Generation and harmonics in interior permanent magnet wind generator

This paper investigates the harmonics of voltages and currents of interior permanent magnet wind generators for wind energy conversion system (WECS). The generated voltages of an interior permanent magnet wind generator (IPMWG) are fed to a three-phase diode bridge rectifier in order to produce DC power. However, the use of diode bridge rectifier introduces high intensity of harmonics in the generated currents of the IPMWG. The harmonic contents of laboratory 1 kW, 5 kW, and 45 kW interior permanent magnet wind generators for wind energy system are analyzed for different rotor speed of the wind turbine. The fast Fourier transform (FFT) is used to determine the voltage and current harmonics of an IPM wind generator. The analyses have revealed that 5^th, 7^th, and 11^th harmonics are significant in the generated currents of the IPMWG using the straight type magnet in the rotor. It is also to be noted from these analyses that both fundamental and 5^th harmonics of output currents of the IPMWG vary linearly with the rotor speed of the wind turbine.