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.     

Novel control algorithm for MPPT with Boost converters in photovoltaic systems

The great advances in efficiency and performance of photovoltaic modules would not be very useful if they do not work close to their maximum power point (MPP). In this paper a novel Sliding Mode Control (SMC) based algorithm is proposed to be implemented in a DC/DC converter in order to make an autonomous photovoltaic system to work at the MPP. Once that the design of the novel algorithm has been detailed (especially the novel part relative to the current reference signal) and its stability has been demonstrated, its performance has been compared with two of the most commonly used algorithms in this scope, i.e., Perturbation & Observation (P&O) and Incremental Conductance (IC) algorithms, in addition to a PI controller because it is one of the preferred controllers in industrial applications. This comparison has been carried out taking into account both simulated and experimental tests. The first focused on their behavior when sudden changes in irradiance and temperature, while the lasts analyzed them when the load resistance was varying arbitrarily in actual facilities (composed of a photovoltaic module Mitsubishi PV-TD185MF5, a Boost converter, a variable load and a real-time data acquisition card dSPACE DSP1104 used as the interface between the control algorithm implemented in Simulink/Matlab and the real photovoltaic module). After completing tests under different conditions, we found that the proposed SMC based algorithm outperforms the PI controller and the P&O and IC algorithms, especially in experiments carried out using actual facilities.     

光伏电池最大功率点跟踪方法的研究

在光伏发电系统中,为了提高光伏电池的利用效率,需要对光伏电池的最大功率点进行跟踪。分析了在跟踪控制中常见的扰动跟踪法和功率数学模型法,比较了它们的优缺点,并基于这两种方法提出了一种改进的跟踪方法,利用MATLAB对该方法进行了仿真研究,仿真结果验证了该方法的有效性。     

Application of a combined particle swarm optimization and perturb and observe method for MPPT in PV systems under partial shading conditions

This paper explains the development of a new algorithm for maximum power point tracking (MPPT) in large PV systems under partial shading conditions (PSC). The new algorithm combines the use of particle swarm optimization (PSO) for MPPT during the initial stages of tracking and then employs the traditional perturb and observe (PO) method at the final stages. The methodology has been first simulated in two different PV configurations under varying shading patterns and experimentally verified using a microcontroller based experimental system. The integration of swarm intelligence with PO algorithm is shown to yield faster convergence to the global maximum power point (GMPP) than when the two methods are individually used. The oscillations in the output power, voltage and current of the PV system with the proposed method are the least when compared to the ones obtained during PSO based MPPT.     

Implementation of photovoltaic water pumping system with MPPT controls

To increase the output efficiency of a photovoltaic (PV) system, it is important to apply an efficient maximum power point tracking (MPPT) technique. This paper describes the analysis, the design and the experimental implementation of the tracking methods for a stand-alone PV system, using two approaches. The first one is the constant voltage (CV) MPPT method based on the optimum voltage, which was deduced experimentally, and considered as a reference value to extract the optimum power. The second one is the increment conductance (Inc-Cond) MPPT method based on the calculation of the power derivative extracted by the installation. The output controller can adjust the duty ratio to the optimum value. This optimum duty ratio is the input of a DC/DC boost converter which feeds a set of Moto-pump via a DC/AC inverter. This paper presents the details of the two approaches implemented, based on the system performance characteristics. Contributions are made in several aspects of the system, including converter design, system simulation, controller programming, and experimental setup. The MPPT control algorithms implemented extract the maximum power point (MPP), with satisfactory performance and without steady-state oscillation. MATLAB/Simulink and dSpace DS1104 are used to conduct studies and implement algorithms. The two proposed methods have been validated by implementing the performance of the PV pumping systems installed on the roof of the research laboratory in INSAT Tunisia. Experimental results verify the feasibility and the improved functionality of the system.     

A new approach in tracking maximum power under partially shaded conditions with consideration of converter losses

The fact that photovoltaic panels are very sensitive to non-uniform insolation conditions, which can occur several times a day, causes a decrease of efficiency and so increases time for return on investment. This work presents a maximum power point tracking algorithm (MPPT) operating on the load characteristic in order to take the converters losses into account. In addition, the proposed MPPT deals with the problems of shadowing for which the power-load characteristic can present two or more local maximums close to each other. Considering the converters losses it can be shown that the maximum output power of the photovoltaic panels does not necessarily coincide with the maximum output power of the converters. The proposed MPPT algorithm tracks the maximum power with the intention of reducing the total losses including those of converters. Its performance is verified by simulation and confirmed by experimental results.     

Real-time simulation platform for photovoltaic system with a boost converter using MPPT algorithm in a DSP controller

Recently, real-time simulation of renewable energy sources are indispensible for evaluating the performance of the maximum power point tracking (MPPT) controller, especially in the photovoltaic (PV) system in order to reduce cost in the testing phase. Nowadays, real time PV simulators are obtained by using analog and/or digital components. In this paper, a real-time simulation of a PV system with a boost converter was proposed using only the digital signal processor (DSP) processor with two DC voltage sources to emulate the temperature and irradiation in the PV system. A MATLAB/Simulink environment was used to develop the real-time PV system with a boost converter into a C-program and build it into a DSP controller TMS320F28335. Besides, the performance of the real-time DSP-based PV was tested in different temperature and irradiation conditions to observe the P-V and V-I characteristics. Further, the performance of the PV with a boost converter was tested at different temperatures and irradiations using MPPT algorithms. This scheme was tested through simulation and the results were validated with that of standard conditions given in the PV data sheets. Implementation of this project helped to attract more researchers to study renewable energy applications without real sources. This might facilitate the study of PV systems in a real-time scenario and the evaluation of what should be expected for PV modules available in the market.     

分布式光伏发电系统最大功率点跟踪技术比较研究

基于当前光伏阵列最大功率点跟踪技术的研究现状,介绍了适用于分布式光伏发电系统最大功率点跟踪的各种常用控制方法,阐述了每一种控制方法的技术原理,分析和比较了这些常用控制方法的特点,总结了各自的优点和缺点,最后对分布式光伏发电系统最大功率点跟踪方法的选择问题进行了探讨,并指出了具体选择方法时应综合考虑的各种因素。     

具有MPPT功能的智能户用光伏充电系统研究

光伏充电系统采用了恒流充电和du/dt恒压限流充电相结合的管理模式,在一定时间内以电压的变化量接近零,并使充电电流达到最小设定量作为判断蓄电池充电终止的条件,采用了电压自寻优算法实现了光伏电池的最大功率点跟踪.试验表明,系统除了具有智能化管理的特点外,光伏电池的最大功率点跟踪效果明显,且不用考虑日照强度和温度对光伏电池的影响,在一定程度上能够提高光伏电池的输出功率.     

Differentiation of multiple maximum power points of partially shaded photovoltaic power generators

Partial shading conditions have a major effect on the electrical characteristics of photovoltaic (PV) power generators. In this paper, the effects of partial shading on maximum power points (MPPs) of a PV power generator have been systematically studied by using Simulink simulation model of a PV power generator composed of 18 series-connected PV modules. It is shown that the local MPPs can be classified into MPPs at low and high voltages based on the MPP operating point of the PV generator. The results also show that based on the MPP current and voltage it is possible to directly know if the MPP at high voltages is a local or a global MPP. The differentiation between local and global MPPs at high voltages is based on the voltage difference between the actual MPP voltage at high voltages and the theoretical MPP voltage under corresponding uniform conditions. This differentiation method was also tested to work correctly by utilizing experimental measurements of the Tampere University of Technology Solar PV Power Station Research Plant. By using this method, it can be identified if the system is operating at a local or a global MPP. This method can further be utilized to develop global MPP tracking algorithms.     

Comprehensive analysis and design of multi-leg fuel cell boost converter

This paper presents the design and development of a practical multi-leg fuel cell boost converter. The applied multi-leg topology and the interleaved switching method can effectively reduce fuel cell current ripple to meet the suggested limitation of 4%. Input inductors play a critical role for ripple current reduction, while output capacitors are used for specified output voltage performance. In the selection of the input inductors and the output capacitors, this paper uniquely presents an analytic method for obtaining optimum parameter values. The design considerations include leg number, switching frequency, output loads, and dynamic response. Novel equivalent models with equivalent series resistors for multi-leg boost converters are proposed. This model can simplify the analysis of multi-leg converters and is thus used for compensation design. To verify the analytic results, Intersil ISL6556B integrated circuit is used to implement two-, three-, and four-leg fuel cell boost converters rated 1000 W. Finally, the experimental results show that the four-leg one can have lower ripple factor than its two- and three-leg counterparts, and meet the limitation of fuel cell output current ripple factor of 4%.     

Expanding photovoltaic penetration with residential distributed generation from hybrid solar photovoltaic and combined heat and power systems

The recent development of small scale combined heat and power (CHP) systems has provided the opportunity for in-house power backup of residential-scale photovoltaic (PV) arrays. This paper investigates the potential of deploying a distributed network of PV + CHP hybrid systems in order to increase the PV penetration level in the U.S. The temporal distribution of solar flux, electrical and heating requirements for representative U.S. single family residences were analyzed and the results clearly show that hybridizing CHP with PV can enable additional PV deployment above what is possible with a conventional centralized electric generation system. The technical evolution of such PV + CHP hybrid systems was developed from the present (near market) technology through four generations, which enable high utilization rates of both PV-generated electricity and CHP-generated heat. A method to determine the maximum percent of PV-generated electricity on the grid without energy storage was derived and applied to an example area. The results show that a PV + CHP hybrid system not only has the potential to radically reduce energy waste in the status quo electrical and heating systems, but it also enables the share of solar PV to be expanded by about a factor of five.     

A fast and low cost analog maximum power point tracking method for low power photovoltaic systems

Low power photovoltaic (PV) systems are commonly used in stand-alone applications. For these systems, a simple and cost-effective maximum power point tracking (MPPT) solution is essential. In this paper, a fast and low cost analog MPPT method for low power PV systems is proposed. By using two voltage approximation lines (VALs) to approximate the maximum power point (MPP) locus, a low-complexity analog MPPT circuit can be developed. Theoretical derivation and detailed design procedure will be provided in this paper. The proposed method boasts the advantages such as simple structure, low cost, fast tracking speed and high tracking efficiency. To validate the correctness of the proposed method, simulation and experimental results of an 87 W PV system will also be provided to demonstrate the effectiveness of the proposed technique.     

Efficient soft-switched boost converter for fuel cell applications

The dc voltage generated from fuel cell is low in magnitude, unregulated and load dependent. Hence, it is required to be regulated and boosted by high performance dc-dc converter. In this paper, a fully soft-switched pulse-width-modulated dc-dc boost converter has been proposed for fuel cell applications. The proposed converter operates at high switching frequency with high efficiency and large power to volume ratio. A laboratory prototype model of the proposed converter has been designed and fabricated for charging a battery bank at 110 V from a fuel cell stack SR-12 of Avista Lab. The experimental results were found in close agreement with the predicted behavior.     

Modeling and maximum power point tracking (MPPT) method for PV array under partial shade conditions

Influenced by partial shade, PV module aging or fault, there are multiple peaks on PV array's output power–voltage (P–V) characteristic curve. Conventional maximum power point tracking (MPPT) methods are effective for single peak P–V characteristic under uniform solar irradiation, but they may fail in global MPP tracking under multi-peak P–V characteristics. Existing methods in literature for this problem are still unsatisfactory in terms of effectiveness, complexity and speed. In this paper, we first analyze the mathematical model of PV array that is suitable for simulation of complex partial shade situation. Then an adaptive MPPT (AMPPT) method is proposed, which can find real global maximum power point (MPP) for different partial shade conditions. When output characteristic of PV array varies, AMPPT will adjust tracking strategies to search for global peak area (GPA). Then it is easy for conventional MPPT to track the global MPP in GPA. Simulation and experimental results verify that the proposed AMPPT method is able to find real global MPP accurately, quickly and smoothly for complex multi-peak P–V characteristics. Comparison analysis results demonstrate that AMPPT is more effective for most shade types.     

Sliding mode controller for the single-phase grid-connected photovoltaic system

A sliding mode controller for the single-phase grid-connected photovoltaic system has been proposed in this paper. Contrary to the conventional controller, the proposed system consists of maximum power point tracker (MPPT) controller and sliding mode current controller only. The proposed MPPT controller generates current reference directly from the solar array power information and the current controller uses the sliding mode technique for the tight regulation of current. The new MPPT controller does not require the measurement of the voltage derivative which can be a cause of divide-by-zero singularity problems. The sliding mode controller has been constructed based on a time-varying sliding surface to control the sinusoidal inductor current and solar array power simultaneously. The proposed system can avoid the current overshoot and make optimal design for the system components. The structures of a proposed system are simple, but they show the robust tracking property against modeling uncertainties and parameter variations. The mathematical modeling is developed and the experimental results verify the validity of the proposed controller.     

1000W太阳能MPPT控制电路的参数确定

太阳能发电作为洁净的和未来最有希望的发电方式之一,越来越受到人们的重视。光伏发电系统各个方面的研究都在不断地深入进行着,太阳能发电系统的最大功率点跟踪控制就是其中一个重要的研究课题。从实际应用角度出发,文中详细论述了1000W太阳能MPPT控制电路的参数确定,为高效利用太阳能打下了基础。     

A novel hybrid boost converter with extended duty cycles range for tracking the maximum power point in photovoltaic system applications

Nowadays, a large number of power conversion applications is commonly based on DC/DC converters with high voltage boost capability. Different voltage-boosting techniques have been reported in the literature. Each technique has its own merits and demerits depending on the application, cost, complexity, power density, reliability and efficiency. To meet the growing demand for such applications, new power converter topologies are continuously being proposed. This paper focuses on a novel hybrid boost converter, which combines the conventional boost (CB) and the quadratic boost (QB). This new topology allows the extension of the output voltage gain and the duty cycle range regarding to the original topologies. Thus, it ensures high conversion voltage ratio for almost duty cycle values. Consequently, it has two working modes, one as QB mode and the other one as CB mode. In order to verify the performance of the proposed topology, several simulations have been carried out under Matlab/Simulink environment for both QB and CB modes. The well-known P&O algorithm was implemented into a FPGA (Field Programmable Gate Array) board in order to verify experimentally the designed hybrid boost. Experimental results confirm the convenience of the proposed topology for tracking the maximum power point in photovoltaic systems.     

Analysis of MPPT characteristics in photovoltaic power system

This paper describes characteristics evaluation of the power conditioner which has the function of Maximum Power Point Tracking (MPPT) by “mountain climbing method” through computer simulations. The generated power on the constant voltage control is compared to the one on MPPT with the load matching correction factor (Kpm). In this simulation, the following parameters are chosen, the rate of the voltage ΔV on changing the operating point and of the voltage ΔV_c on checking the maximum point.As a result, the influence of these parameters on Kpm is showed and it is made clear that we should decide the MPPT parameters with care.