Study On PWM Harmonic Analysis And Harmonic Supperssion Method For Inverter

With the further development of power electronics technology, PWM inverter has been widely used in a variety of power electronic devices. In efficient and energy-saving, at the same time, harmonic pollution problem has become increasingly serious. In order to reduce the harmonic pollution and further saving energy, have proposed a variety of PWM control techniques to suppress harmonics. In this paper, based on harmonic analysis for PWM voltage source inverter, studies on selective harmonic elimination technology.First, according to the basic principles of PWM technology and Fourier series theory, mathematical models of output voltage waveform for the sinusoidal PWM inverter and random PWM inverter have built,and has carried out harmonic analysis by simulation of its mathematical model, reached its harmonic distribution of the output voltage waveform, provided a theoretical basis for the study of selective harmonic elimination technology.Secondly, according to the fundamental principles of selective harmonic elimination technology, the mathematical model of output voltage waveform for selective harmonic elimination inverter has built. The mathematical model is nonlinear transcendental equations, based on analysis of Newton iteration method, proposed homotopy algorithm, which has fast convergence in a large area and low demand characteristics for the iterative initial value. Solving process is the first to use non-linear homotopy algorithms for solving transcendental equations, and then obtain exact solutions by Newton iterative method.And by comparison with Newton iterative method, this algorithm have calculation speed, convergence wide-field and high precision calculation et al.Again, by analyzing distribution of switching angle for selective harmonic elimination technology and the extent of the problem of hardware implementation, proposed the optimization strategy, include a switch angle and a narrow pulse are omitted. Without affecting the quality of the output voltage waveform,in order to achieve purpose for easy engineering implementation, reducing power switch loss and elimination of low-harmonic. Finally, the bipolar inverter for selective harmonic elimination have simulated, its output voltage waveform and its spectrogram was analyzed to verify the theoretical analysis is correct. According to these studies has produced a hardware control circuit based on STC89C52RC and compiled software. Through the analysis of experimental results to verify significant advantages, include convergence range and fast convergence speed, the model of harmonic elimination inverter has solved by the use of the new algorithm for combining the homotopy algorithm and Newton iterative method.