Research On Sensorless Vector Control For Permanent Magnet Synchronous Motor Based On High Frequency Signal Injection Method

Permanent magnet synchronous motor has been widely used in high performance drivesystems because of its advantages, such as low cost, high efficiency and good runningperformance. Vector control method is most often used to achieve magnet synchronous motorcontrol results of the high performance permanent. For vector control, the rotor positioninformation must be achieved, and the usual method is to install a speed sensor or amechanical position sensor on the rotor shaft. But this approach will lead to the system costincreased, reliability reduced, easily affected by the environment impact and so on. Therefore,sensorless control technique is proposed to overcome the defects caused by sensors.Sensorless control technology gets rid of mechanical sensor in motor drive systems, notonly can reduce the cost of system, but also can increase the reliability of the system.Sensorless control technology has a great significance in some special operation field, such ashigh speed motor, micro-motor, submarine robotand and home appliances. Currently, thereare a variety of sensorless control methods, but most cannot accurately estimate the rotorposition at low speed. Aiming at this problem, sensorless vector control for permanent magnetsynchronous motor based on high frequency signal injection method is deeply studied in thisthesis, making it accurately estimate the rotor information from high speed to low speed.The main contents of this thesis are as follows:(1) To analyze several coordinate transformation theories, and deduce the mathematicalmodels for permanent magnet synchronous motor in different coordinate systems. Furtherstudy the fundamental principle of vector control, classify various control methods, andanalyze their respective characteristics.(2) Mainly study the principle of high frequency injection method. In detail analyze theseparation of high frequency current, the extraction of negative sequence current, theacquisition of rotor information and the correction of rotor polarity. On this basis, thesensorless vector control system for permanent magnet synchronous motor based on highfrequency injection method is set, and simulation experiment is carried out. The results showthat the high frequency injection method can get good estimation effect, higher precision ofthe speed and rotor position, and well performance of the system control.(3) To study the principle of model reference adaptive control system. The simulationexperiment is carried out by establishing the sensorless vector control system based on themodel reference adaptive method. The simulation results show that this method canaccurately estimate the rotor spatial information, and system control effect is good, when themotor is running at high speed.(4) To contrast the model reference adaptive method and the high frequency injection method. The simulation results show that both of the two methods can accurately estimate therotor speed and position, and the system control effect is also good, when the motor is runningat middle and high speed. However, when the motor is running at low speed, only highfrequency injection method can get higher estimation precision and better control effect.Therefore, the high frequency injection method is more effective to estimate the rotorinformation at full speed range.