The cam-controlled electromechanical rotary power inverter converts a plurality of DC source voltages to an AC power output by an electromechanical mechanism that includes a rotating assembly of cams intermittently contacting a series of brushes connected to the DC source voltages to sequentially add the DC voltages and then sequentially subtract the DC voltages over 360° of rotation of the cam assembly. In this manner, the inverter provides multilevel, e.g., seven discrete voltage levels, which are distributed as output sequentially in an additive manner and then a subtractive mariner to generate nearly sinusoidal voltages. Repeating sequences of brushes and cams over three 120° intervals allows for 3-phase AC voltage output from the inverter.