Design and implementation of variable frequency sine wave output buck-boost inverter

Şener, Yunus
Conventional inverters have pulse-width-modulated output with a fundamental component at the desired frequency and magnitude. These converters are usually buck type and therefore the DC link voltage limits the maximum 3-phase output voltage magnitude. As a consequence, in motor drive applications field weakening is essential after a certain frequency of operation, as it becomes impossible to preserve the rated flux level. In renewable energy applications similar problems arise. When the DC link voltage falls, the rated output voltage at rated frequency is no longer achievable. Therefore, the energy available cannot be extracted from source. Some techniques are used to increase output voltage such as over-modulation. However over-modulation causes harmonics to increase and different problems arise. Thus there are two important issues to be studied for DC to AC conversion; obtaining sinusoidal output and boosting input voltage. Various studies on this topic are searched and analyzed. A method is proposed, implemented and tested. The results show that proposed method enables operation at rated frequency with THD being lower than 5% even if DC-link voltage is %26 lower than nominal voltage.
Citation Formats
Y. Şener, “Design and implementation of variable frequency sine wave output buck-boost inverter,” M.S. - Master of Science, Middle East Technical University, 2016.