Research On The Thermal Cycling System Of External Rotor Permanent Magnet Synchronous Motor Stator Assembly

With the promotion of new energy bus, especially with the state support, electric buses entered a stage of rapid growth. As a core component, drive motor has become a hot topic in recent years. For energy-efficient, permanent magnet synchronous motor has been widely used. Motor's stator assembly will generate amount of heat during operation, and up till now there is no standard for the thermal management design and no specification to verify the heat level of stator assembly. Therefore it has become essential to develop a test system for the stator's design and validation. This test system can also effectively verify the stability of the stator manufacturing process and identify defects. In this paper, the following research was carried out to study a thermal cycling test system for the stator assembly for outer rotor permanent magnet synchronous drive employed by pure electric vehicle.Firstly, an overview of the development of electric vehicle at home and abroad was made to describe the technology advantage of direct-drive external rotor permanent magnet synchronous motor and the blank situation of the stator thermal cycling test.After that, by calculating the losses on some form of external rotor permanent magnet synchronous motors and finite element analysis, the input power for the stator assembly of and temperature collection point position were confirmed. Then a thermal cycling test set for the stator was designed. In this device, a predetermined power input to a stator to generate heat while the stator was cooled by water. The pre-fixed temperature sensors are able to monitoring the temperature change in the stator. The temperatures of various part of the stator collected by a thermal imager are used to analyze the stator's heat level in specific working conditions. This could be an input for the design of a protection scheme. It can verify the stator manufacturing process and identify defects as well. It is proven that this method can obtain design data and verify motor stator assembly for manufacturing defects.Then according to the calculation principle and functional requirement, a testing system was designed and built up.Finally, the test bench was used for testing the stator assembly of an outer rotor permanent magnet synchronous motor and data acquisition and analysis, which provided clear guidance to the product design, manufacturing process and cooling for system.It is proven that this method can effectively obtain design data and verify motor stator assembly for manufacturing defects.