Research On Design Of Three-Phase Four-Leg Inverter For Permanent Magnet Variable Speed Power Take Off System

In the permanent magnet power generation system,in order to meet the power demand of high-power,nonlinear and unbalanced equipment of weapons(radar,artillery,missiles,etc.),and to solve the shortcomings of the traditional three-phase full-bridge inverter such as large weight,weak power supply capacity of nonlinear unbalanced load and low power supply efficiency,the thesis has conducted in-depth analysis and research from the nonlinear model establishment of three-phase four-leg inverter,fast decomposition of sequence components based on comb filter,weak chattering,the thesis presents an in-depth analysis and research on the nonlinear model of the three-phase four-leg inverter,the fast decomposition of sequence components based on comb filter,the algorithm of super-twisting stabilization control,the hardware system of SiC power electronics,the digital simulation and the testing of the prototype equipment.The designed converter can adapt to the unbalanced load capability requirement and has high conversion efficiency.It provides technical accumulation for building a high-efficiency permanent magnet power extraction system based on wide band power electronics.The contents of the thesis mainly include:Firstly,a super-twisting control strategy based on the fast decomposition of the sequential components of the comb filter is proposed.The comb filter converts the nonlinear model of the three-phase four-bridge arm from a three-phase stationary coordinate system to a two-phase rotating coordinate system,which reduces the workload of the control system processor,shortens the calculation time,and improves the control speed of the system.The super-twisting control algorithm effectively overcomes the control chattering problem of the traditional sliding mode control method,and has better stability control capability and speed.Secondly,the hardware circuit with crosstalk suppression and good adaptation of dynamic and static characteristics of SiC-MOSFET is designed,the software program of CPLD and TMS320F28335 is written,and the three-phase four-leg inverter is designed independently.By analyzing the key technical parameters of SiC-MOSFET,with the goal of giving full play to the advantages of high reliability,high power density,high switching frequency and low power loss technology of wide band power devices,the method of SiC-MOSFET driver circuit design is given,and the selection method of passive devices of the main circuit topology circuit and the working principle of key circuits are introduced in detail,and the software design flow chart is given.Finally,model simulation tests under different operating conditions(no-load,fullload,three-phase unbalanced load,sudden load change,etc.)are carried out.The digital simulation model of the three-phase four-leg inverter is established based on the theory of nonlinear model,fast sequence component decomposition algorithm,3DSVPWM modulation,and weak chattering and super-twisting control established in the thesis.The correctness of the proposed theory and method is verified by conducting digital simulation tests.The performance of the prototype device is analyzed by conducting test trials on the three-phase four-leg inverter prototype and recording the dynamic output waveforms of the inverter output voltage and current and its steady-state values under various tests.The tests show that the designed three-phase four-leg inverter can meet the load carrying capacity of unbalanced load and has high conversion efficiency,which verifies the correctness of the designed functional unit circuit and embedded software program.