Research On Distributed Spacecraft Power Supplyand The High Dynamic Digital Control Technology

In traditional spacecraft engineering,the power system usually adopts a centralized architecture for analog control.With the development of space technology,the power requirements of large spacecraft platforms and payloads are increasing,and distributed power systems have become a development trend.In terms of distributed power system control methods,digital control technology can greatly improve flexibility,intelligence and comprehensive performance of power system,and can realize the software definition of converter functions.Its intelligent and flexible characteristics are very suitable for distributed power sources.It’s also an important development direction of spacecraft power control technology.The increasing load of integrated circuits on modern spacecraft requires higher dynamic performance,especially pulsed power spacecraft represented by high-power synthetic aperture radar satellites,which require dynamic performance and anti-jamming performance of the power supply system.The selection of the spacecraft power processor is restricted by the space environment such as radiation,which affects the improvement of the dynamic performance.Therefore,it is very necessary to study how to improve the dynamic response of the system while reducing the complexity of algorithm.It is very necessary to study the application of digital control technology in spacecraft.The research goal of this thesis is to propose the distributed power system architecture of spacecraft based on digital control.Hence,it’s very important to improves the control bandwidth and dynamic response performance and simplify the control algorithm.The research goal of this thesis is to propose a spacecraft digital control distributed power system architecture,on this basis,to study high dynamic performance digital control methods,while reducing the complexity of the algorithm and improving the dynamic response performance of the power system.Aiming at the characteristics of spacecraft’s demand for power systems,a digitally controlled,software-definable spacecraft distributed power system is proposed.Through software definition,the solar array power regulator and battery charge and discharge regulation are reused in the system architecture.At the same time,it can realize the maximum power point tracking control of the solar cell array,and the localized charging and discharging control of the storage battery.Realize the system flexible adaptation,equipment elastic access.Aiming at the application of the synthetic aperture radar satellite distributed pulse power system,a two-domain high dynamic control method is proposed.The hysteresis control is designed outside the digital control loop,which effectively improves its dynamic performance.The control method is verified by experiments.Aiming at the spacecraft primary power supply operating in continuous current mode,the current tracking delay effect of digital predictive current mode control and its elimination method are studied.The current tracking delay effect of the converter under the digital predictive current mode control based on the linear extrapolation method and the state current prediction method is analyzed,and the current tracking delay transfer function is equivalent to the shift of the zero point of the right half plane of the converter,and the compensation parameters are corrected.Improved system bandwidth.Two new control strategies of duty cycle limiting method and duty cycle expansion method are proposed.The correctness of the method is verified through simulation and experiment,and the transient response and stability problems caused by current tracking delay are eliminated,and the algorithm complexity is reduced.At the same time,it effectively improves the transient response speed of the output voltage.Aiming at the secondary power supply operating in discontinuous conduction mode of the spacecraft,a charge-balance digital control method based on current observation was proposed.The average current observer and average current controller were designed.Based on the principle of output capacitance charge balance,it improves the dynamic response speed of output voltage for steps of load and input voltage.From the perspective of frequency domain,the open-loop and closed-loop stability of the system are analyzed deeply,and the influence of various parasitic parameters on the system was studied,and an damped current model was proposed.By introducing an appropriate gain,the effect of parasitic parameters to power system was eliminated.The system bandwidth and dynamic response were improved.In order to further improve the dynamic performance of the secondary power supply with digital charge-balance control,the differential voltage extrapolation algorithm was studied and simplified.By sampling the differential value of the output voltage,according to the output voltage differential value,the voltage is extrapolated after two switching cycles without output to estimate the output voltage.Finally,the calculation of the charge-balance was completed within two switching cycles,the small-signal model of the system was established,and the closed-loop system is analyzed in the frequency domain;the charge damped and its influence on the output voltage were studied,and the constant compensation factor is used to minimize the influence.It further improves the system bandwidth and the dynamic response performance.