Design Of Forward-flyback DC/DC Aerospace Secondary Power Module

As power source of the whole system, secondary electrical power module is the mostbasic component of the spacecraft. Whether the loading system of spacecraft couldachieve performance reliability and desired index eventually depends on it.In other words,the reliability and stability of secondary electrical power module have decisive impact onmission result of the spacecraft. Therefore, it is very import to research and design stableand reliable secondary electrical power module in aerospace field.Based on the demand of distributed power supply in aerospace electronic system, aforward-flyback DC/DC secondary electrical power module was designed andimplemented in this research subject to convert100V bus voltage into8V supply voltage.Additionally, switching power converter was used for its advantages of small size, highpower density and high reliability.A theoretical study about forward-flyback circuit topology was conducted.In thestudy, not only normal operating modal but also some unusual cases of the circuit werediscussed, such as the circulation phenomenon under low loading, the influence oftransformer leakage inductances, etc. Comparison with diode rectifier circuit was alsomade. According to the study, the advange and disadvange of the forward and flybackcircuit were summarized.The circuit parameters were calculated and the hardware circuit of whole powersystem was designed based on analysis of requirement.Furthermore, key technologyapplied in the secondary electrical power module was also introduced, such as drivetransformer isolation and Synchronous rectification. A mathematical model for the mainforward-flyback circuit was proposed.State equations were derived based on the analysisof the work state, so that transfor function of the main circuit could be got usingstate-space average method. Meanwhile, a mathematical model of the whole system wasproposed and transfer functions for each step was established. At last, a compensationnetwork with the control principle was designed for calibration.Experimental verification were conducted based on the theoretical analysis. At first, auxiliary power adjustment was finished to supply electricity to the control circuit. Thencontrol circuit adjustment was done to generate appropriate driving signal for switchvalves so that commissioning of the entire experiment was completed and waveformswere obtained. The experimental results were consistent with theoretical analysis andsimulation results.