Simplified Sensor Based Vector Control of Permanent Magnet Synchronous Motor Drive

This paper presents a sensor-based vector control implementation for a permanent magnet synchronous motor (PMSM) drive using an encoder on a digital signal processor (DSP) platform. A built-in incremental encoder provides the necessary position and speed information for transforming three-phase stationary reference frame of the stator currents to the two-axis rotating d-q reference frame of the rotor. The use of an encoder enables easy computing of rotor position even at very low speeds, which is a major limitation of the back emf estimation based sensorless control techniques. DSP and Embedded coder toolbox of MATLAB, together with the current sensors and incremental encoder, offer a compact, cost effective and simplified system for implementation of the popular vector control technique for AC drives, as compared to a dSPACE controller-based system often discussed in the literature. Also, embedded coder toolbox minimizes the efforts while programming the DSP as the simulink model itself can be used for experimentation merely by modifying its MATLAB 'configuration parameters'. MATLAB/Simulink based simulation results for a vector controlled PMSM drive have been validated with the help of experiments performed on a 3.5 kW laboratory prototype of the PMSM drive fed from a two-level voltage source inverter controlled by sinusoidal pulse width modulation technique.