Miniaturized Low-Voltage Power Converters With Fast Dynamic Response

This paper demonstrates a two-stage approach for power conversion that combines the strengths of variable-topology switched capacitor techniques (small size and light-load performance) with the regulation capability of magnetic switch-mode power converters. The proposed approach takes advantage of the characteristics of complementary metal-oxide-semiconductor (CMOS) processes, and the resulting designs provide excellent efficiency and power density for low-voltage power conversion. These power converters can provide low-voltage outputs over a wide input voltage range with very fast dynamic response. Both design and fabrication considerations for highly integrated CMOS power converters using this architecture are addressed. The results are demonstrated in a 2.4-W dc-dc converter implemented in a 180-nm CMOS IC process and co-packaged with its passive components for high performance. The power converter operates from an input voltage of 2.7-5.5 V with an output voltage of ≤1.2 V, and achieves a 2210 W/in[superscript 3] power density with ≥80% efficiency.Focus Center Research ProgramUnited States. Defense Advanced Research Projects AgencySemiconductor Research CorporationCharles Stark Draper Laborator

Modular multilevel converter with modified half-bridge submodule and arm filter for dc transmission systems with DC fault blocking capability

Although a modular multilevel converter (MMC) is universally accepted as a suitable converter topology for the high voltage dc transmission systems, its dc fault ride performance requires substantial improvement in order to be used in critical infrastructures such as transnational multi-terminal dc (MTDC) networks. Therefore, this paper proposes a modified submodule circuit for modular multilevel converter that offers an improved dc fault ride through performance with reduced semiconductor losses and enhanced control flexibility compared to that achievable with full-bridge submodules. The use of the proposed submodules allows MMC to retain its modularity; with semiconductor loss similar to that of the mixed submodules MMC, but higher than that of the half-bridge submodules. Besides dc fault blocking, the proposed submodule offers the possibility of controlling ac current in-feed during pole-to-pole dc short circuit fault, and this makes such submodule increasingly attractive and useful for continued operation of MTDC networks during dc faults. The aforesaid attributes are validated using simulations performed in MATLAB/SIMULINK, and substantiated experimentally using the proposed submodule topology on a 4-level small-scale MMC prototype

Bistability and pulsations in semiconductor lasers with inhomogeneous current injection

Bistability and pulsation at microwave frequencies are observed in CW GaAs semiconductor lasers with inhomogeneous current injection. Inhomogeneous current injection is achieved with a segmented contact structure. Crucial to the understanding of the characteristics of this device is the discovery of a negative differential electrical resistance across the contacts of the absorbing section. Depending on the electrical bias condition, this negative differential resistance leads to bistability or light-jumps and self pulsations. A simple model based on conventional rate equations with a linear gain dependence on carrier density explains the observed behavior and suggests a new mechanism in inhomogeneously pumped diode lasers for light-jumps and pulsations which does not depend on the condition for the usually proposed repetitively Q-switching. Investigation of the switching dynamics of this bistable optoelectronic device reveals a delay time which is critically dependent on the trigger pulse amplitude and typically on the order of a few nanoseconds with power-delay products of 100 pJ. The observed critical slowing down and its origin is discussed. We also report on the characteristic of this laser coupled to an external optical cavity and we demonstrate successfully that this bistable laser can be used as a self coupled stylus for optical disk readout with an excellent signal to noise ratio

A solid state Marx generator with a novel configuration

The new configuration proposed in this paper for Marx Generator (MG.) aims to generate high voltage for pulsed power applications through reduced number of semiconductor components with a more efficient load supplying process. The main idea is to charge two groups of capacitors in parallel through an inductor and take the advantage of resonant phenomenon in charging each capacitor up to a double input voltage level. In each resonant half a cycle, one of those capacitor groups are charged, and eventually the charged capacitors will be connected in series and the summation of the capacitor voltages can be appeared at the output of the topology. This topology can be considered as a modified Marx generator which works based on the resonant concept. Simulated models of this converter have been investigated in Matlab/SIMULINK platform and the acquired results fully satisfy the anticipations in proper operation of the converter

Voltage-Controlled Superconducting Quantum Bus

We demonstrate the ability of an epitaxial semiconductor-superconductor nanowire to serve as a field-effect switch to tune a superconducting cavity. Two superconducting gatemon qubits are coupled to the cavity, which acts as a quantum bus. Using a gate voltage to control the superconducting switch yields up to a factor of 8 change in qubit-qubit coupling between the on and off states without detrimental effect on qubit coherence. High-bandwidth operation of the coupling switch on nanosecond timescales degrades qubit coherence

Performance Comparison of Phase Change Materials and Metal-Insulator Transition Materials for Direct Current and Radio Frequency Switching Applications

Advanced understanding of the physics makes phase change materials (PCM) and metal-insulator transition (MIT) materials great candidates for direct current (DC) and radio frequency (RF) switching applications. In the literature, germanium telluride (GeTe), a PCM, and vanadium dioxide (VO2), an MIT material have been widely investigated for DC and RF switching applications due to their remarkable contrast in their OFF/ON state resistivity values. In this review, innovations in design, fabrication, and characterization associated with these PCM and MIT material-based RF switches, have been highlighted and critically reviewed from the early stage to the most recent works. We initially report on the growth of PCM and MIT materials and then discuss their DC characteristics. Afterwards, novel design approaches and notable fabrication processes; utilized to improve switching performance; are discussed and reviewed. Finally, a brief vis-á-vis comparison of resistivity, insertion loss, isolation loss, power consumption, RF power handling capability, switching speed, and reliability is provided to compare their performance to radio frequency microelectromechanical systems (RF MEMS) switches; which helps to demonstrate the current state-of-the-art, as well as insight into their potential in future applications

Fault mode operation strategies for dual H-bridge current flow controller in meshed HVDC grid

Peer ReviewedPreprin

Advances in solid state switchgear technology for large space power systems

High voltage solid state remote power controllers (RPC's) and the required semiconductor power switches to provide baseline technology for large, high power distribution systems in the space station, all electric airplane and other advanced aerospace applications were developed. The RPC's were developed for dc voltages from 28 to 1200 V and ac voltages of 115, 230, and 440 V at frequencies of 400 Hz to 20 kHz. The benefits and operation of solid state RPC's and highlights of several developments to bring the RPC to technology readiness for future aerospace needs are examined. The 28 V dc Space Shuttle units, three RPC types at 120 V dc, two at 270/300 V dc, two at 230 V ac and several high power RPC models at voltages up to 1200 V dc with current ratings up to 100 A are reviewed. New technology programs to develop a new family of (DI)2 semiconductor switches and 20 kHz, 440 V ac RPC's are described

An Advanced Three-Level Active Neutral-Point-Clamped Converter With Improved Fault-Tolerant Capabilities

A resilient fault-tolerant silicon carbide (SiC) three-level power converter topology is introduced based on the traditional active neutral-point-clamped converter. This novel converter topology incorporates a redundant leg to provide fault tolerance during switch open-circuit faults and short-circuit faults. Additionally, the topology is capable of maintaining full output voltage and maximum modulation index in the presence of switch open and short-circuit faults. Moreover, the redundant leg can be employed to share load current with other phase legs to balance thermal stress among semiconductor switches during normal operation. A 25-kW prototype of the novel topology was designed and constructed utilizing 1.2-kV SiC metal-oxide-semiconductor field-effect transistors. Experimental results confirm the anticipated theoretical capabilities of this new three-level converter topology