Design of a Solid-State Circuit Breaker for a DC Grid-Based Vessel Power System

Electric propulsion and integrated hybrid power systems can improve the energy efficiency and fuel consumption of different kinds of vessels. If the vessel power system is based on DC grid distribution, some benefits such as higher generator e ciency and lower volume and cost can be achieved. However, some challenges remain in terms of protection devices for this kind of DC grid-based power system. The absence of natural zero crossing in the DC current together with the fast and programmable breaking times required make it challenging. There are several papers related to DC breaker topologies and their role in DC grids; however, it is not easy to find comprehensive information about the design process of the DC breaker itself. In this paper, the basis for the design of a DC solid-state circuit breaker (SSCB) for low voltage vessel DC grids is presented. The proposed SSCB full-scale prototype detects and opens the fault in less than 3 us. This paper includes theoretical analyses, design guidelines, modeling and simulation, and experimental results

Architecture, Voltage, and Components for a Turboelectric Distributed Propulsion Electric Grid (AVC-TeDP)

The purpose of this effort was to advance the selection, characterization, and modeling of a propulsion electric grid for a Turboelectric Distributed Propulsion (TeDP) system for transport aircraft. The TeDP aircraft would constitute a miniature electric grid with 50 MW or more of total power, two or more generators, redundant transmission lines, and multiple electric motors driving propulsion fans. The study proposed power system architectures, investigated electromechanical and solid state circuit breakers, estimated the impact of the system voltage on system mass, and recommended DC bus voltage range. The study assumed an all cryogenic power system. Detailed assumptions within the study include hybrid circuit breakers, a two cryogen system, and supercritical cyrogens. A dynamic model was developed to investigate control and parameter selection

Driving and Protection of High Density High Temperature Power Module for Electric Vehicle Application

There has been an increasing trend for the commercialization of electric vehicles (EVs) to reduce greenhouse gas emissions and dependence on petroleum. However, a key technical barrier to their wide application is the development of high power density electric drive systems due to limited space within EVs. High temperature environment inherent in EVs further introduces a new level of complexity. Under high power density and high temperature operation, system reliability and safety also become important. This dissertation deals with the development of advanced driving and protection technologies for high temperature high density power module capable of operating under the harsh environment of electric vehicles, while ensuring system reliability and safety under short circuit conditions. Several related research topics will be discussed in this dissertation. First, an active gate driver (AGD) for IGBT modules is proposed to improve their overall switching performance. The proposed one has the capability of reducing the switching loss, delay time, and Miller plateau duration during turn-on and turn-off transient without sacrificing current and voltage stress. Second, a board-level integrated silicon carbide (SiC) MOSFET power module is developed for high temperature and high power density application. Specifically, a silicon-on-insulator (SOI) based gate driver board is designed and fabricated through chip-on-board (COB) technique. Also, a 1200 V / 100 A SiC MOSFET phase-leg power module is developed utilizing high temperature packaging technologies. Third, a comprehensive short circuit ruggedness evaluation and numerical investigation of up-to-date commercial silicon carbide (SiC) MOSFETs is presented. The short circuit capability of three types of commercial 1200 V SiC MOSFETs is tested under various conditions. The experimental short circuit behaviors are compared and analyzed through numerical thermal dynamic simulation. Finally, according to the short circuit ruggedness evaluation results, three short circuit protection methods are proposed to improve the reliability and overall cost of the SiC MOSFET based converter. A comparison is made in terms of fault response time, temperature dependent characteristics, and applications to help designers select a proper protection method

Design and Implementation of High-Efficiency, Lightweight, System-Friendly Solid-State Circuit Breaker

Direct current (DC) distribution system has shown potential over the alternative current (AC) distribution system in some application scenarios, e.g., electrified transportation, renewable energy, data center, etc. Because of the fast response speed, DC solid-state circuit breaker (SSCB) becomes a promising technology for the future power electronics intensive DC energy system with fault-tolerant capability. First, a thorough literature survey is performed to review the DC-SSCB technology. The key components for DC-SSCB, including power semiconductors, topologies, energy absorption units, and fault detection circuits, are studied. It is observed that the prior studies mainly focus on the basic interruption capability of the DC-SSCB. There are not so many studies on SSCB’s size optimization or system-friendly functions. Second, an insulated gate bipolar transistor (IGBT) based lightweight SSCB is proposed. With the reduced gate voltage, the proposed SSCB can limit the peak fault current without the bulky and heavy fault current limiting the inductor, which exists in the conventional SSCB circuit. Thus, the specific power density of the SSCB is substantially improved compared with the conventional design. Meanwhile, to understand the impact of different design parameters on the performance of SSCB, an analytical model is built to establish the relationship between SSCB dynamic performance and operating conditions considering the key components and circuit parasitics. Simulation and test results demonstrate the accuracy of the proposed model. To limit the fault current with the proposed SSCB without a current limiting inductor, power semiconductors need to operate in the active region temporarily. During this interval, a severe voltage oscillation has been observed experimentally, leading to the DC-SSCB overstress and eventually the failure. A detailed MATLAB/Simulink model is built to understand the mechanism causing the voltage oscillation. Three suppression methods using enhanced gate drive circuitry are proposed and compared. Test results based on a 2kV/1kA SSCB prototype demonstrate the effectiveness of the proposed oscillation mitigation method and the accuracy of the derived model. Meanwhile, when the system fault impedance is close to zero (e.g., high di/dt), the influence of the parasitic inductance contributed by interconnection (e.g., bus bar, module package, etc.) cannot be neglected. To study the influence of the bus bar connections on SSCB with high di/dt, a Q3D extractor is adopted to extract the parasitic parameters of the SSCB and understand the influence of different bus bar connections. A vertical bus bar is proposed to suppress the side effect and verified by the Q3D extractor and experimental results. Finally, a system-friendly SSCB is demonstrated. The proposed gate drive enables the SSCB to operate in the current limitation mode for the overcurrent limitation. The current limitation level and limitation time can be tuned by the gate drive. Then, this dissertation provides an all-in-one solution with integrated circuitries as the fault detector, actuator for the semiconductor’s operating status regulation, and coordinated control. This allows the developed SSCB to limit system fault current not exceeding short-circuit current rating (SCCR) and also take different responses under different fault cases. The feasibility and the effectiveness of the proposed system-friendly SSCB are validated with experimental results based on a 200V/10A SSCB demonstrator

MEDIUM VOLTAGE DC SOLID STATE CIRCUIT BREAKER BENCH TEST

Next generation fleets will rely on medium-voltage direct-current (MVDC) electric power distribution systems utilizing high power density and high-efficiency components. One key gap to make such MVDC systems feasible is a super-fast, high-efficiency, and high power density protection device. The U.S. Navy has previously developed a 1 kV, 1 kA solid state circuit breaker (SSCB). A new 2 kV, 1.2 kA SSCB has been designed by NPS with collaborating partners that has quadrupled power density. This innovative insulated gate bipolar transistor (IGBT)-based SSCB consists of anti-series IGBT modules, a parallel resistor-capacitor (RC) branch, and an electronically triggered metal-oxide varistor (MOV) branch. The novel electronically controlled MOV is comprised of a MOV in series with a silicon controlled rectifier (SCR) passively triggered during the IGBT turn-off process, improving the trade-off between the leakage current and clamping voltage. The use of a lower IGBT gate voltage allows the elimination of current limiting inductors, increasing the SSCB power density. This thesis focuses on the switching and thermal tests necessary to validate the implemented concepts, and the data will be used for down-selecting technical directions, improving the SSCB performance. The results show that the SSCB is sufficient to interrupt most faults while containing peak current and voltage within design parameters and the efficiency target can be met with comfortable thermal margins.Lieutenant, United States NavyApproved for public release. Distribution is unlimited

Architecture, Voltage and Components for a Turboelectric Distributed Propulsion Electric Grid

The development of a wholly superconducting turboelectric distributed propulsion system presents hide unique opportunities for the aerospace industry. However, this transition from normally conducting systems to superconducting systems significantly increases the equipment complexity necessary to manage the electrical power systems. Due to the low technology readiness level (TRL) nature of all components and systems, current Turboelectric Distributed Propulsion (TeDP) technology developments are driven by an ambiguous set of system-level electrical integration standards for an airborne microgrid system (Figure 1). While multiple decades' worth of advancements are still required for concept realization, current system-level studies are necessary to focus the technology development, target specific technological shortcomings, and enable accurate prediction of concept feasibility and viability. An understanding of the performance sensitivity to operating voltages and an early definition of advantageous voltage regulation standards for unconventional airborne microgrids will allow for more accurate targeting of technology development. Propulsive power-rated microgrid systems necessitate the introduction of new aircraft distribution system voltage standards. All protection, distribution, control, power conversion, generation, and cryocooling equipment are affected by voltage regulation standards. Information on the desired operating voltage and voltage regulation is required to determine nominal and maximum currents for sizing distribution and fault isolation equipment, developing machine topologies and machine controls, and the physical attributes of all component shielding and insulation. Voltage impacts many components and system performance

Discussion on Electric Power Supply Systems for All Electric Aircraft

The electric power supply system is one of the most important research areas within sustainable and energy-efcient aviation for more- and especially all electric aircraft. This paper discusses the history in electrication, current trends with a broad overview of research activities, state of the art of electrication and an initial proposal for a short-range aircraft. It gives an overviewof the mission prole, electrical sources, approaches for the electrical distribution system and the required electrical loads. Current research aspects and questions are discussed, including voltage levels, semiconductor technology, topologies and reliability. Because of the importance for safety possible circuit breakers for the proposed concept are also presented and compared, leading to a initial proposal. Additionally, a very broad review of literature and a state of the art discussion of the wiring harness is given, showing that this topic comes with a high number of aspects and requirements. Finally, the conclusion sums up the most important results and gives an outlook on important future research topics

Specification, Control, and Applications of Z-Source Circuit Breakers for the Protection of DC Power Networks

There is a highly-increasing demand for the DC power transmission and distribution in modern power systems for the integration of newly-installed renewable energy resources and storage systems to the existing utilities. Application of DC power systems in electric ships, battery energy devices, high-voltage DC networks, smart grids, electric vehicles, microgrids, and wind farms is a recent trend that is being highly investigated. The fault protection of DC systems is an essential but challenging issue that needs careful attention to maintain system operation reliability and device safety. In this research, the specification, control, and application of Z-source breakers (ZCBs) are investigated for DC network protection. Initially, the power loss associated with the topology of ZCBs is a key consideration in the design, and thus, the most efficient ZCB topology is identified. In this study, the topology of inter-cross-connected bi-directional ZCB (ICC-BZCB) was selected due to its least power loss when operating in a steady-state condition. Based on ICC-BZCB, a new approach of parameter specification is proposed by considering the reverse-recovery time of thyristors. The proposed approach ensures the turnoff action of ZCB in practical application. Its effectiveness was verified by experimental tests on a hardware testbed in the laboratory. Secondly, a new method of specifying the Z-source capacitances is proposed to identify the high-impedance faults in DC power networks. The method defines the principle of HIF detection and interruption by monitoring the status of Z-source capacitances. Finally, the assessment of cable length limit for ZCB application is analyzed for the DC system applications