Research On Key Technologies Of Torque Coupled Dual Switched Reluctance Motor Drive System

In the context of the continuous transformation and development of modern industry to the direction of low carbonization,informationization and intelligence,new energy vehicles account for the total number of car ownership is a high growth trend.As the core component of electric vehicles,the performance of drive motors determines the efficiency and performance of electric vehicles.Compared with singlemotor drive,dual-motor drive system is widely used in the electric vehicle industry due to its advantages in power output and acceleration performance as well as the flexibility of control methods.Switched Reluctance Motor has the advantages of outstanding speed regulation performance and low manufacturing cost.The torque coupled dual switched reluctance motor drive system combines the advantages of SRM and dual motor drive system and is suitable for electric vehicle drive system.This thesis addresses the drive system efficiency optimization,torque pulsation suppression and fault diagnosis related issues,with the following main aspects:Firstly,an online efficiency optimization method based on neural network algorithm is studied to improve the efficiency of the dual-motor drive system.The power distribution scheme of the dual-motor system is optimized and designed,and the maximum efficiency and the corresponding optimal torque distribution ratio under different operating conditions are calculated offline.A neural network model is derived from the offline data for training and learning,and the relationship between the working conditions and the optimal torque distribution ratio is established to achieve the online optimization of the maximum efficiency point under different working conditions.The method improves the overall operating efficiency of the torque-coupled dual switched reluctance motor drive system online,independent of the motor model.Simulations and experiments verify the effectiveness of the method.Secondly,in order to suppress the torque pulsation of the dual-motor drive system and reduce the operation noise,the influence of the rotor phase difference of the drive system on the torque pulsation is analyzed for the characteristics of the torque pulsation of the dual-switched reluctance motor system,and an online torque pulsation optimization method based on the torque model prediction is studied.The phase difference interval is divided according to the difference of torque overlap in the phase change area of the dual motor,and the torque sharing function and the steady-state torque compensation strategy of the dual motor are used to achieve torque pulsation suppression.From the simulation data comparison,the optimal phase difference interval for system assembly is obtained.The torque pulsation values of the system with different torque distribution ratios of the dual motor are calculated offline,and the offline data are fitted to establish the mathematical expression of torque pulsation with respect to the torque distribution ratio.The online torque pulsation optimization is achieved by adding a discrete torque prediction model,changing the torque distribution ratio at a fixed step at the next moment,and comparing the torque pulsation to take the minimum value and update the torque distribution ratio.This pulsation suppression strategy has good steady-state and dynamic performance.Simulations and experiments verify the effectiveness of the method.Thirdly,a fault diagnosis method based on switch state decoding is investigated to diagnose power switching device faults in the drive system.The phase voltage transitions under different fault types are analyzed according to different operating modes of the power converter and its switching states.A hardware circuit without voltage sensor is designed for phase voltage detection and voltage superposition signal output,and the voltage superposition signal has a one-to-one correspondence with the switching state of the power converter.By comparing the actual switching state and the control signal derived from the decoding,the determination of the fault type and the fault switch location are realized.The method is simple to decode and calculate,and is applicable to a variety of control methods.Simulations and experiments verify the effectiveness of the method.