Cascaded diode clamped inverter based grid‐connected photovoltaic energy conversion system with enhanced power handling capability and efficiency

Abstract

Abstract This paper proposes a high power factor converter based symmetrical topology entitled cascaded diode clamped half‐bridge multi‐level inverter for high voltage photovoltaic (PV) applications along with a hybrid multi‐level pulse width modulation technique. Due to the restriction of peak inverse voltage (PIV) on switching devices, the PV array voltage is restricted. Also, operating at high current causes switching losses and degrades the efficiency, hence limiting its power enhancement. Unbalance in the capacitor voltages leads to high PIV across the devices, which is undesirable. The proposed topology allows connecting double times PV array voltage keeping the PIV and current alike cascaded H‐bridge multi‐level inverter, hence increasing the efficiency, and thereby reducing cost and space. It ensures a capacity enhancement in renewable energy systems linked to on/off‐grid applications. The projected scheme allows even power distribution among the sources along with maximum and efficient energy conversion. The control scheme adopted has the ability to balance dc‐link capacitor voltage in each half‐bridge results in equal PIV and switching losses across all the devices. Simulations of PV connected modified topology is carried out and validated with experimental results.

Keywords

• Power electronics, supply and supervisory circuits
• Capacitors
• Power system management, operation and economics
• Solar power stations and photovoltaic power systems
• Power convertors and power supplies to apparatus
• Voltage control