In order to achieve the high-efficiency operation of dual-motor four-wheel-drive electric vehicle ( DMFWDEV) , an optimum torque distribution strategy based on motor loss mechanism is proposed. First of all, the feature of driving power loss of a DMFWDEV is analyzed and a math model for optimum torque distribution is put forward. Then, based on d-q equivalent model for surface-mounted permanent magnet synchronous motor, a power loss model for dual motor system is created and the formula for the optimal torque distribution coefficient βo of dual motor system is derived. Finally, the effects of temperature difference between two motors on βo are tested on the tes-ting platform for dual motor system, verifying the rationality of the torque distribution strategy proposed. The results show that for the DMFWDEV equipped with same kind of motor in both front and rear axles, it is preferable to adopt the driving mode with equally-divided torque between front and rear motor rather than that with single motor. With former mode, the negative effects of power loss in cranking non-operational motor on driving efficiency can be avoi-ded in low-load condition, while the minimum driving power loss can be achieved in medium and high load condi-tions. Besides, the effects of temperature difference between front and rear motor on the strategy of equally-divided torque with optimal efficacy is relatively trivial.%为实现双电机四轮驱动电动车的高效运行,提出了一种基于电机损耗机理的最优转矩分配策略.首先分析了双电机四轮驱动电动车驱动功耗特征,提出了最优转矩分配数学模型;接着基于面贴式永磁同步电机d-q等效模型,构建了双电机系统损耗模型,推导了双电机能效最优的转矩分配系数βo公式;最后在双电机测试平台上,测试了双电机温差对βo的影响规律,验证了所提出的转矩分配策略的合理性.结果表明,对于前后轴匹配相同动力系统的双同步电机驱动电动车,应优先采用双电机平分转矩驱动模式,而非单电机驱动模式.平分转矩驱动模式在低负荷工况,可避免非工作电机拖转损耗对驱动效率造成的负面影响;而在中高负荷工况,可实现最小驱动功耗;此外,前后电机温差对上述能效最优平分转矩策略影响较小.
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