Ship with direct drive permanent magnet generator

Ship with direct drive permanent magnet generator

In the process of ship operation, fuel costs account for a large proportion of ship management costs. In order to reduce operating costs, at the same time, with the promotion of global green ships and smart ships, more ships try to choose to install shaft generators and frequency converters. , Make full use of the redundant power reserved by the ship's main engine to drive the shaft generator to generate electricity, shut down or reduce the auxiliary diesel generator set to generate electricity to meet the power needs of the ship's normal navigation. This saves the light diesel consumption of the auxiliary diesel power generation unit, significantly reduces the ship’s operating costs, avoids the simultaneous operation of multiple equipment during the ship’s journey, reduces the heat source and air pollution, reduces the cabin exhaust pressure, and reduces The noise of multiple oil engines working at the same time is reduced, and the working environment of the cabin is improved.

Current status of marine generators

When the ship is running, the internal combustion propulsion host drives the propeller to run at a speed ranging from 100 to 550 rpm, and at the same time, the electric excitation generator is driven to generate electricity between 1000 rpm and 2200 rpm through the speed-up gearbox. After power generation, it is connected to a stable frequency and stabilized power supply, which converts the unstable frequency and unstable voltage generated by the generator into a stable frequency and stable voltage three-phase power supply. The stable frequency and stabilized voltage power supply can be switched in parallel with the auxiliary generator set. Supply water pumps, fans and other electrical equipment on board.

At present, there are three transmission modes of ship with generator:

Host free end acceleration type

Main engine + gear box double drive type

The existing ship-mounted generators have the following disadvantages:

1. Because the electric excitation generator can only run at high speed, in the above three installation methods, the internal combustion host must use a gearbox to increase the speed to drive the electric excitation generator. This gearbox will generate certain losses and increase at the same time. An auxiliary device is added, which increases the complexity of the supporting equipment and wastes valuable space on the ship.

2 The existing generator is equipped with an electric excitation system, the generator structure is complicated, the control is cumbersome, the generator has a large volume, a large loss, and a low efficiency, which affect the reliability of the system.

3 The excitation winding of the generator generates serious heat, and the excitation winding is set on the generator rotor. Due to the air gap between the stator and rotor of the motor, the heat from the excitation winding is difficult to transfer to the outer surface of the motor through the contact and heat conduction of the iron core. The generator needs external ventilation. The heat generated on the generator rotor can only be taken away from the heat source of the generator's excitation winding, so that the ocean moisture directly enters the inside of the motor, exposing the motor windings to the ocean environment and affecting the life of the motor.

Brief introduction of our company's ship belt direct drive permanent magnet generator system

The ship with a direct-drive Permanent Magnet Generator is directly powered by the free end of the independent diesel propulsion engine, eliminating the need for gearboxes to increase speed. The generator rotates at the same speed as the main diesel propulsion engine. The stabilized power supply converts the unstable frequency and unstable voltage generated by the generator into a three-phase power supply with stable frequency and stable voltage. The stabilized frequency stabilized power supply can be switched in parallel with the auxiliary generator set, and is responsible for the ship's power supply task.

Compared with traditional marine generators, this system has the following advantages:

●The generator adopts a direct-drive low-speed permanent magnet generator. The generator can work at low speed and variable speed to generate electricity. The generator is fully suitable for the reality of the main engine variable speed work, eliminating the need for gearboxes, simplifying the structure, improving reliability, and saving Valuable cabin space.

●The generator has a permanent magnet structure, no excitation winding, no excitation loss, no heat generation of the rotor, the generator only needs to cool the outer surface of the motor to dissipate the heat generated by the stator winding of the generator, and the cooling air does not need to enter the inside of the motor. It can adopt a closed structure, and the protection level can reach IP55, which is suitable for marine environment requirements. It prevents the salt mist and moisture from the ocean from entering the motor, and the generator has a long life.

●The generator runs efficiently in the entire speed range, saving oil consumption. Compared with the existing ship-mounted generators, omitting the gearbox can save 6% of losses. The permanent magnet excitation of the generators can save 8% of the generator excitation losses. The stronger air gap magnetic field can make the permanent magnet generator stator Energy saving is 2%. After adopting direct-drive permanent magnet generator, the system efficiency can be comprehensively improved by 16%.

●The generator adopts high-performance rare earth magnet steel, with high performance index, compact structure, and the volume and weight are reduced by 50% compared with the electric excitation generator, which reduces the precious installation space.

●The generator can continue to use the stabilized frequency and stabilized power supply of the existing shaft generator, and the matching of the equipment is good.