Research On Braking Energy Feedback Control Strategy Of Permanent Magnet Synchronous Motor For Electric Vehicle

Fuel vehicles bring convenience to people's daily travel,at the same time,there are serious pollution emissions.Under the requirements of energy conservation and emission reduction,electric vehicles have become the main research direction of the automobile industry in the future because of the advantages of high energy efficiency,zero emission,light structure and ready to charge.Due to the restriction of battery materials and battery manufacturing technology,the electric vehicle has a short distance of continuous navigation.As the driving device of electric vehicle,the electric motor can convert the energy consumed by traditional mechanical braking into electric energy and feed back to the battery to increase the range.Therefore,it is of great significance to study and improve the dynamic performance of the main drive motor and the energy feedback control strategy in the braking process of the electric vehicle.Firstly,this paper deduces the mathematical model of PMSM in three-phase ABC coordinate system,two-phase static coordinate system and rotating coordinate system,then analyzes the vector control method of PMSM Based on DC voltage outer ring and DC-AC shaft current inner ring,and deduces the basic energy feedback principle of PMSM control system in electric vehicle,including the generation of PMSM The working mode and the specific process of energy flow in the converter with SVPWM modulation.Secondly,in the process of electric vehicle braking,due to the coupling between the current components of DQ axis will increase the energy loss of the system,resulting in the reduction of the feedback efficiency,the current inner loop control algorithm in the rotating coordinate system is studied in detail: the shortcomings of the traditional PI algorithm are analyzed in theory,and a unit matrix decoupling algorithm is proposed,which can transmit the closed loop of the current inner loop The unit diagonalization of the recurrence function can effectively decouple the DQ axis component of the stator current and reduce the loss power.On the other hand,in order to improve the dynamic performance and anti-interference performance of bus voltage when the battery is in constant voltage charging mode,a voltage controller based on Fuzzy PID is proposed.The simulation and test results show that the fuzzy PID control algorithm is used in the bus voltage outer loop,which can effectively improve the dynamic performance and anti-interference ability of the system in the braking process compared with the traditional PI control method.At the same time,the unit matrix decoupling is used in the current inner loop,the current tracking performance is significantly improved,and the direct axis current is strictly controlled around 0,which effectively solves the current coupling problem High energy feedback efficiency and fast and accurate tracking control variables.Finally,the unit matrix current decoupling algorithm and the voltage controller based on Fuzzy PID are tested under the slow braking and emergency braking of electric vehicle.The simulation and experimental results show the effectiveness of the algorithm.