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significantly reduced. The final proposed PMSM configuration is developed studying motor’s torque behaviour and minimizing stator flux linkage for the efficiency enhancement. Another important requirement for the optimal HEV’s operation is the minimization of motor’s losses during different driving cycles or the overall profile of the HEV [26]. It is evident that design parameters that are optimized for one average assumed drive cycle are not necessarily optimal when an alternative use of the vehicle is carried out [27]. At least twelve characteristics points of representative driving cycles should be used for the analysis of motor’s performance according to [28]. These points have to include acceleration, cruis- ing and regenerative modes for more accurate fuel consumption calculation. A methodology based upon the overall driving cycle efficiency of the traction drive, which also takes into account the inverter losses, cooling system specifications and energy consumption of other subsystems, is presented in [29]. The implementation of the appropriate cooling system and the determination of its specifications are also of great importance as stated in [30]. 2.2. Description of proposed methodology The complex problem of the development of high-power density direct-drive SPMSMs for a light HEV can be solved by using a knowledge-based system (KBS), similar to that analyti- cally described in [31]. The proposed architecture scheme (depicted in Figure 1) involves a number of knowledge sources (KS) and several layers that interact with each other, in order to ensure that the final solution is acceptable from technical, economical and manufacturing point of view. The first two layers (layer 0 and 1) incorporate the provided information about Figure 1. Structure of the developed knowledge-based system software. Design, Optimization and Modelling of High Power Density Direct-Drive Wheel Motor for Light Hybrid Electric Vehicles http://dx.doi.org/10.5772/intechopen.68455 129