Study On The Control Strategies For Dual-motor Dynamic Coupling Drive Of Underground Mining Vehicles

Traditional diesel-driven explosion-proof trackless rubber-tired cars have serious tail gas pollution,which makes the air foul under the mine,so in recent years purely electric explosion-proof trackless rubber-tired cars have developed rapidly.A coal mining machinery company designed a type of explosion-proof trackless rubber-tired car with a single explosion-proof drive motor.The following problems were found in the design process: Once the explosion-proof drive motor is damaged,the vehicle will fail to resume its operation;in order to guarantee the propulsion of the vehicle,the power of the explosion-proof drive motor is large,which causes an endurance mileage of the vehicle.To improve the problem,the enterprise proposed a project named "A Type of Trackless Rubber-tired Cars Driven by Explosion-proof Lithium-ion Battery".The purpose was to design a type of explosion-proof trackless rubber-tired car with dual explosion-proof drive motors.Based on the project,this thesis focuses on the study on control strategy for the driving system.In order to accomplish the above research goals,the following work is done in this thesis.First,a comparative analysis of the structure of general dual-motor driving systems is made.Combined with the advantages,the working conditions and design index,a driving system structure with double explosion-proof drive motors independently driving the front and rear driving axle is proposed.Then,the new structure and working mode are introduced,and its energy saving mechanism is analyzed theoretically.Second,aiming at the proposed driving system structure and combined with the dynamic and economic performance indexes,a parameter matching program is designed in MATLAB.According to the operation results,the parameter matching requirements of explosion-proof drive motors(rated power,rated speed of revolution,rated torque,maximum speed of revolution and maximum torque)and of explosion-proof power battery(capacity of battery pack)are put forward.According to the matching parameters,a certain type of 25 kW low-speed explosion-proof drive motor and a certain type of ironic phosphate lithium explosion-proof battery pack are selected.According to the selected explosion-proof drive motors,we draw the efficiency map of the explosion-proof drive motors,the power balance map of vehicle driving and the performance map of vehicle climbing,proving that the selected motors can meet the requirements of the vehicle for dynamic performance.Third,aiming at the proposed structure and the selected explosion-proof drive motors,the control strategy for the driving system is formulated,and then this thesis studies the demand torque calculation,drive mode division and torque allocation respectively.In terms of demand torque calculation,the torque and speed of revolution of the current driving system are calculated according to the established working conditions.In terms of drive mode division,the drive modes in the work area are divided on the basis of the principle of the minimum electric power of explosion-proof drive motors.The threshold value of switching drive modes is determined according to the division results.In terms of torque allocation,on the basis of the principle of achieving the highest driving system efficiency,the principle of allocating the coupling driving power of double explosion-proof drive motors is formulated.After that,the torque allocation strategy is considered for the case where the tire-road friction coefficient decreases and driving wheels skid.Fourth,an off-line simulation model of the driving system is constructed on the basis of MATLAB/Simulink.First of all,the modeling principles and formulas of components and assembly modules are introduced,and then the economic performance of the driving system is simulated.The simulation results show that the structure proposed in this thesis has higher economic performance than the traditional drive system with a single explosion-proof drive motor.Fifth,a vehicle test is carried out,which is mainly divided into dynamic performance test and economic performance test.The results of the dynamic performance test show that the proposed structure can meet the requirements for dynamic performance well.In the economic performance test,when the vehicle runs at the speed of 25km/h,the endurance mileage of the vehicle equipped with the driving system with a single explosion-proof drive motor is 94 km,while that of the vehicle equipped with the structure proposed in this thesis is 107 km,further proving its economic advantage.