Protection Scheme Analysis of LLC Series Connected Auxiliary Power Supply for HV SiC Grid-Connected Inverters

Auxiliary power supplies (APS) in high voltage silicon carbide (SiC) applications, such as 10 kV systems, require high insulation capability and low coupling capacitance. A common APS topology is the LLC series-connected design, where a high voltage wire runs through multiple cores to provide isolated outputs. However, faults like short circuits or open circuits at one output can disrupt other output voltages. This paper examines a potential protection scheme for this configuration, highlighting its pros and cons. The analysis aims to provide a balanced view of how the proposed scheme can improve APS performance and reliability in high voltage SiC applications, while considering the associated trade-offs.