Increased DC-to-AC power conversion efficiency in a scalable, flexible, resilient, cascading inverter driver topology. Plural power cells, which include a rectifier and an inverter, are arranged in a series/parallel topology. Use of plural power cells increases efficiency by reducing voltage transition losses and by increasing duty cycle. Also, the power cells output AC to an electric motor using a forward-looking controller that responds to varying power demand while maintaining motor speed at a maximum efficiency level. Power output is varied by varying the width of rectifier output pulses to the inverters while maintaining pulse voltage. Transitions between power levels are smoothed by pulse density modulation. Pulse density, determined automatically in the inverter, begins high and gradually becomes less dense so voltage changes rapidly then slowing gradually. The topology and power cell components allow faulty power cells 10 to be isolated and bypassed.