A maximum power point tracker for PV systems using a high performance boost converter

This work deals with the design and experimental implementation of a MPP-tracker for photovoltaic systems, which is a high efficiency dc/dc boost converter operating in continuous conduction mode (CCM). The converter is able to draw maximum power from the PV panel for a given solar radiation level and environment temperature by adjusting the duty cycle of the converter. Additionally, a passive nondissipative turn-on turn-off snubber is used, so that high efficiency and reduced electromagnetic interference (EMI) levels due to the soft switching operation can be obtained. The snubber improves the converter efficiency since the energy that would be dissipated during turning on and turning off is transferred to the load. The control technique, implemented with a single-chip microcontroller 80C51, is based on the perturbation and observation method, where the maximum power point is tracked with periodical calculation of the panel output power. Simulation and experimental results describe the performance of the proposed MPP-tracker.     

Step-up maximum power point tracker for photovoltaic arrays

This paper discusses a new maximum power point tracker (MPPT), which has been devised and tested at the laboratory. This MPPT is a high-frequency set-up dc-to-dc power conditioning unit. Simple and inexpensive analog circuitry is used to continually maximize the true PV array output power rather than maximizing the current or voltage at either the PV array or load. The control circuit is designed such that the actual current and voltage are sensed directly from the PV array. These two signals are then multiplied by a single-chip multiplier.The multiplier output charges or discharges two separate RC circuits of different time constants. These two RC signals are then mixed to set the duty cycle of a pulse width modulated signal to continually track the array maximum power point.This MPPT is simple and inexpensive; and it continuously tracks the true PV array maximum power point regardless of the load type.     

New algorithm using only one variable measurement applied to a maximum power point tracker

A novel algorithm for seeking the maximum power point of a photovoltaic (PV) array for any temperature and solar irradiation level, needing only the PV current value, is proposed. Satisfactory theoretical and experimental results are presented and were obtained when the algorithm was included on a 100 W 24 V PV buck converter prototype, using an inexpensive microcontroller. The load of the system used was a battery and a resistance. The main advantage of this new maximum power point tracking (MPPT), when is compared with others, is that it only uses the measurement of the photovoltaic current, I_PV.     

A maximum power point tracking for photovoltaic-SPE system using a maximum current controller

Processes to produce hydrogen from solar photovoltaic (PV)-powered water electrolysis using solid polymer electrolysis (SPE) are reported. An alternative control of maximum power point tracking (MPPT) in the PV-SPE system based on the maximum current searching methods has been designed and implemented.Based on the characteristics of voltage–current and theoretical analysis of SPE, it can be shown that the tracking of the maximum current output of DC–DC converter in SPE side will track the MPPT of photovoltaic panel simultaneously.This method uses a proportional integrator controller to control the duty factor of DC–DC converter with pulse-width modulator (PWM).The MPPT performance and hydrogen production performance of this method have been evaluated and discussed based on the results of the experiment.     

A novel maximum power point tracker for thermoelectric generation system

In this paper, a novel hybrid maximum power point tracking (MPPT) method is proposed and investigated. The proposed MPPT technique combines the simplicity of perturb and observe (P&O) method and the fast tracking ability of open circuit voltage (OCV) method. The advantages of the proposed MPPT approach include fast tracking speed, no additional circuit required and no temporary power loss. To validate the feasibility of the proposed MPPT technique, an 1.2 kW thermoelectric generation system for industrial waste heat recovery is also constructed, experimental results show that comparing with conventional P&O technique, the proposed method can improve the tracking speed for 42.9% and 86.2% when temperature differences are ΔT = 60 °C and ΔT = 180 °C, respectively. Moreover, the energy loss can be improved by 24.0% and 87.0% when temperature differences are ΔT = 60 °C and ΔT = 180 °C, respectively.     

An improved maximum power point tracking method for photovoltaic systems

In most of the maximum power point tracking (MPPT) methods described currently in the literature, the optimal operation point of the photovoltaic (PV) systems is estimated by linear approximations. However these approximations can lead to less than optimal operating conditions and hence reduce considerably the performances of the PV system. This paper proposes a new approach to determine the maximum power point (MPP) based on measurements of the open-circuit voltage of the PV modules, and a nonlinear expression for the optimal operating voltage is developed based on this open-circuit voltage. The approach is thus a combination of the nonlinear and perturbation and observation (P&O) methods. The experimental results show that the approach improves clearly the tracking efficiency of the maximum power available at the output of the PV modules. The new method reduces the oscillations around the MPP, and increases the average efficiency of the MPPT obtained. The new MPPT method will deliver more power to any generic load or energy storage media.     

Combined maximum power point tracking and output current control for a photovoltaic-electrolyser DC/DC converter

This paper covers the design and the implementation of the control strategy of a DC/DC converter aimed for hydrogen production from photovoltaic sources. This control scheme provides tight control of the injected current to the electrolyser and, if required, maximum power point tracking of the photovoltaic source, by means of two independent external control loops. The two outer loops create a reference signal for an inner control loop, which adjusts the duty cycle of the DC/DC converter and sets the output inductor current to the desired value. Embedded design, which includes analog and digital electronics, has been considered for the practical implementation. Converter and control loop modelling, simulation and experimental validation are discussed in this work.     

Robust maximum power point tracker using sliding mode controller for the three-phase grid-connected photovoltaic system

A robust maximum power point tracker (MPPT) using sliding mode controller for the three-phase grid-connected photovoltaic system has been proposed in this paper. Contrary to the previous controller, the proposed system consists of MPPT controller and current controller for tight regulation of the current. The proposed MPPT controller generates current reference directly from the solar array power information and the current controller uses the integral sliding mode for the tight control of current. The proposed system can prevent the current overshoot and provide optimal design for the system components. The structure of the proposed system is simple, and it shows robust tracking property against modeling uncertainties and parameter variations. Mathematical modeling is developed and the experimental results verify the validity of the proposed controller.     

New maximum power point tracker for PV arrays using fuzzy controller in close cooperation with fuzzy cognitive networks

The studies on the photovoltaic (PV) generation are extensively increasing, since it is considered as an essentially inexhaustible and broadly available energy resource. However, the output power induced in the photovoltaic modules depends on solar radiation and temperature of the solar cells. Therefore, to maximize the efficiency of the renewable energy system, it is necessary to track the maximum power point of the PV array. In this paper, a maximum power point tracker using fuzzy set theory is presented to improve energy conversion efficiency. A new method is proposed, by using a fuzzy cognitive network, which is in close cooperation with the presented fuzzy controller. The new method gives a very good maximum power operation of any PV array under different conditions such as changing insolation and temperature. The simulation studies show the effectiveness of the proposed algorithm.     

基于微分跟踪器光伏最大功率跟踪优化控制

光伏发电是一非线性系统,针对光伏系统易受电网工作方式和工作环境的影响,在分析电导增量法的基础上,利用MATLAB/Simulink搭建了光伏阵列数学模型,针对传统电导增量法存在跟踪速度慢及误判的问题,采用微分-跟踪器方法,对电导增量法进行改进优化。仿真结果表明,采用微分-跟踪器改进后的电导增量法能够快速、准确地跟踪光伏系统最大功率,能够有效抑制各种扰动,减少了误判几率,系统的动态性能及稳定性都优于常规电导增量法,从而提高了系统的鲁棒性。     

A photovoltaic powered electrolysis converter system with maximum power point tracking control

One of the main problems for renewable and other innovative energy sources is the storage of energy for sustainability. This study focuses on two different scenarios to benefit from solar energy more efficiently. Photovoltaic (PV) energy is converted to the desired voltage level using a buck converter for generating hydrogen with electrolysis process. A maximum power point tracking (MPPT) algorithm is used to benefit from the photovoltaic sources more efficiently. The basic electrolysis load for hydrogen production needs low voltage and high current and controlled sensitively to supply these conditions. The photovoltaic powered buck converter for electrolysis load was simulated in MATLAB/Simulink software using a perturb and observe (P and O) MPPT algorithm and PI controller. The simulation results show that in normal, short circuit and open circuit working conditions the PV and load voltages are stabilized. The efficiency of the proposed system is reached more than 90% for high irradiance levels.     

A novel maximum power point tracker based on analog and digital control loops

In this paper, a new maximum power point tracking (MPPT) system for photovoltaic applications is presented. The proposed system consists of two analog loops, a current and a voltage loop, built around a boost converter and a digital loop for the computation of the maximum power point. The analog loops provide a fast response to sudden changes of irradiance conditions while the digital loop, enhancing the accuracy, allows the implementation of various MPPT algorithms and facilitates the integration of additional control and monitoring features. Different existing systems are simulated and compared. A small signal model for the proposed system is developed and a novel compensation method is found. The compensation is designed in such a way that it makes the system independent of the input panel used and also of the load connected at the output. In order to have fast simulation results, a macromodel is developed allowing comparison between different algorithms. Furthermore the “perturb and observe” (P&O) algorithm is improved to obtain a better response for changing irradiance conditions.     

限定寻优区间的风力机最大功率点跟踪控制

自适应转矩控制是为改善风力机跟踪性能而提出的一种最大功率点跟踪控制方法,但是由于受到风速变化的干扰,导致该方法难以搜索至最佳增益系数。文章针对该问题提出一种改进自适应转矩控制方法。该方法通过分析自适应转矩控制的最佳增益系数与风速条件的关系,并据此设置增益系数的寻优区间,以剔除偏离最佳值较大的异常值。研究结果表明,与自适应转矩控制、传统功率曲线法和减小转矩增益控制相比,新方法能有效改善上述问题,并显著提高风能捕获效率。     

A reliable, fast and low cost maximum power point tracker for photovoltaic applications

This work presents a new maximum power point tracker system for photovoltaic applications. The developed system is an analog version of the “P&O-oriented” algorithm. It maintains its main advantages: simplicity, reliability and easy practical implementation, and avoids its main disadvantages: inaccurateness and relatively slow response. Additionally, the developed system can be implemented in a practical way at a low cost, which means an added value. The system also shows an excellent behavior for very fast variables in incident radiation levels.     

Evaluation of a new maximum power point tracker (MPPT) applied to the photovoltaic stand-alone systems

In this paper a comparative study through experimental work between a new low-cost maximum power point tracker (MPPT) and the conventional configurations of the photovoltaic (PV) regulators under different atmospheric conditions is presented. The comparison is made by means of the energy production obtained by the PV generator of each system. From the results obtained it can be concluded that, depending on the charge state of the batteries, the MPPT can increase the overall efficiency of the system between 2.8% and 18.5% compared with the performance of a conventional system.     

Matching three-phase AC loads to PVG for maximum power transfer using an enhanced version of the Akbaba model and double step-up converter

The matching of three-phase AC loads to photovoltaic generators (PVGs) for maximum power transfer using an enhanced version of the Akbaba model for I–V characteristic of PVGs is investigated. With an enhanced version of the Akbaba model, the model parameters are expressed directly in terms of percent solar radiation. With this improvement on the Akbaba model, only a single input, which is the percent solar radiation for a particular location on the globe, is required for the calculation of the complete performance of the PVG-load system, including available maximum (peak) power. With this new approach all previously needed iterative calculations to determine system performance are eliminated. As an application example, this new approach is applied to the matching of a three-phase load to PVG for maximum power transfer through a double DC–DC step-up converter and a six-step inverter. The effectiveness and accuracy of the model is demonstrated through detailed numerical results.     

改进型Sepic变换器在光伏MPPT系统中的应用

设计了一种基于三开关的改进型Sepic变换器,将其应用于光伏发电系统最大功率跟踪(MPPT)控制中。基于改进型Sepic变换器的光伏发电实验系统进行了实验研究,实验结果表明了采用该改进型的Sepic变换器在传输效率和故障隔离方面的优越性。     

Synchronized pulsed dc-dc converter as maximum power position tracker with wide load and insolation variation for stand alone PV system

This paper investigates the interest focused on employing parallel connected dc-dc converter with high tracking effectiveness under wide variation in environmental conditions (Insolation) and wide load variation. dc-dc converter is an essential part of the stand alone PV system. Paper also presents an approach on how duty cycle for maximum power position (MPP) is adjusted by taking care of varying load conditions and without iterative steps. Synchronized PWM pulses are employed for the converter. High tracking efficiency is achieved with continuous input and inductor current. In this approach, the converter can he utilized in buck as well in boost mode. The PV system simulation was verified and experimental results were in agreement to the presented scheme.     

带有最大功率点跟踪功能的光伏充电器

利用自寻优的方法，采用BUCK拓扑结构，实现光伏阵列最大功率点的跟踪，提高光伏系统的效率。介绍了在光伏充电器中MPPT的实现方法。同时还叙述了电路的硬件结构与系统的软件实现。通过样机对比试验证明，采用寻优后能提高充电器的充电效率。     

Theoretical assessment of the maximum power point tracking efficiency of photovoltaic facilities with different converter topologies

The operating point of a photovoltaic generator that is connected to a load is determined by the intersection point of its characteristic curves. In general, this point is not the same as the generator’s maximum power point. This difference means losses in the system performance. DC/DC converters together with maximum power point tracking systems (MPPT) are used to avoid these losses. Different algorithms have been proposed for maximum power point tracking. Nevertheless, the choice of the configuration of the right converter has not been studied so widely, although this choice, as demonstrated in this work, has an important influence in the optimum performance of the photovoltaic system. In this article, we conduct a study of the three basic topologies of DC/DC converters with resistive load connected to photovoltaic modules. This article demonstrates that there is a limitation in the system’s performance according to the type of converter used. Two fundamental conclusions are derived from this study: (1) the buck–boost DC/DC converter topology is the only one which allows the follow-up of the PV module maximum power point regardless of temperature, irradiance and connected load and (2) the connection of a buck–boost DC/DC converter in a photovoltaic facility to the panel output could be a good practice to improve performance.