Research And Implementation Of Intermediate Frequency Aero Ground Power Supply With DC Microgrid Hybrid Power Supply

As the second generation of aviation ground power supply,intermediate frequency aviation ground static variable-frequency power supply is designed to provide high-quality 400Hz/115 V voltage for civil aircraft and military aircraft during ground maintenance,starting and maintenance of airborne equipment.With the rapid development of power semiconductor technology and modern power electronic technology,excellent electrical performance,low electromagnetic interference,lightweight have become the mainstream development trend.However,due to its output voltage frequency is much higher than 50 Hz,there are problems of low quality of the output voltage waveform with asymmetrical load and rectifier load.In response to these problems,a T-type three-level inverter is designed in this thesis,and a single-phase control method combining Second Order Generalized Integrator(SOGI)and Park transform is proposed for three-phase asymmetrical load.The feasibility of the research is verified by simulation and experiment.At the same time,in view of the large power consumption when bridge-borne equipment replaces aircraft auxiliary engine to supply power to landing aircraft,a hybrid power supply scheme based on AC power grid and DC microgrid is proposed to improve the utilization rate of renewable energy in the airport.First,the principle and commutating process of the T-type three-level inverter is analyzed,the mathematical model in the abc coordinate system and the dq coordinate system is deduced,and the sine wave pulse width modulation strategy and the space vector pulse width modulation strategy are described in detail,including the specific implementation steps of the sector judgment,calculating the duration of basic vector,and seven-segment wave state distribution.In terms of control strategy,the proportional-integral(PI)control strategy of voltage-current dual-loop of three-phase inverter is introduced in this thesis,and the coupling relationship and decoupling mode of dq axis voltage components is deduced.Due to single-phase inverter cannot use coordinate transformation for non-steady state error PI controller,and in order to adapt to the three-phase asymmetrical load,a single-phase dual-loop control strategy based on SOGI and Park transformation is proposed based on the split-capacitor these-phase inverter.The principle and control process of the new control strategy are interpreted.And by analyzing the harmonic characteristics of the rectifier load,the harmonic suppression technology based on repetitive control and proportional resonance control are introduced.Finally,an experimental prototype of 8kVA medium frequency aviation ground power supply is developed,and the hardware and software design method of the prototype are introduced.The hardware design includes DC bus capacitor selection,LC filter parameter calculation and control circuit design.The software design includes the overall structure of the software,the PI dual-loop decoupling control algorithm based on SOGI and Park transform,and the repetitive control algorithm.The simulation and experiment are carried out for two problems with three-phase asymmetrical load and rectifying load,and the applicability of the above method is verified by experimental waveform and THD analysis.The voltage unbalance degree with asymmetric load is less than 0.1% under the three working conditions.The controller adopts the control strategy based on SOGI and Park transformation when the experimental prototype is with asymmetrical load,and the controller switches to repetitive control when with rectifier load.