Performance Improvement of Scalar Feedback Control for Induction Motors by Using Third Harmony Injection SPWM

Abstract

Induction motor is widely used in some applications. As time goes by, control of induction motor is expected to has fast response to load changes and transient response. Speed precision is also required in some applications. Scalar control is known because of simplicity. Limitations of conventional scalar control are slow response and uncontrolled speed. In other hands, vector control provides a great response of induction motor, but the implementation is relatively difficult. Different modulation technique can change the speed response of induction motor. Injecting third harmony injection to induction motor does make a significant change of induction motor s speed response. This paper intends to analyse induction motor s response by injecting third harmony injection on scalar control. Injecting third harmony signal to SPWM will improve motor s transient response and feedback response under loaded condition. The software is embedded using DSP microcontroller using fixpoint arithmetic to achieve faster computation time and to reduce memory usage.