Reduced DC Link Voltage Active Power Filter Using Modified PUC5 Converter


 In this paper the 5-level Packed U-Cell (PUC5) inverter is reconfigured with two identical DC links operating as an active power filter (APF). Generally, the peak voltage of an APF should be greater than the AC voltage at the point of common coupling (PCC) to ensure boost operation of the converter in order to inject harmonic current into the system effectively; therefore, full compensation can be obtained. The proposed modified PUC5 (MPUC5) converter has two equally regulated separated DC links, which can operate at no load condition useful for APF application. Those divided DC terminals amplitudes are added at the input of the MPUC5 converter to generate a boosted voltage that is higher than the PCC voltage. Consequently, the reduced DC links voltages are achieved since they do not individually need to be higher than the PCC voltage due to the mentioned fact that their summation has to be higher than PCC voltage. The voltage balancing unit is integrated into modulation technique to be decoupled from the APF controller. The proposed APF is practically tested to validate its good dynamic performance in harmonic elimination, AC side power factor correction, reactive power compensation and power quality improvement.


  1. Active Power Filter
  2. PUC5
  3. Harmonic Elimination
  4. Power Factor Correction
  5. Power Quality



The MPUC5 configuration has been introduced as a modification to the PUC5 topology with the advantage of DC voltage boosting. It has been employed as an APF with reduced DC link voltages. The voltage balancing between DC capacitors in the APF has been done by the redundant switching states. Since the two capacitors voltages are regulated without external controllers, a simple cascaded control technique has been implemented to keep the sum of two DC voltages values at the reference level as well as synchronizing the source current with grid voltage. Finally, the performance of the MPUC5 APF has been tested practically. Results have shown that the proposed configuration operated well in current harmonic elimination, reactive power compensation and power factor correction.


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