Active Impedance Network Buck-Boost Three-Level T-Type Inverter With Enhanced Voltage Gain

Abstract

This paper proposes a new PWM technique for a reduced-component-count active impedance network (RCC-AIN) three-level inverter to maximize the input/output (I/O) voltage gain. Although the max boost control (MBC) technique offers the same I/O voltage gain, it suffers from the drawback of low-frequency (LF) ripples of the source current. In contrast, the proposed PWM technique is a combination of improved MBC (IMBC) and a new switching state pattern that eliminates this drawback and offers up to 79% reduction in the peak-to-peak ripple value of the source current while maintaining the same I/O voltage gain as MBC. The cumulative sum of ripple components is used to find the exact maximum and minimum peaks of the source current over the fundamental period. The proposed switching pattern doubles the switching frequency of a boosting switch to limit the current spikes of capacitors during state change-over. The RCC-AIN topology was analyzed in various voltage-boosting techniques, and the proposed PWM technique utilizes the full potential of the RCC-AIN topology in a better way. The findings have been verified using theoretical calculations, simulation, and experimental results.

Keywords

• Active impedance network
• space vector PWM
• shoot-through
• switched boost inverter
• three-level T-type inverter
• Z-source inverter