DUAL-T-TYPE SEVEN-LEVEL BOOST ACTIVE-NEUTRAL- POINT-CLAMPED (DTT-7L-BANPC) INVERTER

Abstract

The conventional three-level active-neutral-point-clamped (ANPC) inverter requires high DC-link voltage at least twice the peak of AC output. To reduce the DC-link voltage, a recent topology that enhanced the voltage gain from half to unity has been presented. In this project, an alternative ANPC topology is established by using two T-type inverters. Two floating capacitors with self-voltage balancing capability are integrated to achieve a voltage-boosting gain of 1.5. In addition, the proposed topology is capable of generating seven voltage levels. Its operation is validated through circuit analysis followed by experimental results of a prototype.

Existing System

In the existing system, a three-level active-neutral-point-clamped (ANPC) (3LANPC) inverter is widely used in the industry for DC–AC power conversion.

Proposed System

The proposed topology is called a “dual-T-type seven-level boost ANPC” (DTT-7L-BANPC) following its circuit structure, which comprises two T-type inverters. Considering that all the power switches are metal-oxide-semiconductor field effect transistors (MOSFETs), the proposed ANPC inverter requires only two additional power switches to those in the previous study. Two floating capacitors (CF1 and CF2) are integrated to achieve a voltage-boosting gain of 1.5. With the magnitude of each level is 0.5Vdc, the proposed topology is capable of generating seven levels from –1.5Vdc to 1.5Vdc.

Architecture

Proposed DTT-7L-BANPC inverter