Voltage Tracking Research Articles

A New, Scalable and Low Cost Multi-Channel Monitoring System for Polymer Electrolyte Fuel Cells.

In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level.

Control of Three-Phase Voltage Source Converters with the Derivative-Free Nonlinear Kalman Filter

The paper is concerned with proving differential flatness of the three-phase voltage source converter (VSC) model and its resulting description in the Brunovsky (canonical) form. For the linearized canonical model of the converter a feedback controller is designed. At a second stage, a novel Kalman Filtering method (Derivative-free nonlinear Kalman Filtering) is introduced. The proposed Kalman Filter is redesigned as disturbance observer for estimating additive input disturbances to the VSC model. These estimated disturbance terms are finally used by a feedback controller that enables the DC output voltage track desirable setpoints. The efficiency of the proposed state estimation-based control scheme is tested through simulation experiments.

Dual Mode-Multiple Output SEPIC Converter Integrated with Passive Ripple Cancelling Circuit for Standalone PV Energy Harvesting System

This document addresses an exhaustive standalone Photovoltaic (PV) energy harvesting system considering two crucial issues: system efficiency and cost effectiveness. It contributes a compact resolution with a combined feature of Dual Mode-Multiple Output (DMMO) associated with input ripple reduction technique. Control strategy incorporates with aspect of Maximum Power Point Tracking (MPPT) and output voltage levels regulation. A theoretical analysis is conducted to evaluate the effect of ripple current on PV power. Proposed dual mode converter achieves efficiency of 98.36% and 97.76% respectively for mode-1 and mode-2 operation. However, simulation is performed applying MATLAB/SIMULINK tools to analyze the feasibility of the recommended system.

Double Integral Sliding Mode MPPT Control of a Photovoltaic System

This brief proposes a new maximum power point tracker (MPPT) for a stand-alone photovoltaic (PV) system using the concept of double integral sliding mode controller (DISMC). Performance of a sliding mode controller (SMC) is greatly influenced by the choice of the sliding surface. A double integral SMC uses double integral of tracking voltage error term in its sliding surface to eliminate steady-state error apart from providing robust control actions in face of system uncertainties. However, there is still difficulty of increased chattering and slow transient response in DISMC. In this brief, the objective is to exploit the merits of the DISMC for designing an MPPT for PV system whilst the disadvantages of chattering and slow transient response are alleviated by choosing a new sliding surface. The design of this new DISMC-MPPT system considers the uncertainties in weather conditions and variations in load. This MPPT has been implemented using a pulsewidth modulator controlled dc/dc converter to keep the switching frequency constant. Thus, designing the control and filter circuits becomes simpler. The effectiveness of the proposed DISMC has been validated using simulation and experimental results using a prototype PV control system setup.

Resonant–Repetitive Combined Control for Stand-Alone Power Supply Units

This paper investigates a combined resonant–repetitive (RR) control structure for a three-phase four-leg dc/ac converter power supply. The RR control configuration is composed by a resonant controller tuned at the system fundamental frequency working in conjunction with a plug-in-type repetitive controller. The resonant part of the control scheme is used to assure prompt tracking of the inverter output voltage and to achieve as fast as possible system response to load variations; to this purpose, it is tuned at the fundamental frequency. At the same time, the resonant controller is able to stabilize the system without the necessity of any further additional controller; the repetitive part of the scheme is implemented for the fine regulation at the system harmonic frequencies. The proposed control configuration is used to regulate the power supply output voltage, providing very good tracking of the output voltage reference even in the presence of a nonlinear load. Experimental validation from a 40-kVA converter prototype is presented to validate the operation of the proposed converter and control.

CCII+ Based on QFGMOS for Implementing Chua s Chaotic Oscillator

A new design of a positive-type second-generation current conveyor (CCII+) based on quasi-floating gate MOSFETs (QFGMOS) is introduced. The proposed CCII+ is compared with others showing bandwidth advantages, e.g. it reaches 257MHz and 523MHz for the voltage tracking (between ports Y to X) and current tracking (between ports X to Z), respectively, while the parasitic resistance at port X is low as Rx=5.1794Ω. This new CCII+ is used to implement Chua's diode that is modeled by a piecewise-linear (PWL) function consisting of two negative slopes and two break points. That way, Chua's chaotic oscillator is designed using standard CMOS technology of 0.5μm. SPICE simulation results are provided to show the suitability of the proposed CCII+ based on QFGMOS for generating chaotic phenomena through implementing Chua's circuit.

Tracking Algorithms and Voltage Controllers Used to Obtain the Maximum Power Point of PV Arrays

In this paper, a fuzzy proportional derivative and/or a classical proportional integral is used to control the terminal voltage of the photovoltaic (PV) array connected to the input of a dc/dc step-up converter. The voltage reference is tracked continuously by employing a perturb and observe and the incremental conductance algorithms in order to make the PV array operate as close as possible to the maximum power point (MPP). However, these techniques produce oscillations around the MPP, which can be reduced by applying adaptive steps instead of fixed steps. Additionally, this paper presents the complete mathematical model of the power converter associated with a PV array where the parasitic elements are included. Simulations and experimental results under different environmental conditions are presented to demonstrate the effectiveness of the proposed approach.

DC-Link Voltage Coordinated-Proportional Control for Cascaded Converter With Zero Steady-State Error and Reduced System Type

Cascaded converter is formed by connecting two subconverters together, sharing a common intermediate dc-link voltage. Regulation of this dc-link voltage is frequently realized with a proportional-integral (PI) controller, whose high gain at dc helps to force a zero steady-state tracking error. Such precise tracking is, however, at the expense of increasing the system type, caused by the extra pole at the origin introduced by the PI controller. The overall system may, hence, be tougher to control. To reduce the system type while preserving precise dc-link voltage tracking, this paper proposes a coordinated control scheme for the cascaded converter, which uses only a proportional dc-link voltage regulator. The resulting converter is thus dynamically faster, and when compared with the conventional PI-controlled converter, it is less affected by impedance interaction between its two subconverters. The proposed scheme can be used with either unidirectional or bidirectional power flow, and has been verified by simulation and experimental results presented in this paper.

The <inline-formula> <tex-math notation="LaTeX">$H_{\infty }$ </tex-math></inline-formula> Control Method of Grid-Tied Photovoltaic Generation

Microgrid allows high penetration of renewable energy sources, and provides technical foundation for the grid connection and operation of distributed generations (DGs). The negative impacts caused by DGs should be reduced inside the microgrid. Photovoltaic (PV) generation is one of the major distributed energy sources, and the performance of PV generation systems connected to microgrid directly affects power quality and other technical indexes of the microgrid. Thus, the research of flexible microgrid connection control for PV generation system has both theoretical significance and practical value. This paper makes a concise exposition on the H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> control theory and applies this theory to the flexible microgrid connection control for PV generation systems. This paper focuses on the specific situation where the microgrid is grid tied to the main power grid. We establish the mathematical model of PV generation system and adopt the H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> control theory to design a voltage tracking controller. Theoretical analysis proved that our control system is internally stable. Simulations under six different conditions are performed using MATLAB/Simulink, and the results demonstrate that the grid-tied PV generation system using H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> controller has high control accuracy and robustness.

Boost converter with adaptive reference tracking control for dimmable white LED drivers

An LED driver consisting of dimmable current regulators and a boost converter with adaptive reference tracking control (ARTC) is proposed. The ARTC is realized with only one integrator and one subtractor to detect the voltage variation among the current regulators and then to generate an adaptive reference tracking voltage. Based on the reference tracking voltage, the driving voltage of the boost converter is dynamically adjusted, so as to not only maintain a minimum voltage on the current regulator but also keep the required LED-string current. A prototype control circuit including ARTC and PWM control fabricated with TSMC 0.35-μm 2P4M CMOS process validates the proposed technique. The measurement results show that the driving voltage of the boost converter is automatically regulated to compensate for the voltage alteration on the current regulators. Furthermore, the overall efficiency of the LED driver with ARTC is 6.1% better than that of the LED driver without ARTC.

Improved transient response of controllers by synchronizing the modulator with the load step: application to v2ic

V 2 I c is a ripple-based control with an excellent performance for load transients and reference voltage tracking because it exhibits a feedforward of the load current and the error of the output voltage. However, if V 2 I c is modulated with constant frequency, constant on-time or constant off-time, its dynamic response is hindered by delays in the response. This paper proposes a technique that synchronizes the clock of the converter to initialize the duty cycle when a worst-case load transient occurs using the current through the output capacitor to detect load transients. It is exemplified on a V 2 I c control but it is applicable to most of controllers as it only acts on the modulator.

Power Control of PWM Rectifier with Resistive and Reactive Load

The realization of power modeling and power control of PWM rectifier with resistive and reactive load is based on the method of Lyapunov. Firstly, PWM rectifier's mathematical power model is established in d-q synchronous rotating coordinates, and balance point is found according to the control requirement of the system and analysis the stability of the equilibrium point according to the Lyapunov method and invariant theory. Then PWM rectifier's power controller has been gotten through damping injection. The designed power controller realizes fast voltage tracking and makes the net side power factor as 1, which has great inhibitory effect on resistive and inductive disturbance. Influence on the system exerted by different damping injection is analyzed and feasibility of PWM rectifier's power control based on Lyapunov method is verified.

DC inclined-plane tracking and erosion test of insulating materials

The paper reviews previous work on the DC inclined plane test and suggests equivalent DC voltage levels in parallel to AC voltage in the ASTM inclined plane tracking and erosion test. The aim of this work is to provide a basis for standardizing the inclined plane test for DC voltage. Round robin tests done in five laboratories on five specimens of a silicone rubber material were done with the purpose of establishing appropriate ratios by which the equivalent DC voltages can be determined with respect to the corresponding AC voltages. These levels were determined as 67% and 87%, for +DC and -DC respectively, of the AC initial tracking voltage, and for practical purposes, these levels are rounded to 70 and 90%.

Voltage Tracking of a Single-phase Inverter in an Islanded Microgrid

Voltage source inverters (VSI's) are generally used to interface with the distributed generators (DG) in microgrid. The voltage quality of the network is controlled on the basis of reference voltage tracking strategy of the VSI. In this paper, mathematical formula is derived for voltage tracking strategy, and its validity and robustness are demonstrated for both steady-state and transient conditions. Furthermore, the eectiveness of various controller has been analysed on the system response, and the eects of control gain parameters on the system characteristics are studied using root locus analysis. The performance of the system is found to be eective to track the reference grid voltage (Vg*)

No-Load Grid Connection Control Strategy of Double-Fed Induction Generator in Wind Power Generation System

A control strategy and implement method for the no-load cutting-in of double-fed induction generator in power system are introduced. The paper analyze the basal principle of DFIG under no-load condition, and build the correspondent mathematical model. Then according to the model, the paper propose a control strategy on the basis of magnetic flux linkage vector orientation control. Using simulation software set up a simulation model. The result of simulation showed that: the no-load grid connection control strategy can effectively keep the stator voltage track the time-varing grid voltage. At the interconnection instant, the impulse current is almost zero, thus the soft cutting-in of DFIG is well realized.

A wide output range voltage-mode buck converter with fast voltage–Tracking speed for RF power amplifiers

A high switching frequency voltage-mode buck converter with fast voltage-tracking speed, wide output range and PWM/PSM control strategy for radio frequency (RF) power amplifiers (PAs) has been proposed. To achieve the fast voltage-tracking speed, the maximum charging and discharging current control method has been used, and the filter inductor and capacitor values are reduced. A novel compensated error amplifier (EA) is presented to realize the wide output range. The investigated converter has been fabricated with GF 0.35μm CMOS process and can operate at 5MHz with the output voltage range from 0.6V to 3.4V. The experimental results show that the voltage-tracking speed can achieve 8.8μs/V for up-tracking and 6μs/V for down-tracking. Besides, the recovery time is less than 8μs when the load change step is 400mA.

Method on Fault Detection and Diagnosis for Track Circuit Based on Main Rail Voltage

This paper proposes a method of the fault detection and diagnosis for the railway circuit of ZPW-2000 system based on the main track voltage curve. Exact curve matching fault detection method and SVM-based fault diagnosis method are adopted. Based on envelope algorithm, exact curve matching method is used to match the detected current curve with the reference curve so as to predict whether the curve would have fault or not. Then, the SVM-based fault diagnosis method is used to make sure that the fault classification could be diagnosed intelligently. The experiment results show that the proposed method can accurately identify the track circuit fault state, and the accuracy rate in the diagnosis of the fault location is above 99%, which verify the effectiveness of the method in the fault detection and diagnosis.

Analytical synthesis of voltage‐mode even/odd‐nth‐order differential difference current conveyor and fully differential current conveyor II‐grounded resistor and capacitor universal filter structures

SummaryA complete definition of an odd/even‐nth‐order notch or band‐reject filter transfer function is presented. Based on the differences between the input voltage and (i) an nth‐order high‐pass; (ii) a traditional nth‐order notch; and (iii) an nth‐order all‐pass filtering transfer function, a systematic method has been proposed to derive a universal filter structure that can realize voltage‐mode odd/even‐nth‐order low‐pass, band‐pass, high‐pass, all‐pass and traditional notch filters. The intrinsic capability of voltage‐mode addition and subtraction of the two active elements, differential difference current conveyors and fully differential current conveyors, is used to advantage in the aforementioned synthesis procedure. Based upon the definition of an nth‐order notch or band‐reject filter transfer function proposed in this paper, the aforementioned universal one has been further extended to the newly defined nth‐order band rejection filter. The voltage and current tracking errors of the two active elements are compensated by varying the resistances of the proposed filter. Filtering feasibility, stability, component sensitivities, linear and dynamic ranges, power consumption, and noise are simulated using H‐Spice with 0.35 µm process. Compared to some of the recently reported universal biquads, the new one is shown to enjoy the lowest component sensitivities and the best output accuracy for all‐pass signals. Moreover, Monte Carlo and two‐tone tests for intermodulation linearity simulations are also investigated. Copyright © 2014 John Wiley &amp; Sons, Ltd.

A comparator-based cyclic analog-to-digital converter with multi-level input tracking boosted preset voltage

In this paper, we propose a comparator-based switched-capacitor (CBSC) architecture using a multi-level input tracking preset voltage scheme. The CBSC is used to compensate for technology scaling and to reduce the power consumption of a 2.8 MS/s 10-bit cyclic analog-to-digital converter (ADC). A multi-level preset voltage tracks the input voltage in order to improve the conversion rate without consuming additional power. Additionally, a comparator, current sources, and a feedback capacitor are shared to reduce the power and area of this cyclic ADC. Near the Nyquist-rate, a prototype implemented in 0.18 μm CMOS technology has a signal-to-noise and distortion ratio of 53.69 dB and a spurious-free dynamic-range of 62.36 dB, while consuming 0.73 mW of power.

가변출력전압 AC/DC 컨버터를 이용한 파라메트릭 어레이 트랜스듀서용 고효율 전력증폭기의 설계

Parametric array transducers are used for long-range and highly directional communication in an underwater environments. The power amplifiers for parametric array transducers should have sufficient linear output characteristic and high efficiency to avoid communication errors, system heating, and fuel problems. But the conventional power amplifier with fixed source voltage is very low efficient due to large power loss by the big difference between the fixed source voltage and the amplifier output voltage. Thus to solve the problems this paper proposes the high efficiency power amplifier for parametric array transducers. The proposed power amplifier ensures high linearity of output characteristic by utilizing the push-pull class B type amplifier and furthermore gets high efficiency by applying the envelope tracking technique that variable source voltage tracks the envelope of the amplified signal. Also the paper suggests the detailed circuit topology and design guideline of class B push-pull type amplifier and variable output voltage AC/DC converter. Its characteristics are verified by the detailed simulation and experimental results.