Research On Three-level Inverter Based On Space-vector Control

There has been much consumption of high-voltage and capacity electrical energy in China, so VVVF will bring considerable economic and social benefits. However, the current domestic research is still not mature in this area. There has not a sound system theory and superior market products. Therefore, the study which applies to the relevant equipment and technology is of great realistic significance and research value.Multi-level inverter has been one of the research focus topics in the field of high-voltage and capacity electrical energy. Through different combinations of switches, multi-level ladder wave output voltage can effectively improve capacity and voltage pressure levels of inverters, reduce the output voltage harmonic and switching losses. Because there are so many topologies and control strategies of multi-level inverter. The diode clamp-type three-level inverter (NPC) is studied and space-vector PWM (SVPWM) is analyzed in this thesis.The relevant theory of multi-level inverter, in turn the working principle of diode clamp-type three-level inverter, SVPWM modulation algorithm, the problems and their solutions approach about neutral point potential imbalance are presented. On above basis, MATLAB was used to simulate to realize the designs. The results prove that the algorithm designed can produce the desired output voltage waveform and the control effect of neutral point potential is very obvious.Through theoretical study in the realization of the three-level inverter with space-vector control, a control system for AC motor has been constructed. DSP (TMS320LF2407A) was the control center of the system. Many appropriate power electronic devices are used to set up the hardware circuits which contain the main circuit, driver circuit, snubber circuit and so on. All system includes not only drawing, PCB, welding of the hardware circuits, but also the theoretical study of space-vector modulation strategy for DSP control software. At last it realizes the circuit control.Through the analysis of experiments waveform and data, it proves that the design for three-level inverter with SVPWM control strategy is correct, and the output voltage waveform is more approaching a sine wave.