Research On Motor Vector Control Strategy For New Energy Vehicles

With the increasing severity of energy crisis and energy security related issues,as well as the rapid development of China’s photovoltaic power generation industry and ultra-high voltage transmission industry in recent years,new energy vehicles have unique advantages in China’s huge market.The control strategy of the drive motor is an important research field of modern new energy electric vehicles.The design and selection of motor control strategies corresponding to different speeds plays a vital role in the performance of electric vehicles.The Permanent Magnet Synchronous Motor（PMSM）is widely used in the field of electric vehicles due to its many advantages.From a practical point of view,this paper conducts the following research on the control str ategy of PMSM:（1）The basic structure and principle of PMSM are studied,such as the influence of the layout of permanent magnet material on the external characteristics of the motor;The three basic mathematical models of motor are studied,namely,the mathematical models in static three-phase coordinate system,static two-phase coordinate system and synchronous rotation two-phase coordinate system.Clark transformation and Park transformation of different coordinate systems are studied;The principle and implementation of Space Vector Pulse Width Modulation（SVPWM）are studied.（2）Field-Oriented Control（FOC）is studied,the4)₍（9）=0 control strategy and the Maximum Torque Per Ampere control（MTPA）are adopted for the low-speed range;In the control of full-speed range,the MTPA is adjusted by Flux-Weakening control（FW）,which is combined with full-speed range FOC;For the FOC studied,the speed range,stability,response speed of motor speed,torque and 3 phase current under different working conditions are comprehensively analyzed.And by adjusting the PI parameters to obtain an output curve with rapid response,small static error and high stability.By simulating the motor operation under common operating conditions of electric vehicles such as load start,overtaking acceleration,etc.,it provides a theoretical reference for the research on the control strategy of electric vehicle drive motors.（3）The traditional FOC uses the rotor position sensor to obtain the motor speed,rotor position and other related information,and this method may cause information collection deviation due to the change of sensor performance.Therefore,the Position Sensorless Control（PSC）is studied.The core content of this control strategy is to accurately estimate the rotor position.Selecting the High-Frequency injection method（HF）in low-speed range,and the Sliding-Mode Observer（SMO）in high-speed range.By designing simulation models and analyzing PSC strategies,obtaining rotor position estimation results and motor output characteristics.The results show that the accurate motor rotor position estimation results have been obtained,which provides a certain reference value for the practical application of control strategies.（4）The physical simulation of PSC is carried out,SMO is verified,the stable performance of the motor is judged by the current curve of the motor,and the speed curve and the error curve of the motor in both no-load and loaded condition are output.