Three-Phase Inverter

Used to supply three-phase loads
Three single-phase inverters could be used, however, 12 switches are necessary, as a result, less efficient
Consists of three legs, one for each phase
One of the two switches in a leg is always ON at any instant
Output of each leg depends on Vs and the switching status

Three-Phase PWM Inverter

${v_{ab}}(t) = \sum\limits_{n = 1,3,5,..}^\infty {\frac{{4{V_S}}}{{n\pi }}\sin (\frac{{n\pi }}{3})\sin n(\omega t + \frac{\pi }{6})}$

${v_{bc}}(t) = \sum\limits_{n = 1,3,5,..}^\infty {\frac{{4{V_S}}}{{n\pi }}\sin (\frac{{n\pi }}{3})\sin n(\omega t - \frac{\pi }{2})}$

${v_{ca}}(t) = \sum\limits_{n = 1,3,5,..}^\infty {\frac{{4{V_S}}}{{n\pi }}\sin (\frac{{n\pi }}{3})\sin n(\omega t - \frac{{7\pi }}{6})}$

$\begin{array}{l} {V_{Ln(rms)}} = \frac{{4{V_S}}}{{\sqrt 2 n\pi }}\sin (\frac{{n\pi }}{3})\\ {V_{L1(rms)}} = \frac{{4{V_S}}}{{\sqrt 2 \pi }}\sin (\frac{\pi }{3}) = 0.7797{V_S} \end{array}$