The use of electronic equipment and other dc-compatible appliances in homes and offices is increasing at a very fast rate, as well as the distributed generation of energy. These two statements will most likely trigger, in a near future, the adoption of district-scale dc grids, connecting dc microgeneration plants and consumers, in an effort to cut the number of conversion steps required to deliver power to dc appliances. DC–DC converters will be fundamental in these systems, allowing the establishment of several voltage levels. The reliability of these converters plays a critical role, ensuring service continuity of the loads connected to them. With the increment of reliability in mind, this paper proposes a simple yet effective open-circuit fault diagnostic method suitable for interleaved dc–dc boost converters, but equally functional for other dc–dc converter topologies. The improvements introduced in this paper greatly simplify the diagnostic action, while making the correct diagnostic of faults independent of the switching duty cycle. Moreover, an alternative reconfiguration scheme is proposed to mitigate the adverse impacts of such faults. To prove the effectiveness of these strategies, a three-phase interleaved boost converter prototype was used in the experiments.

Direct Current (DC) power system protection presents a major challenge due to its unique characteristics, namely the absence of natural zero current crossing points. Thanks to their features, DC protection devices allow the safe commutation of the fault current. Selective protection and fast fault isolation are key features that any Direct Current Circuit Breaker (DCCB) should feature, assuring minimal power outages and the effective protection of sensitive electronic components. To overcome the liabilities of mechanical circuit breakers (MCBs) and solid-state circuit breakers (SSCBs), several novel concepts of hybrid circuit breakers (HCBs) have been proposed over the years, to take advantage of the benefits of both the MCBs and SSCBs. This paper presents an up-to-date state of the art on the technologies applied to DC HCBs and describes novel HCB concepts. Design considerations, challenges and future trends are also discussed.

The use of fuel cells in DC microgrids has been receiving a lot of attention from researchers and industry since both technologies can deliver clean energy with little to no environmental impact. To effectively integrate fuel cells in DC microgrids, a power converter that can equate the fuel cell’s voltage with the DC microgrid’s reference voltage is required. Based on the typical output voltages of fuel cells, buck-boost topologies are commonly used in this type of application. A variety of DC-DC buck-boost topologies, showing distinctive merits and drawbacks, are available in the literature. Therefore, this paper compiles, compares and describes different DC-DC buck-boost topologies that have been introduced in the literature over the past few years. Additionally, some design considerations are addressed, and future work is proposed.

In recent years, multiphase machines have been presented as a good alternative to the classical three-phase machines, mainly due to their ability to operate smoothly under fault conditions. Due to multiple stator phase arrangements, existing fault diagnostic (FD) methods are not sufficiently universal and cannot be applied to the multiple configurations of multiphase machines. In this regard, the current research proposes a universal and effective online diagnostics technique based on the computation and monitoring of a relevant severity factor, which is defined as the ratio of the zero, negative and positive voltage symmetrical components. The Short Time Least Square Prony’s (STLSP) approach is used to implement this method online in LabVIEW environment. In addition to the wide applicability of the method, the obviation of any motor parameter estimation and limited requirements regarding variables measurements make the proposed approach extremely advantageous for motors with high number of phases. This article addresses at stator faults in symmetrical six-phase induction machines (6PIM). The proposed method’s experimental results on six-phase motor drive platforms demonstrate the excellent generalization capability of the proposed method, as well as high accuracy and robustness, along with the ability to accurately distinguish between the occurrence of Inter-Turn Short Circuit (ITSC) faults and the presence of Unbalance Supply Voltage (USV) conditions. A 6PIM is put through its paces in both healthy and faulty conditions. The obtained results demonstrate the effectiveness of the proposed method for diagnosing the occurrence of ITSC faults and USV operating conditions with high reliability, fastness and high precision.

In recent years, the adoption of Synchronous Reluctance Machine (SynRM) drives for safety-critical equipment has witnessed notorious growth. The difficulties inherent to monitoring and fault diagnostics of SynRM drives are highly prominent. Inter-turn short-circuit faults (ITSCFs) are among the failure modes which are most critical and, simultaneously, more challenging to identify, in all types of motor drives. Still, the effective diagnostic task becomes even more challenging in SynRM drives, because of the harmonic pollution and intricated control configuration. To overcome the aforementioned challenges, the current research proposes a universal and effective online diagnostics technique, based on the computation and monitoring of a relevant severity factor, defined as the ratio of the zero, negative and positive voltage symmetrical components. The Short Time Least Square Prony’s (STLSP) approach is used to implement this method online in LabVIEW environment. In addition to the wide applicability of the method, the obviation of any motor parameter’s estimation and reduced requirements regarding variables’ measurements make the proposed approach extremely advantageous for motor drives with complex control architecture and operating conditions. The experimental results demonstrate the excellent generalization capability of the proposed method, as well as high accuracy and robustness. To confirm the claims, the proposed technique is implemented on a 2.2 kW SynRM drive, tested in both healthy and faulty conditions.

The use of electronic equipment and other DC-compatible appliances in dwellings and offices is increasing at a very fast rate, as well as the distributed generation of energy. These two statements will certainly trigger, in a near future, the adoption of district-scale DC grids, connecting DC micro-generation plants and consumers, in an effort to cut the number of conversion steps required to deliver power to DC appliances. DC-DC converters will be fundamental in these systems, allowing the creation of several voltage levels. The reliability of these converters plays a key role, ensuring service continuity of the loads connected to them. With the increase of reliability in mind, this paper applies an open-circuit fault-diagnostic method suitable for several DC-DC converter topologies. A new reconfiguration strategy is proposed to mitigate the adverse impacts of such faults. To prove the effectiveness of these strategies, a three-phase interleaved boost converter prototype was used in the experiments.