A novel outer rotor axial primary magnetic circuit permanent magnet generator

Wind energy has attracted persistent attention as a renewable energy, so it is very significant to research the permanent magnet generator which is an essential part of wind energy conversion system. This paper proposes a novel outer rotor axial primary magnetic circuit permanent magnet generator. For the sake of small size and light weight with extra low speed for direct coupling, the outer rotor structure is used. The stator windings are adopted double fractional-slot concentrated to reduce the cogging torque. The most highlight is a novel axial primary magnetic circuit. Through the air gap magnetic flux density test experiments, there exists the linear relationship of the negative slope between the magnetic flux density and the air gap. This novel type of magnetic circuit structure makes greatly improved the sensitivity gap, so that the key technology such as structure design, process route determined and manufacturing become easier to achieve, significantly reduce generator costs, ease of construction practical application. Meanwhile, the novel outer rotor axial primary magnetic circuit permanent magnet generator can overcome the problems of the lager overall start reluctance generator torque and the lower wind energy conversion rate under the condition of small wind.