Flux-switching motors (FSM) are competitive candidates for in-wheel traction systems. However, the analysis of FSMs presents difficulty due to their complex structure and heavy magnetic saturation. This paper presents a methodology to rapidly construct, adapt, and solve a variable magnetic equivalent circuit of 12-stator-slot 10-rotor-tooth (12/10) FSMs. Following this methodology, a global MEC model is constructed and used to investigate correlations between the radial dimensions and the open-circuit phase flux linkage of the 12/10 FSM. The constructed MEC model is validated with finite element analysis and thus proved to be able to assist designers with the preliminary design of flux-switching motors for different in-wheel traction systems. 1. Introduction With the rising concern on environmental issues, hybrid/electric vehicles (HEV/EV) have attracted an increasing interest from public and industry since the end of the 20th century. The fast developing technology of HEV/EV has also introduced a revolutionary traction concept to vehicles designers, namely, in-wheel traction. By putting electric motors in the wheels, the drivetrain is greatly simplified. Mechanical axes can thus be removed, which creates extra space for the cargo and reduces the total weight of the vehicle [1, 2], as shown in Figure 1(a). These advantages of simplicity and freedom make the in-wheel traction a preferable traction mode for vehicle designers. Figure 1: In-wheel traction—(a) an electric truck with large cargo and (b) an in-wheel motor. For the design of an in-wheel traction system, there are two possible topologies, namely, direct driving and indirect driving. In a direct-driving system, the electrical motor is directly driving the wheel without a gearbox, as shown in Figure 1(b). This direct-driving in-wheel module provides a maximum simplicity for the system design; thus, it is commonly adopted in most existing in-wheel traction systems. However, due to the absence of gearbox, the electrical motor of a direct-driving system needs to provide a high torque. The high torque in-wheel motor increases the wheel mass and consequently reduces the passenger comfort [3]. To solve this problem, an indirect-driving in-wheel module, shown in Figure 2(a), can be adopted, in which the electrical motor is indirectly driving the wheel through a gearbox. By this means, the required torque for the motor is reduced (Figure 2(b)), and the wheel mass is maintained. Different topologies of the in-wheel traction lead to different requirements and constraints for the motor design. Nevertheless,
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