Analysis and design of energy storage for current-source 1-ph Grid-connected PV inverters

Copyright © 2008 IEEEThis paper examines the analysis and design of a DC link inductor for a current source 1-ph grid-connected photovoltaic (PV) inverter. Firstly the effect of voltage or current ripple on the PV array average output power is examined using a normalized PV output characteristic. Secondly the design of the inductor and in particular the trade-off between the PV array output power loss and the inductor copper loss are discussed. An inductor was built and a comparison of the calculated and measured loss breakdown is presented.G. Ertasgin, D.M. Whaley, N. Ertugrul and W.L. Soon

Analysis and design of single-phase current-source grid-connected PV inverter

This paper investigates the performance of a 150 W single-phase current-source grid-connected inverter for photovoltaic (PV) applications. The constant-current source is realized using a large DC link inductor and the inverter is implemented using a single boost switch, a H-bridge inverter and a CL output filter. Although the DC link inductor causes the inverter to be less efficient than an equivalent voltage-source inverter, it offers lower cost due to the zero-current switching and lower number of components. In addition, the output current is easily controlled using the boost switch and offers simple open-loop and feed-forward control. The paper compares the simulated and measured inverter performance with regards to output power, total harmonic distortion and power factor. Additionally the scaling of the concept to a higher power (1.2 kW) inverter was also investigated using simulations.G. Ertasgin, W.L. Soong and N. Ertugru

Implementation and performance evaluation of a low-cost current-source grid-connected inverter for PV applications

This paper investigates the performance of a 150 W single-phase current-source grid-connected inverter for PV cells. The constant-current source is realised using a DC link inductor and the inverter is implemented using a single boost switch, a H-bridge inverter and an LC output filter. Although the DC link inductor causes the inverter to be less efficient than an equivalent voltage-source inverter, it offers lower cost due to the zero-current switching and lower number of components. In addition, the output current is easily controlled using the boost switch and simple open-loop control. The inverter input is simulated using the dark I-V configuration of two PV cells. The advantage of this arrangement is the ability to conveniently simulate the PV cell over a wide range of irradiances. The entire system is implemented to verify the simulation results. Furthermore, the paper also examines the proposed inverterpsilas ability to deliver sinusoidal current to the grid whilst meeting the appropriate standards, i.e. total harmonic distortion and power factor requirements. Additionally, the inverterpsilas ability to maximise the PV cell and inverter output power is shown.Ertasgin, G.; Whaley, D.M.; Ertugrul, N. and Soong, W.L

A current-source grid-connected converter topology for Photovoltaic systems

This paper investigates the performance of a gridconnected current-source converter topology for PV cells. The constant current source is realised by a large DC link inductor connected in series with the PV panel. A boost switch (named as current waveshaper) is used to produce a modulated output current that resembles the rectified grid voltage, which is in-phase with the grid. An H-bridge inverter with line-frequency commutated thyristors “unfolds” the output of the current waveshaper to produce a sinusoidal AC output current. The proposed converter concept is verified with simulations and preliminary experimental results.G. Ertasgin, D.M. Whaley, N. Ertugrul and W.L. Soon

Investigation of a low-cost grid-connected inverter for small-scale wind turbines based on a constant-current source PM generator

This paper describes a novel low-cost grid-connected inverter for small-scale wind turbines based on a high-inductance PM generator operating in a constant-current output mode. The PM generator is connected to a switched-mode rectifier (SMR) which consists of an uncontrolled rectifier and a switch. The combination of the high-inductance generator and uncontrolled rectifier produces a constant DC current. The switch is used to modulate this current and produces an output current whose fundamental component is a full-wave rectified sinewave and is in-phase with the grid voltage. A line-frequency commutated H-bridge inverter and LC output filter is used to produce a sinusoidal output grid current. The concept is verified using simulations and experimental resultsDavid M. Whaley, Gurhan Ertasgin, Wen L. Soong, Nesimi Ertugrul, James Darbyshire, Hooman Dehbonei, Chem V. Naya