Low-speed Sensorless Vector Control Strategy Of Permanent Magnet Synchronous Motor For Electric Vehicle

Under the dual pressure of environment and energy,the new energy electric vehicle with high efficiency,environmental protection and energy saving has been developed rapidly.At the same time,there are a lot of technical problems which need to be solved urgently in the development of electric vehicle industry.Permanent magnet synchronous motor(PMSM)has become the first choice in the existing drive system of electric vehicle because of its advantages such as high power density,high efficiency and good torque performance.Therefore,control technology of PMSM for electric vehicles has received extensive attention.The key to realize high quality vector control is to obtain the motor speed and rotor position accurately.The traditional closed loop system adopts the mechanical position sensor,which not only increases the cost but also reduces the reliability of the system,especially in the complex conditions and bad working environment.Therefore,the sensorless vector control of PMSM arises at the historic moment and becomes a hot research topic in recent years.The sensorless control method has good control performance in the middle and high speed of the motor,but the control effect is not ideal in the low speed section.Foreign scholars have proposed a method of pulsating high-frequency voltage injection which can effectively detect the rotor position at low speed.However,the filters in the speed feedback and observer caused the system phase delay and limited bandwidth.In addition,the injection of the pulse high frequency signal causes noise.Therefore,an adaptive signal injection method for sensorless PMSM control system is studied in this paper in order to improve the control performance.First,discusses on the structure characteristics and mathematical model of the permanent magnet synchronous motor are conducted,the vector control method and the sensorless control strategy of permanent magnet synchronous motor is summarized.Besides,the working mechanism of voltage space vector algorithm is analyzed.On this basis,the mathematical model of the motor under the high frequency voltage injection method is deduced on the research object of insert permanent magnet synchronous motor,and concerns on low speed performances.The principle of injection and the process of extracting the high frequency response signal containing the position information analyzed in detail.And the design of the observer is discussed.Then the control strategy of id = 0 is adopted,the control algorithm is simulated and analyzed by computer tools.The sensorless control strategy of permanent magnet synchronous motor based on square wave high frequency voltage injection is studied,aiming at the problem of system bandwidth limitation and dynamic performance caused by the introduction of the filter by the high frequency voltage injection method.So,a new method of separating the fundamental signal and the high frequency response current signal is proposed,which reduces the use of the filter in the control system.Optimize the system bandwidth and system dynamics by optimizing the parametric design on the observer link.And the correctness of the method is verified by simulation.Based on the theory research and simulation analysis on the main chip TMS320F28335,an experimental platform is build based on the position sensorless control system of permanent magnet synchronous motor of square wave high frequency voltage signal Injection.The experimental study on the no-load acceleration,deceleration and load condition of the motor is carried out,and the reliability and effectiveness of the proposed control algorithm are verified.