Circulating power analysis in dual-input planetary gear mechanisms employed in in-wheel motor-driven electrical vehicles

Abstract

Electric vehicles (EVs) are known for their power efficiency and lower pollution levels compared to traditional vehicles. The design of dual-motor EV systems, utilizing planetary gear trains, is a significant area of research. The impact of power circulation on losses in novel and patented planetary gear mechanisms has not been extensively explored in previous configuration design studies, despite its importance as a key component of the mechanism. Accurately understanding the power distribution in a dual-motor system seems to be crucial for fully comprehending an invention. This paper explores the positive aspects and drawbacks of PGT configuration, with a focus on efficiency, which may affect competitiveness in real-world applications. If power flow estimation is not possible or if operating constraints prevent it, it is likely that the patent was not thoroughly examined or the inventor lacked experience in the subject matter. A nomograph is a graphical tool used to analyze the relationships between variables in power-split systems, including power flow and efficiency. A systematic approach is proposed for evaluating the performance and power loss of PGTs. Analytical formulas for powers, losses, and efficiency are derived. A parametric study on a wheel hub motor reveals that a higher gear ratio enhances efficiency and performance, with power flow analysis indicating power circulation and amplification. Controlling gear ratios precisely can change power flow direction, enhancing efficiency. Criteria for no power circulation are established, leading to a new configuration.