하프·풀-브리지 셀을 이용한 독립형 태양광 멀티레벨 인버터

강필순,오석규,박성준,김장목,김철우 전력전자학회 2004 전력전자학회 논문지 Vol.9 No.5

A new multilevel PWM inverter using a half-bridge and full-bridge cells is proposed for the use of stand-alone photovoltaic inverters. The configuration of the proposed multilevel PWM inverter is based on a prior 11-level shaped PWM inverter. Among three full-bridge cells employed in the prior inverter, one cell is substituted by a half-bridge cell. Owing to this simple alteration, the proposed inverter has three promising merits. First it increases the number of output voltage levels resulted in high quality output voltages. Second, it reduces two power switching devices by means of employing a half-bridge cell. Third, it reduces power imposed on a transformer connected with the half-bridge unit. That is to say, most power is transferred to loads via cascaded transformers connected with low switching inverters, which are used to synthesize the fundamental output voltage levels whereas the output of a transformer linked to a high switching inverter is used to improve the final output voltage waves; thus, it is desirable in the point of the improvement of the system efficiency. By comparing to the prior 11-level PWM inverter, it assesses the performance of the proposed inverter as a stand-alone photovoltaic inverter. The validity of the proposed inverter is verified by computer-aided simulations and experimental results. 본 논문에서는 하프․풀-브리지 셀을 이용하는 새로운 멀티레벨 인버터를 제안하고 독립형 태양광 인버터로서의 가능성을 평가한다. 기본 회로 구조는 기존의 11-레벨형 PWM 인버터에 기초하며 세 개의 풀-브리지 모듈 중 하나의 모듈을 하프-브리지 구조로 대체한다. 이 간단한 회로 구조의 변경으로 제안된 멀티레벨 인버터는 세 가지의 장점을 가지게 된다. 첫째, 출력 전압 레벨 수의 증가를 통해 보다 정현적인 출력 전압 파형을 형성 시킬 수 있다. 둘째, 풀-브리지 모듈 대신 하프-브리지 셀을 이용하므로 두 개의 전력 스위치를 줄일 수 있다. 셋째, 쵸핑용으로 이용되는 인버터와 결합된 변압기에 의해 부하로 전달되는 전력량을 저감 시킬 수 있어 전체 효율 개선에 유리하다. 즉, 대부분의 전력은 저주파 스위칭 동작으로 기본 출력전압을 형성하는 인버터와 이와 결합된 변압기에 의해 부하단으로 전달되고, 고주파 스위칭을 하는 쵸핑용 인버터와 이와 결합된 변압기를 통한 출력은 최종 출력전압을 보다 정현화 하기 위한 목적으로 사용되도록 한다. 기존의 11-레벨형 PWM 인버터와 비교를 통해 제안하는 인버터를 평가하고, 컴퓨터 시뮬레이션 및 실험 결과를 통해 독립형 태양광 인버터로서의 가능성을 입증한다.

Cascaded Single-Phase Boost Inverter Using High Frequency Transformer

( Van Thuan Tran ),( Tan Tai Tran ),( Minh Khai Nguyen ),( Hong Woo Lim ),( Won Bae Kim ) 조선대학교 공학기술연구원 2016 공학기술논문지 Vol.9 No.1

Quasi-switched boost inverter was investigated to replace Z-source inverter and switched-boost inverter in the field of low power applications because it uses one-LC-pair less than Z-source inverter. In this paper, we suggest the configuration of H-bridge quasi-switched boost inverter based on high frequency transformer (H-qSBI) to improve voltage gain factor. The proposed topology contains the same devices like switched boost inverter, where the active switch is replaced by an H-bridge inverter. This paper focuses on analyzing quasi-switched boost inverter (qSBI) implementation and simulating the performing results of cascaded single-phase dual-inverter using high frequency transformer by PSIM simulation software. The results are tested by an input DC voltage of 36 V to generate an AC voltage of 220Vrms/50Hz.

Single-Phase Multilevel PWM Inverter Based on H-bridge and its Harmonics Analysis

Woo-Seok Choi,Hae-Kon Nam,Sung-Jun Park 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

The efficient electric power demand management in electric power supply industry is currently being changed by distributed generation. Meanwhile, small-scale distributed generation systems using renewable energy are being constructed worldwide. Several small-scale renewable distributed generation systems, which can supply electricity to the grid at peak load of the grid as per policy such as demand response programs, could help in the stability of the electric power demand management. In this case, the power quality of the small-scale renewable distributed generation system is more significant. Low prices of power semiconductors and multilevel inverters with high power quality have been recently investigated. However, the conventional multilevel inverter topology is unsuitable for the small-scale renewable distributed generation system, because the number of devices of such topology increases with increasing output voltage level. In this paper, a single-phase multilevel inverter based on H-bridge, with DC_Link divided by bi-directional switches, is proposed. The proposed topology has almost half the number of devices of the conventional multilevel inverter topology when these inverters have the same output voltage level. Double Fourier series solution is mainly used when comparing PWM output harmonic components of various inverter topologies. Harmonic components of the proposed multilevel inverter, which have been analyzed by double Fourier series, are compared with those of the conventional multilevel inverter. An inverter prototype is then developed to verify the validity of the theoretical analysis.

유효 무효전력 분리 제어기반의 DPWM을 이용한 플라잉 커패시터 듀얼 인버터 전력 손실 저감 방법

이준석,김태형,윤범렬,이준희 대한전기학회 2022 전기학회논문지 Vol.71 No.8

Output voltages of dual inverter are generated by the output voltage difference between the primary inverter and the secondary inverter in a dual-inverter. Thus, the dual-inverter has an advantage that produces the higher output voltages than the single inverter. However, the loss of dual-inverter increases because its topology consists of 12 switching devices. Besides, the flying capacitor dual-inverter requires not only a control for motor but also a control that balances the voltage of flying capacitor in secondary inverter. In this paper, a DPWM method for reducing the power loss in both inverters is proposed under the separation control which outputs the active power in the primary inverter and the reactive power in the secondary inverter. In the proposed DPWM method, the primary inverter with an unity PF minimizes the power loss and the secondary inverter with a zero PF also minimizes the power loss considering the magnitude and phase of a current. An effectiveness of the proposed method is verified with simulations and experiments.

Extended Boost Single-phase qZ-Source Inverter for Photovoltaic Systems

Hyun-Hak Shin,Honnyong Cha,Hongjoon Kim,Heung-Geun Kim 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

This study presents an extended boost single-phase qZ-source DC?AC inverter for a single-phase photovoltaic system. Unlike the previously proposed single-phase qZ-source and semi-qZ-source inverters that achieve the same output voltage as that of the traditional voltage-fed full-bridge inverter, the proposed inverter can obtain higher output than input voltage. The proposed inverter also shares a common ground between DC input voltage and AC output voltage. Thus, possible ground leakage current problem in non-isolated grid-tied inverters can be eliminated with the proposed inverter. A 120 W prototype inverter is built and tested to verify the performance of the proposed inverter.

Transient Operation Characteristics of 30kW Scale CVCF Inverter-based Micro-grid System

Marito Ferreira(페레이라 마리토),Hu-Dong Lee(이후동),Jian Shen(신건),Dae-Seok Rho(노대석) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.7

이산화탄소 배출의 저감을 위하여 도서지역의 신재생에너지전원 및 ESS의 도입이 확대되면서, 디젤발전기 대신 CVCF 인버터가 주 전원인 Micro-grid(MG) 시스템을 안정적으로 운용하는 방안들이 연구되고 있다. 그러나, CVCF 인버터 기반의 MG 시스템에서는 전체 부하보다 신재생에너지전원의 출력이 큰 경우에 에너지 Sinking(과도상태) 현상이 발생하게 된다. 이 때, CVCF 인버터용 배터리의 SOC 상태에 따라, 배터리 전압이 급격히 상승하여, 인버터의 과전압보호동작에 의해 CVCF 인버터가 탈락되어 MG 전체 계통에 정전을 유발할 수 있다. 따라서, 본 논문에서는 CVCF 인버터를 기반으로 한 도서지역용 MG 시스템의 안정적인 운용을 위하여, 에너지 Sinking이 발생한 경우의 운용특성을 분석하고, CVCF 인버터가 에너지 Sinking 시에 탈락되는 것을 사전에 방지할 수 있는 MG 시스템의 과도상태 운용전략을 제안한다. 또한, CVCF 인버터, 태양광전원, 수용가부하로 구성된 30kW급 MG 시스템 시험장치를 구현하여, 실 계통에서의 에너지 Sinking에 의한 CVCF 인버터 기반 MG 시스템의 과도상태 시 운용특성을 제시한다. 한편, 30kW급 시험장치와 제안한 운용전략을 바탕으로 MG 시스템의 과도상태 운용특성을 분석한 결과, CVCF 인버터용 배터리의 전압과 SOC에 따라 인버터가 탈락하는 과도상태를 사전에 방지할 수 있어, 본 논문의 유용성을 확인하였다. For the purpose of reducing carbon dioxide (CO₂) emissions in island areas, countermeasures are being studied to operate off-grid micro-grid (MG) systems in a stable manner by increasing the proportion of renewable energy sources (RES) instead of diesel generators (DG). However, in the operation of a constant-voltage and constant-frequency (CVCF) inverter-based MG system, a phenomenon of energy sinking can occur when the output of renewable energy sources (RES) is greater than customer loads in the off-grid MG system. The voltage of the battery system in the CVCF inverter of the MG system can rapidly increase depending on the state of charge (SOC), and then blackout in the entire MG system might occur due to the shut-down of the CVCF inverter. Therefore, in order to overcome these problems, this paper deals with a transient operation strategy for a CVCF inverter-based MG system to prevent the shut-down of the CVCF inverter despite the energy sinking phenomenon. Based on the transient operation strategy, we implemented a test device for a 30-kW CVCF inverter-based MG system in order to find out the transient operation characteristics related to energy sinking in the CVCF inverter. From test results based on a transient operation strategy, it was confirmed that the shut-down of the CVCF inverter can be prevented according to the SOC and voltage of the battery system in a CVCF inverter.

Operation Strategy of CVCF Inverter-based Micro-grid System Considering Energy Sinking

Lee Hu-Dong,Ferreira Marito,Tae Dong-Hyun,Lee Il-Moo,Rho Dae-Seok 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.3

For the purpose of reducing carbon dioxide (CO 2 ) emissions on island areas, operation methods of constant voltage and constant frequency (CVCF) inverter-based micro-grid(MG) system are being studied by replacing diesel generator with renewable energy sources (RES). However, in the operation of CVCF inverter-based MG system, phenomenon of energy sinking can be occurred when the total output power of RES is greater than total customer loads in inverter-based off -grid MG system. Where, the voltage of the battery system in CVCF inverter to form MG system can rapidly increase depending on the SOC(state of charge) condition, and then blackout in the entire MG system might be occurred due to the shut-down of CVCF inverter. Therefore, in order to overcome these problems, this paper presents transient operation algorithm based on 3 operation modes such as non-critical transient mode, critical transient mode and restoration mode, in order to prevent the shut-down of CVCF inverter with the energy sinking phenomenon in advance. Based on the proposed algorithm, this paper performs the modeling of 30 kW CVCF inverter-based MG system using PSCAD/EMTDC. From the simulation results based 3 operation modes, it is confi rmed that the shut-down of the CVCF inverter can be prevented in advance according to operation conditions of SOC and voltage of the battery system in a CVCF inverter.

Cascaded H-Bridge Five Level Inverter for Grid Connected PV System using PID Controller

Sivagamasundari, M.S.,Mary, P. Melba The Institute of Electronics and Information Engin 2016 Journal of semiconductor technology and science Vol.16 No.4

Photovoltaic energy conversion becomes main focus of many researches due to its promising potential as source for future electricity and has many advantages than the other alternative energy sources like wind, solar, ocean, biomass, geothermal etc. In Photovoltaic power generation multilevel inverters play a vital role in power conversion. The three different topologies, diode-clamped (neutral-point clamped) inverter, capacitor-clamped (flying capacitor) inverter and cascaded h-bridge multilevel inverter are widely used in these multilevel inverters. Among the three topologies, cascaded h-bridge multilevel inverter is more suitable for photovoltaic applications since each pv array can act as a separate dc source for each h-bridge module. This paper presents a single phase Cascaded H-bridge five level inverter for grid-connected photovoltaic application using sinusoidal pulse width modulation technique. This inverter output voltage waveform reduces the harmonics in the generated current and the filtering effort at the input. The control strategy allows the independent control of each dc-link voltages and tracks the maximum power point of PV strings. This topology can inject to the grid sinusoidal input currents with unity power factor and achieves low harmonic distortion. A PID control algorithm is implemented in Arm Processor LPC2148. The validity of the proposed inverter is verified through simulation and is implemented in a single phase 100W prototype. The results of hardware are compared with simulation results. The proposed system offers improved performance over conventional three level inverter in terms of THD.

Cascaded H-Bridge Five Level Inverter for Grid Connected PV System using PID Controller

M. S. Sivagamasundari,P. Melba Mary 대한전자공학회 2016 Journal of semiconductor technology and science Vol.16 No.4

Photovoltaic energy conversion becomes main focus of many researches due to its promising potential as source for future electricity and has many advantages than the other alternative energy sources like wind, solar, ocean, biomass, geothermal etc. In Photovoltaic power generation multilevel inverters play a vital role in power conversion. The three different topologies, diode-clamped (neutral-point clamped) inverter, capacitor-clamped (flying capacitor) inverter and cascaded h-bridge multilevel inverter are widely used in these multilevel inverters. Among the three topologies, cascaded h-bridge multilevel inverter is more suitable for photovoltaic applications since each pv array can act as a separate dc source for each h-bridge module. This paper presents a single phase Cascaded H-bridge five level inverter for grid-connected photovoltaic application using sinusoidal pulse width modulation technique. This inverter output voltage waveform reduces the harmonics in the generated current and the filtering effort at the input. The control strategy allows the independent control of each dc-link voltages and tracks the maximum power point of PV strings. This topology can inject to the grid sinusoidal input currents with unity power factor and achieves low harmonic distortion. A PID control algorithm is implemented in Arm Processor LPC2148. The validity of the proposed inverter is verified through simulation and is implemented in a single phase 100W prototype. The results of hardware are compared with simulation results. The proposed system offers improved performance over conventional three level inverter in terms of THD.

추진시스템의 5-레그 인버터 적용가능성 분석

임영설(Young-Seol Lim),신덕호(Duck-Ho Shin),이준석(June-Seok Lee),이교범(Kyo-Beum Lee) 한국철도학회 2017 한국철도학회 학술발표대회논문집 Vol.2017 No.05

본 논문에서는 철도차량의 추진시스템을 위한 5-레그 인버터의 적용가능성을 분석한다. 먼저 도시철도차량의 동작 조건을 고려하여 5-레그 인버터의 IGBT 소자를 선정하고 이를 바탕으로 손실분석을 진행한다. 5-레그 인버터의 손실분석결과를 기존 도시철도 차량의 방열설계에 반영하여 3-레그 인버터의 온도분포보다 낮은 온도분포 결과를 확인하고 이를 바탕으로 5-레그 인버터의 적용가능성을 제시한다. 또한, 5-레그 인버터 추진시스템의 신뢰도 분석을 3-레그 인버터 추진시스템과 비교하여 신뢰도 측면에서 향상됨을 확인한다. This paper analyzes applicability of five-leg inverter for the train propulsion system. First, five-leg inverter`s IGBT module is applied by considering the operation conditions of subway train. Through the results, loss analysis is implemented. Next, When reflecting the result of five-leg inverter`s loss analysis in thermal design of existing subway train, it confirms that five-leg inverter`s temperature distribution is lower than three-leg inverter`s temperature distribution and suggests the applicability of five-leg inverter. Also, When five-leg inverter`s reliability analysis is compared with three-leg inverter`s reliability analysis, the result of analysis verifies improvement in terms of reliability.