Joule losses and torque ripple caused by current waveforms in small and medium wind turbines

Grid-connected small and medium wind turbines are a promising technology to further increase the share of renewable energy sources. Although their impact on the environment is proven to be advantageous, the cost effectiveness still needs to increase. In this paper, the impact of the passive diode rectifier on the Joule losses in the generator is investigated. Passive diode rectifiers cause unwanted harmonics in the current waveform and a low power factor, increasing the losses. The capacitance value at the output of this rectifier has a large influence on these harmonics. The amount of harmonics could be reduced by including an inductance in series with the generator terminals. However, this results in a higher reactive power demand, which also affects the losses. In this paper, the impact of both the capacitor and inductance values on the losses are investigated.