Quasi-Two-Level Operation of a Five-Level Flying-Capacitor Converter

Gierschner, Sidney; Hein, Yves; Gierschner, Magdalena; Ali, Sajid; Eckel, Hans-Günter

doi:10.23919/epe.2019.8915445

Cited by 15 publications

(8 citation statements)

References 8 publications

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“…α-Oligothiophenes have been of interest for more than 20 years, especially because of their unique molecular and material characteristics at higher n. These highly conjugated oligomers and polymers have utility as nonlinear optical components, for charge storage, and in molecular electronics. 136 Thiophene rings linked through the 2-2′ position exhibit such properties, with a ππ* gap that decreases asymptotically with the number of rings, 137 and close-lying molecular orbitals that coalesce into band-like electronic structures (reminiscent of semiconductors) as the number of rings becomes sufficiently large. 138 Polythiophene and its derivatives are generally able to donate and accept electrons fairly easily without decomposition.…”

Section: Bis-heterolepticmentioning

confidence: 99%

Transition Metal Complexes and Photodynamic Therapy from a Tumor-Centered Approach: Challenges, Opportunities, and Highlights from the Development of TLD1433

et al. 2018

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Transition metal complexes are of increasing interest as photosensitizers in photodynamic therapy (PDT) and, more recently, for photochemotherapy (PCT). In recent years, Ru (II) polypyridyl complexes have emerged as the most widely studied systems for both PDT and PCT. Their rich photochemical and photophysical properties derive from a variety of excited-state electronic configurations accessible with visible and near-infrared light, and these properties can be exploited for both energy-and electron-transfer processes that can yield highly potent oxygen-dependent and/or oxygen-independent photobiological activity. Selected examples highlight the use of rational design in coordination chemistry to control the lowest-energy triplet excited state configurations for eliciting a particular type of photoreactivity for PDT and/or PCT effects. These principles are also discussed in the context of the development of TLD1433, the first Ru(II)-based photosensitizer for PDT to enter a human clinical trial. The design of TLD1433 arose from a tumor-centered approach, as part of a complete PDT package that included the light component and the protocol for treating nonmuscle invasive bladder cancer. Briefly, this review summarizes *

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Section: Bis-heterolepticmentioning

confidence: 99%

Transition Metal Complexes and Photodynamic Therapy from a Tumor-Centered Approach: Challenges, Opportunities, and Highlights from the Development of TLD1433

et al. 2018

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“…Considering all cells, the mean voltage deviation with CL balancing is approximately half that observed with OL balancing, i.e., 10.8% instead of 21.8%, respectively. The proposed CL balancing concept compared to methods proposed in the literature, e.g., [31,32], avoids the operation with opposite voltage ripple on FCs, therefore, the switch voltages are not unbalanced by a maximum peak-to-peak voltage ripple of the FCs, which significantly improves the symmetry of the switches' blocking voltages as shown above. This highlights the superiority of the proposed CL balancing concept.…”

Section: Balancing With Non-zero Output Currentmentioning

confidence: 96%

“…With Q2L modulation, the intermediate voltage levels are only used during the switching transitions. The bridgeleg's output voltage thus transitions between the two DC voltage levels (positive and negative) in a staggered fashion [22][23][24][28][29][30][31][32][33][34]. Note that these staggered transitions of the the Q2L-MMC and Q2L-FCC topologies feature lower average dv/dt compared to the (MV) 2-level converters, which is beneficial for the design of EMI filters and magnetics such as medium-frequency transformers, and lowers the stress of the electric insulation [29,[35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the evaluation of Q2L modulation, including the selection of number of levels, dimensioning of FCs, switching frequency and modulation index have been considered in [33]. In [31], methods of FC voltage balancing through adaptation of delay times without using redundant switching sequences are presented for a Q2L-operated 5-level FCC (Q2L-5L-FCC). In this context, switching sequence refers to the order in which the individual FC cells are commutated during a single Q2L transition.…”

Section: Introductionmentioning

confidence: 99%

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Load-Independent Voltage Balancing of Multi-Level Flying Capacitor Converters in Quasi-2-Level Operation

et al. 2021

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Quasi-2-level (Q2L) operation of multi-level bridge-legs, especially of flying-capacitor converters (FCC), is an interesting option for realizing single-cell power conversion in applications whose system voltages exceed the ratings of available power semiconductors. To ensure equal voltage sharing among a Q2L-FCC’s switches, the voltages of a Q2L-FCC’s minimized flying capacitors (FCs) must always be balanced. Thus, we propose a concept for load-independent FC voltage balancing: For non-zero load current, we use a model predictive control (MPC) approach to identify the commutation sequence of the individual switches within a Q2L transition that minimizes the FC or cell voltage errors. In case of zero load current, we employ a novel MPC-based approach using cell multiple switching (CMS), i.e., the insertion of additional zero-current commutations within a Q2L transition, to exchange charge between the FCs via the charging currents of the switches’ parasitic capacitances. Experiments with a 5-level FCC half-bridge demonstrator confirm the validity of the derived models and verify the performance of the proposed load-independent balancing concept.

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“…In this aspect, the molecular band gaps are parameters of central importance when determining possible applications of conducting polymers [9,10]. In fact, the molecular band gap control is essential to enhance electroluminescence of organic light-emitting diodes (OLED) [11] as well to improve the efficiency of light absorption in photovoltaic cells [12]. The search for materials with small band gaps has been motivated, by the need to develop organic polymers semiconductors with high electrical conductivity [13,14].…”

Section: Introductionmentioning

confidence: 99%

Toward Bottom-up Optoelectronic Design of Increasing Fluorination Low Bandgap in <i>PDTPQ<SUB>X</SUB>-types</i> Copolymers for Organic Photovoltaics Devices

Koudjina¹,

Affi²,

Sawadogo³

et al. 2021

IJCTC

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Organic photovoltaic performance has been investigated about the fluorination effects as one part on the optoelectronic properties. The quantum chemical accuracy of the optoelectronic and structural properties based on D-A (Donor-Acceptor) conjugated copolymers as PDTPQ X -type (Poly-dithieno-pyrrol-Quinoxaline) has been tediously exposed. The Donor-Acceptor in the copolymers was in our case constitutes to the Donor part in the photovoltaic device, while the Acceptor starting is the PC 60 BM in the same device, which composed the photovoltaic solar cells. The choice of the Donor part in the copolymers was obtained by their HOMO-LUMO bandgap and UV-visible absorption. The bandgap of the Donor part must be higher than that of the Acceptor part for an untroubled charges transfer from the Donor to the Acceptor according to the photovoltaic principle. The substitution of fluorine atoms (0F, 1F, 2F) on the quinoxaline constituents is an effective way to low the HOMO and LUMO energy levels of the alternating copolymers. This fluorine effect has been explored on the optoelectronic properties such as the HOMO-LUMO band gap E gap energy, the fill factor FF, the open circuit voltage V oc , the electron transfer energy ∆E et , the excitation energy ∆E ex , the absorption wave length λ and the oscillator strength OS. The equilibrium geometry at the ground state, the electronic structures as the frontier orbital isosurface have been obtained under the caster of the density functional theory (DFT) assist by the time-dependent density functional theory (TD-DFT) with M05 as exchange-correlation functional to come with 6-311G(d,p) basis set. Calculations were performed both in vaccuum and Chlorobenzene (CB) solvent with IEFPCM quantum model. All this has been done with the aim to enhance the energy gap, the V oc values and the fill factor FF, which exposed the nanomorphology as the topology of the solar cells photoactive layers. The results of this study show that these promote compounds systems as in the fluorination order are excellent candidates to build photovoltaic device in aim to enhance the open-circuit voltage for donor-acceptor heterojunctions used in organic solar cells.

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Quasi-Two-Level Operation of a Five-Level Flying-Capacitor Converter

Cited by 15 publications

References 8 publications

Transition Metal Complexes and Photodynamic Therapy from a Tumor-Centered Approach: Challenges, Opportunities, and Highlights from the Development of TLD1433

Transition Metal Complexes and Photodynamic Therapy from a Tumor-Centered Approach: Challenges, Opportunities, and Highlights from the Development of TLD1433

Load-Independent Voltage Balancing of Multi-Level Flying Capacitor Converters in Quasi-2-Level Operation

Toward Bottom-up Optoelectronic Design of Increasing Fluorination Low Bandgap in <i>PDTPQ<SUB>X</SUB>-types</i> Copolymers for Organic Photovoltaics Devices

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Quasi-Two-Level Operation of a Five-Level Flying-Capacitor Converter

Cited by 15 publications

References 8 publications

Transition Metal Complexes and Photodynamic Therapy from a Tumor-Centered Approach: Challenges, Opportunities, and Highlights from the Development of TLD1433

Transition Metal Complexes and Photodynamic Therapy from a Tumor-Centered Approach: Challenges, Opportunities, and Highlights from the Development of TLD1433

Load-Independent Voltage Balancing of Multi-Level Flying Capacitor Converters in Quasi-2-Level Operation

Toward Bottom-up Optoelectronic Design of Increasing Fluorination Low Bandgap in &lt;i&gt;PDTPQ&lt;SUB&gt;X&lt;/SUB&gt;-types&lt;/i&gt; Copolymers for Organic Photovoltaics Devices

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Toward Bottom-up Optoelectronic Design of Increasing Fluorination Low Bandgap in <i>PDTPQ<SUB>X</SUB>-types</i> Copolymers for Organic Photovoltaics Devices