| The load simulation system of Electric Vehicle(EV)adopts the motor-towing control mode to simulate the load characteristics of EV driving motor on different road surfaces.It is not constrained by natural environment and flexibly sets experimental parameters,which greatly improves the research efficiency.The load characteristics of actualized EV drive motor can be reproduced accurately under laboratory conditions.Permanent magnet synchronous motor(PMSM)has the advantages of high power density,wide speed range and high operating efficiency.When the simulation of EV load characteristics based on PMSM is realized,it is beneficial to simplify the control complexity of simulation system and has important application value and implementation significance for the research of EV load simulation system.In this paper,the EV load simulation under laboratory conditions is realized by theoretical derivation,simulation analysis and experimental verification.The EV load system modeling,dynamic load simulation strategy,simulation system stability and simulation accuracy are mainly explored.Firstly,the mathematical model of the actual EV driving motor and its load system is established to provide reference and comparison for the subsequent simulation.In this paper,the basic structure,mathematical model,control strategy and mathematical model of the EV load characteristics of the EV drive motor(PMSM)are studied,and the stability of the actual EV load system is analyzed.The load characteristics of the EV drive motor are analyzed by the simulation results of the EV on different road surfaces.It provides comparison and reference for subsequent stability derivation,simulation analysis and experimental results of the simulation system.Secondly,by using electromechanical analogy method for steady state simulation strategy is improved,the dynamic load simulation strategy acceleration feedback simulation strategy is studied,under the strategy of this kind of simulation system stability is analyzed,it is concluded that to simulate the EV of moment of inertia is greater than the rotary inertia of the simulation system can simulate the divergence and instability of EV simulation system;In order to expand the range of moment of inertia of the simulation system,a first-order low-pass filter was added into the acceleration feedback loop,and the stability conditions of the simulation system after the introduction of the low-pass filter were deduced,that is,the influence of filtering time constant and discrete time on the stability of the simulation system was analyzed.In order to avoid the introduction of the lowpass filter to a great extent,reduces the simulation accuracy problems,studied the dynamic simulation of torque feedforward strategy,in discrete state stability analysis under the strategy of the simulation system and simulation accuracy,comparison and analysis results show that compared with the simulated acceleration feedback strategy,torque feedforward simulation strategy has a good stability and accuracy.Considering the driving slip of the EV in the extreme motion state,the mathematical model of the EV load system considering the slip characteristics is established and the simulation research is carried out.The stability analysis of the actual EV load system considering the slip characteristics is carried out,which provides a comparison and reference for the subsequent stability exploration of the simulation system.In order to accurately reproduce the variation history of EV slip,an acceleration feedback simulation strategy considering slip characteristics was proposed,and the stability of the simulation system under the dynamic simulation strategy was analyzed,that is,the influence of acceleration filtering depth and discrete time on the stability of the simulation system considering slip characteristics was analyzed.In order to avoid the problem that the introduction of low-pass filter would reduce the simulation accuracy,a torque feedforward dynamic simulation strategy was proposed considering the slip characteristics,and the discrete domain transfer function of the simulation system under this dynamic simulation strategy was deduced and analyzed.The results show that,compared with the acceleration feedback simulation strategy considering the slip characteristics,The torque feedforward simulation strategy considering slip characteristics has good stability and simulation accuracy.Finally,an experimental platform of EV load simulation system was built based on RT-Lab realtime simulator,and experiments were carried out on the EV simulation system without considering slip characteristics and under the simulation strategy considering slip characteristics,respectively,to verify the correctness of theoretical derivation and the feasibility of the proposed simulation strategy. |
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