Point Tracking Strategy Research Articles

Real-time Maximum Power Point Tracking with Single Current Monitoring

This paper brings forward the Single-Current-Based method which can realize the output power of the solar cell reach the maximum value within this period of time by controlling the current to maximum. The paper firstly elaborates the principle and the function of Single-Current-Based MPPT strategy, and then it includes the main design of DC-DC convertor, and the design of stepping PWM controller which base on the CMOS digital circuit hardware logical programming. Besides, the paper shows the experimental process and results in detail for the analysis of the feasibility of the system and shows its success on achieving the effect of Single-Current-Based method of the MPPT controlling system, which also shows the advantages from other maximum power point tracking strategies.

Vibration Energy Scavenging System With Maximum Power Tracking for Micropower Applications

In this work, we present a vibration-based energy scavenging system based on piezoelectric conversion for micropower applications. A novel maximum power point (MPP) tracking scheme is proposed to harvest the maximum power from the vibration system. A time-multiplexing mechanism is employed to perform energy harvesting and MPP tracking alternately. In the MPP tracking mode, a voltage reference that represents the optimal output voltage at the MPP is generated. A control unit then uses this reference to track the system operation around the MPP. The proposed system is capable of self-starting up without the help of an energy buffer. As a result, it is suitable for battery-less applications or when the energy buffer is completely drained. This tracking scheme has very small power overhead and is simple to implement in VLSI. Hence, it is especially applicable for micropower systems. The entire design was fabricated in a 0.35-μ m CMOS process. Experimental results verified the proposed MPP tracking scheme and demonstrated the system operation. Measurement results show that the power harvesting efficiency of the electrical circuitry is higher than 90%.

Modeling and Simulation of Three Phase Photovoltaic Grid-Connected Generation System

According to the principle of photovoltaic(PV) grid-connected generation, the maximum power point tracking (MPPT) and grid-connected control strategy were presented in this paper. Based on the V-I characteristic curve of photovoltaic array, it built the mathematic model of photovoltaic array and the MPPT algorithm. Through adopting the double-loop feedback control strategy, it achieved the unit power factor control. Lastly, with the example system, it implemented the simulations analysis including the sunlight changing and the temperature changing. The simulation results show that the proposed models and the control strategy are correct.

MPPT of Photovoltaic Power Generation Based on Double Fuzzy Controllers

This paper mainly discussed the non-linear characteristics of photovoltaic cell and the importance of maximum power point tracking (MPPT) strategy. Most of MPPT control methods had the shortcomings of inaccuracy, tardiness, complexity and big fluctuations nearby the MPP which greatly reduced the efficiency of large photovoltaic power generation system. Double fuzzy logic control (DFLC) method can solve this problem The judgment condition of choosing FLC was listed in which FLC 1 targeted to less shake and made the curve become more smooth and steady nearby the MPP, FLC 2 was combined by fuzzy control and PID algorithm, and both of them aim to realize the optimization control of PV system. The results of simulation show that the proposed control strategy can track the MPP of PV system very accurately and quickly along with the rapid change of the ambient environment.

Topological Overview of Powertrains for Battery-Powered Vehicles With Range Extenders

The paper presents a topological overview of hybrid powertrains for battery-powered vehicles reinforced by range extenders. First, tradeoffs of employing high energy versus high power battery are revealed. Then, different topologies of battery-ultracapacitor hybrids are discussed, highlighting pros and cons of each configuration. The superiority of fully active hybrids is indicated, obtained at the expense of increase of power electronic circuitry, control effort, and efficiency. The second part of the paper focuses on two types of range extenders: renewable energy and fuel-based units. The operation strategy is shown to be different for each range extender type. The renewable-energy-based range extender should be operated employing either passive or active maximum power point tracking strategy and hence not be involved in the powertrain energy balancing. It is shown that such a strategy allows the rest of system to perceive the renewable energy range extender (RERE) as a part of the load and act accordingly. Solar array is given as an example of a RERE and the possible connection topologies are discussed. On the other hand, the fuel-based range extender (FBRE) should be operated near the lowest specific fuel consumption point employing maximum efficiency point tracking strategy. Fuel cells and internal combustion engines are specified as examples of FBREs. The complete powertrain is shown to resemble a dc microgrid with source, storage, and load units connected through power management circuitry to a common dc link.

A Modular Self-Controlled Photovoltaic Charger With InterIntegrated Circuit ( $\hbox{I}^{2}\hbox{C}$) Interface

This paper presents a modular self-controlled photovoltaic (PV) charger with maximum power point tracking (MPPT) and pulse-charging schemes. The studied PV modules can be flexibly parallel connected through interleaved operation using an interintegrated circuit (I2C) interface. The MPPT control of PV panel is implemented by using a current-sensing technique with the on-state resistance of the power switch. Both an expensive hall-effect sensor and additional current-sensing resistor are not needed. A pulse-charging scheme without extra battery-current sensor is also designed to prolong the lifetime of the acid-lead battery. The operation principles and design considerations of the proposed PV charger are analyzed and discussed. A laboratory prototype is implemented and tested to verify its feasibility.

Maximum Power Point Tracking of Multiple Photovoltaic Arrays: A PSO Approach

Multiple photovoltaic (PV) modules feeding a common load is the most common form of power distribution used in solar PV systems. In such systems, providing individual maximum power point tracking (MPPT) schemes for each of the PV modules increases the cost. Furthermore, its v-i characteristic exhibits multiple local maximum power points (MPPs) during partial shading, making it difficult to find the global MPP using conventional single-stage (CSS) tracking. To overcome this difficulty, the authors propose a novel MPPT algorithm by introducing a particle swarm optimization (PSO) technique. The proposed algorithm uses only one pair of sensors to control multiple PV arrays, thereby resulting in lower cost, higher overall efficiency, and simplicity with respect to its implementation. The validity of the proposed algorithm is demonstrated through experimental studies. In addition, a detailed performance comparison with conventional fixed voltage, hill climbing, and Fibonacci search MPPT schemes are presented. Algorithm robustness was verified for several complicated partial shading conditions, and in all cases this method took about 2 s to find the global MPP.

Comparison of MPPT Strategies for Solar Modules

The paper studies the behavior of three different Maximum Power Point Tracking (MPPT) strategies applied to solar modules: three-point perturb and observe, fixed-step incremental conductance, and variable-step incremental conductance. It starts with a brief description of each method and then it compares them considering three criteria: simplicity of implementation, capability to follow irradiance variations and sensitivity to noise in the required measurements. Diverse simulations have been performed and the main results are presented.

Energetic Macroscopic Representation and Inversion-Based Control Illustrated on a Wind-Energy-Conversion System Using Hardware-in-the-Loop Simulation

Study of a wind-energy-conversion system (WECS) is a very attractive topic for students. The analysis of an entire WECS requires knowledge of different scientific fields, which are of interest for future engineers. In this paper, energetic macroscopic representation is used to describe a complete WECS. This synthetic graphical tool yields a natural decomposition of the studied WECS with respect to physical laws. Moreover, a control scheme is easily deduced from this description using inversion-based rules. Thus, maximum-power point-tracking strategies and drive controls can be defined. The simulation of the studied WECS is directly transposed to Matlab-Simulink. Moreover, a hardware-in-the-loop simulation of the WECS is studied using an actual induction generator and an electrical drive to simulate the wind turbine. This graphical methodology is used in the electrical engineering Masters degree at the University of Lille (France).

Analysis and Design of Maximum Power Point Tracking Scheme for Thermoelectric Battery Energy Storage System

The analysis and design of an adaptive maximum power point tracking (MPPT) scheme using incremental impedance are presented. A small-signal model is mathematically derived, and the impact of two major design parameters, which are scaling factor and sampling interval, is analyzed in the frequency domain. Four factors which specifically affect the MPPT response are also clearly addressed. Based on this analysis, a design methodology to achieve a desirable transient response, while retaining system stability, is developed. The design methodology is implemented and verified with hardware experiments on a thermoelectric generator battery energy storage system, which indicate agreement between dynamic response and target bandwidth.

Maximum Power Point Tracking Scheme for PV Systems Operating Under Partially Shaded Conditions

Current-voltage and power-voltage characteristics of large photovoltaic (PV) arrays under partially shaded conditions are characterized by multiple steps and peaks. This makes the tracking of the actual maximum power point (MPP) [global peak (GP)] a difficult task. In addition, most of the existing schemes are unable to extract maximum power from the PV array under these conditions. This paper proposes a novel algorithm to track the global power peak under partially shaded conditions. The formulation of the algorithm is based on several critical observations made out of an extensive study of the PV characteristics and the behavior of the global and local peaks under partially shaded conditions. The proposed algorithm works in conjunction with a DC-DC converter to track the GP. In order to accelerate the tracking speed, a feedforward control scheme for operating the DC-DC converter is also proposed, which uses the reference voltage information from the tracking algorithm to shift the operation toward the MPP. The tracking time with this controller is about one-tenth as compared to a conventional controller. All the observations and conclusions, including simulation and experimental results, are presented.

A Preliminary Study of the Distributed Maximum Power Point Tracker Designs for Different types of Solar Cells in Solar and Electric Vehicle Arrays

For solar and electric vehicles, a highly distributed maximum power point tracking (MPPT) scheme is preferred. A maximum power point (MPP) tracker has been previously presented for a single triple junction cell. The Texas Instruments MSP430 microprocessor, which is designed for 1.8 V applications, provides the tracking intelligence. However, the MPP cell voltages of other cell types under different environmental conditions may fall well below 1.8 V. This paper conducts a preliminary study of four maximum power point tracker designs for different cell types, which cover an input supply voltage range from 0.3 to 3.0 V. A comparison of the applications, the topologies and the costs of the four designs is summarised at the end of the paper.

Comparison of the performance of maximum power point tracking schemes applied to single-stage grid-connected photovoltaic systems

This work presents a comparison of various maximum power point tracking (MPPT) techniques applied to 1-phis, single-stage, grid-connected photovoltaic (PV) systems. A representative single-stage grid-connected PV system, based on buck-boost converter topology operating in discontinuous current mode (DCM) with sine-triangle pulse width modulation (SPWM) and feeding sinusoidal power into the grid, is considered for this study. MPPT techniques are compared on the basis of the time taken to reach (track) the MPP, operating point oscillations in the vicinity of MPP and the dependence of the algorithms, if any, on array configuration and parameters. Comparison is also made on the basis of the energy extracted from the PV source during the transient tracking phase. In this context, an energy tracking factor term (ETF) is introduced and defined. It is observed that all the MPPT schemes studied have their own merits and demerits. The ripple correlation and β methods offer an overall good combination of desirable features. All the results of this study are presented.

Enhanced LCMPPT Control Strategy for Single Stage Power Conversion

The authors previously proposed a new maximum power point tracking strategy based on limit cycle phenomena (LCMPPT) for a grid connected PV system with dc linked two power conversion stages. This paper enhances its principle for the systems with single power conversion stage such like a battery charging system. Since, it needs only one current sensor, it is cost effective being easy to implement by using a low cost PIC microprocessors. Experimental results in proto-type system have been shown to prove its validity and usefulness.

Dynamic maximum power injection control of AC photovoltaic modules using current-mode control

Maximum power point tracking (MPPT) strategies are an essential part of photovoltaic (PV) power converters' control. These algorithms maintain the operation of the PV panel at the optimal point for maximum performance. In addition, the power converter must synchronise with the electricity grid and inject the power extracted from the PV panel. These two tasks are executed by the controller in the power conditioning unit. This, however, results in complicated control loops. Moreover, the interaction with the grid may cause stability problems in the power converter during voltage disturbances. The dynamic control of PV modules connected to the electricity supply presented by the authors provides a substantial improvement in power converter stability and ease of implementation. This strategy combines grid power injection control and PV MPPT into a single control block. The first objective is achieved using current-mode control to shape the current injection whereas the latter objective exploits the dynamic behaviour of the PV panel to determine changes in the grid current magnitude. An implemented prototype system shows the performance of the proposed strategy and the results are compared against commercially available inverters.

MPPT of photovoltaic systems using extremum - seeking control

A stability analysis for a maximum power point tracking (MPPT) scheme based on extremum-seeking control is developed for a photovoltaic (PV) array supplying a dc-to-dc switching converter. The global stability of the extremum-seeking algorithm is demonstrated by means of Lyapunov's approach. Subsequently, the algorithm is applied to an MPPT system based on the perturb and observe method. The steady-state behavior of the PV system with MPPT control is characterized by a stable oscillation around the maximum power point. The tracking algorithm leads the array coordinates to the maximum power point by increasing or decreasing linearly with time the array voltage. Off-line measurements are not required by the control law, which is implemented by means of an analog multiplier, standard operational amplifiers, a flip-flop circuit and a pulsewidth modulator. The effectiveness of the proposed MPPT scheme is demonstrated experimentally under different operating conditions.

Power tracking for nonlinear pv sources with coupled inductor SEPTIC converter

The photovoltaic (PV) generator exhibits a nonlinear i-v characteristic and its maximum power (MP) point varies with solar insolation. In this paper, a V2-based MP point tracking (MPPT) scheme is developed using a buck-boost transformation topology. Although several buck-boost transformation topologies are available we have considered here a coupled inductor SEPIC converter for experimentation. To achieve almost ripple-free array current we have used ripple steering phenomena with the help of integrated inductor. This integrated inductor not only reduces the magnetic core requirements but also improves converter performance. Mathematical models are formulated and tracking algorithm is evolved. A combined PV system simulation model is developed in the SIMULINK. For a given solar insolation, the tracking algorithm changes the duty ratio of the converter such that the solar cell array (SCA) voltage equals the voltage corresponding to the MP point. This is done by the tracking algorithm, which mainly computes the power proportional to square of terminal voltage and changes the duty ratio of the converter so that this power is maximum. The proposed algorithm is implemented in real-time with the help of Analog Device ADMC-401 DSP evaluation module. The tracking program is developed to perform experimental investigations using analog-to-digital converter (ADC) interrupt. Using this processor we are able to track the MP within 200 ms. The proposed peak power tracking effectiveness is demonstrated through simulation and experimental results.

Feedforward maximum power point tracking of PV systems using fuzzy controller

A feedforward maximum power (MP) point tracking scheme is developed for the interleaved dual boost (IDB) converter fed photovoltaic (PV) system using fuzzy controller. The tracking algorithm changes the duty ratio of the converter such that the solar cell array (SCA) voltage equals the voltage corresponding to the MP point at that solar insolation. This is done by the feedforward loop, which generates an error signal by comparing the instantaneous array voltage and reference voltage. The reference voltage for the feedforward loop, corresponding to the MP point, is obtained by an off-line trained neural network. Experimental data is used for off-line training of the neural network, which employs back-propagation algorithm. The proposed fuzzy feedforward peak power tracking effectiveness is demonstrated through the simulation and experimental results, and compared with the conventional proportional plus integral (PI) controller based system. Finally, a comparative study of interleaved boost and conventional boost converter for the PV applications is given and their suitability is discussed.

Novel control strategies for variable-speed doubly fed wind power generation systems

This paper presents a novel control strategy for a brushless doubly fed machine (BDFM) applied to variable-speed wind power generation systems. A 7 kW proof-of-concept laboratory prototype is used to investigate the proposed control algorithm. The paper discusses the use of an adaptive maximum power point tracking (MPPT) strategy to implement an efficiency maximization loop in parallel with the regular maximum tip speed ratio tracker, without the measurement of mechanical quantities. The overall power output of the generation system is increased with a minimal increase in controller cost. A 100 kW case study is included to describe the prospects of the proposed control strategy for a typical wind power generation site on the Oregon coast.

Comparing two neural networks for pattern based adaptive process control

AbstractAn adaptation strategy based on an analysis of patterns exhibited in the recent controller error history is presented. The strategy is a two parameter adaptation, where the gain and time constant of the controller's internal model are adjusted to make the closed loop error response match a target pattern. Both a back‐propagation network and a vector quantizer network (VQN) are compared as pattern analysis tools. This strategy is established for a number of model based controllers and is demonstrated here using the Generalized Predictive Control algorithm. Details of this set point tracking strategy are presented along with demonstrations on both simulated and real single loop processes that experience significant changes in process gain and time constant. Results show both networks to be equally capable at pattern recognition with the VQN's ease of training and implicit ability to assess the accuracy of the pattern match as deciding factors in network selection.