I have written a small, look-up table based static inverter that generates pseudo sine waves at 60 and 400Hz in single, two phase (90 degrees) and three phase (120 degrees). The program generates PWM output that only needs filtering at the 9th harmonic and above. By driving a couple of FETs (complementary outputs provided) into a small 12VAC transformer seconday, you get 115VAC at the primary. Works well at both frequencies. Anybody interested?