Influence of CCM and DCM operation on converter efficiency and power density of a Single-Phase Grid-Tied Inverter

In this paper the Continuous Current Mode (CCM) and Discontinuous Current Mode (DCM) operations of a Single-Phase Grid-Tied Inverter are compared regarding efficiency and power density. Main design guidelines and component models are introduced for both operation modes. Optimal design is used to perform the comparative analysis. It was found that for range of switching frequencies from 10kHz to 100kHz, and nominal power of the inverter between 0.5kW and 2kW, the CCM operation was the most efficient design and had the highest power density. Also, it was pointed out that the main drawback for design based on DCM operation are the high peak inductor current and the required output filter capacitor. The higher peak current for DCM designs produced higher losses in all cases. Also, the output filter capacitor limited the reduction in volume for high switching frequency operation.