A single-source photovoltaic power conditioning system using asymmetric cascaded multilevel inverter

Manoharan, Mohana Sundar; Ahmed, Ashraf; Kim, Hyun Woo; Park, Joung‐Hu

doi:10.1109/icpe.2015.7167761

Cited by 8 publications

(13 citation statements)

References 11 publications

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“…6 illustrates the current flow path based on the switching operation under a couple of different voltage levels. The state equations of the asymmetric multilevel inverter under the stand-alone mode of operation are given below [32]: …”

Section: Dynamic Characteristics Analysis Under Standalone and Gmentioning

confidence: 99%

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A Flyback-Assisted Single-Sourced Photovoltaic Power Conditioning System Using an Asymmetric Cascaded Multilevel Inverter

Manoharan¹,

Ahmed²,

Park³

2016

Journal of Power Electronics

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This paper proposes a power conditioning system (PCS) for distributed photovoltaic (PV) applications using an asymmetric cascaded multilevel inverter with a single PV source. One of the main disadvantages of the cascaded multilevel inverters in PV systems is the requirement of multiple isolated DC sources. Using multiple PV strings leads to a compromise in either the voltage balance of individual H-bridge cells or the maximum power point tracking (MPPT) operation due to localized variations in atmospheric conditions. The proposed PCS uses a single PV source with a flyback DC-DC converter to facilitate a reduction of the required DC sources and to maintain the voltage balance during MPPT operation. The flyback converter is used to provide input for low-voltage H-bridge cells which processes only 20% of the total power. This helps to minimize the losses occurring in the proposed PCS. Furthermore, transient analyses and controller design for the proposed PCS in both the stand-alone mode and the grid-connection mode are presented. The feasibility of the proposed PCS and its control scheme have been tested using a 1kW hardware prototype and the obtained results are presented.

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Section: Dynamic Characteristics Analysis Under Standalone and Gmentioning

confidence: 99%

“…A simplified block diagram of the control scheme is shown in Fig. 8 [32]. The designed controller was built and tested in PSIM software, and the result for a stepresponse of 50% load current is shown in Fig.…”

Section: A Stand-alone Operationmentioning

confidence: 99%

A Flyback-Assisted Single-Sourced Photovoltaic Power Conditioning System Using an Asymmetric Cascaded Multilevel Inverter

Manoharan¹,

Ahmed²,

Park³

2016

Journal of Power Electronics

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“…For a cascade inverter with asymmetrical DC voltage sources, the high-voltage full-bridge inverter (HVFB) is generally switched at low-frequency (the same as the fundamental frequency of the inverter output voltage) and the low-voltage full-bridge inverter (LVFB) is generally controlled by pulse-width modulation (PWM) and switched at high frequency. This reduces the switching losses and the dominant high-frequency harmonics [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Seven‐level cascade inverter with asymmetrical DC voltages

Jou

et al. 2017

IET Power Electronics

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This study proposes a novel seven-level cascade inverter (SLCI) with asymmetrical DC voltages. The proposed SLCI consists of two full-bridge inverters, a DC-DC converter (DDC) and a DC power source. The DC power source is parallel connected to the high-voltage full-bridge inverter (HVFB). The DDC is used to create a DC voltage with half of the DC power source and connect to the low-voltage full-bridge inverter (LVFB). The HVFB is switching at low frequency, and the LVFB is switching at high frequency. The salient points of the proposed SLCI are that only one DC power source is required and no transformer is used. Therefore, the power circuit for the proposed SLCI is simplified. A hardware prototype is established in order to verify the functions of the proposed SLCI. The tested results show that the functions of the proposed SLCI are as expected.

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“…For example, it is 180Hz in this For a 7-level asymmetric multilevel inverter, there are four operating modes depending on the voltage levels. The switching states are shown in Table I [29].…”

Section: B Grid-connection Modementioning

confidence: 99%

“…Using the state-space averaging technique, the control-toinductor current transfer function (G id ) has been derived as shown in equation (15) [29].…”

Section: B Grid-connection Modementioning

confidence: 99%

A New Photovoltaic System Architecture of Module-Integrated Converter with a Single-sourced Asymmetric Multilevel Inverter Using a Cost-effective Single-ended Pre-regulator

Manoharan¹,

Ahmed²,

Park³

2017

Journal of Power Electronics

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In this paper, a new architecture for a cost-effective power conditioning systems (PCS) using a single-sourced asymmetric cascaded H-bridge multilevel inverter (MLI) for photovoltaic (PV) applications is proposed. The asymmetric MLI topology has a reduced number of parts compared to the symmetrical type for the same number of voltage level. However, the modulation index threshold related to the drop in the number of levels of the inverter output is higher than that of the symmetrical MLI. This problem results in a modulation index limitation which is relatively higher than that of the symmetrical MLI. Hence, an extra voltage pre-regulator becomes a necessary component in the PCS under a wide operating bias variation. In addition to pre-stage voltage regulation for the constant MLI dc-links, another auxiliary pre-regulator should provide isolation and voltage balance among the multiple H-bridge cells in the asymmetrical MLI as well as the symmetrical ones. The proposed PCS uses a singleended DC-DC converter topology with a coupled inductor and charge-pump circuit to satisfy all of the aforementioned requirements. Since the proposed integrated-type voltage pre-regulator circuit uses only a single MOSFET switch and a single magnetic component, the size and cost of the PCS is an optimal trade-off. In addition, the voltage balance between the separate H-bridge cells is automatically maintained by the number of turns in the coupled inductor transformer regardless of the duty cycle, which eliminates the need for an extra voltage regulator for the auxiliary H-bridge in MLIs. The voltage balance is also maintained under the discontinuous conduction mode (DCM). Thus, the PCS is also operational during light load conditions. The proposed architecture can apply the module-integrated converter (MIC) concept to perform distributed MPPT. The proposed architecture is analyzed and verified for a 7-level asymmetric MLI, using simulation results and a hardware implementation.

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A single-source photovoltaic power conditioning system using asymmetric cascaded multilevel inverter

Cited by 8 publications

References 11 publications

A Flyback-Assisted Single-Sourced Photovoltaic Power Conditioning System Using an Asymmetric Cascaded Multilevel Inverter

A Flyback-Assisted Single-Sourced Photovoltaic Power Conditioning System Using an Asymmetric Cascaded Multilevel Inverter

Seven‐level cascade inverter with asymmetrical DC voltages

A New Photovoltaic System Architecture of Module-Integrated Converter with a Single-sourced Asymmetric Multilevel Inverter Using a Cost-effective Single-ended Pre-regulator

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