Modulation Rectifier Research Articles

Output characteristics of none-series compensated inductive wireless power transfer link operating at load-independent-voltage-output frequency

The most important performance merits of inductive wireless power transfer links (IWPTL) operating at load-independent-voltage-output (LIVO) frequency are efficiency and output characteristics. It was recently demonstrated that none-series (NS) compensated IWPTL operating at LIVO frequency outperforms its series-series (SS) and series-none (SN) compensated counterparts in terms of efficiency. In order to complete the comparison, this paper presents output characteristics modeling and analysis (namely, relation between output voltage and load power) of a practical NS-compensated IWPTL operated at LIVO frequency. It is demonstrated that even though the system is operated at LIVO regime, its output voltage remains load-dependent due to practical issues. The lower bound of the output voltage range corresponds to operation under rated loading and is derived using phasor domain equivalent circuit, assuming continuous conduction mode (CCM) of the receiving-side diode rectifier without neglecting equivalent series resistances. On the other hand, upper bound of the output voltage range corresponds to operation under zero loading (inevitably imposing discontinuous conduction mode (DCM) of the receiving-side diode rectifier) and is obtained using time-domain solution of corresponding differential equations system due to the fact that classical phasor analysis fails to accurately describe DCM operating NS-compensated IWPTL. The proposed method is applied to a 1 kW, 400 V NS-compensated IWPTL operated at LIVO frequency and is well-verified by simulations and experiments. Comparison with output voltage characteristics of SS and SN-compensated IWPTLs assert the advantage of NS-compensated topology.

Performance Analysis of VRLA Battery for DC Load at Telecommunication Base Station

The high level of power outage in Sukabumi-Cianjur area has influenced the operations of telecommunication industry in the vicinity. This has shortened the battery life at the Base Station (BTS). This study aims to analyze the performance of a (new) VRLA battery against a DC load (BTS) to support the continuity of BTS operation in case of a power outage. The research method used is a (new) battery charge-discharge procedure. Parameters are analyzed by determining the on-site battery discharge duration, the pressure at the battery terminals between cells during backup, and the capacity of the rectifier module to support fast charging. To support fast charging, the rectifier with the formula N+1 and C-rate is 10% and C15 is 15% of the battery capacity. The internal impedance value is 3.4 mΩ and the battery terminal pressure (torque) is 9-11 N/m. The battery performance analysis of the four BTS shows that two of them managed to do a backup, while the other two did not provide good performance.

A Novel Three-Vector-Based Model Predictive Direct Power Control for Three-Phase PWM Rectifier

A novel strategy of three-vector-based model predictive direct power control (MPDPC) is proposed for three-phase Pulse-width Modulation (PWM) rectifier. Under ideal grid conditions, three-vector MPDPC is studied, and a good control effect has been achieved. However, under the unbalanced power grid condition, the traditional control strategy has some problems, such as a high harmonic content of current and large instantaneous power pulsation. A new three-vector model predictive control is proposed based on the new instantaneous power theory, and the objective function is established by instantaneous power error. The duty cycle of the selected vector is calculated by solving the optimal objective function. Under an unbalanced power grid, this paper takes a three-phase PWM rectifier as a research object, and carries out simulation and experimental tests on the traditional and new control strategies. The experimental results show that the new control strategy has lower current harmonics, and eliminates the twice grid-frequency oscillation of the grid in instantaneous power.

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.

Implementation on the dSPACE 1104 of VOC-SVM based anti-windup PI Controller of a three-phase PWM rectifier

<p><span>The study made in this paper concerns the use of the voltage-oriented control (VOC) of three-phase pulse width modulation (PWM) rectifier with constant switching frequency. This control method, called voltage-oriented controlwith space vector modulation (VOC-SVM). The proposed control scheme has been founded on the transformation between stationary (α-β) and and synchronously rotating (d-q) coordinate system, it is based on two cascaded control loops so that a fast inner loop controls the grid current and an external loop DC-link voltage, while the DC-bus voltage is maintained at the desired level and ansured the unity power factor operation. So, the stable state performance and robustness against the load’s disturbance of PWM rectifiers are boths improved. The proposed scheme has been implemented and simulated in MATLAB/Simulink environment. The control system of the VOC-SVM strategy has been built based on dSPACE system with DS1104 controller board. The results obtained show the validity of the model and its control method. Compared with the conventional SPWM method, the VOC-SVM ensures high performance and fast transient response.</span></p>

Output Voltage and Resistance Assessment of Load-Independent-Voltage-Output Frequency Operating Inductive Wireless Power Transfer Link Utilizing Input DC-Side Measurements Only

The paper puts forward a method for predicting output voltage and resistance of a series-series (SS) compensated inductive wireless power transfer (IWPT) link operating at load-independent-voltage-output (LIVO) frequency. The link is a part of the static system (reported by the authors in earlier works), wirelessly delivering power into an enclosed compartment without any secondary-to-primary feedback. The proposed algorithm employs input DC-side quantities (which are slow-varying and nearly noise-free, thus measured utilizing low-cost, low-bandwidth sensors) only to monitor output DC-side quantities, required for protection and/or control. It is shown that high estimation accuracy is retained as long as system parameter values are known and the phasor-domain equivalent circuit is valid (i.e., upon continuous-conduction mode (CCM) of the diode rectifier, where the proposed methodology utilizes the recently revealed modified diode rectifier equivalent model for enhanced accuracy). Under light loading (i.e., in discontinuous conduction mode (DCM)), a nonlinear correction is combined with the proposed technique to retain accuracy. The proposed methodology is well-verified by application to a 400 V to 400 V, 1 kW static IWPT link by simulations and experiments.

An Ultrafast Quasi‐Non‐Volatile Semi‐Floating Gate Memory with Low‐Power Optoelectronic Memory Application

AbstractSemi‐floating gate (SFG) memory based on 2D materials shows ultrahigh‐speed operations and fills the huge gap between volatile memory and nonvolatile memory technology in time scale. In this study, a SFG FET with a programmable rectification mode based on the 2D WS2 is achieved. The innovative use of the quasi‐non‐volatile programmable p–n junction photovoltaic effect successfully provides an ultra‐low power consumption photovoltaic quasi‐non‐volatile memory. The device exhibits a switching ratio of more than 107 at constant drain‐source voltage Vds = ±5 V. In the p–n junction mode, after removing the gate voltage for 1 h, the rectification ratio of the device is 105. Combined with ultra‐fast operation speed, which can provide perspectives on possible directions of the next generation for low‐power high‐speed semi‐floating gate FET applications.

Unattached irregular scene text rectification with refined objective

Recently, text recognition tasks have reached a high level with deep learning-based methods. The techniques are widely applied in different fields, and nowadays most researchers aim to build an effective approach to deal with irregular text in scene images. In this work, we propose a GAN-based framework to rectify scene text with rotation, curving, or other distortions. Unlike previous rectification modules that rely on the recognition networks, our model can be utilized either as an independent model or an extra component. Therefore, annotations of the text content are not required to train the model. And we utilize a refined training objective with the proposed sample loss, which is able to effectively control pixels in the output images that are supposed to be sampled from input ones. Experiments on public benchmarks demonstrate the effectiveness of our method. The code will be publicly available on github soon.

Synchronous Generator Rectification System Based on Double Closed-Loop Control of Backstepping and Sliding Mode Variable Structure

Low-voltage and high-current direct current (DC) power supplies are essential for aerospace and shipping. However, its robustness and dynamic response need to be optimized further on some special occasions. In this paper, a novel rectification system platform is built with the low-voltage and high-current permanent magnet synchronous generator (PMSG), in which the DC voltage double closed-loop control system is constructed with the backstepping control method and the sliding mode variable structure (SMVS). In the active component control structure of this system, reasonable virtual control variables are set to obtain the overall structural control variable which satisfied the stability requirements of Lyapunov stability theory. Thus, the fast-tracking and the global adjustment of the system are realized and the robustness is improved. Since the reactive component control structure is simple and no subsystem has to be constructed, the SMVS is used to stabilize the system power factor. By building a simulation model and experimental platform of the 5 V/300 A rectification module based on the PMSG, it is verified that the power factor of the system can reach about 98.5%. When the load mutation occurs, the DC output achieves stability again within 0.02 s, and the system fluctuation rate does not exceed 2%.

Scalable image-based indoor scene rendering with reflections

This paper proposes a novel scalable image-based rendering (IBR) pipeline for indoor scenes with reflections. We make substantial progress towards three sub-problems in IBR, namely, depth and reflection reconstruction, view selection for temporally coherent view-warping, and smooth rendering refinements. First, we introduce a global-mesh-guided alternating optimization algorithm that robustly extracts a two-layer geometric representation. The front and back layers encode the RGB-D reconstruction and the reflection reconstruction, respectively. This representation minimizes the image composition error under novel views, enabling accurate renderings of reflections. Second, we introduce a novel approach to select adjacent views and compute blending weights for smooth and temporal coherent renderings. The third contribution is a supersampling network with a motion vector rectification module that refines the rendering results to improve the final output's temporal coherence. These three contributions together lead to a novel system that produces highly realistic rendering results with various reflections. The rendering quality outperforms state-of-the-art IBR or neural rendering algorithms considerably.

고조파 및 불평형 성분을 가지는 계통 환경에 따른 3상 펄스폭변조정류기 성능 비교 연구

In this paper, the input and output performance of a three-phase pulse width modulation (PWM) rectifier operated by each of three different control techniques based on current control and power control in the grid with harmonics and unbalanced components are compared and analyzed. Regardless of the basic and high-efficiency types, the same current-controlled and power-controlled techniques showed similar performance in the harmonics and unbalanced grid conditions. In all grid conditions with harmonics and unbalanced components, the output voltage by the power-controlled rectifier has a lower ripple value than the output voltage by the current-controlled rectifier. Therefore, in terms of output voltage ripple, it is confirmed that the power-controlled rectifier shows more robust characteristics in harmonics and unbalanced grid condition.

COMPARATIVE STUDY OF SINGLE-PHASE PWM RECTIFIER CONTROL TECHNIQUES

In this study, 2.5 kW single-phase pulse-width modulated rectifier is simulated with three different control techniques to investigate the performance of controllers. Rectifier simulation is performed in Matlab / Simulink environment by using hysteresis current control, sinusoidal pulse width modulation and voltage oriented control techniques. In the performance comparison of the control techniques, considering the switching frequencies, the total harmonic content of the current drawn from the grid, the phase difference between the grid voltage and the grid current, and the DC bus voltage regulation at the output are considered as comparison criteria. The switching frequency is set to 35 kHz in sinusoidal pulse width modulation and voltage oriented control techniques. Since the switching frequency is variable in the hysteresis current control technique, the average and instantaneous switching frequency are calculated for different hysteresis band values. In the results with the technique, the switching frequency varies between 18.52 kHz and 47.6 kHz, while the average switching frequency is 34.6 kHz. As a result, the total harmonic distortion of the grid current with hysteresis current control, sinusoidal pulse width modulation and voltage oriented control techniques is 3.69%, 1.12% and 1.82%, respectively. The synchronization with the grid voltage is achieved with all techniques, and the DC voltage is regulated with active power.

Fuzzy Logic Control Based Maximum Power Point Tracking for Wind Energy Conversion System

Variable speed operation and direct drive wind turbines are the modern developments in the technology of Wind energy conversion system (WECS). WECS comprises a Permanent Magnet Synchronous Generator (PMSG) driven by a wind turbine, a generator side AC/DC rectifier, boost converter and a grid-side DC/AC converter and grid. The wind turbine converts part of the kinetic energy of the wind into mechanical energy which intern is converted into electrical energy via the generator. Since the generator output frequency is variable depends on the wind conditions, the FLC based MPPT is used to extract the maximum possible output power by controlling the generator speed. In this, the grid connected wind energy conversion system is considered. Wind turbine, PMSG model and FLC algorithm were simulated in Matlab/Simulink and the mechanical and electrical characteristics such as rotor speed, torque, induced voltage and current have been observed for various wind speeds. Also the DC link voltage has been measured with IGBT based controlled rectifier mode to stabilize the output frequency. From the simulation results, FLC based MPPT method has proven that it can extracted the maximum output power for the varying wind speed conditions.

Lyapunov Function Based Flux and Speed Observer Using Advanced Non-linear Backstepping DVC for PWM-Rectifier Connected Wind-turbine-driven PM Generator

In this paper, modeling, and speed/position sensor-less designed Direct Voltage Control (DVC) approach based on the Lyapunov function are studied for three-phase voltage source Space Vector Pulse Width Modulation (SVPWM) Rectifier Connected to a Permanent Magnet Synchronous Generator (PMSG) Variable Speed Wind Power Generation System (VS-WPGS). This control strategy is based on voltage orientation technique without mechanical speed sensor. Advanced Non-linear Integral Backstepping Control (IBSC) of the Generator Side Converter (GSC) has the ability to have a good regulation of the DC link voltage to meet the requirements necessary to achieve optimal system operation, regardless of the disturbances caused by the characteristics of the drive train or some changes into the DC load. The estimation of the speed is based on Model Reference Adaptive System (MRAS) method. This method consists in developing two models one of reference and the other adjustable for the estimation of the two d-q axis components of the stator flux from the measurement of currents, the speed estimated is obtained by canceling the difference between the reference stator flux and the adjustable one using Lyapunov criterion of hyper-stability. Some results of simulation using Matlab/Simulink® are presented, discussed to prove the efficiency and robustness of the system control policy for WPGS against external and internal perturbations.

CIA-SSD: Confident IoU-Aware Single-Stage Object Detector From Point Cloud

Existing single-stage detectors for locating objects in point clouds often treat object localization and category classification as separate tasks, so the localization accuracy and classification confidence may not well align. To address this issue, we present a new single-stage detector named the Confident IoU-Aware Single-Stage object Detector (CIA-SSD). First, we design the lightweight Spatial-Semantic Feature Aggregation module to adaptively fuse high-level abstract semantic features and low-level spatial features for accurate predictions of bounding boxes and classification confidence. Also, the predicted confidence is further rectified with our designed IoU-aware confidence rectification module to make the confidence more consistent with the localization accuracy. Based on the rectified confidence, we further formulate the Distance-variant IoU-weighted NMS to obtain smoother regressions and avoid redundant predictions. We experiment CIA-SSD on 3D car detection in the KITTI test set and show that it attains top performance in terms of the official ranking metric (moderate AP 80.28%) and above 32 FPS inference speed, outperforming all prior single-stage detectors. The code is available at https://github.com/Vegeta2020/CIA-SSD.

DC Bus Voltage Regulation Strategy in Maritime DC Power System for Minimized Converter Loss

In a maritime dc power system, the rectified dc-bus voltage of a permanent magnet synchronous generator is generally regulated by the pulsewidth modulation (PWM) operation of an active ac/dc converter. This article proposes a dc bus voltage regulation strategy exploiting the six-step operation. Under the six-step operation, the switching loss of the converter can be significantly reduced, compared to the PWM operation. Moreover, due to the higher modulation index and the less flux-weakening current of the six-step operation, the conduction loss can also be reduced. By employing diode rectification mode at light load, the conduction loss induced by the non-negligible ripple current of the six-step operation could be minimized. This article implements a controller for the proposed dc bus voltage regulation strategy and verifies its validity with simulation and experimental setup. According to the simulation and the experimental test, the converter efficiency at the rated load is enhanced by 0.6% and 0.4%, and the converter loss is reduced by up to 70% and 19%, respectively.

Wide-Range Operation of High Step-Up DC-DC Converters with Multimode Rectifiers

This paper discusses the essence and application specifics of the multimode rectifiers in high step-up DC-DC converters. It presents an overview of existing multimode rectifiers. Their use enables operation in the wide input voltage range needed in highly demanding applications. Owing to the rectifier mode changes, the converter duty cycle can be restricted to a range with a favorable efficiency. It is shown that the performance of such converters depends on the front-end inverter type. The study considers current- and impedance-source front-end topologies, as they are the most relevant in high step-up applications. It is explained why the full- and half-bridge implementations provide essentially different performances. Unlike the half-bridge, the full-bridge implementation shows step changes in efficiency during the rectifier mode changes, which could compromise the long-term reliability of the converter. The theoretical predictions are corroborated by experimental examples to compare performance with different boost front-end inverters.

The efficiency of the active controlled rectifier operation in the mains voltage distortion mode

Goal. Checking the efficiency of the active rectifier with differences types of control systems in conditions of deep voltage distortions of a three-phase three-wire supply network. Methodology. The authors have used the Matlab/Simulink software environment to create a model of an active rectifier with various types of control systems as part of a frequency electric drive. We performed a series of simulations of the operating modes of an active rectifier with various control systems when the supply voltage is distorted. Results. When the active rectifier is operating in an unregulated mode, the distortions of the current and mains voltage exceed the maximum permissible values. The quality indicators of the mains current and mains voltage are significantly higher than the normally permissible values. In the absence of voltage distortions in the supply network, the operation of the active rectifier can effectively eliminate the distortions of the mains current, regardless of the type of control system of the active rectifier. In conditions of deep distortions of the supply network voltage, the operation of an active rectifier with a vector control system is more efficient than with a parametric control system. Originality. Criteria for determining the quality of consumed electricity at the connection point of the circuit are proposed. Practical significance. Recommendations have been developed for the use of active rectifier control systems when working with a distorted power supply voltage.

AC-DC Converter Operation for Active Sinusoidal Line Converter.(Dept.E)

The paper describes and implements a stand-alone! unity power factor, controllable current source converter system. It is based on high frequency PWM technique. The converter topology is chosen to operate for both inverter and rectifier modes. Firstly, the principle of operation is discussed. Then. the presented AC-DC converter that demands only sinusoidal active current is studied Most features of the converter are dearly interpreted for resistive and dynamic loads. On the basis of the given analysis, the paper provides PWM converter design guidelines for unity power factor operation. Also, a novel control strategy is proposed, which .allows to fulfill all the specifications; in particular zero reactive power demand and very low distorted line currents have been guaranteed. The proposed method in this paper utilizes simultaneously the control variables: modulation index D (variab1e PWM pattern) and power angle 8 (position of the PWM pattern). The instantaneous control for both achieves high--dynamic response and insensitiveness to parameter variations and disturbances. Also, the presented control structure employs power factor adjustment capability. This development provides a low cost solution, where no digital signal processors or large memories for the PWM generation are required. Results from device Lwei PSPlCE confirm the validity of the proposed method and the performed analysis. The proposed system can be utilized for power conditioning, DC and AC drive applications.

Voltage Sensorless Direct Power Control for PWM Rectifier Under Distorted Network Using Improved Virtual Flux Estimator

Generally, AC-DC conversion system in the power system use the diode-bridge based rectifiers that cannot be reversible and causes high current distortion. Besides, they reduce the power factor and energy quality. recently, the application of three-phase pulse width modulation (PWM) rectifier has been risen quickly due to breakthrough advancement in the power devices. This converter offers sinusoidal input currents and minimized harmonic distortion and unity power factor. This work presents an improved sensorless control for performance enhancement purpose of the PWM-rectifier. The proposed control strategy uses the virtual flux principle with second-order generalized integrator (SOGI) in order to overcome the accompanying drawbacks of using pure integrator of low-pass filters for estimation. The integration of improved virtual flux estimator with direct power control saves the cost of using many voltage sensors which can increase the reliability and effectivity of the control system. Moreover, it improves control robustness and against highly distorted network. The different proposed approaches have been investigated through simulation using MATLAB/Simulink software.