Second-Order Model-Free Predictive Speed Control of PMSM Drives with Comparison of Cascaded and Non-Cascaded Speed Control Schemes

This paper presents a new predictive speed control algorithm for the Permanent Magnet Synchronous Motor (PMSM) drive using the model-free control theory. In the proposed methodology, the motor speed is directly controlled by the q -axis voltage reference signal instead of the conventional cascaded control of speed and q-axis current. On this basis, a second-order ultralocal model is defined, relating the second derivative of motor speed to the q-axis voltage. The unknown function of the ultralocal model is estimated using a second-order Extended State Observer (ESO). A comparative analysis is conducted through simulations among four different speed control methods, including the proposed method and the first-order model-free speed control for the non-cascaded control scheme, as well as the Proportional-Integral (PI) controller and model-free controller for the cascaded speed control scheme. According to the results, the proposed method achieves a faster dynamic response compared to the rest of the control approaches.