Research On Maximum Torque Per Ampere Control Strategy Of Flux Leakage Controllable Permanent Magnet Motor

With the continuous development of human society,the negative effects such as energy crisis and ecological environment problems are becoming more and more prominent.“Energy saving and emission reduction” and “green efficiency” have become the focus of global attention.Governments from various perspectives have formulated relevant guidance and support policies to promote energy saving and emission reduction to stimulate the development of efficient green technologies.Electric vehicles(EVs)have received extensive attention from governments and auto companies in various countries,which have become one of the main directions of green and energy-saving development in the automotive industry.As the key of the electric drive system,the performance of the motor system directly determines the driving and handling performance of the EVs.In addition,EVs ususally face a variety of complex operating conditions such as fast start and stop,frequent acceleration and deceleration,high-speed cruise,etc.,which puts forward strict requirements for the motor system,such as strong load capacity,fast response,high efficiency and wide speed regulation performance.In recent years,interior permanent magnet(IPM)motor has been widely used in the field of EVs due to its advantages of high power density,high torque density,high efficiency and superior dynamic performance.However,for the IPM motor,it is difficult to achieve a wide speed regulation range and maintain a high maximum output torque because of its constant permanent magnet excitation flux.Hence,flux leakage controlled permanent magnet(FLCPM)motor has been proposed.The FLCPM motor can achieve the adjustment of the main magnetic flux by a special rotor design with a controllable magnetic flux leakage circuit.Consequently,the FLCPM motor has a high load capacity,a wider speed regulation range,and resistance to demagnetization at high speed.However,the variable leakage flux makes the flux linkage and inductance parameters of the FLCPM motor change nonlinearly,which puts forward higher requirements for its drive control.Aiming at the characteristics of controllable leakage flux of FLCPM motor,combined with maximum torque per ampere(MTPA)control strategy,this thesis proposes a MTPA control strategy based on self-optimization of equivalent parameter.Combined with the active disturbance rejection control(ADRC)technology,the MTPA control system of FLCPM motor is constructed.The purpose of this thesis is to solve the problems of poor dynamic response performance and large current caused by the change of dynamic parameters of the FLCPM motor,which improve the operation efficiency of the FLCPM motor.The specific work content of this thesis is as follows:1)According to the research background of the drive motors for EVs,this thesis introduces the research status of drive motors for EVs and variable flux motors including FLCPM motors.At the same time,the research status of permanent magnet motor control strategy and FCLPM motor control strategy are introduced.The influence of controllable magnetic flux leakage characteristics of FLCPM motor on motor control is expounded,and the research significance and content of this thesis are clarified.2)The topological structure of the FLCPM motor is analyzed in detail.The principle of magnetic flux leakage control is expounded according to the simplified magnetic circuit diagram of the motor structure.The inductance and flux characteristics of FLCPM motor are analyzed based on finite element method.Then,the mathematical model of FLCPM motor is deduced,which lays the foundation for constructing the drive control system of FLCPM motor.3)The basic vector control system of the FLCPM motor is constructed.Also,the simulation analysis model of the FLCPM motor is established based on MTPA control strategy with constant parameters.To improve the dynamic performance of the FLCPM motor control system,ADRC is used to design the speed loop controller of the motor control system.Finally,the results of PI controller and ADRC controller are compared by experiments.Also,the correctness and effectiveness of the FLCPM motor simulation and ADRC controller are verified.4)Aiming at the problems of flux linkage parameter change and inductance parameter change caused by flux leakage change of FLCPM motor,a MTPA control strategy of FLCPM motor based on self-optimization of equivalent parameter is proposed.The mapping relationship between equivalent parameters and stator current in different torque regions is constructed,and the equivalent parameter is corrected in real time,thereby reducing the armature current and improving the operating efficiency of the FLCPM motor.5)Based on the d SPACE1007 hardware-in-loop simulation platform,the experimental platform of the FLCPM motor system is built.The characteristics of the FLCPM motor and the related control strategies are studied and analyzed,respectively,which verifies the effectiveness of the control strategies proposed in this thesis.