Selective harmonic elimination method for unequal DC sources of multilevel inverters

Figures & data

Figure 1. (a) Asymmetric cascaded single-phase inverter; (b) output waveform at low mi; (c) output waveform at high mi with V₁≠ V₂.

Figure 2. Modulation index ($mi$) versus the ratio $V_1/V_2.$

Figure 3. For mi = 0.6 to 1.1, (a) ${\alpha }_1$ versus $V_1/V_2$ (b) ${\alpha }_2$ versus $V_1/V_2.$

Figure 4. System block diagram.

Figure 5. (a) Output voltage for V₁= 10.8 V, V₂= 18 V, V₁/V₂ = 0.6, mi = 0.7, α₁ = 29.48° and α₂ = 89.13°, (b) output voltage spectrum.

Figure 6. (a) Output voltage for V₁= 16.2 V, V₂= 18 V, V₁/V₂ = 0.9, mi = 0.9, α₁ = 10.61° and α₂ = 66.41°, (b) output voltage spectrum.

Figure 7. (a) Output voltage for V₁= 28.8 V, V₂= 18 V, V₁/V₂ = 1.6, mi = 1.1, α₁ = 26.94° and α₂ = 34.92°, (b) output voltage spectrum.

Figure 8. Harmonic analyses versus V₁/V₂ ratio for V₁= 18 V; (a) Value of fundamental component; (b) Values of third harmonic component and its multiples; (c) Other lower harmonic components. (d) THD versus V₁/V₂ ratio for different values of modulation index.

Figure 9. (a) Output voltage for V₁= 10.8 V, V₂= 18 V, V₁/V₂ = 0.6, mi = 0.7, α₁ = 29.48 and α₂ = 89.13°, (b) output voltage spectrum where cursor X1 at 250 Hz and cursor X2 at 350 Hz.

Figure 10. (a) Output voltage for V₁= 16.2 V, V₂= 18 V, V₁/V₂ = 0.9, mi = 0.9, α₁ = 10.61° and α₂ = 66.41°, (b) output voltage spectrum where cursor X1 at 250 Hz and cursor X2 at 450 Hz.

Figure 11. (a) Output voltage for V₁= 28.8 V, V₂= 18 V, V₁/V₂ = 1.6, mi = 1.1, α₁ = 26.94° and α₂ = 34.92^o, (b) output voltage spectrum where cursor X1 at 250 Hz and cursor X2 at 350 Hz.