Comparison of single-phase three-level pulse width modulation strategies

Five methods for producing three-level pulse width modulation for single-phase inverters are compared. The basic strategies are described and the advantages and disadvantages of each method are expressed in terms of complexity and implementation. Experimental and simulation results are presented to highlight the differences between the resulting pulse width modulated waveforms and to demonstrate the relative harmonic content resulting from each strategy. Key characteristics that define a harmonic minimised waveform are highlighted and it is shown that sampling-based methods for the generation of pulse width modulated waveforms show considerable advantages when compared to exact switching angle methods.