Seven‐level power conversion system for solar power generation system

Abstract

This study proposes a seven‐level power conversion system for a solar power generation system. This seven‐level power conversion system consists of a DC–DC power converter and a cascade DC–AC inverter. The cascade DC–AC inverter comprises a full‐bridge inverter and a T‐type inverter. The T‐type inverter generates a three‐level quasi‐square‐wave voltage and the full‐bridge inverter provides a three‐level high‐frequency pulse voltage. The amplitude of the three‐level quasi‐square‐wave voltage is double that of the three‐level high‐frequency pulse voltage, so seven levels of AC voltage are synthesized. Only the full‐bridge inverter with lower DC bus voltage uses high‐frequency switching so switching losses are effectively reduced. The novelty of the proposed cascade DC–AC inverter is that the output power of T‐type inverter is controlled by regulating the DC bus voltage, so no real power is supplied from the full‐bridge inverter and an independent power source is not required to provide power to the full‐bridge inverter. The negative terminal voltage for solar cell array keeps almost constant to reduce the leakage current of proposed seven‐level power conversion system. A hardware prototype with a digital signal processor controller is developed to verify the performance of seven‐level power conversion system for a solar power generation system.

Keywords

Identifiers

DOI

10.1049/iet-rpg.2019.1439

Journal

IET Renewable Power Generation

Year

2020