A full-bridge converter supplying an $RLE$ load is shown in figure. The firing angle of the bridge converter is $120$°. The supply voltage $v_{m}(t) =200\pi \sin (100\pi t) V, R=20\Omega, E=800 V$. The inductor $L$ is large enough to make the output current $I_{L}$ a smooth dc current. Switches are lossless. The real power fed back to the source, in $kW$, is _________.
