Research On Energy-saving Control Strategy For Hydrostatic Transmission Construction Vehicles Based On Power Identification

Hydrostatic Transmission technology(HST)has been widely used in military vehicles,public transportation and construction vehicles in recent years,because of its high power density and the ability to achieve infinite speed control.In this paper,aiming the energy-saving control of the hydrostatic transmission construction vehicles with flow coupled hydraulic system is adopted in the driving system and the working system.With the driving and working hydraulic system flow as the control target variable,the decoupling between the output speed of the hydraulic motor and the engine speed is achieved through the coordinated control of the engine speed and the hydraulic pump displacement.Based on the power following energy management control strategy of the hybrid technology,this paper proposes an energy-saving control method based on power identification for the flow coupling hydrostatic transmission system.Through the identification of the demand power of the driving system and the working system,can be completed the energy-saving control of the engineering vehicles,including the engine and hydraulic system,realize the "demand distribution" of the output power of the engine.The main contents of this paper are as follows:Firstly,a layered control system architecture is constructed to realize the energy saving control method based on power recognition.Based on the structure characteristics and control requirements of the hydrostatic transmission construction vehicle,carried out the research on the control architecture of the control system;The layered control system design method was used to construct the layered overall architecture of the control system,and the control structure of three sub-control strategies,such as the demand power identification control strategy,the engine working point planning and coordination control strategy,and the hydraulic system coordination control and auxiliary control strategies;And the key technologies necessary to realize the control function are planned.Secondly,the strategies involved in the vehicle control system of hydrostatic transmission are studied.Based on the comprehensive analysis of the driver’s intention and the real-time acquisition of the pressure signal of the hydraulic system,developed the power identification strategy of the overall demand power of the hydrostatic transmission system;In consideration of the influence of engine operating conditions on the dynamic performance and economic performance of the hydrostatic transmission construction vehicle,the planning method of engine working point for the hydrostatic transmission construction vehicle is proposed;Developed the coordinated control strategy of engine and driving/working variable pump displacement,which can realize decoupling between the driving/working variable pump flow and engine speed;For the energy-saving control requirements of hydrostatic transmission construction vehicle working special conditions such as ramp or high power demand condition,designed the corresponding auxiliary control strategies for hydrostatic transmission system,improved the adaptive ability of the control system in the diversified operating environment.Finally,the pressure data collected from the actual vehicle experiment is used as load input for the simulation model,and verified the control effect of control strategies by MATLAB/Simulink and AMESim simulation.In order to guarantee the authenticity of the simulation model,improve the credibility of simulation results,a experiment platform was set up to collect the load data of hydrostatic transmission construction vehicle under the driving and operating conditions,the experimental data is used as the load input of the combined simulation model;Using MATLAB/Simulink and LMS Imagine.Lab AMESim software to establish a joint simulation model for the control system and transmission system of hydrostatic transmission construction vehicle;Based on the simulation results obtained by the joint simulation model,the control effect of the control strategies developed in this paper is analyzed and verified.The control method proposed in this paper and the corresponding research results can provide reference for the development of the primary(variable pump-quantitative motor)or the primary and secondary joint regulation(variable pump-variable motor)closed hydrostatic transmission of construction vehicles or highway vehicles control system.