Torque optimization method based on dual-motor layout and convex optimization algorithm for pure electric vehicles

Abstract

The invention relates to a dual-motor arrangement of a battery electric vehicle and a torque optimization method based on a convex optimization algorithm. The method comprises the following steps thatS1, according to a parameter of the vehicle, a longitudinal dynamics model is built; S2, a cyclic working condition of the vehicle is selected, according to the selected cyclic working condition, therequirement torque Tdem (k), requirement power Pdem (k) and biggest requirement torque Tdem, max and biggest requirement power Pdem and max of the vehicle are calculated; S3, under the premise that the capacity of a vehicle battery meets the power performance requirement, according to values of the Tdem, max and Pdex, and max, the motor size and battery size of the vehicle are selected; S4, the convex optimization processing is carried out on the motor and battery of the vehicle by the convex optimization algorithm; S5, the working state of each part of a vehicle transmission system is restricted; S6, a cost target function is determined. The method selects the dual-motor arrangement, the defect is made up that the work efficiency of the electric vehicle motor is low due to the single motor arrangement, the computing time of the optimization algorithm is quick, and the result is accurate.

Description

Technical field [0001] The invention belongs to the technical field of new energy vehicles, and relates to a torque optimization method based on a dual-motor arrangement of a pure electric vehicle and a convex optimization algorithm. Background technique [0002] With the increasing shortage of global oil resources and the increasing environmental pollution caused by the exhaust emissions of traditional automobiles, all countries are strongly supporting the development of pure electric vehicles. Compared with traditional cars or hybrid cars, pure electric cars have the outstanding advantages of zero emissions and no pollution. [0003] The transmission system of a pure electric vehicle is usually composed of a power battery, a drive motor, and a gearbox. With the maturity of motor control technology, existing electric vehicles have adopted a transmissionless structure to directly control the speed of the motor to realize the change of vehicle speed. The prior art mostly uses one p...

AI Technical Summary

Problems solved by technology

Although such a drivetrain arrangement is simple, most of the motors work in low-efficiency areas and waste a lot of battery power

In order to solve the problem of the motor working in the low-efficiency area, scholars have studied the use of two relatively small motors with the same performance to evenly distribute the required torque. By making the two motors work in the high-efficiency area at the same time, the efficiency of the drive train Efficiency, although two identical motors work in coordination with each other, it can avoid the fact that one motor works in the low-efficiency zone, but the strategy of equal torque distribution is easy to control, but it cannot guarantee that the control strategy is optimal

The above two arrangements will make the battery power not fully utilized. However, in order to ensure the power of the vehicle, the size of the battery must be increased, resulting in a higher cost of pure electric vehicles and hindering the development of electric vehicles.

[0004] At present, the dynamic programming (DP, Dynamic Programming) algorithm in the optimization algorithm can guarantee that its optimal solution is the global optimum, but the calculation time of DP increases exponentially with the increase of control variables, and the calculation burden is relatively large.

An electric vehicle with a dual-motor structure adopts an even torque distribution strategy. Although this control strategy is simple and can save time, it cannot guarantee that the torque distribution is globally optimal.

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