1.Purpose and significance (including domestic and foreign research status analysis)

In the current global energy crisis and the increasingly harsh atmospheric pollution, the search for alternatives for traditional internal combustion engines has begun. Various countries and institutions are conducting continuous research and development work on this. Almost all vehicle manufacturers, including well-known automobile companies at home and abroad, are looking forward to work hard in develope new energy vehicles that meet the market demand. As a result, the development of the drive system o new energy vehicles has been put on the historical stage. The drive system is the core part of an electric vehicle which determines the mechanism of the electric vehicle. The drive system of an electric vehicle is arranged in a manner that depends on the motor drive system.

In this design, a centralized electric drive system is adopted for new energy vehicles. The centralized drive is similar to the traditional car drive structure, replacing the internal combustion engine with electric motors and related components, and transmitting the motor output torque to the left and right wheels to drive the car through mechanical transmissions such as transmissions and reducers, son the basis of the traditional car structure. With a little modification, the operation technology is mature, safe and reliable. However, heavy volume and relatively low efficiency are some of the demerits of the system.

1.1Status of domestic research

1.1.1Research on electromagnetic interference

Because of the complexity in the actual operating conditions of electric vehicle electric drive systems, it is difficult to analyze the problem of conducted electromagnetic disturbance characteristics. So in 2017, researchers[1] at Tianjin University of Technology[1] used fuzzy clustering to develop a solution to meet the complexity of the operating conditions of electric drive systems. This solution makes it easy to study the electromagnetic disturbance characteristics of low-voltage systems under complex conditions.

Ji Zhang et al.[2], in view of the fact that electric vehicles generate strong electromagnetic interference due to high-power, high-current driving components, there are more serious safety hazards than traditional vehicles. In this paper, Ansoft software RMxprt, Maxwell 2D and Simplorer are used. The simulation module carries out the electromagnetic compatibility (EMC) simulation study of the electric vehicle drive system, and the effect of reducing the distributed capacitance and adding the buffer and filter circuit to reduce the common mode current is verified by analysis.

1.1.2 Dynamic research

Man Li et al.[3] optimized the transmission ratio of pure electric vehicle transmission system, established a multi-objective function with minimum acceleration time and minimum energy consumption rate, and considered the conditional constraints such as climbing, starting and high-end utilization. Combined with the particle swarm optimization algorithm, using Matlab programming and simulation, the results show that the optimization model of the transmission ratio of the pure electric vehicle transmission system is reasonable, that is, the power of the electric vehicle is improved, and the energy consumption is also reduced.

Wenwen Li et al.[4] used the pure electric vehicle for urban use as the research object, analyzed and analyzed the parameters of the power transmission system, and matched the parameters of the whole vehicle dynamic system according to the parameters of the vehicle and the dynamic and economic requirements. The initial matching power system parameters are optimized with the goal of improving transmission efficiency. With the shortest acceleration time and the maximum driving range as the optimization goal, the objective function and the constraint condition are used to form the fitness function of the gear ratio with the penalty function. The genetic algorithm is used to optimize the optimal parameters of the power system.