Relationships of DC line voltage, three-phase 6-step wave output, SPWM output and SVPWM output.

Relationships of DC line voltage, three-phase 6-step wave output, SPWM output and SVPWM output. Assuming V_\mathrm{dc} is DC voltage.

Three phase square wave output

V_\mathrm{phase-fundamental-amplitude}=\frac{2}{\pi}V_\mathrm{dc}\approx0.6366\ V_\mathrm{dc}

V_\mathrm{line-line-fundamental-amplitude}=\frac{2\sqrt{3}}{\pi}V_\mathrm{dc}\approx1.1027\ V_\mathrm{dc}

M_{i_\mathrm{three-phase-square-wave-output}}=\frac{1.1027}{1.1027}=1

Three phase SPWM wave maximum output

V_\mathrm{phase-fundamental-amplitude}=\frac{1}{2}V_\mathrm{dc}=0.5\ V_\mathrm{dc}

V_\mathrm{line-line-fundamental-amplitude}=\frac{\sqrt{3}}{2}V_\mathrm{dc}\approx0.866\ V_\mathrm{dc}

M_{i_\mathrm{three-phase-SPWM-maximum-output}}=\frac{0.866}{1.1027}\approx0.7854

Three phase SVPWM wave maximum output

V_\mathrm{phase-fundamental-amplitude}=\frac{2}{\sqrt{3}}\frac{1}{2}V_\mathrm{dc}=\frac{1}{\sqrt{3}}V_\mathrm{dc}\approx0.5774\ V_\mathrm{dc}

V_\mathrm{line-line-fundamental-amplitude}=\sqrt{3}\cdot\frac{1}{\sqrt{3}}V_\mathrm{dc}= V_\mathrm{dc}

M_{i_\mathrm{three-phase-SVPWM-maximum-output}}=\frac{1}{1.1027}\approx0.9069

Reference

The modulation index of pulse width modulation (PWM)