Sliding mode control of PMSM based on robust differentiator

In order to realize high speed and high precision position control of some rocket launcher servo system, aimed at all kinds of uncertainties such as widely changing moment of inertia and load moment, and strong impact moment, super-twisting algorithm is introduced to design speed controller and current controller. In order to guarantee mover speed to track its reference signal strictly when the system bears parameter variation and external disturbance, the speed sliding mode and direct axis current sliding mode are selected respectively. In the end, simulation is carried out to verify that this control algorithm has strong robstness to load variation and parameter change, and decreases chattering phenomenon effectively. This controller can improve control performance of the servo system and therefore has much practical meaning.

1 Introduction

Ac servo system is a typical servo control. So far, research and application of ac servo system have gained many achievements. In addition, it has obtained good technological performances such as wide range speed adjustment, high speed and precision, and fast dynamic response. Hence, it is widely used and developed. Three phases pmsm is derived from synchronous motor. It eliminates brush and overcomes fatal weakness of synchronous motor. Besides, it has excellences such as small volume, low inertia and high efficiency. Thus, it has [1]–[2][3][4][5] been widely used since its appearance. PMSM has simple structure, high ratio of torque-current and big ratio of torque-inertia. In addition, pmsm is more easily realized than three phases ac asynchronous motor and has been widely used in high precision servo system. In addition, PMSM can more easily realize vector control than three phases asynchronous motor, thus it is widely used in high precision rotation control. With respect to a kind of system such as rocket launch ac servo system that possesses widely ranged parameters and load, conventional control can't achieve high speed and high precision requests.