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Freddy, Tan Kheng Suan,Lee, June-Hee,Moon, Hyun-Cheol,Lee, Kyo-Beum,Rahim, Nasrudin Abd Institute of Electrical and Electronics Engineers 2017 IEEE transactions on industrial electronics Vol.64 No.9
<P>This paper underpins the principles for generating reactive power in single-phase transformerless photovoltaic (PV) inverters. Two mainstream and widely adopted PV inverters are explored, i.e., H5 and HERIC. With conventional modulation techniques, reactive power cannot be realized in H5 and HERIC due to the absence of freewheeling path in negative power region. Based on the study, modulation techniques are proposed to provide bidirectional current path during freewheeling period. With proposed modulation technique, reactive power control is achieved in H5 and HERIC inverters, without any modification on the converter structures. The performances of the proposed modulation techniques are studied via MATLAB simulation and further validated with experimental results.</P>
Review of wide band‑gap technology: power device, gate driver, and converter design
Krishna Ravinchandra,Tan Kheng Suan Freddy,June-Seok Lee,Kyo-Beum Lee,Homer Alan Mantooth,Vinesh Thiruchelvam,Jerome Ignatius Yuen Yi Xian 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.8
This paper reviewed the state-of-the-art wide band-gap (WBG) technology from material level to system level. The properties of semiconductor materials, i.e., silicon carbide and gallium nitride, were investigated. The electrical characteristics of commercial power devices, which include static and dynamic performances, were assessed, and compared. The design requirements of WBG gate drivers were then underpinned, and various gate driver topologies were reviewed. Finally, their implementation in power electronic converters and performances were evaluated.
Hussain A. Attia,Tan Kheng Suan Freddy,Hang Seng Che,Ahmad H. El Khateb 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1
Recently, the use of LLCL filters for grid inverters has been suggested to give better harmonic attenuation than the commonlyused L and LCL filters, particularly around the switching frequency. Nevertheless, this filter is mainly designed for constantswitching frequency pulse width modulation (CSF PWM) methods. In variable switching frequency PWM (VSF PWM), theharmonic components are distributed across a wide frequency band which complicates the use of a high order filter, includingLCL and LLCL filters. Recently, a confined band variable switching frequency (CB-VSF) PWM method has been proposed anddemonstrated to be superior to the conventional constant switching frequency (CSF) PWM in terms of switching losses. However,the applicability of LLCL filters for this type of CB-VSF PWM has not been discussed. In this paper, the authors study thesuitability of an LLCL filter for CB-VSF PWM and propose design guidelines for the filter parameters. Using simulation andexperimental results, it is demonstrated that the effectiveness of an LLCL filter with CB-VSF PWM depends on the parametersof the filters as well as the designed variable frequency band of the PWM. Simulation results confirm the performance of thesuggested LLCL design, which is further validated using a lab scale prototype.
Attia, Hussain A.,Freddy, Tan Kheng Suan,Che, Hang Seng,El Khateb, Ahmad H. The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1
Recently, the use of LLCL filters for grid inverters has been suggested to give better harmonic attenuation than the commonly used L and LCL filters, particularly around the switching frequency. Nevertheless, this filter is mainly designed for constant switching frequency pulse width modulation (CSF PWM) methods. In variable switching frequency PWM (VSF PWM), the harmonic components are distributed across a wide frequency band which complicates the use of a high order filter, including LCL and LLCL filters. Recently, a confined band variable switching frequency (CB-VSF) PWM method has been proposed and demonstrated to be superior to the conventional constant switching frequency (CSF) PWM in terms of switching losses. However, the applicability of LLCL filters for this type of CB-VSF PWM has not been discussed. In this paper, the authors study the suitability of an LLCL filter for CB-VSF PWM and propose design guidelines for the filter parameters. Using simulation and experimental results, it is demonstrated that the effectiveness of an LLCL filter with CB-VSF PWM depends on the parameters of the filters as well as the designed variable frequency band of the PWM. Simulation results confirm the performance of the suggested LLCL design, which is further validated using a lab scale prototype.