Hybrid electric vehicle electric motors for optimum energy efficiency: A computationally efficient design

This paper proposes a new optimal design approach of a permanent magnet synchronous motor (PMSM) in hybrid electric vehicles (HEVs). It aims to solve the key research problem of how to find a viable and computationally efficient solution to achieve the maximum energy efficiency of the motor over the driving cycles. A one-dimensional analytical model is, firstly, built and validated to design the geometric parameters and calculate motor efficiency, maintaining high fidelity calculation with low computational cost. Then, by analyzing the motor energy distribution of the driving cycle, the energy efficiency is characterized by representative points, which can dramatically reduce the computation time during the optimal design. Leveraging by these points, the approximation model is presented to replace the PMSM optimization model to further reduce the computational cost. Finally, a combinatorial optimization algorithm is developed to return and characterize the PMSM optimal design in the studied scenario benefiting in the energy-loss reduction. The performance of the approach has been illustrated and verified with a HEV dynamics model. The results show that the optimal design approach can reduce the motor energy losses by 18.35% and improve the HEV fuel economy by 3.2% over the driving cycle compared with the initial design.