In this paper, a novel PWM technique insuring the self-balancing of the capacitors voltages has been proposed for the attained nine-level packed U cells (PUC) converter. In the traditional fifteen-level operation, the capacitors voltages have to be maintained around their references using a state variable feedback which requires three sensors, two for the capacitors voltages and one for the load current. By applying the proposed PWM technique to the fifteen-level PUC converter, self balancing of the capacitors voltages is attained, which results in the proposed nine-level converter. The proposed balancing technique is achieved without any closed loop regulation or sensors. The proposed concept has been verified by mean of simulations performed in the Matlab Simulink environments. Simulation results show that even under severe DC bus voltage and load parameters variations, the capacitors voltages remains around their required values. Harmonics contents of load current depend on the modulating signal frequency. Moreover, even under low frequencies, the total harmonics distortion remains reduced.
- Packed U cells
- Multilevel converters
- Self balancing
- PWM technique
A sensor-less self balancing PWM technique applied to the fifteen-level PUC inverter was presented in this paper. It allows a fast open loop regulation of the PUC inverter capacitors voltages without using any additional circuit. Indeed, the self balancing is achieved without using any state variable feedback or sensors. The proposed concept was verified by simulation results.
 Y. Ounejjar and K. Al-Haddad “A novel high energetic efficiency multilevel topology with reduced impact on supply network”, The 34th Annual Conference of the IEEE Industrial Electronics Society, pp.489-494, 10-13 November 2008, Orlando, Florida, USA
- Ounejjar, Y., K. Al-Haddad et L. Gregoire.. “Packed U Cells Multilevel Converter Topology: Theoretical Study and Experimental Validation”. IEEE Transactions on Industrial Electronics, vol. 58, n°4, p.1294-1306, (April 2011).
 X. h. Zhang and W. k. Yue, “Neutral point potential balance algorithm for three-level NPC inverter based on SHEPWM,” in Electronics Letters,vol. 53, no. 23, pp. 1542-1544, 11 9 2017
 M. Sleiman, K. Al-Haddad, H. F. Blanchette and H. Y. Kanaan, “Insertion Index Generation Method Using Available Leg–Average Voltage to Control Modular Multilevel Converters,” in IEEE Transactions on Industrial Electronics, vol. PP, no. 99, pp. 1-1.
 I. López et al., “Modulation Strategy for Multiphase Neutral-Point- Clamped Converters,” in IEEE Transactions on Power Electronics, vol. 31, no. 2, pp. 928-941, Feb. 2016.