Computer-aided analysis of SPWM inverter

With the application of complex modulation in SPWM inverters, the signal forming of inverters depends on digital system more and more. In the digital system, the sample-hold wave approximates the analogy modulation signal, which is the obvious feature defferent from the analogic system. This paper studies the techniques to produce SPWM switching point by sample-hold modulation signal modulated with delta carry signal. The techniques include the computing the switching points of the symmetric and asymmetric SPWM and computing the switching points at the modulation ratio more than one and that less than one. The output voltages are expressed in Fourier series. Simulation results show: this method can be used not only to produce SPWM signal to drive power devices but also to simulate and analize all kinds of complex SPWM wave.