Phase Control Scheme Research Articles

融合计算全息术与纳米印刷术的多功能超表面研究进展

Computer-generated holography and nanoprinting are two typical applications of optical metasurfaces. Recently, merging holography and nanoprinting into a multifunctional metasurface becomes an emerging research hotspot, which has prospective applications in multi-folded anti-counterfeiting, information decoding and multiplexing, multi-channel image display and VR/AR, etc. In this paper, based on the features of metasurface-based nanoprinting and computer-generated holography, the advances in the research of merging them were classified and characterized in detail. Specifically, the merging methods were discussed in detail which included orthogonal-polarization multiplexing scheme, in-plane arrangement scheme, multilayer-stacking scheme, simultaneous spectrum and phase control scheme, complex amplitude modulation scheme, orientation degeneracy scheme. The future development of multifunctional metasurfaces was prospected.

A Novel Coding Metasurface for Wireless Power Transfer Applications

We propose and implement a novel 1-bit coding metasurface that is capable of focusing and steering beam for enhancing power transfer efficiency of the electromagnetic (EM) wave-based wireless power transfer systems. The proposed metasurface comprises 16 × 16 unit cells which are designed with a fractal structure and the operating frequency of 5.8 GHz. One PIN diode is incorporated within each unit cell and enables two states with 180 ° phase change of the reflected signal at the unit cell. The two states of the unit cell correspond to the ON and OFF states of the PIN diode or “0” and “1” coding in the metasurface. By appropriately handling the ON/OFF states of the coding metasurface, we can control the reflected EM wave impinged on the metasurface. To verify the working ability of the coding metasurface, a prototype metasurface with a control board has been fabricated and measured. The results showed that the coding metasurface is capable of focusing beam to desired direction. For practical scenarios, we propose an adaptive optimal phase control scheme for focusing the beam to a mobile target. Furthermore, we prove that the proposed adaptive optimal phase control scheme outperforms the random phase control and beam synthesis schemes.

An Intersection Signal Control Mechanism Assisted by Vehicular Ad Hoc Networks

The urban intersection signal decision-making in traditional control methods are mostly based on the vehicle information within an intersection area. The far vehicles that have not reached the intersection area are not taken into account, which results in incomplete information and even incorrectness in decision-making. This paper presents an intersection signal control mechanism assisted by far vehicle information. Using the aid of real-time information collection for far vehicles through vehicular ad hoc networks (VANETs), we can consider them together and calculate the accumulative waiting time for each intersection traffic flow at a future moment to make the optimal signal decision. Simulation results show that, under three different traffic flow environments—same even traffic flows, same uneven traffic flows, and different traffic flows—the two proposed implementation schemes based on the mechanism (fixed phase and period timing improvement scheme, and dynamic phase and period control scheme) show good performances, in which the average waiting time and the ratio of long-waiting vehicles are both less than the results of the traditional signal timing scheme. Especially, in the second scheme, the waiting time was reduced by an average of 38.6% and the ratio of long-waiting vehicles was reduced by an average of 7.67%.

Simulation of Three Phase Voltage Controlled Soft Switching Start of Induction Motor Drive

In this paper a three phase voltage regulator (thyristor based) with RL load and induction motor load is simulated for fixed firing angle first. As was seen from the results obtained that the induction motor response is highly impaired with this fixed firing angle starting. The transient response as well as the steady state response is highly oscillatory in nature. Then a suitable firing scheme was developed to vary the firing angles of each thyristor in reference to the zero crossing of the respective phase voltages. The control circuit was studied for R-L load first and then the induction motor was simulated with this firing angle control scheme. The basic objective of this work is to improve the transient response of the voltage regulator fed induction motor. One basic requirement for the induction motor to have an improved transient response is that the applied voltage to the motor must gradually increase. The same was achieved with the proposed control logic. Next the fault mode (short circuit and open circuit switch fault) analysis of the induction motor was taken up. Till now not much work has been done on this fault tolerant induction motor drive. Here a 2-phase close loop control was adopted to improve response of the induction motor in fault mode. We used both the voltage control loop as well as the current control loop to do so. Unfortunately not much can be done on this fault tolerant operation as the time was very short. Till the speed and torque pulsation during a short circuited switch fault was greatly improved by adopting this two phase control strategy.

Improved Sensorless Phase Control of Stand-Alone Brushless Doubly-Fed Machine Under Unbalanced Loads for Ship Shaft Power Generation

The brushless doubly-fed machine (BDFM) without a brush and slip ring has some advantages of high operation reliability and less maintenance cost, which is very suitable for the ship shaft power generation. In this application, the BDFM mainly works on the stand-alone state, in which the power winding (PW) voltage should be controlled directly. The unbalanced load is a typical working state, which mostly results in the unbalance of PW voltage and affects the normal operation of loads severely. The sensorless control strategy can enhance the operation safety under extreme environment and cut down the cost effectively, which is highly desired to be applied in the BDFM-based ship shaft power generation. In this paper, an improved sensorless phase control strategy is proposed, which can work effectively under the unbalanced load condition. First, the sensorless operation is achieved by controlling the $q$ -component of PW voltage, which can realize the phase control simultaneously. Then, the unbalanced compensation is designed in details. Finally, both simulation and experiments have demonstrated that, by the proposed method, the PW voltage phase can be controlled precisely and the voltage unbalance factor is lower than the permissible level.

Closed-loop combustion phase control for multiple combustion modes by multiple injections in a compression ignition engine fueled by gasoline-diesel mixture

Partially premixed combustion with low octane fuel aims to reduce NOx and soot emission simultaneously without fuel consumption penalty. Cylinder pressure based combustion phase control is an essential technology for partially premixed combustion. A novel closed-loop combustion phase control strategy for multiple combustion modes is proposed in the current study. The combustion modes are classified into three basic categories based on injection patterns and heat release stages: (1) with only one heat release stage; (2) with two separated heat release stages; (3) with two overlapped heat release stages. Crank angle when 50% fuel is consumed (CA50) is chosen as the combustion phase indicator for the first case. Start of combustion (SOC) of each heat release stage is the combustion phase indicator for the second case. Both SOC and CA50 are the combustion phase indicators for the third case. Each combustion phase is closed-loop controlled by a proportional–integral (PI) controller with the timing adjustments of the corresponding injection. The control strategy is verified under different operating conditions in a 1.9 L light duty diesel engine fueled by gasoline-diesel mixture (volumetric 70% gasoline, 30% diesel). The experimental results show that the control strategy is able to control the combustion phase, reduce cylinder to cylinder variations as well as cycle to cycle variations under the operating conditions with exhaust gas circulation (EGR) rates of 10% and 15%.

Restraining the Demand Side Power Fluctuation of Active Distribution Network Using 0°/180° Phase Controlled Electric Spring

In active distribution network, the random power output by wind/solar distributed generation may cause the stochastic fluctuation of demand side power, which will bring difficulties to power dispatching. In this paper, a method of restraining the demand side power fluctuation of active distribution network is proposed, in which a new power electronic device—electric spring—is applied by 0°/180° phase control strategy. Firstly, the basic principles of electric spring are introduced. Secondly, the reason for demand side power fluctuation of active distribution network is analyzed. After that, the 0°/180° phase control strategy of electric spring is proposed to restrain the demand side power fluctuation of active distribution network and the selection basis of noncritical loads is also obtained. The simulation results show that the method proposed in this paper is effective and the obtained selection basis of noncritical loads is reasonable.

Ancillary services provided by photovoltaic inverters: Single and three phase control strategies

Photovoltaic (PV) inverters are power electronic based converters with fast response in the range of milliseconds. Besides, due to solar irradiance variation, these converters have excess capacity that can be used to provide ancillary services to the main grid. Traditionally, ancillary services such as reactive power injection and frequency support are provided by hydro and thermal generation. This work is focused on the analysis of how PV inverters can perform ancillary services and support the grid. Control strategies for reactive power injection and harmonic current compensation are explored. Furthermore, the inverter current saturation plays an important role, once high currents can damage the inverter or reduce its lifetime. Case studies for single and three-phase PV inverters are presented. It is observed that the ancillary service priority must be defined in order to guarantee PV inverter operation under nominal conditions.

Latching control using optimal control method for a raft-type wave energy converter

ABSTRACTThe method of efficient wave energy harvesting is a significant research field. As a kind of phase control strategy, latching control has been widely applied to point-absorption wave energy converters (WECs). However, the determination of latching duration is a difficult problem especially when the WEC is a multi-degree-of-freedom (DOF) system or includes multiple oscillators. This paper relates to latching control for a raft-type WEC with multiple DOFs and including two oscillators. The control law between latching and unlatching is decided by using the optimal control method, which avoids computing the latching duration directly. Simulations are performed to evaluate how large the benefit that latching control can bring to the raft-type WEC is. Results show that the benefit in terms of ratio between average captured power with latching control and that without control can reach 10.54 in regular waves, whereas it achieves 5.23 in random seas. Furthermore, the influence of wave parameters on the benefit is investigated.

Proposal of optimum tuning of semiactive TMDs used to reduce harmonic vibrations based on phase control strategy

Tuned mass dampers (TMDs) are a well-established technology for passive structural vibration control involving harmonic vibrations. Some design issues are critical to guarantee the proper functioning of the device, in particular, the adequate tuning and the adequate space to accommodate the TMD stroke. With regard to the first aspect, semiactive TMDs were proposed as an alternative means of correcting the vibrating frequency of the device by adding a semiactive element between the TMD and the structure. In this case, several control strategies have been proposed, among which phase control has proven to lead to excellent results. However, in the framework of this control approach, the minimization of the structure displacements is often used as the main objective of the control, as the relative displacements of the TMDs mass are considered a secondary issue, which nevertheless may be a crucial aspect in some applications. In this context, this paper proposes a strategy to optimally tune the semiactive TMD, taking into account a balance between the level of the reduction of the structural response and the amplitude of the TMD stroke. The optimal tuning is found by minimizing the system stationary mechanical energy. The problem is formulated as an optimization process, and the corresponding results are presented and discussed.

Microwave phase-control scheme based on optical beat wave generation and propagation in an optical fiber

A microwave phase-control scheme is proposed and experimentally demonstrated. Two lasers are combined in an optical fiber coupler to generate a beat signal. The beat frequency is tuned by controlling the frequency of one laser. Using the phase shift of the beat waves with different frequencies during the propagation in an optical fiber, the phase of the radio-frequency (RF) signal generated by a photodetector (PD) can be controlled. Using the phase shift during the propagation of beat waves in an optical fiber with different beat frequencies, the phase of the RF signal generated by a PD connected to the fiber can be controlled. A tunable phase shift ranging from 0 deg to 1400 deg is obtained for frequencies from 6 to 10 GHz. This scheme offers the advantages of fast tuning and precise phase control of an RF signal.

A non-minimum phase robust nonlinear neuro-wavelet predictive control strategy for a quadruple tank process

In process industries model-plant mismatch is a significant problem. Quadruple tank process (QTP) can be configured both in minimum phase and non-minimum phase (NMP). However, in NMP, the control of QTP poses a challenge. This paper addresses that and presents a novel robust wavelet based non-minimum phase control (NMPC) strategy for the challenging QTP using genetic algorithm to find the optimised value of the manipulated variables in NMPC at every sampling time. The QTP is modelled based on wavelet neural network. The simulation results indicate that significant improvements have been achieved both in modelling and control strategies for a QTP system compare to conventional approaches such as the Levenberg-Marquardt.

A non-minimum phase robust nonlinear neuro-wavelet predictive control strategy for a quadruple tank process

In process industries model-plant mismatch is a significant problem. Quadruple tank process (QTP) can be configured both in minimum phase and non-minimum phase (NMP). However, in NMP, the control of QTP poses a challenge. This paper addresses that and presents a novel robust wavelet based non-minimum phase control (NMPC) strategy for the challenging QTP using genetic algorithm to find the optimised value of the manipulated variables in NMPC at every sampling time. The QTP is modelled based on wavelet neural network. The simulation results indicate that significant improvements have been achieved both in modelling and control strategies for a QTP system compare to conventional approaches such as the Levenberg-Marquardt.

A rule-based phase control methodology for a slider-crank wave energy converter power take-off system

The slider crank is a proven mechanical linkage system with a long history of successful applications, and the slider-crank ocean wave energy converter (WEC) is a type of WEC that converts linear motion into rotation. This paper presents a control algorithm for a slider-crank WEC. In this study, a time-domain hydrodynamic analysis is adopted, and an AC synchronous machine is used in the power take-off system to achieve relatively high system performance. Also, a rule-based phase control strategy is applied to maximize energy extraction, making the system suitable for not only regular sinusoidal waves but also irregular waves. Simulations are carried out under regular sinusoidal wave and synthetically produced irregular wave conditions; performance validations are also presented with high-precision, real ocean wave surface elevation data. The influences of significant wave height, and peak period upon energy extraction of the system are studied. Energy extraction results using the proposed method are compared to those of the passive loading and complex conjugate control strategies; results show that the level of energy extraction is between those of the passive loading and complex conjugate control strategies, and the suboptimal nature of this control strategy is verified.

Energy constraints in pulsed phase control of chaos

Phase control of chaos is a powerful technique but little is known about its physical constraints, relevant for real systems. As a fact, it has not been explored whether this technique can also be applied when the controlling perturbation is not harmonic. Here we apply phase control on a driven double well Duffing oscillator using periodic rectangular pulsed perturbations instead of the classical sinusoidal perturbations. Experimental measurements and numerical simulations show that this kind of perturbation is also able to stabilize the chaotic orbits for an adequate selection of the phase. Furthermore, as the duty cycle of the perturbation (that is, the fraction of the time that the periodically pulsed control is active) is increased, two separate regimes occur. In the first one, the perturbations leading to stabilization of periodic solutions are of constant energy (taken as the product of the duty cycle and the amplitude) and in the second one, a saturation phenomenon occurs, implying that increasing energy values of the perturbations are wasted. Our results unveil the versatility of the pulsed phase control scheme and the importance of energy constraints.

Control of a dendritic neuron driven by a phase-independent stimulation

A dendritic neuron model exhibits bistability under continuous weak stimulation – the oscillatory synchronized regime and the quiet regime coexist. Complex nonlinear dynamics is observed when the neuron undergoes not only phase-dependent continuous weak stimulation, but also when it is driven by an external phase-independent stimulation. In the latter case basin boundaries between the synchronized and the quiet regime become complex and fractal. Simple strategies based on control pulses are not sufficient in these circumstances, because it becomes difficult to predict the dynamics of the neuron after the application of the control pulse. Therefore, a new neural control method is proposed. Initially, a weak phase control strategy is applied until fractal basin boundaries evolve into a deterministic manifold. Consequently, a single control pulse is immediately applied and the neuron evolves into the calm state.

Effect of Synthetic Levers on Nickel Phosphide Nanoparticle Formation: Ni5P4 and NiP2.

Due to their unique catalytic, electronic, and redox processes, Ni5P4 and NiP2 nanoparticles are of interest for a wide-range of applications from the hydrogen evolution reaction to energy storage (batteries); yet synthetic approaches to these materials are limited. In the present work, a phase-control strategy enabling the arrested-precipitation synthesis of nanoparticles of Ni5P4 and NiP2 as phase-pure samples using different Ni organometallic precursors and trioctylphosphine (TOP) is described. The composition and purity of the product can be tuned by changing key synthetic levers, including the Ni precursor, the oleylamine (OAm) coordinating solvent and TOP concentrations, temperature, time, and the presence or absence of a moderate temperature soak step to facilitate formation of Ni and/or Ni-P amorphous nanoparticle intermediates. Notably, the 230 °C intermediate step favors the ultimate formation of Ni2P and hinders further phosphidation to form Ni5P4 or NiP2 as phase-pure products. In the absence of this step, increasing the P/Ni ratio (13-20), reaction temperature (350-385 °C), and time (10-48 h) favors more P-rich phases, and these parameters can be adjusted to generate either Ni5P4 or NiP2. The phase of the obtained particles can also be tuned between pure Ni2P to Ni5P4 and NiP2 by simply decreasing the OAm/TOP ratio and/or changing the nickel precursor (nickel(II)acetylacetonate, nickel(II)acetate tetrahydrate, or bis(cyclooctadiene)nickel(0)). However, at high concentrations of OAm, the product formed is the same regardless of Ni precursor, suggesting the formation of a uniform Ni intermediate (an Ni-oleylamine complex) under these conditions that is responsible for product distribution. Intriguingly, under the extreme phosphidation conditions required to favor Ni5P4 and NiP2 over Ni2P (large excess of TOP), the 20-30 nm crystallites assemble into supraparticles with diameters of 100-500 nm. These factors are discussed in light of a comprehensive synthetic scheme utilized to control P incorporation in nickel phosphides.

Robust Phase Control through Hetero-Seeded Epitaxial Growth for Face-Centered Cubic Pt@Ru Nanotetrahedrons with Superior Hydrogen Electro-Oxidation Activity

Controllable synthesis of metallic nanocrystals (NCs) with tunable phase, uniform shape, and size is of multidisciplinary interests but has still remained challenging. Herein, a robust phase control strategy is developed, in which seeds with a given phase are added to guide the epitaxial growth of the target metal to inherit the seeds’ phase. Through this strategy, M@Ru (M = Pt, Pd) NCs in the face-centered cubic (fcc) phase, a metastable phase for Ru under ambient conditions, were synthesized with the hydrothermal method. The Pt@Ru NCs showed not only the pure fcc phase but also high morphology selectivity to tetrahedrons surrounded by {111} facets. As revealed by density function theory (DFT) calculations, the preferentially epitaxial growth of Ru atom layers on the nonclosest-packed facets of hetero fcc metal seeds led to the formation of fcc Ru shells. Furthermore, the fcc Pt@Ru tetrahedrons/C showed electrocatalytic activity enhancement with more than an order of magnitude toward hydrogen oxidation r...

Clutch fill control of an automatic transmission for heavy-duty vehicle applications

In this paper an integrated clutch filling phase control for gearshifts on wet clutch transmissions is developed. In a clutch-to-clutch shift of an automatic transmission, in order to obtain smooth gearshift, it should synchronize the oncoming clutch and the off-going clutch timely as well as precise pressure control for the engagement of the oncoming clutch. However, before the oncoming clutch pressure starts to increase, the initial cavity of the clutch chamber has to be filled first. The filling time and stability of the fill phase are very important for the clutch control. In order to improve the shift quality of the automatic transmission which is equipped on heavy-duty vehicles, the electro-hydraulic clutch actuation system is analysed and modelled. A new fill phase control strategy is proposed based on the system analysis as well as the control parameters are optimized according to the variation of the oil temperature and engine speed. The designed strategy is validated by a simulation work. The results demonstrate that the proposed control strategy and parameters modified method can transit the shift process from the fill phase to the torque phase effectively.

A phase synchronization control scheme for LCL‐T type high‐frequency current source in parallel connection

SummaryConsidering the applications of high voltage gate driving system and contactless power transmission, a current‐based power distribution is adopted as a kind of replacement of voltage based high‐frequency Alternating Current (AC) power distribution system. In order to implement high‐frequency current source, an LCL‐T resonant inverter is examined with constant current characteristic and high conversion efficiency. First, the resonant topology is studied as a high‐frequency power source, including circuit principle, operational cycle analysis, and AC analysis. The effective control and high conversion efficiency are both achieved by LCL‐T resonant inverter. Second, the phase angle control scheme is explored to improve the synchronization performance in parallel system formed by multiple of LCL‐T resonant inverters. Lastly, a prototype of parallel system is evaluated by simulation and experiment results, both of which are constructed by two resonant inverters with rated peak current of 2 A, rated output frequency of 30 kHz, and rated output power of 100 W. The experimental results in accordance with simulation prove that the better phase synchronization of output currents is achieved by the phase angle control. Hence, the high‐frequency resonant topology and phase control scheme are a feasible realization of current source that can be used to feed current‐based high‐frequency power distribution system. Copyright © 2015 John Wiley & Sons, Ltd.Index Terms—high‐frequency AC (HFAC), power distribution system (PDS), LCL‐T resonant inverter, current source, phase angle control.