Harmonic Analysis of a Three-Level Sinusoidal PWM Inverter Using the Method of Pulse Pairs

A method used to determine the harmonic components of the output of a three-level sinusoidal PWM inverter is presented. The method calculates the Fourier coefficients of each individual positive pulse pair of the output PWM waveform and adds them together using the principle of superposition to calculate the Fourier coefficients of the entire PWM output signal. This method allows direct calculation of harmonic magnitudes and angles without having to use linear approximations, look-up tables, or Bessel functions. The method presented is a general method that can easily be extended to other types of multilevel inverters and PWM schemes such as space vector modulation. The method has also been tested and proven to be valid in the overmodulation region