Analysis of a Hybrid Current Source Converter with Bi-directional Power Flow Capability

Current source converters (CSCs) present the desirable characteristics of inherent load and converter short- circuit protection. Silicon controlled rectifiers (SCR) based CSCs are rugged and affordable but they create low order harmonics and do not allow active and reactive power to be controlled independently. These drawbacks can be overcome with topologies based on more costly force-commutated switches. This paper proposes a hybrid three-phase CSC that employs three SCRs and four IGBTs and presents features comparable to the fully controllable CSC. The inherent commutation constraints of the SCRs are taken into consideration in the selection of a suitable space vector (SV) modulation technique. Comparisons with the fully controllable CSC are provided for a fair assessment of the potential of the proposed hybrid CSC. The theoretical analysis is verified by means of simulations.