Research And Implementation Of Sliding Mode Control Of Servo Motor Based On DSP

The permanent magnet synchronous motor (PMSM) is a superiority performance and widely used motor. The control technology of PMSM has developed rapidly with the fast development of power electronics technology, micro-electronic technology and modern control theory. The position and speed precise control of PMSM system build in the speed closed-loop control, so how to acquire rotor position and speed signal is a most important strategy in the whole system. At present, in mostly regulation drive systems, the mostly method is to install a position sensor in the rotor shaft. But the sensors increase the cost and decrease the reliability. In these backgrounds, there has been an increased interest in developing techniques to obtain the position and speed information for the PMSM without external position sensors. Position sensorless control for PMSM will be widely used in some special or low precision situation. We can measure the physical quantity such as three phase current, voltage etc to estimate the position and speed through special observer strategy. The speed regulation system of PMSM without sensor not only has a simple structure, high efficiency, excellent performance and easy maintenance, but also has a small volume, low cost, high reliability and some special application. This paper, on the background of application of sinusoidal PMSM, applying the method based on SMO (Sliding Mode Observer), has researched and accomplished the sensorless vector control of drive and control system.Firstly, this paper introduced the structure and mathematic model of PMSM. Then the paper use Simulink to build the emulation model of PMSM, expatiate the theoretical basis of spacial vector pulse width modulation (SVPWM) and the wave generation, and did some research in closed-loop control strategy. The system is controlled according to the control theory of sliding mode observer. In order to weaken the oscillation of system, discontinuous control in the conventional SMO is replaced by hyperbolic tangent function with parameter adjustable via fuzzy control. So the position and speed of PMSM is real-time estimated and the estimated position is modified continuously. Theoretical analysis and Matlab simulation results show that the proposed strategy has stronger robustness and restricts the oscillation effectively.Secondly, the main structures of the software and hardware based on TMS3202407A DSP are studied. The principle and realization method of the main functional blocks are also illuminated. To the hardware, each part of the design and debugging of the peripheral circuits are thoroughly discussed. The software has been programmed with assembly language. Sensorless PMSM double close-loop vector control with feedback of speed and current are realized. The flow charts of main program and PWM interrupt service routine are given. The main module of sensorless PMSM vector control such as SMO rotor position estimation, speed calculation, generation of sine and cosine, vector coordinate transformation, PI regulators, SVPWM vector modulation are all accomplished in the PWM interrupt service routines.Finally, the program were debugged in the CCS3.1 and experiments were did without load. The results confirmed the correctness of the system design.