Linear Permanent Magnet Generator

Wave energy and tidal power have always been an area of interest in many nations since there is an immense potential  in these energy sources. But, the problem of energy conversion has always been a daunting issue. The traditional energy conversion devices use rotary generators which are high speed  and convert the mechanical force to electricity.

To combat these adversities, growing interest has begun in linear permanent magnet generator for energy conversion. The motion of the rotor in a linear generator is unlike the traditional rotary generator. The  main difference between the two is the motion is going straight up and down  in a linear generator. Because of this linear feature it is possible to couple the motion of the rotor to the reciprocating vertical motion of the ocean waves. By coupling, we can eliminate the use of gearboxes and power take off schemes.  A linear alternator is most commonly used to convert reciprocating (i.e. back-and-forth) motion directly into electrical energy. Because of this ability, this type of permanent magnet alternator is suitable for tidal action and production of electricity from that motion.

Still many considerations are to be taken into account to get the desired efficiency. If the rotor speed is low then i.e. if the frequency is low then a larger construction is required which increases the overall cost. Hence newer designs are required which increases the efficiency along with smaller designs. The linear permanent magnet can be designed in a tubular form as well as a flat structure depending upon the application. Leakage is limited in flat type generators due to symmetrical structure. 

There are several factors which are important to the output of the generator of this type:

·         Number of turns

·         Area of magnetic surface

·         Revolutions/second

·         Tesla of the magnet ( flux intensity)

·         Number of poles

Harnessing the ocean energy has been escalating  since the developments of newer technologies like the permanent magnet alternators. Due to a lack of gearboxes, the maintenance has become easy and inexpensive. The efficiency has increased which has made the overall projects profitable and attractive for people to invest in.