Inverter (drive)

An inverter is the power-electronic stage that converts DC to a controlled AC output, the building block of variable-frequency and electric-propulsion drives. Switching IGBTs under pulse-width-modulation control synthesize a variable-frequency, variable-voltage three-phase waveform from the DC link, setting motor speed and torque. In diesel-electric and battery-hybrid propulsion the inverter feeds the propulsion motor and can regenerate braking energy back to the bus. Larger drives use multilevel or active-front-end topologies to cut harmonic distortion on the ship’s network and meet the THD limits of the electrical class rules.