Based On The Dsp Novel Asymmetric Six-level Inverter Shepwm Control Method

With the development of power electronic technology, the inverter technology is used very widely. The inverter is that the device changes DC to AC, such as new energy source power generation, AC electrical drive, UPS, frequency converter etc. Traditionally, the output PWM pulse wave of the inverter contains only 2 levels. Thus, a high common mode voltage as well as a high du/dt could be existed in the system, both of which will put a threat to the insulation of the motor windings. Besides, the design of the output filter is comparatively complicate due to the high THD (Total Harmonious Distortion). In order to find a solution to these questions, the multilevel inverter is used.Multilevel inverters include an array of power semiconductors and capacitor voltage sources, the output of which generate voltages with stepped waveforms. The most attractive features of multilevel inverters are as follows: they can generate output voltages with extremely low distortion and lower du/dt; they draw input current with very low distortion; they generate smaller common-mode (CM) voltage, thusreducing the stress in the motor bearings. In addition,using sophisticated modulation methods, CM voltages can be eliminated; they can operate with a lower switching frequency. Today, multilevel inverters are extensively used in high-power applications with medium voltage levels.This thesis presents the most important topologies like diode-clamped inverter (neutral-pointclamped), capacitor-clamped (flying capacitor) and cascaded multicell with separate dc sources and so on. Then it also presents the most relevant control and modulation methods developed for this family of converters: multilevel sinusoidal pulsewidth modulation, multilevel selective harmonic elimination, and space-vector modulation. According to their features, multilevel selective harmonic elimination is proposed for the new topology. The simulation of three phases as well as the phase multilevel inverter has been done with MATLAB and the result is satisfying, then researching on the result of the simulation.The thesis researches on the multilevel inverter by the control technology of DSP. The use of Digital Signal Processor (DSP) controller simplifies the control system, improves the performance of the system and makes it possible to apply some optimizing algorithm, the paper researches on the design of hardness circuits and software.Hardness circuits include main circuit, buffer circuit, zone circuit and drive circuit. In the software part, the programs have been finished. SHEPWM is implemented and based on TMS320LF2407A DSP. After experimentation and debugging, the practical results are recorded, which show that the circuits are applicable and its control is effective.