Hybridisation ratio for hybrid excitation synchronous motors in electric vehicles with enhanced performance

Abstract

For electric vehicles (EVs) with severe acceleration requirement, the selected motor would be inevitably overdesigned to meet the acceleration requirement. To address this, the motor constant power speed ratio (CPSR) should be increased to remove part of the overdesign. There are different flux weakening techniques that are used to increase motor maximum speed (and increase the CPSR). Among them, hybrid excitation synchronous motor (HESM) advantages have been benefited in this study. CPSR depends on hybridisation ratio (HR) of the excitation system, and the motor inductance. The relation is analytically derived in this study. In addition to increasing CPSR, HR can control the place of motor high-efficient area over the efficiency map, which can increase EV total efficiency. A search algorithm has been developed, here, to find the optimal HR of a nonoptimal HESM. The final design gives an efficient motor performance with less overdesign in drivetrain. Compared with the original permanent magnet synchronous motor, 4.1% improvement in total efficiency for an average city-highway driving cycle has been achieved, and 16% decrease in rated values of drivetrain elements is obtained.

Overview of Hybrid Excitation in Electrical Machines

“…Several studies have expressed the ratio of the flux from the FW to the flux from the PM, for example, the study of the influence of the "ratio of hybridization" by Ammar et al [10,[29][30][31][32].…”

“…Such benefits have been studied by Cinti et al [34], who compared PM machines and HE machines, and showed the advantages of operating with a good efficiency at variable speeds. Such strategies for flux weakening in hybrid excitation have been studied by Giulii-Capponi et al [39,40], Amara et al [29], ShahMohammadi et al [32], and Michieletto et al [41].…”

“…Hybrid excitation can be used to improve the torque-speed relation of relative conventional PMSM [32] (illustrated in Figure 3). At low speeds, the torque can be increased by a higher back EMF, E, considering that the torque is given by…”

Passive and Active Coupling Comparison of Fuel Cell and Supercapacitor for a Three‐Wheel Electric Vehicle

“…Leisure activity vehicles are typically characterized as being light and compact, but with a high acceleration and speed capabilities. In this regard, sizing problem should ascertain the minimum required component dimensions to satisfy the requested power for all the constraints specified in Table 2 [30]. Based on the specifications, the FC needs to be sized in a way to supply the maximum power for a long distance, continuous, and high-speed driving.…”

Design and Experimental Verification of Adaptive Speed Region Control for Hybrid Excitation Claw-Pole Synchronous Machine

“…Hence, neglecting the influence of the temperature, magnetic saturation, and hysteresis loss [22], several basic equations of the HECPSM, including voltage, flux linkage and electromagnetic torque, can be expressed as…”