Dynamic Voltage Scaling Aware Delay Fault Testing

The application of Dynamic Voltage Scaling (DVS) to reduce energy consumption may have a detrimental impact on the quality of manufacturing tests employed to detect permanent faults. This paper analyses the influence of different voltage/frequency settings on fault detection within a DVS application. In particular, the effect of supply voltage on different types of delay faults is considered. This paper presents a study of these problems with simulation results. We have demonstrated that the test application time increases as we reduce the test voltage. We have also shown that for newer technologies we do not have to go to very low voltage levels for delay fault testing. We conclude that it is necessary to test at more than one operating voltage and that the lowest operating voltage does not necessarily give the best fault cover

A 5 kW Bi-directional multilevel modular DC-DC converter (MMCCC) featuring built in power management for fuel cell and hybrid electric automobiles

Journal ArticleAbstract- A new capacitor clamped modular dc-dc converter with bi-directional power handling capability will be presented in this paper. This inductor-free design is modular, and it is possible to integrate multiple loads and sources simultaneously in the converter. Moreover, this 5 kW dc-dc converter can produce multiple ac outputs to feed power to ac loads get further control over the conversion ratio of the circuit. This high efficiency modular converter has flexible conversion ratio, and it could be successfully used in a multi-bus power system by virtue of its inherent power management properties

Modular DC-DC Converters

DC-DC converter is one of the mostly used power electronic circuits, and it has applications in various areas ranging from portable devices to aircraft power system. Various topologies of dc-dc converters are suitable for different applications. In high power applications such as the bi-directional dc-dc converter for dual bus system in new generation automobiles, several topologies can be considered as a potential candidate. Regardless of the topology used for this application, the reliability of the converter can be greatly enhanced by introducing redundancy of some degree into the system. Using redundancy, uninterrupted operation of the circuit may be ensured when a fault has occurred. The redundancy feature can be obtained by paralleling multiple converters or using a single modular circuit that can achieve this attribute. Thus, a modular dc-dc converter with redundancy is expected to increase the reliability and reduce the system cost. Recently, the advancement in power electronics research has extended its applications in hybrid electric automobiles. Several key requirements of this application are reliable, robust, and high efficiency operation at low cost. In general, the efficiency and reliability of a power electronic circuit greatly depend on the kind of circuit topology used in any application. This is one of the biggest motivations for the researchers to invent new power electronic circuit topologies that will have significant impact in future automobile industry. This dissertation reviews existing modularity in power electronic circuits, and presents a new modular capacitor clamped dc-dc converter design that has many potential uses in future automotive power system. This converter has multilevel operation, and it is capable of handling bi-directional power. Moreover, the modular nature of the converter can achieve redundancy in the system, and thereby, the reliability can be enhanced to a great extent. The circuit has a high operating efficiency (\u3e95%), and it is possible to integrate multiple voltage sources and loads at the same time. Thus, the converter could be considered as a combination of a power electronic converter and a power management system. In addition to the new dc-dc converter topology, a new pair of modular blocks defined as switching cells is presented in this dissertation. This pair of switching cells can be used to analyze many power electronic circuits, and some new designs can be formed using those switching cells in various combinations. Using these switching cells, many power electronic circuits can be made modular, and the modeling and analysis become easier

30kW, 200V/900V, thyristor LCL DC/DC converter laboratory prototype design and testing

ACKNOWLEDGMENT The authors would like to acknowledge significant input from Aberdeen University technician, A. Styles, in building this converterPeer reviewedPostprin

Simulation verification techniques study. Subsystem simulation validation techniques

Techniques for validation of software modules which simulate spacecraft onboard systems are discussed. An overview of the simulation software hierarchy for a shuttle mission simulator is provided. A set of guidelines for the identification of subsystem/module performance parameters and critical performance parameters are presented. Various sources of reference data to serve as standards of performance for simulation validation are identified. Environment, crew station, vehicle configuration, and vehicle dynamics simulation software are briefly discussed from the point of view of their interfaces with subsystem simulation modules. A detailed presentation of results in the area of vehicle subsystems simulation modules is included. A list of references, conclusions and recommendations are also given

Universal multilevel DC-DC converter with variable conversion ratio, high compactness factor and limited isolation feature

Journal ArticleA multilevel dc-dc converter with programmable conversion ratio (CR) is presented in this paper. This converter is a modified version of the MMCCC converter. A universal version of the MMCCC is developed in this paper, and the CR can be easily changed within a wide range. The MMCCC converter is based on capacitor-clamped topology, and the conversion ratio of the circuit depends on the number of active modules. However, like any other capacitor-clamped circuit, the MMCCC circuit requires a large number of transistors and capacitors to attain a high conversion ratio (CR). In this paper, a new circuit module will be introduced that can be connected in a cascade pattern to form the new converter. By using the new modular cell, it is possible to attain very high conversion ratio using a limited number of components, and thus more compactness compared to the predecessor MMCCC circuit can be achieved

A Model of DC-DC Converter with Switched-Capacitor Structure for Electric Vehicle Applications

In this paper, a DC-DC converter with an innovative topology for automotive applications is proposed. The goal of the presented power converter is the electrical storage system management of an electric vehicle (EV). The presented converter is specifically compliant with a 400 V battery, which represents the high-voltage primary source of the system. This topology is also able to act as a bidirectional power converter, so that in this case, the output section is an active stage, which is able to provide power as, for example, in the case of a low-voltage battery or a supercapacitor. The proposed topology can behave either in step-down or in step-up mode, presenting in both cases a high gain between the input and output voltage. Simulation results concerning the proposed converter, demonstrating the early feasibility of the system, were obtained in a PowerSIM environment and are described in this paper

Evaluating Built-in ECC of FPGA on-chip Memories for the Mitigation of Undervolting Faults

Voltage underscaling below the nominal level is an effective solution for improving energy efficiency in digital circuits, e.g., Field Programmable Gate Arrays (FPGAs). However, further undervolting below a safe voltage level and without accompanying frequency scaling leads to timing related faults, potentially undermining the energy savings. Through experimental voltage underscaling studies on commercial FPGAs, we observed that the rate of these faults exponentially increases for on-chip memories, or Block RAMs (BRAMs). To mitigate these faults, we evaluated the efficiency of the built-in Error-Correction Code (ECC) and observed that more than 90% of the faults are correctable and further 7% are detectable (but not correctable). This efficiency is the result of the single-bit type of these faults, which are then effectively covered by the Single-Error Correction and Double-Error Detection (SECDED) design of the built-in ECC. Finally, motivated by the above experimental observations, we evaluated an FPGA-based Neural Network (NN) accelerator under low-voltage operations, while built-in ECC is leveraged to mitigate undervolting faults and thus, prevent NN significant accuracy loss. In consequence, we achieve 40% of the BRAM power saving through undervolting below the minimum safe voltage level, with a negligible NN accuracy loss, thanks to the substantial fault coverage by the built-in ECC.Comment: 6 pages, 2 figure

Control of DC power distribution system of a hybrid electric aircraft with inherent overcurrent protection

In this paper, a novel nonlinear control scheme for the on-board DC micro-grid of a hybrid electric aircraft is proposed to achieve voltage regulation of the low voltage (LV) bus and power sharing among multiple sources. Considering the accurate nonlinear dynamic model of each DC/DC converter in the DC power distribution system, it is mathematically proven that accurate power sharing can be achieved with an inherent overcurrent limitation for each converter separately via the proposed control design using Lyapunov stability theory. The proposed framework is based on the idea of introducing a constant virtual resistance at the input of each converter and a virtual controllable voltage that can be either positive or negative, leading to a bidirectional power flow. Compared to existing control strategies for on-board DC micro-grid systems, the proposed controller guarantees accurate power sharing, tight voltage regulation and an upper limit of each source's current at all times, including during transient phenomena. Simulation results of the LV dynamics of an aircraft on-board DC micro-grid are presented to verify the proposed controller performance in terms of voltage regulation, power sharing and the overcurrent protection capability

Control of DC power distribution system of a hybrid electric aircraft with inherent overcurrent protection

In this paper, a novel nonlinear control scheme for the on-board DC micro-grid of a hybrid electric aircraft is proposed to achieve voltage regulation of the low voltage (LV) bus and power sharing among multiple sources. Considering the accurate nonlinear dynamic model of each DC/DC converter in the DC power distribution system, it is mathematically proven that accurate power sharing can be achieved with an inherent overcurrent limitation for each converter separately via the proposed control design using Lyapunov stability theory. The proposed framework is based on the idea of introducing a constant virtual resistance at the input of each converter and a virtual controllable voltage that can be either positive or negative, leading to a bidirectional power flow. Compared to existing control strategies for on-board DC micro-grid systems, the proposed controller guarantees accurate power sharing, tight voltage regulation and an upper limit of each source's current at all times, including during transient phenomena. Simulation results of the LV dynamics of an aircraft on-board DC micro-grid are presented to verify the proposed controller performance in terms of voltage regulation, power sharing and the overcurrent protection capability