Recent years have seen power electronic converters rapidly approach high power densities while also being designed for high power capabilities. Owing to their effectiveness in energy conversion and control, modern power electronic converters have gained significant popularity in critical applications. Thus, the reliability and robustness of these converters to faults becomes an important area of research. This paper proposes an active redundancy module (ARM) and overlapped switching scheme as a modular, topology independent fault tolerant solution to be utilised for isolated DC-DC converters. The proposed ARM allows for convenient incorporation of fault tolerance in any given power converter topology without altering its fundamental principles of operation, and the overlapped switching scheme facilitates soft switching and current sharing within the ARM, thus reducing losses and improving the overall performance of the ARM. The proposed solution is analysed and validated through simulation as well as experimental results, followed by a discussion in comparison to existing fault tolerant solutions.

It is well known that fixed-frequency constant-coupling series(capacitor)-series(capacitor) (S(C)-S(C)) compensated inductive wireless power transfer links (IWPTL) may be designed to operate with load-independent voltage gain (LIVG) within bounds dictated by parameters of the loosely coupled transformer (LCT). Lately, it has been shown that these bounds may be extended by employing series(inductor)-series(capacitor) (S(L)-S(C)) or series(capacitor)-series(inductor) (S(C)-S(L)) compensation networks, allowing attaining arbitrary LIVG at the expense of utilizing full-rating inductors as compensation elements. This work proposes a design method allowing to simultaneously attain arbitrary LIVG with S(C)-S(C) compensated IWPTL and minimize inverter VA rating. The revealed methodology is validated in PSIM simulation and experiments.

DC miniature circuit breakers (MCB’s) are being used widely in low voltage dc (LVDC) grids for protection of dc systems against short circuit and over current faults. DC-MCB interrupts the fault when the fault current reaches the preset value. MCBs take a longer time for the fault interruption due to the mechanical inertia between the breaker contacts and also due to high dc currents, which may create protection issues in highly critical systems. Hence, improvements in the performance of existing DC-MCB is proposed by connecting a parallel power semiconductor branch to it. In the proposed configuration, only a power device and its control circuit is added which helps in faster commutation and transfer of current. Proposed concept also improves reliability of the DC-MCB as there is no arcing in the fault interruption process. This paper presents the experimental validation of the proposed concept in a dc system with a nominal rating of 100VDC/6A. Paper also elucidates the performance comparison of both the proposed concept and the DC-MCB.

DC microgrid is gaining more popularity due to the advent and advancements in renewable energy sources, however, there are some challenges in its development such as protection of dc equipment from short-circuit faults. This paper proposes a modified solid-state dc circuit breaker for bidirectional power flow protection that reduces current stress on semiconductor devices during commissioning and reclosing. And also a method of system re-breaking or reclosing depending on the fault existence has been proposed. This circuit breaker topology has been verified with varying system parameters using the spice simulation tool. The protection of dc system by the proposed circuit breaker is experimentally verified for a system rating of 100V/10A.

Reliability of DC grid is measured in terms of fault interruption time of the switchgear. Unlike AC systems, DC systems do not encounter zero crossing of fault current. Hence the DC circuit breaker should be capable of very fast fault interruption and isolation. Solid state circuit breakers (SSCB) exhibit fast fault interruption at the expense of substantially large conduction power loss due to on-state drop of semiconductor devices. Hybrid circuit breakers yield better performance in terms of efficiency although the principal hurdle remains in demagnetization of network inductance after mechanical breaker is completely turned off. This paper proposes two hybrid DC circuit breaker (DCCB) topologies using coupled inductor to mitigate this issue. The coupled inductor forms a resonant circuit with a commutation capacitor during the fault to turn off the mechanical switch at zero current. Commutation capacitor is charged through the circuit elements; hence the requirement for external pre-charging circuit is eliminated. Moreover, the capacitor is charged to unipolar DC voltage only, enabling use of electrolytic capacitor. Proposed topologies do not require surge arrester to demagnetize the DC network once fault is cleared. One of the proposed circuit breaker topologies is designed for bidirectional power flow, implying its use in multi terminal DC transmission system or DC micro-grid. Detailed analysis and design of the proposed circuit breakers are presented in this paper and validated through simulation and experimental results.