Good Motors for Wind Turbineby David Karanja
The main role of a wind turbine is to extract energy from wind that spins the rotor. The movement and rotation of rotors provide power to generators, which generate electricity. Wind turbines are used in pumping water, cutting timber and recharging electrical batteries. Wind turbines provide pollution-free opportunities to generate energy. There are several types of motors used in wind turbines, and they vary in size and application.
Stepper motors can be sourced from old computer printers. If purchased, they are cheap and affordable and can generate alternating current (AC) power at low rates of rotation compared with similarly sized direct current (DC) motors. Stepper motors are applicable in small wind turbines. During installation of a wind turbine, small turbine blades are placed on the motor shaft. Stepper motors can either be large or small in size. Small stepper motors are less than 1 inch in diameter. The rounds per minute required to generate useful voltage depends on the number of steps in the stepper motor. Generally, stepper motors operate at around 200 rounds per minute.
Brushed DC Motors
Brushed DC motors are mainly applicable to home-built wind turbines. Power in a brushed DC motor originates from a commutator spinning the electromagnets on the brushed motor. A properly brushed DC motor has high efficiency levels at around 70 percent. A high-quality brushed motor has an axle made from hardened stainless steel, a stack of laminations, wire and brushes. One of the advantages of making use of a brushed DC motor is that one does not require any gearing and yet a battery gets charged by voltages produced in light wind. In addition, brushed DC motors are readily available.
Induction motors have been widely applied in the construction of wind turbines because of their ruggedness and simplicity. A large number of industrial AC motors are induction motors. In induction motors, the stator windings induce a flow of current in the rotor conductors. An induction motor basically constitutes a rotor, an armature and a stator containing windings connected to an energy source that is polyphased. An induction motor can be converted into a self-excited generator through the addition of capacitors. The use of a torque to drive the induction motor can change it to an alternator. Large induction motors have an efficiency as high as 95 percent.
- wind turbine image by MAXFX from Fotolia.com