High-Voltage Capacitor Constant Current Charging Technology For Pulsed Plasma Thrusters

The performance of the Pulsed Plasma Thruster(PPT)high-voltage storage capacitor charging power supply determines the thrust accuracy of the PPT,the maximum repetition frequency of the pulse discharge,and the overall efficiency of the PPT system.This paper studies the high-voltage capacitor charging power supply such as increasing current output capability,voltage accuracy,voltage repeat stability,and power efficiency.Firstly,by reviewing the topology of the known PPT high-voltage charging power supply and combining the working characteristics of the PPT,the LCC resonant converter is selected as the charging topology of the high-voltage capacitor.And set it to work in resonant current discontinuous mode(DCM)to obtain zero current soft switching(ZCS)characteristics.By comparing the current output characteristics of the single pulse output(DCM1)and the double pulse output(DCM2)in the discontinuous mode,DCM2 is further determined as the main operating mode,and the mode is solved by modal analysis.The critical discontinuous resonant frequency expression provides a basis for pulse frequency modulation and PI-based current closed-loop control reference setting.By comparing the critical discontinuous frequency modulation with the maximum output current under traditional fixed-frequency modulation,the paper validates the constant current charging control scheme based on critical frequency modulation to effectively improve the current output capability.Ensure that the PPT constant current charge is completed within the specified repetition period.Secondly,the power supply operates under low-voltage and high-current input conditions,and the power loss of the converter is most significant with the switching loss and conduction loss of the MOSFET.This paper innovatively introduces the traditional synchronous rectification concept into power supply modulation.By optimizing the trigger timing in DCM2 mode,the ZCS is realized while minimizing the reverse conduction loss of the MOSFET during the energy feedback process of the LCC resonator,thereby improving the conversion efficiency.In this paper,the tracking of the critical discontinuous switching period is used to focus on overcoming the ever-changing outputvoltage disturbance during the charging process.The linear fitting algorithm for simultaneous soft switching and synchronous rectification is described in detail.Thirdly,in order to obtain high-precision PPT electric thrust and ensure the repeatability of the capacitor charging voltage,this paper proposes a soft-switch hysteresis Burst control method based on the hysteresis Burst method to achieve constant voltage control.The ZCS can be realized in the entire process of charging both the constant current and the constant voltage.Not only does it achieve high-precision,low-ripple,constant-voltage output,but it also reduces switching losses.Finally,the hardware circuit design process of the charging power supply is given,and the experiment is carried out on the 2kV/250 mA high-voltage charging power supply experimental prototype to verify the correctness of the above theoretical analysis and the effectiveness of the control strategy.