Variable frequency drives (VFDs) are gaining popularity in the marine industry due to their ability to control the speed of vessels’ electric motors. The VFDs’ capability to precisely control the motor speed increases the propulsion efficiency and lowers fuel consumption.

Another advantage of variable frequency drives is their ability to reduce the starting current of the motor. Starting a motor typically requires a large electric current, which can lead to electrical system instability and motor damages. By reducing the starting current, VFDs help prevent these problems.

There are two main types of variable frequency drives used on vessels: 6/12 pulse and Active Front End (AFE). AFE design, which supports continuous electric motor operation with a low total harmonic distortion (THD) impact on the vessel grid, is used in applications where multiple sources operate on the grid. The 6/12 pulse drives are used for applications where the variable frequency drive is operating on an isolated grid, such as a bow thruster drive on a cargo vessel.