Multi-Objective Optimization of Dual-Motor Four-Wheel-Drive Electric Vehicle Power trains for Enhanced Energy Efficiency and Reduced Cost

Abstract

The increasing demand for high-performance four-wheel-drive (4WD) electric vehicles (EVs) has intensified the need for powertrain architectures that simultaneously deliver superior dynamic performance, high energy efficiency, and reduced manufacturing cost. This study presents a multi-objective optimization framework for the design and control of dual-motor 4WD EV powertrains by jointly optimizing motor power ratings and torque distribution strategies. Three different powertrain configurations were investigated: (i) two identical permanent magnet synchronous motors (PMSMs), (ii) two PMSMs with optimized power ratings, and (iii) a hybrid configuration comprising a PMSM and an induction motor (IM). The optimization process was divided into two stages. First, the optimal power rating of each electric machine was determined through independent powertrain optimization considering both investment and operating costs. Second, an offline map-based torque distribution strategy was employed to identify the optimal torque split between the front and rear axles for minimizing total powertrain losses under different operating conditions. The proposed methodology was evaluated using a high-performance passenger EV with a peak power demand exceeding 350 kW and a target acceleration of 0–100 km/h in 3.8 s. The benchmark configuration employing two identical PMSMs achieved an energy consumption of 14.7 kWh/100 km. Optimization of motor characteristics while retaining two PMSMs reduced energy consumption to 14.4 kWh/100 km, representing a 2.1% improvement. The hybrid PMSM–IM configuration further reduced energy consumption to 13.9 kWh/100 km, corresponding to improvements of 5.8% and 3.6% compared with the benchmark and optimized dual-PMSM configurations, respectively. In addition, the PMSM–IM configuration lowered powertrain cost by approximately 6.7% owing to the reduced reliance on rare-earth permanent magnets. The optimized torque distribution strategy effectively exploited the complementary efficiency characteristics of the two motor types, assigning high-speed, low-torque operating conditions to the IM while utilizing the PMSM for high-torque demands. The results demonstrate that coordinated optimization of motor sizing and torque distribution significantly enhances both energy efficiency and cost-effectiveness in dual-motor 4WD EVs, providing a practical framework for the development of next-generation high-performance electric vehicle powertrains.

Keywords: Four-wheel-drive electric vehicle, Dual-motor powertrain, Permanent magnet synchronous motor, Induction motor, Motor sizing optimization, Torque distribution, Multi-objective optimization, Energy efficiency, Powertrain cost.