High Power Parallel Hybrid DC-DC Converter

The parallel hybrid converter (PHC) is gaining popularity for high voltage direct current (HVdc) applications. The PHC features low energy storage requirement and low conduction losses in the sub-modules (SMs). Moreover, the PHC requires lower number of SMs and switching devices. However, the existing PHC configuration needs harmonic voltage injection in the chain-links (CLs) to feed the ac grid, thereby injecting harmonic currents into the main DC-link. Additionally, the existing PHC lacks dc fault-tolerant capability. A new front-to-front dc-dc configuration called as parallel hybrid dc-dc converter (PHDC) for HVdc application is presented. The proposed PHDC eliminates the need of harmonic voltage injection and provides the dc fault-tolerant capability. Furthermore, the proposed PHDC requires lesser energy storage and smaller interlinking transformers than in the PHC used for ac-dc application. The detailed mathematical analysis with design procedure considering the dc-dc conversion application is presented. The authenticity of the proposed dc-dc converter is verified by both analytical and simulation studies. Finally, a three phase front-to-front experimental setup is tested for different operating conditions and results are presented.