A T-Type Switched-Capacitor Multilevel Inverter With Low Voltage Stress and Self-Balancing

Abstract

This paper proposes a novel T-type multilevel inverter (MLI) based on the switched-capacitor technique. The proposed inverter not only achieves that the maximum voltage stress of the switches is less than the input voltage but also has a voltage boost capability, which makes it suitable in high voltage applications. It is worth mentioning that the proposed inverter features two topology extension schemes which help it achieve a higher output level and voltage gain. With the merit of low voltage stress and reduced power devices, a seven-level inverter can be achieved using only two capacitors. Moreover, capacitor voltage self-balancing capability can simplify the complexity of the circuit and control. The topology, operating principle, modulation strategy and analysis of the capacitor of the inverter are presented. The superiorities of the proposed inverter are investigated by comparing with recently proposed hybrid MLIs and switchedcapacitor MLIs. Finally, a seven-level prototype is constructed to validate the correctness of the theoretical analysis and the feasibility and effectiveness of the proposed inverter. 1 Index Terms-Multilevel inverter, switched-capacitor, low voltage stress, self-balancing, extension. NOMENCLATURE Ac Amplitude of the triangular carriers fc Frequency of the triangular carriers Aref Amplitude of the sinusoidal modulation wave fo Frequency of the sinusoidal modulation wave Vo Output voltage Vdc Voltage of dc source Vs Voltage stress of the switch Ci Capacitor number i Cs Parasitic capacitance of the switch ∆VC2 Voltage ripple of C2 VC2 The voltage of C2 ∆Q1 Discharge amount of C2 during the period of 0-t1 ∆Q2 Discharge amount of C2 during the period of t2-t3 ∆QC2 The maximum discharge amount of C2 QuThe discharge amount of the capacitor when it works at

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