| Pure electric vehicle technology is the hot spot of current automotive technology development.The power assembly is the core component of pure electric vehicles.Its structural form and performance directly affect the layout of the vehicle as well as power and economy.The all-electric integrated power system highly integrated permanent magnet synchronous motors and DAMT.The indicators such as compactness of structure,running economy and shift quality were greatly improved.In order to improve the operation accuracy of the all-electric integrated power system,the effect of actuator magnetic field during DAMT integrated design and the electromagnetic field interference caused by the magnetic field coupling between the motor and the actuator were analyzed.The method of combining theoretical analysis,simulation calculation and experimental study was used to conduct in-depth research on the magnetic isolation design,laiding a foundation for the high-precision operation of the all-electric integrated power system.The main research contents and research results of the paper are as follows:(1)The all-electric integrated power system was analyzed and the electromagnetic field finite element modeling was completed.The structure and working principle of DAMT and PMSM were introduced.Combined with the above structure,the overall structure layout of the all-electric integrated power system and the synchronization process of shifting were analyzed.Based on the specific structural parameters of the all-electric integrated power system,a finite element model of the electromagnetic analysis was established by using the JMAG.(2)The effect of actuator magnetic field during DAMT integrated design was studied and the magnetic isolation was designed.Taking the upshift process as an example,the changes of magnetic circuit structure and the effect,axial magnetic field force after the sleeve was magnetized and influence as well as radial magnetic field force on the meshing gear after magnetization in the DAMT integrated design process were analyzed.Based on the above-mentioned influence mechanism,the magnetic isolation design was performed,and the magnetic isolation effects of different magnetic isolation schemes were compared and analyzed.Finally determined the best magnetic isolation scheme aiming to maximize the operation accuracy of DAMT and verified by magnetic isolation effect test.The results showed that the maximum change of the actuator output force was reduced from 25 N to6.8N,and the maximum force of the joint sleeve was reduced from 335 N to 12.7N,the problem of meshing gear pairs receiving radial suction due to magnetization was bettersolved.The comparison between the experimental value and the simulation value of the output shaft magnetic induction intensity under the all-aluminum scheme verified that the simulation model was reliable and effective.(3)Electromagnetic field coupling characteristic between motor and actuator was analyzed.The magnetic field distribution of the air area at the end of the motor and the actuator as well as the magnetic field leakage of the motor shaft were analyzed under different operating conditions.The magnetic field coupling paths were confirmed.Furthermore,the magnetic field coupling laws of different coupling conditions of each coupling path and specific effects were analyzed.The results showed that motor and actuator generated air-field magnetic field coupling,resulting in a maximum reduction of the actuator output force by about 8.1N during the upshift and a maximum increase of about 10.6N during the downshift compared to before integration.The armature magnetic of the actuator was coupled to the motor through the shaft path,causing a maximum increase of the motor synchronous torque by about 0.85N·m during the upshift and a maximum reduction of about 0.79N·m during the downshift compared to before integration.(4)Magnetic isolation structures suitable for all-electric integrated power system were designed and optimized.Based on the magnetic field coupling laws between the motor and the actuator,the implementation of the magnetic isolation scheme and principle of magnetic field shielding were analyzed.For air-field magnetic field coupling,the shielding effects of different shielding schemes were compared and permalloy-copper double-layer shielding structure was established.The shielding effectiveness was introduced as the optimization target,and parameter optimization of shielding layer thickness was completed.After shielding,the maximum change of the actuator output force was reduced from 8.1N to 4.8N during upshifting,and the maximum change was reduced from 10.6N to 6.2N during downshifting;For magnetic field coupling through shaft path,the shaft magnetic isolation bush was designed and its thickness was optimized.After magnetic isolation,the maximum change of the motor synchronous torque was reduced from 0.85N·m to 0.16N·m during upshifting,and the maximum change was reduced from 0.79N·m to 0.12N·m during downshifting,improving the running accuracy and power output capability of the all-electric integrated power system. |
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