ANALYSIS OF THREE-PHASE SVPWM MICROCONTROLLED INVERTER WITH FOCUS ON HARMONICS GENERATION

Abstract

This work presents SVPWM modulation technique concepts in a simple and direct way, aiming at the level of harmonics generated measurement, in order to evaluate its performance and to compare with another method of modulation widely used and known as SPWM. It also presents the generation algorithm, implemented and simulated in an 8-bit microcontroller. PWM is a technique used by inverters to control induction motors, aiming to control rotation and torque. Several techniques have been developed, the most famous being SPWM, due to its simplicity and performance, and the most recent being SVPWM, which has gained the confidence and preference of designers, mainly due to its performance characteristics. A bibliographic study was necessary to implement the SVPWM with simulations in EXCEL, PSIM, MATHLAB and PROTEUS for a better understanding of the algorithm concepts and construction. Performances of SPWM and SVPWM modulations were evaluated under the same conditions in harmonics generation, by total harmonic distortion measurement, and the SVPWM method presented better results. On the other end, by increasing the number of vectors, this technique may be impracticable when acting with low cost conventional microprocessors. In both techniques, inverters dead times were realized in hardware, by dedicated integrated circuits, so that, besides avoiding crossed conductions, they didn´t influence distortions.