Calculation of the magnetic circuit and test results of a synchronous generator with permanent magnet excitation
The article discusses issues related to the prospects for the use of low-speed synchronous generators with excitation from permanent magnets in wind turbines with a direct (gearless) connection of the shafts of the generator and the wind turbine. This arrangement of wind turbines will increase their reliability and, most importantly, the cost and, as a result, payback during operation. A prototype generator with an external rotor with 13 rotor pole pairs and 12 stator pole pairs was made. For excitation, neodymium magnets NdFeBN38 with dimensions 50×20×9 mm, having a coercive force Hc equal to 955000 A/m and a residual magnetic induction Br equal to 1.235 T, were used. The calculation of the magnetic circuit of the generator was carried out, the magnetic flux and electromotive force (EMF) of the winding coil, coil and, taking into account the winding coefficient of the EMF, induced in the windings of each phase, were determined. Calculated and determined empirically by the dependence of the EMF on the rotation frequency. The maximum discrepancy between the results obtained theoretically and experimentally does not exceed 11 %. The external characteristic of the generator and the dependence of the current, voltage and moment on the shaft on the load resistance were also taken empirically. The tasks of improvement are set taking into account the results obtained and further research of the synchronous generator in the direction of clarifying its energy and power characteristics.