A High Performance And Integrated Power Control And Distribution Unit For Micro-satellites

In recent years,the micro-satellite technology has been developing rapidly.It has outstanding advantages in small volume,light weight,high power density,optimum scale integration,low cost,convenient in transportation,launching flexible,high networking speed.As the development cycle of micro-satellite is short and its on-orbit life is relatively short,new technology and materials,new developing method and procedure can be adopted to meet the needs of the mission.At present,many research institutes,private companies and universities are carrying out research on micro-satellite technology and increasing investment in research and development.Micro-satellite has become an important direction for the future development of satellites.Fourteen micro-satellites,including those that have been launched and are about to be launched,have been developed by Shenzhen Aerospace Dongfanghong Development Ltd.All of the Power Control and Distribution Units are customized,and haven’t been modularized and universally designed,with a long development cycle and higher cost.We began to try to use the industrial mature MPPT control chip on KT-1B,but the tracking accuracy and control efficiency need to be further improved.Other satellites adopt S3 R architecture,and the output voltage of the solar array is clamped by battery,can’t work at the maximum power point,the energy utilization rate,the power density and integration are low.Most of the secondary power conversion adopts the isolated DC/DC modules,which are produced by Interpoint and VPT,they have low efficiency and high heat consumption,resulting in high cost at thermal design.The Power Control and Distribution Units of KT-1A satellite used the domestic thick-film SHLCL-28 solid-state power controller for the first time,it had preliminary fault diagnosis and processing capabilities,but it cannot cover all the critical circuits of the equipment,and cannot predict the fault.In addition,the satellites working on-orbit are affected by the radiation environment in space,which may cause device parameter drift,accelerated aging,and even damage.The solar array power regulation circuit is the energy lifeline of the satellite,and the turn-on and turn-off losses are large,so that the working temperature on-orbit is high,due to unreasonable thermal design,some satellites’ shunt-MOS-tubes are damaged.The SiC devices have excellent radiation resistance,fast turn-on and turn-off,and can operate at higher frequencies.The application of SiC devices in Power Control and Distribution Units can be explored.Starting from the existing problem of Power Control and Distribution Unit,MPPT topology structure and high integration chip were employed by this thesis to build power control unit.The functions of slave computer and secondary power conversion and distribution are involved.Meanwhile,the health detection and fault diagnosis and processing capability are optimized and the integrity and reliability of power control unit are improved either.Furthermore,the feasibility of SiC power devices were studied in the thesis,which will be used in the power control unit,building the foundation further following flight test.