Comparison between unipolar and bipolar single phase grid-connected inverters for PV applications

An inverter is essential for the interfacing of photovoltaic panels with the AC network. There are many possible inverter topologies and inverter switching schemes and each one will have its own relative advantages and disadvantages. Efficiency and output current distortion are two important factors governing the choice of inverter system. In this paper, it is argued that current controlled inverters offer significant advantages from the point of view of minimisation of current distortion. Two inverter switching strategies are explored in detail. These are the unipolar current controlled inverter and the bipolar current controlled inverter. With respect to low frequency distortion, previously published works provide theoretical arguments in favour of bipolar switching. On the other hand it has also been argued that the unipolar switched inverter offers reduced switching losses and generates less EMI. On efficiency grounds, it appears that the unipolar switched inverter has an advantage. However, experimental results presented in this paper show that the level of low frequency current distortion in the unipolar switched inverter is such that it can only comply with Australian Standard 4777.2 above a minimum output current. On the other hand it is shown that at the same current levels bipolar switching results in reduced low frequency harmonics

Comparison between unipolar and bipolar single phase grid-connected inverters for PV applications

An inverter is essential for the interfacing of photovoltaic panels with the AC network. There are many possible inverter topologies and inverter switching schemes and each one will have its own relative advantages and disadvantages. Efficiency and output current distortion are two important factors governing the choice of inverter system. In this paper, it is argued that current controlled inverters offer significant advantages from the point of view of minimisation of current distortion. Two inverter switching strategies are explored in detail. These are the unipolar current controlled inverter and the bipolar current controlled inverter. With respect to low frequency distortion, previously published works provide theoretical arguments in favour of bipolar switching. On the other hand it has also been argued that the unipolar switched inverter offers reduced switching losses and generates less EMI. On efficiency grounds, it appears that the unipolar switched inverter has an advantage. However, experimental results presented in this paper show that the level of low frequency current distortion in the unipolar switched inverter is such that it can only comply with Australian Standard 4777.2 above a minimum output current. On the other hand it is shown that at the same current levels bipolar switching results in reduced low frequency harmonics

Design and Characteristic Investigation of Novel Dual Stator Pseudo-Pole Five-Phase Permanent Magnet Synchronous Generator for Wind Power Application

The main focus of this paper is to design and assess the characteristics investigation of Novel Dual Stator Pseudo-Pole Five Phase Permanent Magnet Synchronous Generator (NDSPPFP-PMSG) for wind power application. The proposed generator has a dual stator and two sets of five phase windings which enhance its power density and fault tolerant capability. The novelty of this generator is based on the fact that, eight magnetic poles are formed using only four poles of actual magnets on both the surfaces of the rotor. For the designing and optimal electromagnetic performance of the proposed generator, a Dynamic Magnetic Circuit Model (DMCM) is reported. To validate the results obtained from DMCM, Finite Element Method (FEM) has been opted owing to its high accuracy. For showing the performance superiority, the proposed generator is compared with two conventional generators namely, Dual Stator Embedded-Pole Five Phase (DSEPFP) and Single Stator Single Rotor Five Phase (SSSRFP) PMSG. To compare their performances, FEM results are considered. The electromagnetic performance namely, generated Electromotive Force(EMF), percentage(%) Total Harmonic Distortion(THD) of generated EMF, generated EMF vs speed, terminal voltage vs load current, electromagnetic torque developed on rotor vs time, %ripple content in the torque, and %efficiency vs load current are investigated for all the three generators. From these investigations, it is found that the power density (power to weight ratio) of the proposed generator is maximum.publishedVersio

An Accurate Efficiency Calculation for PMSG Utilized in Renewable Energy Systems

Considering the importance of optimizing renewable energy systems, this paper aims at calculating the exact efficiency of a stand-alone wind turbine connected to a synchronous generator with permanent magnet excitation (PMSG). By accounting for mechanical and electrical losses (copper losses, stray load losses, iron core losses, friction losses, windings losses, and magnetizing saturation effect), the study investigates the impact of wind speed on the generator's performance and efficiency in addition to the impact of losses on the overall efficiency of (PMSG). The simulation of the PMSG dynamic model 8.5×(10)^3 V․A is executed using MATLAB/Simulink, employing a simplified equivalent circuit that accurately represents the PMSG's behavior under steady-state conditions with resistive loads. Wind speeds of 12 and 14 meters/second are chosen as fixed values to demonstrate the effect of varying wind speed on efficiency. The obtained results reveal the influence of wind speed on the PMSG efficiency. The presented findings contribute to the understanding of PMSG performance and can aid in optimizing the stand-alone wind turbine systems, they also show that the wind had an effect on the efficiency values that were obtained (97.86% at 12m/s and 97.91% at 14 m/s), while the effect of losses was very few around 3%. However, the obtained results are very good compared to previous studies to show the accuracy and validity of the suggested dynamic model

Analysis of Performance of Permanent Magnet Generator Fluks Axial 1 Phasa with Variation Load

With the potential of low water head energy and relatively small water discharge then it takes a low round generator to be applied to the potential of existing energy. The development of Permanent Magnet Generator (PMG), being an alternative considering the pole construction of the rotor is relatively simple compared to conventional generators, so it is technically required a more number of rotor poles in the effort to lower the speed The nominal dial generator. The purpose of this research is to analyze the 1-phase axial generator performance with varied resistive loads and inductive loads. This research has 4 stages of research: 1). Study literature.  2). Carried out testing tools. 3). Measurement of data retrieval.  4). Data analysis. From this research obtained results from the tools and measurements of the data retrieval of the performance of axial generator 1 phase with inductive and resistive load Vaiasi. Load mounted 15 watts, voltage 35.10, current 0.80, RPM 2550 when load 75 Waat, Voltage 11.50, current 1.54, RPM 2220. From these results can be concluded axial generator 1 phase currents also get bigger but voltage and rpm decreases

Controllable single-phase smart synchronous generator towards solar-pneumatic power generation

This paper presents the development of a controllable single-phase surface-mounted permanent magnet synchronous generator (SPSMPMSG) for low speed applications. Presently, the world is faced with degrading climatic conditions that may be worsen if energy need is met by fossil fuel and other conventional means of generation. On the other hand, renewable alternatives are not always of constant speed, and are usually not high enough to turn conventional alternators. There is therefore a need for the development of alternators that can generate electricity from low speed  sources. The development of permanent magnet from rare-earth materials has revolutionized the electrical generator development. Permanent magnet machines are characterized by high torque, low noise, high efficiency and high power factor. The use of these magnets also made it  possible to add computer based controllability making the generator a smart machine. This paper presents a CAD design of smart generator at an input speed of 500rpm to a turbine to produce a constant output of 220V. Simulation and physical test results produce an output of 220V ± 1% and give a clear indication that low speed renewable energy sources can produce usable electrical power. Keywords: Smart generator, Permanent magnet generator, stator, rotor, Computer-aided design

Modern Control Approaches for a Wind Energy Conversion System based on a Permanent Magnet Synchronous Generator (PMSG) Fed by a Matrix Converter

This “paper proposes a super-twisting adaptive Control Approaches for a Wind Energy Conversion System Based on a Permanent Magnet Synchronous Generator (PMSG) Fed by a matrix sliding mode for tracking the maximum power point of wind energy conversion systems using permanent magnet synchronous generators (PMSGs). As the adaptive control algorithm employed retains the robustness properties of classical wind energy conversion system control methods when perturbations and parameter uncertainties are present, it can be considered an effective solution; at the same time, it reduces chattering by adjusting gain and generating second-order adaptive control methods. The Egyptian power system (EPS), a three-zone interconnected microgrid (MG), and a single machine linked to the grid are only a few examples of the power systems for which this article introduces the concept of direct adaptive control (SMIB).The goal of our work is to maximize the captured power by solving a multi-input multi-output tracking control problem. In the presence of variations in stator resistance, stator inductance, and magnetic flux linkage, simulation results are presented using real wind speed data and discussed for the proposed controller and four other sliding mode control solutions for the same problem. The proposed controller achieves the best trade-off between tracking performance and chattering reduction among the five considered solutions: compared to a standard sliding mode control algorithm, it reduces chattering by two to five orders of magnitude, and steadystate errors on PMSG rotor velocity by one order of magnitude”. The purpose of this article is to examine wind turbine control system techniques and controller trends related to permanent magnet synchronous generators. The article presents an overview of the most popular control strategies for PMSG wind power conversion systems. There are several kinds of nonlinear sliding modes, such as direct power, backstepping, and predictive currents. To determine the performance of each control under variable wind conditions, a description of each control is presented, followed by a simulation performed in MATLAB /Simulink. This simulation evaluates the performance of each control in terms of reference tracking, response times, stability, and signal quality. Finally, this work was concluded with a comparison of the four controls to gain a better understanding of their effects. “Moreover, it reduces the above-mentioned steady-state error by four orders of magnitude compared to a previously-proposed linear quadratic regulator based integral sliding mode control law.  A dynamic model is simulated under both variable step and random wind speeds using the DEV-C++ software, and the results are plotted using MATLAB. The obtained results demonstrate the robustness of the proposed controller in spite of the presence of different uncertainties when compared to the classical direct torque control technique

Performance Enhancement of a Variable Speed Permanent Magnet Synchronous Generator Used for Renewable Energy Application

The paper aims to develop an improved control system to enhance the dynamics of a permanent magnet synchronous generator (PMSG) operating at varying speeds. The generator dynamics are evaluated based on lowing current, power, and torque ripples to validate the effectiveness of the proposed control system. The adopted controllers include the model predictive power control (MPPC), model predictive torque control (MPTC), and the designed predictive voltage control (PVC). MPPC seeks to regulate the active and reactive power, while MPTC regulates the torque and flux. MPPC and MPTC have several drawbacks, like high ripple, high load commutation, and using a weighting factor in their cost functions. The methodology of designed predictive voltage comes to eliminate these drawbacks by managing the direct voltage by utilizing the deadbeat and finite control set FCS principle, which uses a simple cost function without needing any weighting factor for equilibrium error issues. The results demonstrate several advantages of the proposed PVC technique, including faster dynamic response, simplified control structure, reduced ripples, lower current harmonics, and decreased computational requirements when compared to the MPPC and MPTC methods. Additionally, the study considers the integration of blade pitch angle and maximum power point tracking (MPPT) controls, which limit wind energy utilization when the generator speed exceeds its rated speed and maximize wind energy extraction during wind scarcity. In summary, the proposed PVC enhanced control system exhibits superior performance in terms of dynamic response, control simplicity, current quality, and computational efficiency when compared to alternative methods