Bidirectional Six-Pack SiC Boost-Buck Converter Using Droop Control in DC Nano-Grid

Area of Science:

• Electrical Engineering
• Power Electronics
• Renewable Energy Systems

Background:

• DC nano-grids require efficient and reliable bidirectional power converters.
• Existing converters face challenges in managing voltage stability and current sharing.
• Silicon Carbide (SiC) technology offers advantages in efficiency and compactness for power modules.

Purpose of the Study:

• To propose and validate a novel bidirectional boost-buck converter topology for DC nano-grids.
• To enhance efficiency and reduce switching losses through a hybrid control scheme.
• To improve DC link voltage regulation and current sharing accuracy using droop control.

Main Methods:

• A cascaded topology combining an interleaved boost converter and a buck converter was designed.
• A six-pack SiC intelligent power module (IPM) was employed for high efficiency and compactness.
• A hybrid control scheme was implemented to minimize switching operations and enable smooth mode transitions.
• DC droop control was integrated as a secondary control for voltage regulation and current sharing.

Main Results:

• The proposed converter demonstrated reduced switching losses due to the hybrid control scheme.
• Smooth transitions between boost and buck modes were achieved without requiring current controller switchover.
• Enhanced accuracy in current sharing was observed while effectively regulating DC link voltage without sag.
• Experimental validation with two 20 kW prototypes confirmed the converter's performance.

Conclusions:

• The developed bidirectional boost-buck converter with SiC IPM and droop control is effective for DC nano-grids.
• The hybrid control strategy significantly reduces switching losses and improves operational smoothness.
• The system achieves superior current sharing and DC link voltage regulation, addressing key challenges in nano-grid power management.