Evolution and Development Prospects of Electric Propulsion Systems of Large Sea Ships

Large sea ships take a huge part in world trade, passenger transport and providing supply to remote areas. There are various ship classes, designed not only for transportation of goods, but also to perform special tasks. The mentioned type of ships includes icebreakers designed to support navigation in the Arctic region. They are distinguished by a large displacement and high-capacity propulsion plant, as well as a dynamic mode of operation with frequent reverses. Many other ship types also use an electric drive in their propulsion systems, which is due to operating conditions and reliability requirements. Electric propulsion systems have the ability to change the direction of rotation with frequent repeated cycles. Currently, AC electric propulsion systems are used most widely, replacing obsolete DC motors. With a retrospective view of electric propulsion systems, a sequential development becomes obvious. The modern marine electric drive should be further improved in terms of its capacity and operation cost-effectiveness. The last of these tasks is mainly to increase efficiency and reduce losses both when converting the frequency of the supply voltage and in general in all parts of the electric propulsion system. In practice, with the modern development of technology, the reserve for improving properties of electric components is not so great. In this case, the single way to increase the efficiency of shipboard electric propulsion systems is reducing the number of functional units on the way from ship generators to the engine motor. The authors proposed a number of technical solutions for improving ship electrical propulsion systems; the novelty is confirmed by patents for inventions. One of the solution effects is the simplification of the functional circuit of the electric propulsion system, which corresponds to the general development trend- a decrease in the number of functional units and elements on the way from the ship energy source to the electric engine.