Triangular Conduction Mode (TCM) Operation of 4-level Flying Capacitor Boost Converter In PV Solar Application

This paper introduces a four-level flying capacitor boost DC–DC converter for photovoltaic (PV) systems. Compared to traditional boost converter, this four-level boost converter has three times smaller of voltage stress on switches and three times bigger of frequency applied for inductor. Therefore, these characteristics allow the deployment of lower voltage rating switches and reduced inductance, which makes higher efficiency and low cost. Additionally, this paper also discusses about zero-voltage switching (ZVS) model for four-level boost converter in triangular conduction mode (TCM) operation. With ZVS model, the minimum inductor current can be derived, and the required dead-time can be calculated, which results the reduction in the duty cycle loss. Moreover, the switching frequency range is calculated from the range of load in TCM operation, which leads to the reduction of inductor current ripple and the conduction loss at light load. The experimental results of a flying capacitor multi-level DC–DC converter is implemented with a maximum output power of 400 W. The result shows the efficiency of variable frequency is better than the fixed frequency in TCM operation.