The application of wind turbine technology in low wind speed regions such as Southeast Asia has recently attracted increased attention. Wind turbines are designed as special structures with low starting torque, and many starting torque minimization processes exist for permanent magnet synchronous generators (PMSGs). Plurality is applied to decrease the starting torque in radial flux permanent magnet disk generators. The most popular starting torque minimization method uses a magnet skew technique. When used at 20°, this technique reduced starting torque by 4.72% (on load) under 500 rpm at 50 Hz for 120 min. By contrast, a PMSG with magnet skew conditions set at under 2° reduced electrical power by 3.86%. For high-speed PMSGs, magnet skew techniques affect the generation of heat in the coils (stator), with heat decrease at the middle of the coil, on its surface and between the coils at 2.90%, 3.10% and 2.40%, respectively. PMSGs were installed in vertical axis wind turbines (VAWTs), and heat generation in relation to wind speed and electrical power was assessed. Magnet skew techniques can be used in PMSGs to reduce staring torque, while skew techniques also reduce electrical power and heat generated at the stator.

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Abstract. This work investigated the effects of changing the skewing angle of a magnet coil on starting torque in a permanent magnet generator (PMSG) fitted in a low speed vertical wind turbine. The optimal skew angle of the magnet-coil was found to be 15–0 (degrees), generating 1.22 (N-m) starting torque and 295.40 (W) compared with a skew angle of 0–0 (degrees). This skew angle reduced starting torque and power by 5.43 % and 1.96 %, respectively. A Savonius and H-Darrieus stacked turbine blade operated at a wind speed of 1.90 m/s and 1.31 N-m torque. This blade was used in a fully operational vertical wind turbine, was connected to the PMSG that can cut-in speed of 2.1 m/s. It was concluded that a 15–0 (degree) skewing angle magnet-coil can be applied to a low speed vertical wind turbine.