Energy Efficiency Attenuation Mechanism And Control Of Distributed Drive Electric Vehicle Drive System

Electric vehicle has become the focus of future automobile development because of its advantages of fast speed-up,low pollution and outstanding comfort.However,due to the difference of battery density and control system in the drive system,the driving range is obviously insufficient compared with the traditional fuel vehicles.In order to improve the energy efficiency of the drive system and increase the driving range of electric vehicles,the energy consumption analysis and optimization control of the drive system of electric vehicles are studied.In order to solve the problem of excessive motor loss caused by motor iron loss in the drive system,the vector control method of asynchronous motor based on loss is adopted.Firstly,the mathematical model of induction motor considering iron loss is established,and then the optimal rotor flux linkage under steady-state operation is obtained by mathematical expression of asynchronous motor.Finally,the efficiency of asynchronous motor is improved by controlling the optimal rotor flux under different steady-state conditions.In order to solve the problem that the switching loss is greatly affected by the excessive switching frequency of inverter in the drive system,a multi PWM modulation strategy based on switching frequency is adopted.The loss composition of the inverter is analyzed,and the change trend of the inverter under different output power is obtained by combining the calculation method of each loss.Finally,the switching loss of the inverter is reduced by establishing the modulation strategy selection scheme under different switching frequency.In order to maximize the energy efficiency of the whole drive system,a hierarchical control strategy based on the optimal rotor flux is designed.The outer layer maximizes the output power by finding the optimal value of the rotor flux of the asynchronous motor under different steady-state conditions;the inner layer selects different modulation strategies by analyzing the switching frequency of the inverter to ensure that the harmonic content of the inverter is not damaged At the same time,the switching loss is reduced appropriately.The simulation model of the drive system is established by using Matlab / Simulink simulation module,and the hierarchical control effect is analyzed.The experimental results show that the efficiency of the induction motor can reach 88.9% under steady-state condition,which is 12% higher than other control methods;the efficiency of the inverter is about 95.5%at low switching frequency,and 1.5% higher than the original control at high switching frequency.Compared with the traditional control scheme,the efficiency of the whole drive system is improved by nearly 14%,and the control effect is good.