The Research On IPMSN Sensorless Vector Control Based On High Frequence Signal Injection

In order to get high performance in the speed and position closed-loop controlsystem of permanent magnet synchronous motor, the motor is usually installed withmechanical photoelectric encoder and rotary transformer which are used formeasuring the position and speed of rotor. But it is easily to cause some instableproblems particularly in some environments where the mechanical photoelectricencoder is vulnerable to the external condition of it by the influence of themselvessuch as volume, quality and cost. As a resolution of this problem, the speed sensorlessvector control technology is very hot in the field of AC speed control in recent years.Because the back electromotive force is so weak that it can’t be measured precisely inlow speed, and generally high frequency injection method is used in low speed. In thispaper, method based on high frequency voltage injection is used to detect the rotorposition information. The main achievements of this paper are summarized as follows:1) Firstly, the model of interior permanent magnet synchronous motor and thetransformational relationship of each coordinate axis are established and the problemcaused by nonlinear and strong coupling of the motor are solved by the transformationbetween different coordinate axis.Finally, several basic vector control strategies ofIPMSM are introduced for a further research on sensorless vector control technology.2)The basic theories of methods of rotating high frequency voltage signalinjection and high frequency voltage pulse injection which is applied to the speedsensorless vector control system of PMSM are specifically analyzed and the filterblock model of them are simplified. The simulations of them are conducted and theresults of them show that the high frequency voltage pulse injection is more difficultto debug and more sensitive to the variable parameters than rotating high frequencyvoltage signal injection, but the dynamic effect of it is better. Both of them areavailable to no-load operation at low speed and the position traces of them areprecise.3)The influential factors of speed sensorless vector control system with highfrequency voltage injection are discussed. The dead time effect of inverter leads to sixadditional disturbance voltages with equal amplitude during each period anddistortion of current response waveform affect the precision of rotor positionestimation. The stator resistance and time delay of the system lead an offset in positive and negative sequence currents and an additional DC component. The ratio ofsaliency impacts the error estimation of rotor position and may cause a failure. Asimulation about several influential factors is conducted.4)Finally, the hardware and software design is completed and experiments areinducted to prove the correction and availability of the control algorithm.Experimental results show that the permanent magnet synchronous motor speedsensorless vector control system reliability and stability based on the rotationhigh-frequency voltage injection method.