Wind Permanent Magnet Generators: Battery Charging Application

The market for small wind turbines is providing added electrification needed in remote areas. Many parts of the world are still running on electricity from batteries rather than electrical grids laid by national power corporations.  Telecom companies who have to provide uninterrupted signals in remote areas rely on batteries and generators to get electricity. Another area that uses battery back up is Marine operations.  Off grid wind turbines are proving to be more and more valuble in these situations.

Wind speed is not always constant and it is usually highest during the night hours when people are not using much electricity. Storage of this night-time electricity can charge the battery and become an important method to utilize this electricity that could be lost.

Installing a small wind permanentmagnet generator at remote sites can provide battery charging at a much lower cost than diesel generation or charging stations. Since there are no recurring costs with wind energy, the payback period of the initial setup cost is minimal. 

 In marine environments where the sources of electricity are scarce, batteries are the only viable option and due to high wind speed at sea, these wind turbine battery charging options become a very profitable and convenient source. The overall cost of electricity is reduced. Also with battery usage the overall capacity of the site is doubled. The wind turbine produces the electricity and the battery stores the the extra electricity.

The initial setup is simple. The connection diagram is shown below.

Since the generator is a permanent magnet one, the efficiency obtained in converting mechanical energy to electrical energy is maximum. It is more than 90%, which means more than 90% of the applied mechanical force by the wind is converted into electricity. Compared to 70% provided by traditional generators the amount of wastage is minimal. With such high efficiencies in permanent magnetgenerators, the fuel savings are more, the batteries last longer and overall cost of using electricity is decreased.

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. 

10 kW Permanent Magnet Generator

10kW Design

The 10kW permanentmagnet generator finds its applications in residential houses on country sides, farming sites, small business setups etc. This has empowered owners to a great extent to reduce utility bills. Other than these, 10kW wind turbine setups are very famous in telecom sector, on or off grid residential areas, rural schools etc. Areas with no electricity grids or with unreliable grids depend on wind energy most of the time.

Very high efficiency and long lasting design have made 10kW system a favorite amongst rural   land owners and farmers. Farmers can expect a very short payback period of less than 5 years which makes their fuel cost go down.

 When designing a 10kW wind turbine, many considerations have to be kept in mind. This is not a very small setup. Issues like weight of the whole turbine, tower, braking system etc play an important role while designing. These windmills have to be made to withstand strong wind conditions since potential of generating electricity during high wind conditions are much more.  Also during strong wind conditions the design and strength of the whole setup comes into play. These winds can damage strong structures easily, hence the material of the wind blades and the tower strength have to be strong enough to withstand winds at 150 km/hr. 10 KW designs have to be robust and dependable for these wind conditions. With a yield of 40,000 -60,000 kWh, users can increase their benefits by selling back the electricity to the national grids. 

10kW Generators in Telecom

During past seven years the installation of telecom grids all over the world has increased many folds. During these competitive times, the telecom companies are expanding their networks to regions where there are no electric grids also. The small wind industry is a key player in this field. Wind turbines like 10kW turbines find a huge potential in these areas by providing uninterrupted power supply throughout the day 365 days a year.

Direct Drive 10kW

The many advantages of 10kWpermanent magnet generator especially a 10 kW are reliability, efficiency and reduction in the overall cost of producing electricity. In the direct drive method power is taken directly from the wind turbine without any reductions which was earlier provided by a gearbox.

A 10kW turbine fitted with a direct driven mechanism offers many advantages:

·         More efficient – No power wastage from belts, chains, gearbox etc

·         Drive Stiffness – Avoiding gearbox results in removal of mechanical backlash, hysteresis and elasticity

·         High torque at low speed

·         Noise reduction

·         Increased lifetime

·         The positioning is faster and accurate

Other features of a 10kW design:

Since a 10kW wind generator becomes a large unit and weight is more, the mounting arrangement like tower is made from high tensile foundations. Mechanical fail safe braking system is incorporated for to stop the turbine operations. Heat sensors, over voltage sensors etc are fitted to keep the machinery safe from any damage. At very high wind speeds which can be a danger to the setup, wind shutdown mechanisms are installed to keep the kit from getting blown away.