Compensation of three-phase diode rectifier with capacitive filter working under unbalanced supply conditions using series hybrid active power filter

The currents drawn by three-phase diode rectifiers with capacitive filters under unbalanced supply conditions are highly non-linear and unbalanced. This configuration draws significantly unbalanced currents even with smaller percentage of unbalance in supply voltages and more unbalance in supply voltages leads to an extreme unbalanced situation like single phasing. This study highlights the unbalance line current problem observed in three-phase diode rectifier and proposes its compensation using series hybrid active power filter (SHAPF) working with appropriate control strategy. Four distinct modes of operation under unbalanced supply are identified. A new control algorithm which simultaneously compensates for supply voltage unbalance and source current harmonics is applied to compensate the configuration. An experimental model of three-phase diode rectifier with capacitive filter working under different supply situation is developed to establish identified modes of operation. This configuration is compensated with SHAPF, manufactured using ARM Cortex M4-based microcontroller and the results of compensation are described in this study.