Research Of Sensorless Permanent Magnet Synchronous Motor Vector Control System

In recent years,with the need of construction of energy-saving society and economic growth in China,the motor and its control technology research should put forward to meet with higher requirements,and high-performance motor and its control technology has become the future development trend.At the same time,permanent magnet synchronous motor(PMSM)is attracting more and more attentions in all fields for its high power density,high efficiency and small size.As one of relatively complete control system in many permanent magnet synchronous motor control scheme,the vector control system has characteristics of a wide speed range,start fast,strong braking and so on.In the vector control system of PMSM,mechanical sensors are usually used to obtain the rotor's position and its speed information in real time.But the use of mechanical sensors has the problems of high cost,low reliability,and being susceptible to interference.To deal with these problems mentioned above,a model reference adaptive position free observer is designed in this paper.The observer uses PMSM equation as the reference model and the parametric sub-current equation as the adjustable model.And a suitable adaptive law based on satisfying the Popov stability theory is designed to realize the rotor speed and position estimation.In order to improve the robustness of the system,a design method of sliding mode adaptive position free observer is proposed.By using the rotor velocity estimation method of the sensorless,the sliding mode surface can be established,and the Sigmoid function is used to replace the sign function in the speed observer.on satisfying the Lyapunov stability theory,the rotor speed and position can be accurately estimated when there is abruptly change in the system load torque.Considering that the useful signal SNR is low and is difficult to acquire when the motor runs in low speed.In order to overcome the shortages,a high-frequency sinusoidal voltage signal is injected into the d?-axis of the estimated rotor coordinate system,and the modulated q?-axis high frequency current signal is adjusted by the proportional-integral regulator to identify the rotor speed and position.Through designing a reference position adaptive observer,the speed and position of the rotor can be estimated and the mechanical sensor can be replaced.The sliding mode variable structure is added to the sensorless observer to improve the system performance and its robustness.The high-frequency injection without position observer is designed to realize the estimation of the rotor speed in low-speed operation,and this method widens the applicability of the position-free observer as well.