Research On Sensor-less Braking System Of Permanent Magnet Synchronous Motor

Nowadays,how to solve energy and environmental problems has become a current topic.On this background,electric vehicles have become a hot topic in the world.However,due to the impact of battery storage capacity,electric vehicles are limited in long-distance travel.The motor can recover the energy consumed during braking,which improves the energy efficiency and also extends the one-time driving range of cars.Therefore,the research on electric vehicle braking system has become a key research direction in the field of new energy vehicle development.At present,permanent magnet synchronous motor(PMSM)has been widely used in pure electric vehicles due to its high efficiency,small size and high power density.A key point of the motor control system is that the control system must accurately obtain the motor speed and rotor position in real time.The rotor position information can be accurately obtained by position sensor but the cost of the position sensor is high and the maintenance is difficult.Based on the above reasons,this paper adopts sensor-less control method to study the braking process and braking control strategy of PMSM.This paper introduces the basic mathematical model and vector control strategy of PMSM in different coordinate systems,and introduces the sensor-less control method of PMSM in detail.According to the traditional sensor-less control method,a composite sensor-less control strategy is established to control the motor smoothly at low speed and high speed.And this paper also introduces the principle of optimal feedback braking strategy and proposes a braking control system based on sensor-less control algorithm.Finally,this paper uses Matlab/Simulink platform to build a simulation model which can verify the performance of the hybrid control algorithm at full speed range,and tests the feasibility of using sensor-less control algorithm for braking system and the recovery of electric energy.