This paper comprises the design, analysis, experimental verification and field weakening performance study of a brushless direct current (BLDC) motor for a light electric vehicle. The main objective is to design a BLDC motor having a higher value d-axis inductance, which implies an improved performance of field weakening and a higher constant power speed ratio (CPSR) operation. Field weakening operation of surface-mounted permanent magnet (SMPM) BLDC motors requires a large d-axis inductance, which is characteristically low for those motors due to large air gap and PM features. The design phases of the sub-fractional slot-concentrated winding structure with unequal tooth widths include the motivation and the computer aided study which is based on Finite Element Analysis using ANSYS Maxwell. A 24/20 slot-pole SMPM BLDC motor is chosen for prototyping. The designed motor is manufactured and performed at different phase-advanced currents in the field weakening region controlled by a TMS320F28335 digital signal processor. As a result of the experimental work, the feasibility and effectiveness of field weakening for BLDC motors are discussed thoroughly and the contribution of higher winding inductance is verified.

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The study covers the design, analysis and experimental study of a 1 kW motor which is designed for a special in-wheel motor driven light electric vehicle. The main concern is to design a BLDC motor having a higher value direct-axis phase inductance which is providing high performance field weakening operation. A sub-fractional slot concentrated winding structure with unequal tooth widths is chosen. The design phase is including the motivation and the computer aided design works. A software package based on configurator approach is used to determine the motor parameters in a broad sense. Then the motor is modeled in a Finite Element Analysis (FEA) package for detailed analysis and, particularly the 2D and 3D field analyses are obtained to verify winding inductance value. The designed motor is manufactured precisely and an experimental study is held to verify the design work including the precise measurement efforts for the motor inductance. Also the field weakening operation of the motor is managed by using phase current advance method. Index Terms-Brushless DC motor, field weakening operation, winding inductance

The paper presents a study on the design and analysis of a sub-fractional slot concentrated winding brushless direct current motor (BLDCM) with unequal tooth widths for a light electric vehicle application. This kind of brushless surface permanent magnet (SPM) motor is equipped with easy-to-manufacture features which are crucial for the electrical machinery market, especially for electric motors used in electric vehicles. The structure also responds quite effectively to field weakening operation, because of its inherent higher inductance value. The study is focused on increasing the winding inductance value by using the designs analysed in magnetic analysis software. A selected BLDC motor structure is manufactured and tested to verify the design.