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The measurement and analysis of the spatial morphology and dynamic characteristics of the electric arc plasma inside low voltage circuit breaker is an effective way to improve its breaking performance and modern testing techniques have been applied to the experimental study on switching arc plasma in recent years. However, these techniques usually need to destroy the extinguishing chamber wall and...
This paper discloses the development of modular front-end medium-voltage solid-state transformer (SST) to show system level design, circuit topology, and prototype test results. Each multilevel front-end module consists of two stages: (1) ac to dc boost converter with power factor correction dc and (2) isolated dc-dc LLC converter. The proposed system has been designed, simulated, and fabricated with...
A fully integrated THz phase-locked loop (PLL) is proposed. It is consists of a fundamental PLL and a frequency doubler. In order to improve the oscillation frequency and reduced the phase noise, a feedback network composed of buffer amplifiers and capacitors is introduced to the voltage-controlled oscillator (VCO). The wide locking-range divider chain of PLL consists of an injection-locked frequency...
With the rapid development of inspection techniques, more emphases should be placed on the improvement of the reliability, safety and intelligence of the robot system. In this paper, a framework for the patrol robot that automatically finishes complex task and motion planning in the indoor substation is proposed. To realize real-time response to the environmental changes, the proposed framework keeps...
ECN thresholds have limited operational range and very strict scope. Lower thresholds exacerbate the queue underflow while higher thresholds increase the queueing delays. In this paper, an Adaptive ECN (A-ECN) marking scheme is proposed to enhance the performance of ECN. A-ECN can adaptively adjust ECN marking thresholds in different scenarios to achieve good generality. Therefore, network operators...
This paper presents a new under-actuated resilient robot that has the three recovery processes available, as we proposed elsewhere. The new feature with the proposed resilient robot is such that all the recovery strategies can be accomplished in a 2D plane instead of a 3D space, thus reducing the complexity of the recovery process. The robot also has the ability of switching between a fully-actuated...
The self-adaptive sliding mode position controller based on genetic algorithm optimization is designed for the servo motor drive system. Firstly, the self-adaptive sliding mode position controller is researched to estimate the magnitude of the unknown disturbance in the perturbed system. Then, the adaptive genetic algorithm is used to optimize the ideal adaptive parameters and switching parameters...
While extending network programmability to a larger degree, P4 also raises the risks of incurring runtime bugs after the deployment of P4 programs. These runtime bugs, if not handled promptly and properly, can ruin the functionality and performance of networks. Unfortunately, the absence of runtime debuggers makes troubleshooting of P4 program bugs challenging and intricate for operators. This paper...
In order to reduce high frequency electromagnetic interference (EMI) noise for SiC devices, this paper presents a hybrid structure SiC power module with low parasitic inductance and low ground capacitance that can suppress EMI efficiently. To certify the improvement on EMI, two buck converters, using the same power loop and gate drive, are built for experiment. Two converters use the proposed power...
This paper introduces a dead-time optimization technique for a 2-level voltage source converter (VSC) using turn-off transition monitoring. Dead-time in a VSC impacts power quality, reliability, and efficiency. Silicon carbide (SiC) based VSCs are more sensitive to dead-time from increased reverse conduction losses and turn-off time variability with operating conditions and load characteristics. An...
An improved SiC MOSFET-gate driver integrated half-bridge module with folded layout using direct bonded copper (DBC) substrate is designed, fabricated, and tested. The bottom layer of the DBC is used as part of the power loop to achieve major reduction in the loop stray inductance. Due to the low parasitic inductance and capacitance, the gate resistor is chosen as zero to reduce the switching loss...
The reactive model of Software Defined Networking (SDN) invokes controller to dynamically determine the behaviors of a new flow without any pre-knowledge in the data plane. However, the reactive events raised by such flexible model meanwhile consume lots of the bottleneck resources of the fast memory in switch and bandwidth between controller and switches. To address this problem, we propose SoftRing...
The concept and technologies of fractional calculus have been increasingly applied to model and design circuits and electrical elements. In this work, by combining the principle of harmonic balance and equivalent small parameter method, we develop a new method of steady-state analysis for fractional-order DC-DC converters in discontinuous conduction mode (DCM). The effectiveness of the proposed scheme...
This paper presents a comparison study of AC bus and DC bus topologies for electric vehicle (EV) battery chargers in smart car parks. The two charger systems are compared from two aspects: the features from the user side and the power quality on the grid side. Considering the system reliability, cost, size and conversion stage, the pros and cons of AC and DC buses systems are introduced and summarized...
High voltage direct current (HVDC) transmission systems play an increasingly important role in offshore wind energy and long distance energy transmission systems. Modular multilevel converter (MMC) is an attractive topology for HVDC systems, due to its good modularity, scalability and inherent fault tolerant capabilities. For such topology, model predictive control (MPC) is a promising alternative...
Model predictive control (MPC) is a promising alternative for power electronics and electric drives. Research on fault diagnosis and fault-tolerant control for power converters with MPC is insufficient. Accurate fault diagnosis and fault-tolerant control solutions with easy implementation are very desirable. In this work we propose a novel current based fault diagnosis method of one-and two-phase...
A modulated model predictive control (M2PC) scheme for an indirect matrix converter is proposed in this paper, including an active damping method to mitigate the input filter resonance. The control strategy allows the instantaneous power control and the output current control at the same time, operating at a fixed frequency. An optimal switching pattern is used to emulate the desired waveform quality...
To avoid large overvoltage when the current of the dc-link inductor is interrupted, overlap time is added to the drive signals in current source converters, which results in the extra harmonic in grid current. Waveforms of AC side current before and after added overlap time are achieved from analysis of the current commutation process. The expression of overlap current is given according to the pulse...
The modular paralleled three-level T-Type Inverters (3LT2Is) have been widely used to extend the power capacity. However, zero-sequence circulating currents (ZSCCs) are generated due to the difference of parameters between the paralleled inverters. The ZSCCs will lead to various issues, such as output current distortion, unbalanced current distribution and system loss increasing, etc. The finite control...
A novel space vector PWM (SVPWM) strategy is proposed in this paper to balance the neutral-point voltage (NP) and the floating capacitor voltage for five-level active neutral-point-clamped (ANPC) converter. There are two different switching sequences in each small area. According to the NP offset, different switching sequences are used to control the NP voltage. Since the charge-discharge of the floating...
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