Seminario 242 Finite Control Set Model Predictive Control with Reduced Switching Frequency Applied to Multi-cell Rectifiers Sr. Eduardo E. Espinosa N., Alumno de Doctorado en Ingeniería Eléctrica, LCDA – DIE The utilization of multi-cell converters, through the use of low voltage semiconductors
has permitted to implement medium and high voltage applications as PV farms and
AC drives. In conventional AC drives, this converter requires an input multi-pulse
transformer, which allows the low frequency harmonic cancellation that are generated
by the three-phase diode rectifiers included in each power cell. This multi-pulse
transformer is bulky, heavy, expensive, and must be designed according to the
number of power cells, making the transformer topology dependent. This work
proposes and evaluates a harmonic minimization strategy based on a Finite Control
Set – Model Predictive Control (FCS – MPC), which emulates the harmonic cancellation
of a multi-pulse transformer. This feature allows the minimization of the Total
Harmonic Distortion (THD) of the AC grid current of the multi-cell converter. The
evaluation is focused in one disadvantage of the FCS – MPC, which is its high
switching frequency that causes high losses in the semiconductors. To overcome this
disadvantage, an additional objective function is proposed. Simulation results prove
the theory, with satisfactory results. |