Power rectifier based on open-end converter with floating capacitor under non-sinusoidal and unbalanced input

摘要

This work studies a three-phase power rectifier which consists on an open-end converter composed of two three-phase three-leg converters (converters A and B). Converter A has a floating capacitor on its dc-link. On the other hand, converter B processes power and has a dc load connected to its dc-link capacitor. The voltage ratio considered is 2:1 to maximize the number of levels symmetrically spaced. A level-shifted PWM strategy is presented and dc-link control strategies are proposed for both converters A and B. The dc-link floating capacitor is controlled by means of the common mode voltage, keeping the PWM levels, and it is performed by a PI controller. Additionally, scenarios with non-sinusoidal and unbalanced grid voltages are discussed. It is shown that it is possible to use the maximum capability of the converter A in the compensation of harmonics and negative sequence. Finally, simulation and experimental results are shown to validate the strategies and scenarios presented.