Study On The Division Of Working Mode And Mode-switching Frequency Optimization Of Electric Motor Dual-motor Coupling

Based on the development and application of the dual-motor coupled drive system in pure electric vehicles,this paper studies the working mode switching strategy of the dual-motor drive system,so as to reduce the energy loss of the drive system as well as minimizing the mode switching frequency.In order to complete the research content of this paper,this paper refers to the research results of hybrid vehicle in the field of energy management control strategy,and combines the efficiency characteristics of dual motors to design a global optimal mode switching strategy under driving and braking conditions.Then the global optimal mode switching strategy is regularized to obtain the regularized mode switching strategy.Finally,the Matlab/Simulink simulation model is built to verify the effect of the regularized mode switching strategy.The specific research content includes the following aspects:(1)Introduce the structure and working principle of the two sub-motors coupling power system of the laboratory,and design the parameters of the two sub-motors that meet the requirements according to the vehicle parameters and dynamic requirements,and obtain two sub-motors' efficiency characteristics distribution through Ansys Maxwell software simulation.Finally,determine the optimal speed ratio of the two sub-motors by maximizing the driving-system's efficiency value,and under the best speed ratio,we can obtain the equivalent efficiency characteristic,and we treat it as the efficiency characteristics distribution of two sub-motor driving model.(2)Under the selected cyclic conditions CCBC+WLTC,set the objective function that considers both energy loss and mode switching frequency,and use dynamic programming algorithm to calculate the optimal mode switching strategy under the whole cycle condition.The weight between the loss of the objective function and the mode switching frequency is continuously adjusted,so that the optimal mode switching strategy finally obtained which minimizes the mode switching frequency and ensures that the energy loss is not increased as much as possible.(3)Through the dynamic programming algorithm,the distribution of the working mode spots under the torque-speed coordinate can be obtained,which can be regarded as a classification problem of two-dimensional data.Then,the three working mode points are classified by the support vector machine algorithm to obtain the optimal boundary of mode one and mode two,and the optimal boundary of mode two and mode three.And we can use this boundary as the final regularization mode switching strategy.(4)Using Matlab/Simulink to build the vehicle longitudinal dynamics model,motor model and control system model,and design two contrast mode switching strategies,one of which only considers to make the energy loss being the smallest,the second strategy is based on the first one,to appropriate reduce the frequency of mode switching.And,verify the effect of the three strategies on CCBC,WLTC,NEDC and FTP-75 cycle conditions respectively.