中文摘要：

机载设备需要大量多路输出小功率模块电源。针对270V高压直流输入，研制电机驱动器用的7路输出、32W模块电源。结合变换器要求．指出高效率、高功率密度、高稳压精度及低的交叉调整率是设计的主要难点。在分析4种可能方案后．选取两级式变换器“半桥（D=50％）＋BUCK”方案。为了优化效率，推导了满载条件下变换器总损耗关于频率和输入电压的计算函数，讨论了频率对变换器效率的影响，选取效率最优点对应的开关频率-100kHz。分析结果还表明采用该方案相同频率和负载，输入电压升高效率降低。最后，制作了一台原理样机并给出了实验结果：100kHz开关频率下，随输入电压升高整机效率从84．7％降至76．3％，额定输入时为80．2％，与理论分析一致。此外．损耗分析结果还为效率的进一步优化提供了依据。

英文摘要：

Multiple output and small power modules are widely used in airborne devices. According to 270 V high-voltage DC input, a 7 output and 32W power module was developed to drive the motor. Combined with the requirements of the converter, the high efficiency, high power density, high voltage accuracy and low cross adjust rate are the main diflqculties. A two stage converter composed of a half-bridge （D = 50%） and buck was selected after analyzing four possible solutions. To optimize efficiency, the formula of converter＇s total loss was deduced, which varies with operating frequency and input voltage. The impact of frequency on the converter efficiency was also discussed with a conclusion that the optimal frequency is 100 kHz. The results also show that under the condition of same frequency and load, efficiency decreases with the increase of input voltage. Finally, a prototype was produced and experimental results were given： under the 100 kHz switching frequency condition, the efficiency decrease from 84.7% to 76.3% with the increase of input voltage and corresponding to the rated input voltage the efficiency is 80.2%, both of them are consistent with the theoretical analysis. In addition, the efficiency loss results also provide a basis for further optimization.