Analysis of inverters’ voltage modulation ratio based on wavelet modulation

Abstract:

First, the analytic expressions of fundamental wave and each order of harmonic wave for the output voltage is calculated by the Fourier decomposition method, which is used to analyze the modulation ratio of the three-phase inverter modulated by wavelet modulation. Then, the equation of the voltage modulation ratio (M) is derived and the scope of M is obtained by calculation, giving the range of the linear modulation for the three-phase inverter under the wavelet modulation. Finally, the correctness and rationality of the theoretical analysis is validated by computer simulation. The research result shows that the output voltage quality under the wavelet modulation is better than that under SPWM and SVPWM when the switch frequency is equal to the modulation ratio. In addition, the range of linear modulation under wavelet modulation is larger than that under SPWM and SVPWM.