CSI7: A Modified Three-Phase Current-Source Inverter for Modular Photovoltaic Applications

Abstract

This paper analyzes the performance of a gridtied, wide power range, transformerless, modified threephase Current Source Inverter (CSI), named CSI7. The CSI7 topology is here analyzed along with a suitable Space Vector Modulation (SVM) strategy able to attenuate the excitation of the output CL filter. The theoretical analysis and simple analytic expressions highlighted the performance and limitations of the topology when employed as a singlestage PV inverter, with particular emphasis on injected grid currents distortion and ground leakage current values. The inverter wide input range allows interfacing PV strings of different module count with a simple closed loop control. The principle of operation and control is described, the viability of the CSI7 topology was assessed with simulations and extensive experiments on a full-size laboratory prototype.

A Transformerless Single-Phase Current Source Inverter Topology and Control for Photovoltaic Applications

“…Energies 2018, 11, x FOR PEER REVIEW 3 of 21 two transformerless three-phase CSI, based on the VSC H7 topology, are presented in [27,28]. These schemes are based on traditional differential mode inverters.…”

“…It concludes that for an inductor reduction, higher switching frequencies should be achieved by means of SiC devices, and then the leakage current may be an important issue. In the same way, two transformerless three-phase CSI, based on the VSC H7 topology, are presented in [27,28]. A reduced inductor of 2 mH, but without information regarding the inductor current, is used in [27].…”

“…In the same way, two transformerless three-phase CSI, based on the VSC H7 topology, are presented in [27,28]. A reduced inductor of 2 mH, but without information regarding the inductor current, is used in [27]. Two different modulation strategies are presented in [28], with an inductor of 2 mH for inductor currents of 8 A.…”

“…A transformerless CSI with low leakage current, based on the VSC H5 topology, is presented in [26]. In the same way, two transformerless three-phase CSI, based Energies 2018, 11, 2011 3 of 21 on the VSC H7 topology, are presented in [27,28]. These schemes are based on traditional differential mode inverters.…”

All SiC Grid-Connected PV Supply with HF Link MPPT Converter: System Design Methodology and Development of a 20 kHz, 25 kVA Prototype

“…Various grid-connected photovoltaic system concepts and topologies have been summarized previously [1][2][3][4]: (i) micro inverters [5,6]; (ii) residential systems supplied from a PV string [7,8]; (iii) commercial/residential systems supplied from multiple PV strings having their own maximum power point tracking (MPPT) converters and a central inverter [9,10]; and (iv) commercial/utility-scale PV plants supplied from a common DC link with a central inverter [11]. The central inverter in [11] performs direct conversion of PV power to AC from multiple PV strings.…”