Design and dynamic simulation of interior permanent magnet synchronous motor for electric bicycles

In this thesis, a v-shaped interior permanent magnet synchronous electric motor with 36V and 250W nominal power has been designed for e-bikes, which has been a rising trend recently due to its environmental friendly, low cost and accessibility. The literature and commercial products have been examined in detail, and the design of the embedded magnet synchronous motor has been decided due to its advantages such as the low cost of the magnet due to its rectangular shape, the additional reluctance moment to the magnet moment, the field weakening feature and the ability to exceed the nominal speed. In this context, the motor design was made taking into account the European standard EN15194. This European Standard is intended to cover electrically power assisted bicycles of a type which have a maximum continuous rated power of 250W, of which the output is progressively reduced and finally cut off as the EPAC reaches a speed of 25 km/h, or sooner, if the cyclist stops pedalling. Electric bicycles conforming to the EN 15194 standard do not require a driver's license for use. Initially, the appropriate number of slot and poles was determined in the electrical machine with constraint and performance parameters. Parameters such as torque ripple, winding symmetry, electrical frequency were investigated in the selection of the appropriate slot pole combinations. 3 different slot pole combinations were determined and analytical designs were performed on these combinations and geometries were revealed. The resulting geometries were analyzed using the finite element method (FEM) in Ansys Maxwell software and their performances were compared. Among the 3 models for which analytical calculations were made, the 12 slot 14 pole model selected for optimization was optimized using FEM. The embedded permanent magnet motor is optimized by adjusting parameters such as slot and rotor geometry, magnet angle and thickness, winding turns, etc., aiming to achieve high torque density and efficiency, low torque ripple, and reduced weight. The optimization aims for an optimal design by paying attention to factors such as flux density distribution in the electrical steel, back electromotive force waveform, harmonics, magnetic saturation in the electrical steel and air gap flux distribution. The interior permanent magnet electric motor designed with analytically and FEA has a speed of 2800 rpm and a shaft torque of 1.165 Nm. The motor has a maximum output power of 667.5 W and can continuously provide 340 W of power. The torque ripple is 2.6% of the nominal moment, and the cogging torque is about 1.6% of the nominal torque, providing a comfortable driving experience. Keywords: Embedded Magnet, E-bike, Finite Element Analysis, Torque, Back Electromotive Force, Analytical Analysis, Saliency.