| Extending power battery life has become one of the current research hotspots of new energy passenger vehicles and is expanding to the field of special vehicles.The thesis takes a certain 3m3 battery type downhole load-haul-dump as the research object,based on the attenuation mechanism of battery capacity,the mapping relationship between the key parts such as battery electric load-haul-dump drive system scheme,main component parameters and matching,battery heat dissipation structure and drive control strategy and the life of the power battery was studied in depth.The main research content of the thesis is as follows:(1)The battery life model suitable for the operating conditions of the downhole load-haul-dump was established,and a dual-motor drive scheme based on the power battery life was proposed and the corresponding parameters were optimized and matched.Based on the study of the influence mechanism of power battery life,a battery life model suitable for the operation condition of the load-haul-dump was established,and the validity of the model was verified by experiments;according to the demand of driving force and power in typical operating conditions of the load-hauldump,the power and electric energy under various typical operating conditions of the load-haul-dump were calculated.Based on the principle of probability statistics,the simulated cycle conditions of the battery downhole load-haul-dump were constructed.The coupling effect of the motor peak power and rated speed on the climbing performance,load-hauldump loading performance and acceleration performance of the downhole load-haul-dump was studied,and the parameter matching model of the dual motors was determined.The energy consumption of the dual motor and the original single motor was compared,and the influence of the original single motor drive scheme and the new dual motor drive scheme on the power battery life was studied.It was concluded that the life attenuation value of the dual-motor in the driving conditions was reduced by 17.47% compared with that of the original single-motor driving scheme in a complete cycle,which verified the effectiveness of the dual motor drive scheme.(2)A life-oriented parameters matching optimization method of key components of the drive system of downhole load-haul-dump driven by dual motors was proposed.Based on the matching results of motor and hydraulic torque converter,the dynamic characteristics and traction characteristics of the battery-type downhole load-haul-dump were studied,and the results showed that the battery-type downhole load-haul-dump had good dynamic performance;the support vector machine algorithm was used to construct the mapping relationship between the parameters of the main components of the hydromechanical transmission system of the battery-type downhole load-haul-dump and the energy consumption,and then the transmission ratio of the transmission system and the total transmission ratio of the drive axle was optimized.The simulation results showed that the life attenuation rate of the power battery decreased under the typical cycle conditions of the optimized transmission system,and the life attenuation rate of the power battery decreased most obviously when the second gear was transported with full load,with the attenuation value reduced by 19.77%.(3)The relationship model between heat dissipation structure parameters and power battery life was constructed,and an optimization method of heat dissipation structure parameters of power battery pack was proposed.The thermal model of the single cell battery was established and the thermophysical parameters of the single cell battery were measured experimentally.According to the demand for electricity in the circulating condition of the downhole load-haul-dump and the layout scheme of the power battery of a certain 3m3 battery type downhole,the heat dissipation structure of the battery pack was designed.The influence law of the structural parameters such as the position of the air outlet,the size of the air outlet and the deflector of the heat dissipation structure on the heat dissipation characteristics of the battery pack was studied.The radial basis neural network and particle swarm algorithm were used to optimize its structural parameters and the optimal structural parameter combination was obtained.The simulation results showed that the life attenuation value of the power battery of the downhole load-haul-dump was greatly reduced after optimization,and the life attenuation value of the power battery in the first gear full-load transportation condition decreased the most obviously,which was 27.72% lower than that before optimization.(4)According to the particularity of the drive structure and working conditions of the downhole electric load-haul-dump,based on the analysis of three types of conventional drive control strategies of the vehicle,different control strategies were analyzed and studied from the perspective of extending the life of the power battery.The research showed that the linear pedal control strategy was suitable for the load-haul-dump operation.Based on the selected drive control strategy,an overall comparative analysis of the contribution of the proposed dual-motor drive,transmission ratio parameters and heat dissipation structure parameters to the battery life was conducted,and it was concluded that the overall battery capacity decay was reduced after optimization,with the highest reduction of 19.66% in the first full-load transport complete cycle operating condition.According to the fuzzy control theory,a drive control strategy with torque compensation based on the benchmark MAP torque was proposed.Fuzzy control was used to compensate the basic driving torque to different degrees to adapt to the load change of the load-haul-dump and prevent exceeding the driver’s speed expectation.The simulation experiments showed that the control strategy can effectively identify the driver’s operation intention and make compensation to different degrees according to the speed of the accelerator pedal action applied by the driver to effectively meet the power demanded at work. |
