The Research On SVPWM Control Strategies Of Three-level Inverter And Its Application To Active Power Filter

With the development of power electronic technology, multilevel inverting technology has become a pop research in high pressure and high-power converting fields. It can synthesize multilevel output voltage with the distribution of DC voltage and the combination of different switching actions. Multilevel inverting technology can effectively enhance the capacity and voltage endurance of system, lessen switching loss of the inverter and harmonic distortion of output voltage. Since its emergence, great emphasis has been putting on it in the application of power system.The topology structure and mathematical model of the diode-clamped three-level inverter is researched in this thesis firstly. On the base of it, the three-level SVPWM (space vector pulse width modulation) algorithm is deduced in detail and is improved partly, so the control algorithm is simplified. In order to solve the problem of neutral point balance, the operating time of positive and negative space voltage vectors is timely redistributed. The results of theoretical study and simulation prove that SVPWM algorithm and control of neutral point balance is true and effective.The diode-clamped three-level inverter is applied in the main circuit topology structure of the three-phase three-wire parallel APF (active power filter) in this thesis, harmonic, reactive current detecting method is studied in detail, then the control method to compensate current based on three-level SVPWM is analyzed and realized. Whole system of APF is dynamically simulated in SIMULINK environment of MATLAB software. The simulation results prove that this method has many advantages for harmonic elimination in power system.