I.

Circuit breakers (CBs) are the main protection devices for both alternating current (AC) and direct current (DC) power systems, ranging from tens of watts up to megawatts. This paper reviews the current status for solid-state circuit breakers (SSCBs) as well as hybrid circuit breakers (HCBs) with semiconductor power devices. A few novel SSCB and HCB concepts are described in this paper, including advantage and limitation discussions of wide-band-gap (WBG) devices in basic SSCB/HCB configuration by simulation and 360 V/150 A experimental verifications. Novel SSCB/HCB configurations combining ultra-fast switching and high efficiency at normal operation are proposed. Different types of power devices are installed in these circuit breakers to achieve adequate performance. Challenges and future trends of semiconductor power devices in SSCB/HCB with different voltage/power levels and special performance requirements are clarified.

The ever increasing electric power demand and the advent of renewable energy sources have revived the interest in high-voltage direct current (HVDC) multi-terminal networks. However, the absence of a suitable circuit breaker or fault tolerant VSC station topologies with the required characteristics (such as operating speed) have, until recently, been an obstacle in the development of large scale multi-terminal networks for HVDC. This paper presents a hybrid HVDC circuit breaker concept which is capable of meeting the requirements of HVDC networks. Simulation results are presented which are validated by experimental results taken from a 2.5kV, 700A rated laboratory prototype.

This paper presents the operating principles and modified space vector modulation strategy for a three-phase quasi Z-source neutral point clamped inverter for solar photovoltaic applications. This topology combines the advantages of the neutral point clamped and quasi Z-source inverters. These advantages include single-stage buck-boost power conversion, continuous input current, and low voltage stress of switches. Simulation results are presented to verify the presented concepts.

This paper presents a new and compact printed monopole antenna with broadband circular polarization (CP). The wide axial ratio bandwidth is achieved by placing and feeding a monopole on the side of an FR4 dielectric. In addition, a conventional horizontal ground plane is modified by shortening its width and adding a vertical extension. Experimental results show an |S 11 | and axial ratio (AR) of 123.5% fractional bandwidth (2.6-11 GHz) and 70% fractional bandwidth (3-6.2 GHz), respectively. The presented antenna is compact with an area of 36 mm × 19.5 mm, simple to design and fabricate, and can achieve broadband AR without using: parasitic elements, and perturbations in terms of creating multiple slots and stubs.