Design And Implementation Of 400Hz Intermediate Frequency Power Supply Based On SiC MOSFET

Three-phase medium frequency power supply is a special power source that can convert 50 Hz AC or DC power into medium frequency AC(400Hz is commonly used).It is widely used in aviation,ships,radars and other military fields that have strict requirements on power supply performance.They are required to have the advantages of compact structure,small size,and able to power unbalanced load while satisfying the conditions of pure output waveform and stable working performance.This thesis takes the Si C MOSFET-based three-phase 400Hz/115 V medium frequency power supply as the research object,applies the new power device Si C MOSFET to manufacture medium frequency power supply system,uses its high-speed switching frequency to improve the system power density,and conducts research on its control strategy.Improve the quality of the output waveform.Fast of all,this thesis analyzes its switching process of Si C MOSFET,studies the crosstalk problem in the high-speed switching state of the bridge structure,explains its generation mechanism,and designs a new type of driving circuit to suppress the crosstalk to improve system reliability;Then we analyzed the three-phase inverter system.After comparing a variety of topological structures,we chose a three-phase full-bridge circuit and established its mathematical model in different coordinate systems.We discussed the principle and realization process of the space vector pulse width modulation technology used in the control of the power switching device;We research the system control strategy in the two-phase synchronous rotating coordinate system,design the voltage and current PI double closed-loop control strategy,and analyze the coupling relationship between the voltage and current,giving a decoupling control method.Aiming at the problem that the classic dual-loop control cannot meet the problem of unbalanced load,based on the original control,we propose a method of introducing a quasi-resonant controller to form a composite control system to increase the gain of the secondary component and reduce the unbalance of the output voltage.The simulation model of the control system is built in Matlab/Simulink environment to simulate the three-phase unbalanced load condition to verify the suppression effect of the composite control strategy proposed in this paper on the unbalanced output voltage.The results show that it effectively removes the influence of the fundamental wave double frequency disturbance when the positive and negative sequence voltage components are converted to the rotating coordinate system;Then the software and hardware platform is designed according to the system indicators,the design method of the system hardware circuit is given,the parameters of the key components are determined,and the realization process of the control software based on the digital signal processor is analyzed in detail.Finally,a prototype of 3k VA Si C MOSFET-based 400 Hz medium frequency power system was manufactured.and its various functions and system indicators were tested.We focused on the drive waveform of the Si C MOSFET in the phase-leg configure,the static performance of the no-load and full-load output of the system,and the dynamic performance of the system with unbalanced load.The test results met the expected design requirements.