Research On Control Strategy Of Modular Permanent Magnet Synchronous In-Wheel Motor

Modular motors are arranged in a circumferential arrangement in which the 4 sub motors share the rotor,but each sub motor is controlled by an independent driver.When a set of motor drive systems have some fault,the modular motor still have good fault tolerance,which proves that it has broad prospects in the field of electric vehicles.This paper analyzes the torque distribution factor of each sub motor when the modular motor works normally,the minimum loss control is adopted to the problem of limited endurance for electric vehicles.In view of the fault tolerance ability of modular motor,fault tolerant topology of Three phase four leg and midline interconnection of sub motors are added to modular motor drive system.By comparison,the fault-tolerant topology structure which is most suitable for modular motors is selected?The main research contents include the following aspects:Firstly,due to the fact that each sub motor can be controlled independently.From the point of motor efficiency,An efficiency model for modular motors is constructed on the basis of efficiency model of traditional PMSM,The torque distribution factor is derived when the efficiency of the whole modular motor is highest?Software FLUX is used to compare the efficiency between the 2 module and the 4 module,and verify it with theoretical analysis.Secondly,In order to solve the problem of the limited battery capacity of the electric vehicle and the insufficient endurance,the minimum loss control is adopted.In order to calculate the motor iron loss accurately,FLUX software is used to calculate the relationship between iron loss and speed when the motor is idle,and the iron loss resistance at different speeds is fitted ? Combined with electric vehicle's operation conditions including starting acceleration,low speed operation and high-speed operation,the best speed range of minimum loss control is obtained by comparing with the id=0 control.Thirdly,In order to further improve the fault tolerance of modular motors,the threephase four leg topology and neutral line interconnection scheme of sub motors is added to the modular motor.When the motor is in single-phase open circuit fault,torque distribution factor is derived in order to equalize the heating capacity of the modular motor.The most suitable fault-tolerant scheme is obtained by comparing the cost,the failure module's effect etc.