Research On Anode Power Supply With Wide Input Voltage Range

Electric propulsion system is an advanced new space propulsion technology,which is widely used in communication satellites and deep space exploration.It has a series of advantages such as high specific impulse,high control accuracy and high efficiency.In the Hall effect Thruster system,Power Processing Unit(PPU)is the core component,which is powered by the voltage bus(VBUS).Therefore,the PPU is required to work at wide input voltage condition to adapt to the wide range of VBUS.Anode power supply(APS)is the key component of the PPU,and its performance directly determines the performance of the PPU.Therefore,it is of great significance to research on the APS with a wide range of input voltage.By summarizing the research status of the APS,it is found that most of researchers choose full bridge topology as the topology of the APS.However,the rising space of power density and efficiency is still large.Therefore,this dissertation improves the efficiency and power density by using soft switching technology and improving the operation frequency of the APS.The full bridge LLC topology based on single Ga N device is used as the main power topology of the APS to achieve wide input voltage,high efficiency and high power density.The principle of the main power topology is analyzed.According to the working sequence diagram of each mode,the operation state of LLC is analyzed.The voltage gain is derived by the fundamental analysis.According to the input impedance properties of each mode,the soft switching characteristics of Ga N device is obtained.By analyzing the topology with parasitic capacitance and the reason of its gain failure under light load,the ZVS conditions and gain failure area are given,which provide the basis for the verification of ZVS characteristics and light load characteristics.The parameters of the main power topology are optimized.The basis for selecting quality factor(Q)and inductance ratio(k)is given by analyzing the effects of Q and k on voltage gain as well as Ga N device loss.The optimization method of Q and k is proposed,and the optimal Q and k in this dissertation are obtained.The main power circuit parameters are designed according to the previous analysis.The ZVS characteristics and light load characteristics of the optimized main power topology are veri fied.The extended description function method and simulation method are used to obtain the small signal characteristics of APS.By using the extended description function method,the theoretical part of the small signal model is obtained.By SIMPLIS simulation,the frequency response from control to output is obtained.The compensation network is designed based on the frequency response curve at the minimum input voltage and 110% load.The APS system is designed and verified by simulation and experim ent.All parts of the anode power supply are simulated in SIMPLIS.The steady-state performance are verified.The dynamic performance of the APS are also verified by the simulation of input voltage jumping from the maximum to the minimum and load switching from 100% to 10%.The hardware circuit of APS is built to verify the soft switching characteristics of Ga N device Q1-Q4 at the primary side and rectifier diode Ds1-Ds4 at the secondary side in different modes.