuation of the output voltage is less than 5% when the load fluctuated violently. It has fast dynamic response and good output characteristic.