The Research On The Control Strategy Of Three-Level Inverter Based On Space Voltage Vector Control Method

Recently, the research and design of three-level medium voltage frequency inverter has widely become the hotspot in the area of motion control. Three-level inverter makes a high-power and high-performance voltage-source-inverter possible.Therefore, it is very important to study and design the three-level inverter both in the theory and practical application.The operating principle and basic components of three-level inverter system are studied as following points:1. First the principle of two-level inverter is detailed to introduced, and based on it, the principle of the voltage vector modulating technique is studied, the advantage of the voltage vector modulating calculation is analyzed comparing with other means.2. The next in order, the three-level space voltage vector control method is analyzed in detail. The formulas about PWM pulse and the order of switches action are also presented. The order of switches action is also optimized in this text, which can be propitious to the control of midpoint's voltage.At the same time, the simulating and implement can also be easier.3. The production of capacitance voltage's imbalance belongs to direct current sides of three-level inverter is analyzed in this text. Then, A theory which can realize the balance of midpoint's voltage is introduced;At the same time, A modeling method found on Matlab is hereby brought forward, and then this method's correctness is validated by emulation results.4. The SVPWM modulating means of three-level inverters is simulated by MATLAB, and the correction of modulating means is proved. Comparing with the SVPWM modulating results of two-level inverters, The superiority is futher proved, which belongs to the SVPWM modulating means of three-level inverters at the aspects of restraining harmonicand and minishing switching wastage.