Research On PMSM Controller Of Low-voltage And High-power

With the improvement of people’s living standards,people pay more and more attention to Low speed miniature electric four-wheel cars for its comfort and convenience.Owing to its high efficiency,low loss and simple structure,the low-voltage and high-power permanent magnet synchronous motor(PMSM)has gradually replaced the AC induction motor and becomes an important part of speed control system for electric vehicle.Concentrating on the low-voltage and high-power PMSM,the paper carries out research and design on its control system.The different types of rotor structure of permanent magnet synchronous motor are introduced.The mathematical model of PMSM in ABC coordinate system,αβ coordinate system and dq coordinate system,and its vector control method are described.Aiming at the shortcomings of the existing SVPWM algorithm which has large amount of calculation,an improved SVPWM algorithm is studied,and its mathematical model for PMSM vector control system is established in MATLAB/Simulink.The result of simulation absolutely affirms the feasibility of the algorithm.In order to meet the requirement of positional angle of PMSM vector control system,the position estimation of three-phase switch Hall and the position detection method based on magnetic sensor are discussed.The starting angle given and the estimation principle to solving error of Hall installation in three-phase switched Hall estimation algorithm are described.In this paper,the working principle of the magnetic position sensor,the communication protocol and the correction of absolute 0 for PMSM rotor are studied.Additionally,the accuracy of the magnetic position sensor and the photoelectric encoder are compared.By hardware reservation and software defined methods,the paper combines switched Hall and new magnetic position detection and then,designs a rotor position detection method for PMSM.PMSM uses three-phase Hall to estimate the initial position of the rotor,which will cause large angle error.As a result of this,initial current is very large.To solving the problem,the nonlinear PI control is applied to the low-voltage and high-power PMSM controller.The experimental results show that PMSM system has no overshoot during startup.To control the hardware costs,the paper completes the design of flyback switching power supply,current detection,position signal receptionand MOSFET driver and design of other hardware circuit,and then,completes the software development of control system which combines the features of dsPIC33EP32MC204 chip and hardware circuit.The performance of system is tested on the experimental platform of PMSM vector control system.The test result proves the correctness and validity of the design.