Low-voltage Control Research Articles

Low Voltage Control of Micro-Ionic Thrusters Using the Electrostatic Induced Potential of the Collector

This work presents a low voltage (5 V) control method for micro-ionic thrusters with high operating voltage (>1 kV). When the collector of a micro-ionic thruster is connected to the negative electrode through a 5V switch circuit, and a high DC voltage (1-10 kV) is applied to the emitter, we can get a suitable control voltage (0-4 kV) based on the electrostatic induced potential characteristics of the collector. This voltage control method allows multiple emitters to share one boost circuit of high DC voltage without using multiple high voltage control circuits. Theoretical analysis, simulations, and experiments are conducted to validate our low voltage control method, and the attitude control of a lever device with two ion thrusters in different conditions is realized with a small steady error within 2 seconds.

Realization of Low-Voltage and High-Current Rectifier Module Control System Based on Nonlinear Feed-Forward PID Control

The low-voltage and high-current permanent magnet synchronous generator (PMSG), which has characteristics of high power density, small size, and excellent energy saving, is representative of the generators. As a key module of the integrated DC output system of PMSG, the low-voltage and high-current rectifier module is also a nonlinear time-varying system that is readily influenced by parametric changes and external disturbances. Aiming at the shortcomings of traditional control strategies, this paper proposes a novel low-voltage and high-power rectifier module control strategy based on nonlinear feed-forward PID control. The controller has a wide range of environmental applications because of its greater robustness. At the same time, the introduction of feed-forward control shortens regulation time of the system. Therefore, the combination of the two control methods can improve the dynamic performance of the system without influencing the steady-state performance. The simulation model of an integrated rectifier system based on SVPWM control was constructed by Simulink, which can achieve a rated output of 5 V/300 A. At the same time, the simulation model of the controller is constructed and applied to the rectifier output system of a 5 V/300 A synchronous generator to complete the nonlinear feed-forward PID control. Through the comparison between simulation and experiment, it has been proven that the control method can effectively resist the load disturbances and improve the response speed of the system.

Highly Efficient Uniaxial In-Plane Stretching of a 2D Material via Ion Insertion.

On-chip dynamic strain engineering requires efficient micro-actuators that can generate large in-plane strains. Inorganic electrochemical actuators are unique in that they are driven by low voltages (≈1V) and produce considerable strains (≈1%). However, actuation speed and efficiency are limited by mass transport of ions. Minimizing the number of ions required to actuate is thus key to enabling useful "straintronic" devices. Here, it is shown that the electrochemical intercalation of exceptionally few lithium ions into WTe2 causes large anisotropic in-plane strain: 5% in one in-plane direction and 0.1% in the other. This efficient stretching of the 2D WTe2 layers contrasts to intercalation-induced strains in related materials which are predominantly in the out-of-plane direction. The unusual actuation of Lix WTe2 is linked to the formation of a newly discovered crystallographic phase, referred to as Td', with an exotic atomic arrangement. On-chip low-voltage (<0.2V) control is demonstrated over the transition to the novel phase and its composition. Within the Td'-Li0.5- δ WTe2 phase, a uniaxial in-plane strain of 1.4% is achieved with a change of δ of only 0.075. This makes the in-plane chemical expansion coefficient of Td'-Li0.5-δ WTe2 far greater than of any other single-phase material, enabling fast and efficient planar electrochemical actuation.

Neuromodulation using electroosmosis

Objective. Our laboratory has proposed chemical stimulation of retinal neurons using exogenous glutamate as a biomimetic strategy for treating vision loss caused by photoreceptor (PR) degenerative diseases. Although our previous in-vitro studies using pneumatic actuation indicate that chemical retinal stimulation is achievable, an actuation technology that is amenable to microfabrication, as needed for an in-vivo implantable device, has yet to be realized. In this study, we sought to evaluate electroosmotic flow (EOF) as a mechanism for delivering small quantities of glutamate to the retina. EOF has great potential for miniaturization. Approach. An EOF device to dispense small quantities of glutamate was constructed and its ability to drive retinal output tested in an in-vitro preparation of PR degenerate rat retina. Main results. We built and tested an EOF microfluidic system, with 3D printed and off-the-shelf components, capable of injecting small volumes of glutamate in a pulsatile fashion when a low voltage control signal was applied. With this device, we produced excitatory and inhibitory spike rate responses in PR degenerate rat retinae. Glutamate evoked spike rate responses were also observed to be voltage-dependent and localized to the site of injection. Significance. The EOF device performed similarly to a previously tested conventional pneumatic microinjector as a means of chemically stimulating the retina while eliminating the moving plunger of the pneumatic microinjector that would be difficult to miniaturize and parallelize. Although not implantable, the prototype device presented here as a proof of concept indicates that a retinal prosthetic based on EOF-driven chemical stimulation is a viable and worthwhile goal. EOF should have similar advantages for controlled dispensing of charged neurochemicals at any neural interface.

Design of Real-Time Multi-Level Inverter with Remote Monitoring System

This paper is about a single-phase multi-level inverter that uses DC source, multiple Monocrystalline photovoltaic cells to work. Initially, the simulation will be carried out using a Node MCU and an ATmega 328P to produce the low voltage control signals needed to operate the MOSFET Switching devices. Furthermore, the control signals will be activated by a NodeMCU, allowing the Inverter parameters and control signals to be visualized on the IoT Platform by projecting data to the cloud via ESP8266, allowing remote monitoring of the parameters following the Covid-19 pandemic. With Communication protocols and the use of an open-source framework (ThingsBoard), the user will be able to analyze & track; Study Multi-Level Inverter outputs in real time, allowing for improved performance and reduced E-Waste production.

MIMO Control of a High-Step-Up Isolated Bidirectional DC–DC Converter

This article proposes a multi-input multi-output digital control strategy for a bidirectional interleaved boost converter with coupled inductors, designed to operate as an interface between an ultracapacitor and a high-voltage dc-bus in a hybrid nanogrid. The control strategy keeps the high-voltage side dc-bus of the nanogrid stable when the voltage at the low-voltage side, connected to the ultracapacitor, changes in a wide range. Bidirectional energy flow control with current protection is allowed too. The high-voltage regulation loop is closed around an inner, low-voltage side current control loop. In parallel to these, a third, clamp voltage regulator is set to keep tight control over switch voltage stress. This article discusses the controller organization, the design criteria, and shows the subsequent implementation on a general purpose digital control platform. The achievable performance is experimentally verified on a 1.5-kW converter prototype.

Cholesteric layers with tangential-conical surface anchoring for an electrically controlled polarization rotator

The voltage dependences of polarization characteristics of light passed through the cholesteric layers with tangential-conical boundary conditions have been investigated. It has been shown that such layers allow turning the polarization azimuth more than 70 ∘ because of the unique untwisting effect of the cholesteric helix, due to free azimuthal rotation of the director on the substrate with conical anchoring. Optical cells under study have some advantages (low control voltage, smooth variation of polarization azimuth, simplicity of design) and can be used as an electrically controlled polarization rotator of white light.

Research on the Application of Intelligent Technology in Low Voltage Electric Automation Control System

Based on the background of intelligent technology, the paper describes in detail the architecture and main functions of the electrical automation control system, including data collection, information transmission, electrical control, etc., based on the principles of stability and scalability in the design of low-voltage electrical automation control systems. Design and implementation of the thesis is to explore the performance of the designed system and select the application examples of the electrical automation control system for analysis. The research results show that the electrical automation control system we designed meets the requirements of artificial intelligence regulation and can effectively improve the safety of the system.

Research on optimizing controller parameters based on transient energy function to improve the stability of weak transmission system

This paper takes the Ximeng-Taizhou UHVDC transmission weak transmission end AC system as the background, and proposes to optimize the low-voltage current limiting control link (VDCOL )to improve the stability of the system. First of all, this paper analyzes the working principle and limitations of traditional VDCOL, and proposes that the short-circuit ratio of the sending end and the voltage of the commutation bus at the receiving end are used as the variables of the VDCOL cut-off voltage to achieve the effect of optimizing VDCOL. Make the cut-off voltage a value that changes with the change of the inverter side commutation bus voltage, which can take into account the recovery speed of the AC and DC systems. The process of constructing the transient energy function considering the dynamic characteristics of the DC system is analyzed in detail, and the real-time digital simulation software RTDS is used to build a single-machine infinite-DC simulation example. Based on time-domain simulation software and transient energy function margin method, the optimization of the low-voltage current-limiting control link in the DC control system is verified to improve the stability of the sending-end AC system.

ECRH system upgrade design using dual frequency gyrotrons for EAST

The ECRH (Electron Cyclotron Resonance Heating) system was used in the EAST (Experimental Advanced Superconducting Tokamak) experiments for several years, and some good experimental results have been obtained. However, the performance of the gyrotrons is degraded and the ability to stabilize output RF (Radio Frequency) power is reduced. Two single-frequency 140 GHz gyrotrons are planned to be repaired in order to improve the performance of the gyrotrons. At the same time, some internal components of the gyrotrons (such as collectors, electron guns, mode conversion mirrors) will be upgraded to make the gyrotrons have the output capability of 0.6 MW/1 MW at 105 GHz/140 GHz. The MOUs (Matching Optical Units), transmission lines, the low voltage power supplies, the measurement and control system, and the water-cooling system also need to be modified for the dual-frequency operation of the new gyrotrons. The retrofitted design of the EAST ECRH system using dual-frequency gyrotrons is discussed in the paper. The upgraded ECRH system will be used for future EAST experiments to explore the range of low q95 and high βN, to study the steady-state operation mode for the future nuclear fusion power plants.

Energy-efficient inverter circuit for the low-voltage asynchronous driver controller with autonomous power supply

The design of the energy-efficient inverter circuit for the asynchronous frequency-controlled three-phase electric driver with autonomous low-voltage DC power supply. The components analysis of the electric drive, the main components selection approach: microcontroller, three-phase driver and power transistors. R&amp;D prototype of the energy-efficient inverter circuit was created, characterized by an average consumption current reduced by 5%. Reducing energy losses is achieved by reducing dynamic losses in the power circuits of a low-voltage inverter and using several circuit solutions.

A 65nm CMOS Process Li-Ion Battery Charging Cascode SIDO Boost Converter with 89% Maximum Efficiency for RF Wireless Power Transfer Receiver

This paper proposes a 65nm CMOS process cascode single-inductor-dual-output (SIDO) boost converter for RF wireless power transfer (WPT) receiver. In order to withstand 4.2V Li-ion battery output, cascode 2.5V I/O PFETs are used at the power stage while 2.5V cascode NFETs are used for 1V output to supply low voltage control circuit. By using NFETs, 1V output with 5V tolerance can be achieved. Measurement results show conversion efficiency of 89% at P IN =7.9mW and V BAT =3.4V.

Electroosmosis-Driven Hydrogel Actuators Using Hydrophobic/Hydrophilic Layer-By-Layer Assembly-Induced Crack Electrodes.

Development of soft actuators with higher performance and more versatile controllability has been strongly required for further innovative advancement of various soft applications. Among various soft actuators, electrochemical actuators have attracted much attention due to their lightweight, simple device configuration, and facile low-voltage control. However, the reported performances have not been satisfactory because their working mechanism depends on the limited electrode expansion by conventional electrochemical reactions. Herein, we report an electroosmosis-driven hydrogel actuator with a fully soft monolithic structure-based whole-body actuation mechanism using an amphiphilic interaction-induced layer-by-layer assembly. For this study, cracked electrodes with interconnected metal nanoparticles are prepared on hydrogels through layer-by-layer assembly and shape transformation of metal nanoparticles at hydrophobic/hydrophilic solvent interfaces. Electroosmotic pumping by cracked electrodes instantaneously induces hydrogel swelling through reversible and substantial hydraulic flow. The resultant actuator exhibits actuation strain of higher than 20% and energy density of 1.06 × 105 J m-3, allowing various geometries (e.g., curved-planar and square-pillared structures) and motions (e.g., slow-relaxation, spring-out, and two degree of freedom bending). In particular, the energy density of our actuators shows about 10-fold improvement than those of skeletal muscle, electrochemical actuators, and various stimuli-responsive hydrogel actuators reported to date.

IEC 61439: Alternate Design Verification Methods

Design verification for low-voltage power switchgear and control gear assemblies is intended to verify compliance of the design of an assembly or assembly system with the requirements of IEC61439 series of standards. There are 3 methods of verification. 1. Verification testing 2. Verification comparison with a tested reference design 3. Verification assessment by calculations and design rules including use of appropriate safety margins. The normally preferred verification method is verification by testing. However, verification by assessment and verification by comparison are also alternate verification methods provided by IEC 61439, which are still unexplored. This is in spite of the fact that IEC 61439 states: “ all the permitted means of design verification which includes comparison and assessment are equivalent in terms of performance achieved.” Here, we shall elaborate on the verification assessment and verification comparison methods for Low voltage switchgear and control gear assemblies.

Positive-negative tunable liquid crystal lenses based on a microstructured transmission line

In this work, a novel technique to create positive-negative tunable liquid crystal lenses is proposed and experimentally demonstrated. This structure is based on two main elements, a transmission line acting as a voltage divider and concentric electrodes that distribute the voltage homogeneously across the active area. This proposal avoids all disadvantages of previous techniques, involving much simpler fabrication process (a single lithographic step) and voltage control (one or two sources). In addition, low voltage signals are required. Lenses with switchable positive and negative focal lengths and a simple, low voltage control are demonstrated. Moreover, by using this technique other optical devices could be engineered, e.g. axicons, Powell lenses, cylindrical lenses, Fresnel lenses, beam steerers, optical vortex generators, etc. For this reason, the proposed technique could open new venues of research in optical phase modulation based on liquid crystal materials.

DESIGN AND CONTROL OF LOW VOLTAGE RIDE THROUGH FOR PV-GRID APPLICATIONS

This paper presents the design and control of low voltage ride through (LVRT) for PV-based grid-tied applications. One of the significant features of the proposed system is capable of handling the power quality issue of a power blackout. In the context of considerable power quality improvement schemes, LVRT is one of the most leading grid-tied requirements to be met by the distribution power generation systems. Perturb and Observation (P&O) based Maximum Power Point Tracking (MPPT) has incorporated in the PV system to enhance the performance. The proposed system has a battery energy storage system (BESS) to balance the active and reactive powers. The DC-link voltage of the inverter is controlled in such a way the inverter remains tied to the grid even though during the fault conditions as long as satisfying the modern grid standards.

Design of the Test System for the Ability to Withstand the Overload Current of the Low Voltage Control Equipment Applied in Coal Mines

On the basis of the development prospect of energy industry and the safety production situation of coal mine, the composition structure and working principle of low-voltage control equipment applied in coal mines were analyzed, and the electric power and thermal effect theory of low-voltage control equipment applied in coal mine were studied, and the design scheme of overload resistance test system was put forward, meanwhile, the flameproof electromagnetic starter for coal mines was tested according to the coal industry standard. The test results show that the design of the overload tolerance is reasonable.

Predictive Voltage Control: Empowering Domestic Customers With a Key Role in the Active Management of LV Networks

In order to avoid voltage problems derived from the connection of large amounts of renewable-based generation to the electrical distribution system, new advanced tools need to be developed that are able to exploit the presence of Distributed Energy Resources (DER). This paper describes the approach proposed for a predictive voltage control algorithm to be used in Low Voltage (LV) distribution networks in order to make use of available flexibilities from domestic consumers via their Home Energy Management System (HEMS) and more traditional resources from the Distribution System Operator (DSO), such as transformers with On-Load Tap Changer (OLTC) and storage devices. The proposed algorithm—the Low Voltage Control (LVC)—is detailed in this paper. The algorithm was tested through simulation using a real Portuguese LV network and real consumption and generation data, in order to evaluate its performance in preparation for a field-trial validation in a Portuguese smart grids pilot.

Coordinated Fuzzy-Based Low-Voltage Ride-Through Control for PMSG Wind Turbines and Energy Storage Systems

Coordinated control methods involving a wind turbine (WT) and an energy storage system (ESS) have been proposed to meet several objectives, such as smoothing wind power (WP) fluctuations, shaving peaks, enabling power scheduling, and allowing low-voltage ride-through (LVRT). LVRT requirement is defined by grid operators, and it should be satisfied whenever grid faults occur. Several methodologies have been proposed for the LVRT both with or without the use of an ESS. Furthermore, using an ESS is more advantageous for several WP applications. By using an ESS, WTs can be operated in a more economic and reliable way. However, the installation cost of an ESS is high and it has operation range constraints for charging and discharging. Moreover, the WT operation condition and ESS state-of-charge (SoC) can be different when a grid fault occurs. Therefore, it is necessary to coordinate both units, WT and ESS, for reliable and economic operation during a grid fault. Thus, we propose a coordinated fuzzy-based LVRT method that considers the different operation conditions of a WT and an ESS. From the proposed method, the effective reference powers of a WT and an ESS are evaluated by considering the rotor speed and SoC in the fuzzy control algorithm. The effectiveness of the proposed method is validated by considering two case studies on ESS SoC and WT rotor speed violations.

Multilevel cascaded three-phase inverter with low-voltage ride-through flexible control capability for photovoltaic systems

Multilevel cascaded three-phase inverter with low-voltage ride-through flexible control capability for photovoltaic systems