A photovoltaic (PV) array has non-linear I–V (current–voltage) characteristics and its output power varies with solar insolation level and ambient temperature. There exists only one point, called maximum power point (MPP), on the P–V (power–voltage) curve, where power is maximum and this point varies with the changing atmospheric conditions. Moreover, energy conversion efficiency of PV module is very low and mismatch between source and load characteristics causes significant power losses. Consequently, maximization of power output with greater efficiency is extremely important. Maximum power point tracking (MPPT) is a technique employed to extract maximum power available from the PV module. It traces the PV operating voltage corresponding to the MPP and locks the operating point at MPP and extract maximum power from the array. Till date, many algorithms for MPPT have been reported, each with its own features. In this paper, a comprehensive presentation of working principle of these techniques is made and they are compared against each other in terms of some critical parameters like: number of variables used, complexity, accuracy, speed, hardware implementation, cost, tracking efficiency and so on. This study is aimed at providing a compendium on MPPT techniques for an appropriate selection, based on application requirements and system constraints.

Maximum power point tracking control techniques: State-of-the-art in photovoltaic applications

In P-V (Power-Voltage) curve of a solar panel, there is an optimum operating point such that the PV delivers the maximum possible power to the load. The optimum operating point changes with the solar irradiation, and cell temperature. Therefore, on line tracking of the maximum power point of a PV array is an essential part of any successful PV system. A variety of maximum power point tracking (MPPT) methods is developed. The methods vary in implementation complexity, sensed parameters, and required number of sensors, convergence speed, and cost. This paper presents FPGA based implementation of a simple MPPT algorithm (Perturb-and-observe method) in such a way that does not require special measurements of open circuit voltage or short circuit current.

FPGA based implementation of MPPT of solar cell

The exponential growth of human population worldwide has emphasized the rapidly increased need of electricity. To meet this socio economic demand the research interest has been reinforced in renewable or non-conventional energy resources. One of the popular renewable sources is photovoltaic cell or solar cell. Corresponding to maximum power output there is an optimum operating point in Power-Voltage characteristic curve of photovoltaic cell. This nonlinear characteristic changes with respect to solar insolation, temperature and solar cell property. To cut down the cost of solar electricity online tracking of MPP (Maximum Power Point) is an essential part of successful solar system. A variety of techniques have been developed by the global researchers. In this paper an Evolutionary algorithm, Gravitational Search Algorithm (GSA) is examined in MATLAB environment to get the Maximum Power Point of photovoltaic array. The result is compared with another EA algorithm, Particle Swarm Optimization (PSO).

A GSA based improved MPPT system for PV generation

Nowadays, PV cell which is known as a photovoltaic is one of the most important parts in electrical field to convert photo light to voltage and current at the desired output voltage and frequency by using varies control techniques This project presents design and implementation of FPGA Based Maximum Power Point Tracking (MPPT) Controller for Photovoltaic system The MPPT controller is employed to control and get Maximum Power Point (MPP) from the source Altera DE1 board devices are used as a controller for the implementation of the MPPT system The simulation of this FPGA based MPPT controller is designed and implemented using Quartus II VHDL software tools The results shown, the same signal obtained from Matlab simulink software as compared with Quartus II It has been observed that the designed system has been successfully extracting the MPP from the pseudo sources used in the simulations The system has been evaluated in sunny day and partially shaded conditions to analyze the respective outputs in these conditions

FPGA based maximum power point tracking of photovoltaic system

Several techniques are available for implementing DCDC converters using digital controllers. Some of them are dspace, DSP, FPGA etc. Among these FPGA (Field Programmable Gate Array based implementation provides various advantages in terms of speed, flexibility, low power usage, reduced equipment sizing and massive parallelism. The traditional methods allow fault diagnosis only after the final implementation which leads to extra cost and loss of design time. This paper proposes a smart method of FPGA based implementation of DC-DC Buck Boost converter control system using Matlab and ModelSim. The control algorithm and coding is done by means of VHDL code and implemented using Altera FPGA Board. The FPGA takes control of the entire system and decides whether to increase or decrease the voltage depending on the application. Load is applied and the efficiency is checked at variable load conditions. Also performance comparison is made between a DSP and FPGA to evaluate the effectiveness of both the systems at various operating conditions. All battery powered electronic devices have their voltage range that is in between the range of a fully charged to a semi charged battery. Since the required output may be greater or lesser than the supplied voltage, a buck and boost converter needs to be cascaded to be used for this purpose. Cascading of the two converters results in what is called as the buck-boost converter. the control of these converters has been traditionally implemented using analog methodologies. But due to recent advancements of digital technology, digital controllers haven begun to replace analogue controllers. Digital systems controlled using microcontrollers and Digital Signal Processor (DSP) is being replaced by a more suitable candidate, the Field Programmable Gate Array (FPGA) (2). A Field Programmable Gate Array (FPGA) consists of a matrix of reconfigurable gate array logic circuitry that can be configured in a way depending on the user requirement. These logic blocks when configured and connected create a hardware implementation of a software application (4).

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Design and Implementation of Digital Controller for DC-DC Buck Boost Converter

This paper provides a small power photovoltaic control system based on FPGA. And a new way is applied to trace the maximum power point based on the improved accelerating simplex method. The system perfects the management and protection for the charge and discharge of storage battery also for the load and solar power supply. It's very important part that the techniques of maximum power point tracking and islanding protecting, but also the technique for inverter to connected with grid are discussed at emphasis. Test show that the system can be made use of in several photovoltaic products and obtain the satisfied result.

Fengde Guo

Papers

The Study in Photovoltaic Control System Based on FPGA