Research On The Control Strategy Of Electric Vehicle Drive Motor Under Regenerative Braking State

With the advancement of technology and the importance people attach to the living environment,automobiles are experiencing a shift from fuel vehicles to electric vehicles,but at present,fuel vehicles still account for the major part in the automotive field,which not only cause serious pollution to the environment,but also consume a large amount of oil.Electric vehicles,which mainly consume clean energy,have the advantages of low energy consumption and no pollution,but the problem of its insufficient range has become a hindrance to replace fuel vehicles.This study addresses this problem and investigates the control strategy for the regenerative braking state of the electric vehicle drive motor,with the aim of increasing the rated capacity of the electric vehicle energy storage system and improving the range of the electric vehicle,and the research work is subdivided as follows:The first is the analysis of the principle of regenerative braking energy recovery,the block diagram of the regenerative braking energy recovery principle of electric vehicles is constructed,and the principle is explained,the influencing factors of regenerative braking energy recovery are summarized,the four working states of permanent magnet synchronous motor in the Cartesian coordinate system and the mechanical characteristics of the braking process are elaborated,and the electrical energy generated by electric vehicles in the braking process is derived according to the force of electric vehicles in the braking process.Then,taking the permanent magnet synchronous motor as the research object,the working principle,coordinate transformation and mathematical model of the permanent magnet synchronous motor are described in detail,and on this basis,the spatial voltage vector control method of the permanent magnet synchronous motor is introduced,and the regenerative braking of the permanent magnet synchronous motor is controlled by the SVGWM vector control method.Then,the design of regenerative braking energy recovery system and method was formulated,and the battery-super capacitor hybrid power supply brake energy recovery system based on the dual active bridge DC/DC conversion circuit was formulated,the recovery of braking energy was mathematically reasoned,and the energy flow of the DAB transformation circuit was analyzed under the four working states of electric vehicle uniform speed,climbing acceleration,emergency braking and deceleration braking.Fuzzy-SVPWM regenerative braking energy recovery strategy is proposed by combining the SVPWM vector control method and fuzzy control with the vehicle speed V,the energy storage system’s charge rate SOC value,the brake strength z as input,and the regenerative braking force ratio K as the output are introduced.Finally,the simulation verification of the research method,the application of MATLAB software to the vector control of permanent magnet synchronous motor,the bidirectional flow of the DC/DC conversion circuit energy of the double active bridge,the application of ADSOR software to build a regenerative brake control strategy model based on fuzzy control,the selection of three operating conditions to the design of regenerative brake control strategy experimental simulation comparison,simulation results are expressed in three different operating conditions,The energy recovery efficiency of the regenerative brake fuzzy control strategy designed in this paper is about 8%-20% higher than that of the original regenerative brake control strategy,so as to verify the effectiveness of the control method.