Small Wind Turbine construction and testing
The study and simulation of small wind turbines for rural electrification applications follows local manufacturing wich enables the user with the ability of local maintenance and immediate repairs of possible failures. In the workshop, small wind turbines are constructed from scratch by undergraduate students. Up until now, small wind turbines for battery charging and grid connection have been manufactured, with rotor diameters of up to 4.3 meters.
Axial flux generator bench testing facilities in NTUA, Athens
The bench testing rig is located in the Mechanical Engineering building of NTUA and allows for the testing of axial flux generators of power up to 9kW and maximum diameter of up to 1m. With the use of a 60 HP DC motor, a DC bi-directional drive and a tachogenerator, the axial flux generators can be driven at different and constant revolutions per minute (RPM). Different loads can be applied to the generators such as a grid-tie inverter for grid connection or a 12/24/48V battery bank for battery charging modes, along with a diversion load controller and resistive load. In addition, a three phase ohmic load of maximum power 3.3kW can be connected directly to the generator. A rotary torque transducer with a DAC card is used for measuring the mechanical power in terms of torque and rpm at the shaft of the generator, provided by the DC motor drive, and the electrical output of the generator is measured using an oscilloscope with current and voltage probes.
The experimental setup mentioned allows for a complete analysis of the generator’s behavior under different situations. The following are some of the generator tests that can be performed: generator voltages under no load and at different RPM, voltages and currents under load and at different RPM, input mechanical power, output electrical power and efficiency at constant RPM and varying current, input mechanical power, output electrical power and efficiency at constant current and varying RPM. These tests can also be performed for different loads depending on the application of the generator. Other aspects of the generator such as phase inductance and resistance can also be measured.