Design And Research Of A Multi Channel Air DC-DC Power Supply

With the continuous development of the aviation industry, a growing number of avionics need to input different voltage simultaneously to supply power for electrical equipment. However, in general, the modern switching power supply technology can only meet the needs of single-output power supply. When the number of the output voltage channel increases, the power volume, output ripple and output precision can not be guaranteed to meet the actual needs. In addition, the number of electrical equipment in the interior of the aircraft constantly grows, the power supply equipment required by aviation secondary power supply also continuously increases, and the voltage supplied constantly lowers, showing a higher requirement for the ripple of each output voltage channel and dynamic characteristics. Although the modern advanced aviation equipment is equipped with 28.5V as its rated voltage, much communication, control and protection equipment on the aircraft needs such low-voltage DC power supply as 5V, ?V12.Based on the above problems, a 12-channel output DC/DC power supply with the rated voltage of 27 V has been designed reasonably. The multi-channel power supply includes various fixed output power of the aviation equipment and adds controllable output circuit, increasing the possibility for adding more aviation equipment to meet the needs for production and life.Firstly, this paper has analyzed the development trend of high-frequency switching power supply both at home and abroad in accordance with a large number of data consulted,studied the toplogical structure of the multi-channel output switching power supply,compared the circuit topology of isolated small power DC/DC converters, proposed to use a full-bridge converter as the main circuit topology, and made a systematic and overall scheme.Secondly, according to such an order from input to output to design the circuit, the main circuit includes the input circuit, PWM controller, fixed and controllable output circuit,frequency design circuit, undervoltage protection circuit, stable circuit, current-limited circuit etc. Besides, a rational topology has been chosen, detailed parameters have been calculated, and a integral circuit diagram has been designed.Thirdly, as for the design of the transformer, it has been selected by comparing its advantages with the traditional transformer, applying its insertion technique to reduce the effect of the clutter on the power supply, calculating its primary and secondary number of coil turns and verifying the reliability of data calculated by high-frequency skin effect.Finally, on the basis of the theoretical analysis and circuit design, a prototype of power supply has been developed and main technical indicators have been tested. The results of the overall test show that the indicators have met the basic design requirement and the output voltage is stable.