High Reliability Control Research Articles

An Improved Current-Source-Converter-Based Series-Connected Wind Energy Conversion System

The passive rectifier-based current source converter (CSC) used in the series-connected wind energy conversion system features low cost, high reliability, and simple control, but suffers highly distorted generator stator currents. A new CSC-based wind energy conversion system composed of a multi-phase generator, a passive rectifier, a modular medium-frequency transformer-based converter, and a CSC, is proposed. In addition, two versions of the proposed converter are developed for low- and medium-voltage turbine systems respectively. The operation principle is presented, controls are developed, and simulations and experiments are conducted. Both converters offer excellent generator stator current harmonics performance, while also retaining the advantages of existing CSC-based converters.

Design of Fast Real Time Controller for the SSSC Based on Takagi-Sugeno (TS) Adaptive Neuro-Fuzzy Control System

FACTS (Flexible AC Transmission Systems) technology is one aspect of the power electronics revolution that is taking place in all areas of electric energy. The power transfer capability of a transmission line can be enhanced by using power electronics based system like FACTS that offer high speed and reliable control capability. The Static Synchronous Series Compensator (SSSC) is the second generation of the FACTS controller, which is used to control the power flow in the transmission line. In this paper, a new scheme to control SSSC using adaptive neuro fuzzy logic is proposed, in this controller, Takagi-Sugeno fuzzy rules are trained using off-line neuro fuzzy system, also, instantaneous power theory is used to calculate the power system parameters due to its high accuracy and less computation. The simulation and practical results show that real time application of the proposed controller is possible and robust compared to conventional controllers previously investigated. The experiment results obtained using the dSPACE data acquisition system and Matlab real time toolbox.

Research on Fault-tolerant Control Allocation Technology for X-rudder UUV

X-rudder UUV is a typical redundant control system with high reliability and high control difficulty. This article researches the reconfigurable control allocation technology of X-rudder UUV control, analyzes and sorts out typical fault types of X-rudder UUV, and designs a reconfigurable control allocation algorithm without changing the high-level control law. In the case of partial failure of the rudder surface, the remaining rudder surface is used to complete the movement of UUV, improving the robustness of UUV to faults and damage. The effectiveness of the proposed fault-tolerant control allocation method is verified by simulation.

FEATURES OF THE FIELD WEAKENING MODE IN А SWITCHED RELUCTANCE MACHINE

The magnetic field weakening mode of electric machines is used in modern drives to extend the drive operational speed range when the power supply voltage is limited. In conventional electric drives, a real or fictitious flux control loop, established in a vector control system by using coordinate and phase transformations of corresponding variables, is used for attenuating the motor magnetic flux. Switched reluctance machines have certain design advantages over conventional electric machines; they feature high reliability and wide control possibilities. However, to realize these possibilities, appropriate control outputs should be generated, the choice of which depends on the operational speed range. Another peculiarity of these machines is that there is no separate magnetic flux stabilization or control circuit. The article considers the specific features pertinent to the switched reluctance machine operation in various speed ranges for adequately taking them into account in control algorithms. The studies were carried out using the electric drive simulation model in the MATLAB Simulink environment. It is shown that during the electric drive operation at its limit mechanical characteristic in the low-speed zone under the speed variation conditions, the phase flux linkage average value can be considered almost unchanged. However, control of the average torque carried out by changing the current limitation level is performed at the magnetic flux weakening background. It has been determined that during operation in a high-speed zone at invariable phase switching positions with the speed growing in a natural manner (i.e., without applying control actions), there is an excessive decrease in the flux linkage average value, which leads to a dramatic drop in the phase average torque. This drop can be compensated by progressively shifting the phase engagement position in the leading direction.

Decoupling Characteristics and Torque Analytical Model of Sharing-Suspension-Windings Bearingless Switched Reluctance Motor Considering Flux-Linkage Saturation

As its name indicates, the bearingless switched reluctance motor does not have windings or permanent magnets on the rotor. This has the advantages of simple structure, high reliability and easy control. The sharing-suspension-windings bearingless switched reluctance motor inherits the above characteristics, and has obvious advantages in the research field of bearingless motors with its motor structure of decoupling torque and radial force. In this paper, the sharing-suspension-windings bearingless switched reluctance motor is taken as the research object. The finite element model of the sharing-suspension-windings bearingless switched reluctance prototype is established. The electromagnetic characteristics of the prototype are analyzed. As the premise of motor suspension, the structural decoupling of torque and radial force is analyzed and experimentally verified. Then, the flux-linkage saturation of the motor is derived at the position where the stator and rotor are completely aligned and the stator and rotor are completely unaligned. The torque model of the motor is derived based on the flux-linkage saturation, and the accuracy of the model is verified by the fitting comparison between the theory and the finite element simulation. It lays a theoretical foundation for the subsequent structure optimization design research of the sharing-suspension-windings bearingless switched reluctance motor.

Research on isolation method of spacecraft reaction wheels using electromagnetic shunt damping

The spacecraft flywheel system is widely used in various space missions due to its cleanliness, high reliability and high control accuracy, such as spacecraft attitude control and large-angle turning maneuvers. However, current research agrees that the high-speed rotating flywheel system is one of the main sources of micro-vibration disturbances on spacecraft. In view of the variable speed characteristics of the flywheel, this paper proposes a new vibration isolation system based on Stewart vibration isolation platform and electromagnetic shunt damping (EMSD). Attempts to connect three circuits of pure resistance circuit, resistance-inductance circuit and resistance-inductance-capacitor circuit to the new vibration isolation system in order to improve the isolation performance. Through theoretical analysis and numerical simulation, the effect of circuit parameters on isolation performance of each circuit are studied. The results show that EMSD can significantly reduce the disturbance input of the flywheel, and frequency modulation can be achieved through the conversion circuit to avoid resonance.

A High-Robust Sensor Activity Control Algorithm for Wireless Sensor Networks.

In wireless sensor networks, it is important to use the right number of sensors to optimize the network and consider the key design and cost. Due to the limited power of sensors, important issues include how to control the state of the sensor through an automatic control algorithm and how to power-save and efficiently distribute work. However, sensor nodes are usually deployed in dangerous or inaccessible locations. Therefore, it is difficult and impractical to supply power to sensors through humans. In this study, we propose a high reliability control algorithm with fast convergence and strong self-organization ability called the sensor activity control algorithm (SACA), which can efficiently control the number of sensors in the active state and extend their use time. In the next round, SACA considers the relationship between the total number of active sensors and the target value and determines the state of the sensor. The data transmission technology of random access is used between the sensor and the base station. Therefore, the sensor in the sleep state does not need to receive the feedback packet from the base station. The sensor can achieve true dormancy and power-saving effects. The experimental results show that SACA has fast convergence, strong self-organization capabilities, and power-saving advantages.

Robust Stability of DC Microgrid Under Distributed Control

Compared with AC microgrid, DC microgrid has attracted more and more attention due to their high reliability and simple control. In this paper, we analyze the existence and stability of equilibrium of DC microgrid under distributed control. Firstly, the power-flow equation of the DC microgrid with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> DGs and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> CPLs is built. On this basis, under the limitation of currents of DGs, the sufficient solvability conditions are obtained based on Brouwer’s fixed-point theorem. Secondly, we build the small-signal model to forecast the system qualitative behavior around equilibrium. The eigenvalue analysis based on inertial theorem provides the analysis basis for system stability, then we obtain the robust stability condition based on the properties of a special matrix. The obtained stability conditions provide a reference for establishing a stable DC microgrid. Lastly, simulation results verify the correctness of the proposed theorems.

Demonstration of the reliability of a 5-kW-level oscillating-amplifying integrated fiber laser.

A novel fiber laser called an oscillating-amplifying integrated fiber laser was studied experimentally, in which the oscillating section and amplifying section share the pump between them. Based on this configuration, a 5-kW fiber laser system with optical-optical efficiency of 80.9% and M2 factor of 1.5 was achieved. The startup and shutdown sequence of the laser was studied in detail. When pumps of the laser were deliberately turned on in an inverted order, such as switching on/off the amplifying section before/after the oscillating section, which is normally disastrous in a classic fiber amplifier, the laser system turned out to operate stably at full power level. Thus, it is verified that there is no priority between the amplifier and the seed in this laser system. It combines the advantages of conventional fiber oscillators and fiber amplifiers, including high efficiency, high reliability, good anti-backreflection, and simple control logic.

Energy Management Using a Rule-Based Control Strategy of Marine Current Power System with Energy Storage System

With the rapid development of renewable energy technology, marine current energy is treated as the most desirable form of ocean energies. Due to the nature of marine current energy, simple structure, high reliability, and good control performance are the primary consideration for the energy management strategy. This paper proposes an energy management control strategy based on rules to compensate for the fluctuating power caused by tidal motion. The hybrid energy storage system composed of vanadium redox flow battery (VRB) is applied to reallocate power. Supercapacitor banks (SCBs) are applied as the auxiliary power source to absorb or release the required power according to energy management strategy based on control rules in the marine current power system. SCB makes the grid-connected power track the grid command power and also improves the operational efficiency of the vanadium redox flow battery (VRB). VRB compensates for the low-frequency fluctuating power caused by tidal motion and plays an important role in compensating for the difference in power between the grid-connected power and the grid command power to ensure the reliability of the marine current power system. A simulation model of a 3 MW marine current power system is built to verify the effectiveness of the energy management strategy based on the real marine current velocity data.

Study of a mechanical ventilation system with heat recovery to control temperature in a monitored agricultural environment under Summer conditions

Proper management of the microclimatic environment plays a main role for a more rational use of energy in greenhouses. In particular, ventilation systems in controlled environment agriculture (CEA) are essential to make the indoor environment as compatible as possible with production needs. In this study, a prototype of mechanical ventilation (SIVeMeC: Integrated System for Controlled Mechanical Ventilation) was analysed in cooling mode by simulating, through two climatic rooms, typical Summer outdoor temperature (i.e., 29 °C, 32 °C, 35 °C, 38 °C and 40 °C) and an indoor set-point of 24 °C. The main results show a very high performance of the system and reliable temperature control within the confined environment. Finally, a comparison was made with a representative commercial unit, which confirmed the suitability of SIVeMeC to efficiently manage the internal temperature. • A new mechanical ventilation system has been analysed in CEA application. • Tests were conducted in cooling mode simulating the outside air temperature. • Results show high performance and reliable temperature control. • Energy performances have been compared to that of a typical commercial unit. • Strategies to control the ventilation unit have been proposed.

Serum Hormone Levels, T Lymphocyte Subsets, and Achievement of Pregnancies in Patients with Premature Ovarian Insufficiency following Administration of Ethinylestradiol/Drospirenone

Primary ovarian insufficiency (POI) is closely associated with ovarian hormone deficiency, amenorrhea, menopause, and infertility in women. Hormone replacement therapy remains the mainstay of treatment and management of POI. A combined oral contraceptive (Yasmin) containing 0.02 mg ethinylestradiol and 3 mg drospirenone has been shown to be a well-tolerated and effective combination that provides high contraceptive reliability and good cycle control. Herein, we aim to examine clinical efficacy of ethinylestradiol/drospirenone in treating patients with POI and its effects on serum hormone levels, body mass, lipid metabolism, and T lymphocyte subsets. Retrospective analysis of clinical records and follow-up data from 80 patients with POI was performed. The control group contained 40 patients with POI receiving oral administration of 0.035 mg ethinylestradiol and 2 mg cyproterone acetate once a day for consecutive 21 days with drug withdrawal of 7 days in 3 months. The observation group contained 40 patients with POI receiving oral administration of 0.02 mg ethinylestradiol and 3 mg drospirenone once a day for consecutive 28 days in 3 months. There was no significant difference on serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T), concentrations of high- and low-density lipoprotein cholesterol (HDL-C and LDL-C), and triglycerides (TG), body mass, the numbers of CD+3, CD+4, CD+8 T cells, and ratio of CD+4/CD+8 between the control and observation group ( P &gt; 0.05 ) before treatment. After treatment, serum levels of FSH, LH, and T, concentrations of LDL-C, and TG, body mass, and CD+8 T cells were reduced but the concentration of HDL-C, CD+3, and CD+4 T cells and ratio of CD+4/CD+8 were increased in both two groups ( P &lt; 0.05 ); these changes were more significant in the observation group compared with the control group ( P &lt; 0.05 ). Besides, the total response rate of the observation group was 90.00%, which is higher than that of the control group, 77.50% ( P &lt; 0.05 ). The pregnancy rate of the observation group was 45.00%, which is higher than that of the control group, 30.00% ( P &lt; 0.05 ). Taken together, these results suggest that the combined oral contraceptive (Yasmin) containing 0.02 mg ethinylestradiol and 3 mg drospirenone restores hormone levels, improves body mass and lipid metabolism, and sustains autoimmune function for patients with POI, suggesting ethinylestradiol/drospirenone treatment is effective in treating POI.

Research on servo motor motion control system based on Beckhoff PLC

In order to meet the requirements of high precision, reliability and real-time control of biaxial motion.Taking Beckhoff PLC CX9020 and Yaskawa Σ - 7S series AC servo controller as the control core, using Yaskawa SGM7J series motor and servo driver matching, the X-Y double axis servo motion control system is designed, and the overall hardware design of the control system is carried out. This paper focuses on the parameter setting, analog and digital acquisition, programming and HMI interface setting of servo motor control system. The debugging operation shows that the system runs stably and meets the control requirements of accurate positioning.

New Sensorless Speed Control of a Hybrid Stepper Motor Based on Fuzzy Sliding Mode Observer

Stepper motors are widely used in industrial and consumer applications due to low-cost, high reliability, and open-loop control capability. Though open-loop features a simple structure, it bears low step resolution, high torque ripple, and low energy efficiency. To improve the performance without increasing hardware cost, a fuzzy sliding mode observer (SMO)-based new sensorless speed control structure is proposed. Unlike the conventional sensorless speed control, it does not use Park and inverse Park transformations to transform currents between a-b and d-q coordinates. Instead, it uses a new current transformation method to generate reference currents of stator windings, which not only reduces the calculation burden of the controller, but also improves the stability of the system. To reduce the chattering, a fuzzy logic controller (FLC) embedded into the SMO is designed to adjust the observer gain adaptively, without using the conventional method that replaces the discontinuous sign function with the continuous, such as sigmoid or saturation function. The effectiveness of the proposed controller is verified using MATLAB/Simulink simulation (R2018b, MathWorks, Natick, MA, USA) and experiment by assessing the speed and position tracking abilities.

Propellant Actuated Device for Parachute Deployment during Seat Ejection for an Aircraft Application

Propellant Actuated Devices (PAD) are installed on various combat aircraft of Air Force and Naval bases to perform extremely important operations such as parachute deployment, harness and leg restrain, cable cutting, pullers, seat ejection, bomb release or fuel tanks etc. They are basically called as gas generators. Such devices produce the high temperature and pressure combustion gases on initiation and used to perform different operations. These cartridges are single-shot operating devices. The performance of such kind of PADs cannot be tested by non-destructive techniques. Hence, cartridges are designed to function with high reliability and stringent quality control checks at all levels during entire development cycle. The safety features required during handling, storage and transportation are built in the design of PAD. The cartridges are required to undergo different exhaustive design qualification tests to qualify design aspects. Total life of 6 years is assigned to cartridge after performance degradation study of the propellant which includes 2 years installed life. This paper explains about the development aspects of PAD, its use, function, testing and performance evaluation methodology in a suitable fabricated Velocity Test Rig (VTR). The maximum slug velocity is 121.14 m/s in hot condition and minimum slug velocity is 99.14 m/s in cold condition. The main objective of this paper is to device a novel method to measure actual slug velocity of the aircraft gun inside a cartridge using VTR and Doppler RADAR.

Retransmission Diversity with Channel Selectivity for High Reliable and Low Latency Industrial Wireless Control System

The emerging applications in the 5th generation (5G) network, such as industrial control system and Machine-to-Machine (M2M) communication require high reliability and low latency communication at the same time. The retransmission scheme is one of the practical approaches to increase system reliability when other diversity techniques are avoided due to hardware complexity or significant transmission delay. In order to address such problems, in this paper, we propose a fast yet reliable retransmission scheme. The proposed retransmission scheme leverages the frequency diversity through simple channel selectivity. The channel selectivity is carried out by employing low complexity subcarrier allocation for selecting other channels in Orthogonal Frequency Division Multiplexing (OFDM) transmission. The evaluation results show that the proposed retransmission method outperforms the conventional scheme. The proposed method can reduce the number of retransmission by up to 30%, corresponding to a success rate of 0.9999 . In addition, it can be employed in an industrial Wireless Local Area Network (iWLAN) system with a large number of users. The achievable control duration is around 52-63 μs, an improvement of approximately 36% compared to the conventional system.

Design and Performance of Single Stage Three Phase Solar Photo Voltaic using CTF-UPQC

An algorithm is necessary for high performance, reliable and secure control in three phase solar photovoltaic cell. Three phase single stage solar photovoltaic is designed and analysed in this paper by using control triangular function unified power quality conditioner (PV-CTFUPQC) technique. By using PV-CTFUPQC technique, the functioning of three-phase single stage solar photovoltaic can be improved. To produce fundamental output, PV-CTFUPQC maintains Root mean square (RMS) but in the proposed control RMS block is not needed. By using MATLAB/Simulink platform, three phase solar photo voltaic is designed and simulated. The proposed system function is validated on developed laboratory model. The generation of clean energy and enhancement in quality power are provided by proposed system.

Fabrication technology for high light-extraction ultraviolet thin-film flip-chip (UV TFFC) LEDs grown on SiC

The light output of deep ultraviolet (UV-C) AlGaN light-emitting diodes (LEDs) is limited due to their poor light extraction efficiency (LEE). To improve the LEE of AlGaN LEDs, we developed a fabrication technology to process AlGaN LEDs grown on SiC into thin-film flip-chip LEDs (TFFC LEDs) with high LEE. This process transfers the AlGaN LED epi onto a new substrate by wafer-to-wafer bonding, and by removing the absorbing SiC substrate with a highly selective SF6 plasma etch that stops at the AlN buffer layer. We optimized the inductively coupled plasma SF6 etch parameters to develop a substrate-removal process with high reliability and precise epitaxial control, without creating micromasking defects or degrading the health of the plasma etching system. The SiC etch rate by SF6 plasma was ∼46 μm hr–1 at a high RF bias (400 W), and ∼7 μm hr–1 at a low RF bias (49 W) with very high etch selectivity between SiC and AlN. The high SF6 etch selectivity between SiC and AlN was essential for removing the SiC substrate and exposing a pristine, smooth AlN surface. We demonstrated the epi-transfer process by fabricating high light extraction TFFC LEDs from AlGaN LEDs grown on SiC. To further enhance the light extraction, the exposed N-face AlN was anisotropically etched in dilute KOH. The LEE of the AlGaN LED improved by ∼3× after KOH roughening at room temperature. This AlGaN TFFC LED process establishes a viable path to high external quantum efficiency and power conversion efficiency UV-C LEDs.

High reliability management and control operator risks in autonomous marine systems and operations

This paper's objective is to analyze the main real-time risks in operation of autonomous marine systems, which follow from various levels of autonomy (LoA). High reliability management (HRM) is an established framework for assessing real-time operator performance in complex infrastructures. In this paper, the framework is applied to two cases representing different uses and autonomy levels: one on marine underwater robotics focusing on remotely operated vehicles (ROVs) and subsea intervention, and the other addressing operation of a complex marine surface vessel with a dynamic positioning (DP) system. Usually, autonomous systems are associated with unmanned systems, but several manned systems (for example, ships with complex automation and DP systems) have specific control functionality that can be characterized as autonomous. This paper focuses on manned and unmanned systems with different levels of autonomy and major hazard potential. The most important research finding is having identified multiple, different operational states that vary across two or three LoAs, each state of operations having significantly different risks to be managed in real time. The application of the HRM framework highlights the importance of enabling reliable operator control and online risk management in the development of next generation autonomous marine systems.

UHD 3D medical system of small‐ and medium‐sized monitor

AbstractWith the development of ultra‐high definition (UHD) display technology and stereoscopic 3D display technology, 3D ultra‐high monitor will help surgeons obtain the spatial hierarchy of internal tissues, identify tissue surfaces and blood vessels clearly, locate the focus precisely and reduce surgery time. Compared with normal 2D medical monitors, 3D medical monitors will lose more brightness because of the 3D application, so it is necessary to design a high‐brightness backlight system to guarantee the display stability and the accuracy of the diagnosis. This paper presents a novel processing system for 4K UHD 3D medical monitor with the architecture combined with universal SOC (system on a chip) and specialized FPGA (field programmable gate array). A hardware system is designed with high efficiency and reliable brightness stability control for small‐ and medium‐sized monitors. Furthermore, we analyze the two dimming modes of linear dimming and PWM dimming for a better application in medical monitor.