| Space Solar Array Simulator(SSAS),as an important part of space power test system.Its main function is to simulate the real space solar panel output,provide energy input for spacecraft,and realize the substitute test on the ground.Its performance directly affects the reliability of the test results of the spacecraft power system.In this paper,the response speed,power density,feedback control,algorithm optimization and other aspects of SSAS are studied.The circuits,control subsystem and experimental test platform are designed to verify the feasibility of the scheme.First,based on the volt-ampere characteristics and equivalent circuit of solar cells,the mathematical model is determined,and the successive difference comparison method is used as the method to track the dynamic operating point.At the same time,according to the overall functional requirements of the simulator,the upper and lower computer interfaces arc designed to realize remote parameter setting,measurement and monitoring,preview I-V curve waveform and dynamic display of power output track and other functions.The working principle of the converter is studied,several main circuit topologies are discussed and compared,the forward converter is chosen as the main circuit topology,the working mode is analyzed,and the model of each component in the main circuit is determined.In addition,the main control circuit is designed,including buffer circuit,protection circuit,output distribution circuit and so on.In view of the high power,high current and multi-channel(combination)of SSAS in practical applications,a chassis with strong current isolation,good tensile strength and uniform stress is designed.Secondly,for SSAS control,Xilinx ZYNQ7010 series is selected as the control core,and peripheral circuits are designed,including isolation drive circuit,signal processing circuit,485 communication control output circuit,etc.,and double-loop feedback of voltage and current is determined as the outer loop control of the control system.The response speed and simulation accuracy of SSAS are further improved.According to the idea of successive difference,the difference is compared with the discriminant condition to judge whether it is tracked to the working point and achieve accurate simulation output.Finally,the prototype test platform is built to test and verify the function and performance of the prototype,which is divided into steady state test and closed-loop test.In the steady-state experiment,the output impedance at three operating points on the voltammetry characteristic curve of SSAS is tested,and the output impedance at the open voltage load operating point is between 2～20 Ω,the output impedance at the short circuit current operating point is between 20～100 Ω,and the output impedance at the maximum power point is between 3.2～10Ω.The results show that the output impedance.is within the allowable range.The output voltage of 20 V and 30 V were selected to test the single-channel output voltage ripple,and the peak-to-peak value of the waveform was less than 100 mV,which met the design requirements,In the closedloop experiment part,the PWM waveform output of the simulator is tested,and the waveform output is good.When the load value is changed,it is observed that the output voltage of the simulator changes rapidly and stably,the response time is less than 50 ms,and SSAS has a good dynamic response speed.The test results show that the performance of the simulator is good and the feasibility of the designed scheme is verified. |
