A generator voltage stabilization system of a heavy-duty vehicle hybrid-electric drive system, which has an engine and a generator coupled with the engine for generating power that varies with rotational speed of the engine, includes one or more circuits having at least one of a DC/DC converter and an DC/AC converter configured to be coupled to the generator, and receive varying power input from the generator and provide stabilized voltage output power; and a control computer coupled to the one or more circuits to control the one or more circuits to provide stabilized voltage output power with varying power input from the generator.