Erfan Azimi - Academia.edu (original) (raw)
Papers by Erfan Azimi
IEEE Transactions on Industrial Electronics, 2021
the necessity of using several components in multilevel inverters jeopardizes the reliability of ... more the necessity of using several components in multilevel inverters jeopardizes the reliability of their operation. Hence, the aim of this research is to propose a novel single-phase fault-tolerant topology based on switched-capacitor concept to ensure robustness of the converter in the occurrence of a fault. The proposed single source converter steps up the input voltage seven times with a simple control strategy. Fault Tolerance of the converter is achieved by considering multiple fault cases and providing several redundant switching schemes concerning the type and location of failure. Each switching scheme is designed in a way to ensure the tolerability to both single and multiple open/short circuit failure. Also, self-voltage balancing of the capacitors, as well as the same amount of voltage levels and amplitude in the output is guaranteed. Experimental analysis is carried out, and the results confirm the viability of the proposed inverter under normal and post-fault operating modes.
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
This paper presents a grid-integrated multilevel inverter based on Packed E-Cell (PEC) structure ... more This paper presents a grid-integrated multilevel inverter based on Packed E-Cell (PEC) structure for connecting renewable energy sources to the existing power grids. This dual source topology benefits from low number of semiconductor devices, simple robust control strategy, and smooth current of the capacitors. The shunt-capacitors of the converter are charged or discharged simultaneously to a quarter of the input DC source via horizontally extension design of the circuit. Thus, by applying only one voltage sensor and simple phase disposition pulse width modulation approach (PD-PWM), the operation of the inverter to generate 17-levels for the output voltage is ensured. For improving the dynamic performance of the converter, a closed-loop controller is designed and a precise mathematical analysis is presented as well. Accurate performance of the proposed structure is assessed by calculating theoretical analyses and simulating the inverter in MATLAB Environment.
International Journal of Electronics, 2021
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
The presented article introduces a versatile multilevel inverter based on Packed E-Cell (PEC) top... more The presented article introduces a versatile multilevel inverter based on Packed E-Cell (PEC) topology. This structure is suitable for conversion of photovoltaic energy generations to supply AC loads and uninterruptible power supplies (UPS). Requiring a reduced number of power switches and capacitors compared to other inverters along its control simplicity are the prominent merits of this converter. Thanks to the horizontally extension of the shunt-capacitors, both of them can be charged or discharged to a quarter if the input source, at the same time. Hence, by applying two isolated input sources and one voltage sensor, the proposed inverter generates 17-levels for the output voltage. Simple level shifted pulse width modulation technique (LS-PWM) is used to control the operation of the proposed inverter. Finally, the accurate performance of the proposed multilevel structure is investigated through MATLAB simulations.
2021 International Conference on Smart Energy Systems and Technologies (SEST)
International Journal of Electronics
IEEE Transactions on Power Electronics
Electronics
A bi-level operation scheduling of distribution system operator (DSO) and multi-microgrids (MMGs)... more A bi-level operation scheduling of distribution system operator (DSO) and multi-microgrids (MMGs) considering both the wholesale market and retail market is presented in this paper. To this end, the upper-level optimization problem minimizes the total costs from DSO’s point of view, while the profits of microgrids (MGs) are maximized in the lower-level optimization problem. Besides, a scenario-based stochastic programming framework using the heuristic moment matching (HMM) method is developed to tackle the uncertain nature of the problem. In this regard, the HMM technique is employed to model the scenario matrix with a reduced number of scenarios, which is effectively suitable to achieve the correlations among uncertainties. In order to solve the proposed non-linear bi-level model, Karush–Kuhn–Tucker (KKT) optimality conditions and linearization techniques are employed to transform the bi-level problem into a single-level mixed-integer linear programming (MILP) optimization problem....
Energies
A new structure of switched capacitor multilevel inverter (SCMLI) capable of voltage boosting and... more A new structure of switched capacitor multilevel inverter (SCMLI) capable of voltage boosting and with self-balancing ability is introduced in this article. This advantage is the result of a step by step rise of capacitor voltages in each module, supplied by just one DC voltage source. The proposed topology generates a sinusoidal output waveform with a magnitude several times greater than the input one. Higher output staircase AC voltage is obtained by applying a nearest level control (NLC) modulation technique. The most significant features of this configuration can be mentioned as: fewer semiconductor devices, remarkably low total harmonic distortion (THD), desirable operating under high /low frequency, high efficiency, inherent bipolar voltage production, easy circuit expansion, ease of control and size reduction of the circuit thanks to utilizing neither bulky transformer nor inductor. Moreover, the proposed SCMLI is comprehensively surveyed through theoretical investigation and...
Electronics
This paper aims to present a novel switched-capacitor multi-level inverter. The presented structu... more This paper aims to present a novel switched-capacitor multi-level inverter. The presented structure generates a staircase near sinusoidal AC voltage by using a single DC source and a few capacitors to step-up the input voltage. The nearest level control (NLC) strategy is used to control the operation of the converter. These switching states are designed in a way that they always ensure the self-voltage balancing of the capacitors. Low switching frequency, simple control, and inherent bipolar output are some of the advantages of the presented inverter. Compared to other existing topologies, the structure requires fewer circuit elements. Bi-directional power flow ability of the proposed topology, facilitates the operation of the circuit under wide range of load behaviors which makes it applicable in most industries. Besides, a 13-level laboratory prototype is implemented to realize and affirm the efficacy of the MATLAB Simulink model under different load conditions. The simulation and...
IEEE Transactions on Industrial Electronics, 2021
the necessity of using several components in multilevel inverters jeopardizes the reliability of ... more the necessity of using several components in multilevel inverters jeopardizes the reliability of their operation. Hence, the aim of this research is to propose a novel single-phase fault-tolerant topology based on switched-capacitor concept to ensure robustness of the converter in the occurrence of a fault. The proposed single source converter steps up the input voltage seven times with a simple control strategy. Fault Tolerance of the converter is achieved by considering multiple fault cases and providing several redundant switching schemes concerning the type and location of failure. Each switching scheme is designed in a way to ensure the tolerability to both single and multiple open/short circuit failure. Also, self-voltage balancing of the capacitors, as well as the same amount of voltage levels and amplitude in the output is guaranteed. Experimental analysis is carried out, and the results confirm the viability of the proposed inverter under normal and post-fault operating modes.
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
This paper presents a grid-integrated multilevel inverter based on Packed E-Cell (PEC) structure ... more This paper presents a grid-integrated multilevel inverter based on Packed E-Cell (PEC) structure for connecting renewable energy sources to the existing power grids. This dual source topology benefits from low number of semiconductor devices, simple robust control strategy, and smooth current of the capacitors. The shunt-capacitors of the converter are charged or discharged simultaneously to a quarter of the input DC source via horizontally extension design of the circuit. Thus, by applying only one voltage sensor and simple phase disposition pulse width modulation approach (PD-PWM), the operation of the inverter to generate 17-levels for the output voltage is ensured. For improving the dynamic performance of the converter, a closed-loop controller is designed and a precise mathematical analysis is presented as well. Accurate performance of the proposed structure is assessed by calculating theoretical analyses and simulating the inverter in MATLAB Environment.
International Journal of Electronics, 2021
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
The presented article introduces a versatile multilevel inverter based on Packed E-Cell (PEC) top... more The presented article introduces a versatile multilevel inverter based on Packed E-Cell (PEC) topology. This structure is suitable for conversion of photovoltaic energy generations to supply AC loads and uninterruptible power supplies (UPS). Requiring a reduced number of power switches and capacitors compared to other inverters along its control simplicity are the prominent merits of this converter. Thanks to the horizontally extension of the shunt-capacitors, both of them can be charged or discharged to a quarter if the input source, at the same time. Hence, by applying two isolated input sources and one voltage sensor, the proposed inverter generates 17-levels for the output voltage. Simple level shifted pulse width modulation technique (LS-PWM) is used to control the operation of the proposed inverter. Finally, the accurate performance of the proposed multilevel structure is investigated through MATLAB simulations.
2021 International Conference on Smart Energy Systems and Technologies (SEST)
International Journal of Electronics
IEEE Transactions on Power Electronics
Electronics
A bi-level operation scheduling of distribution system operator (DSO) and multi-microgrids (MMGs)... more A bi-level operation scheduling of distribution system operator (DSO) and multi-microgrids (MMGs) considering both the wholesale market and retail market is presented in this paper. To this end, the upper-level optimization problem minimizes the total costs from DSO’s point of view, while the profits of microgrids (MGs) are maximized in the lower-level optimization problem. Besides, a scenario-based stochastic programming framework using the heuristic moment matching (HMM) method is developed to tackle the uncertain nature of the problem. In this regard, the HMM technique is employed to model the scenario matrix with a reduced number of scenarios, which is effectively suitable to achieve the correlations among uncertainties. In order to solve the proposed non-linear bi-level model, Karush–Kuhn–Tucker (KKT) optimality conditions and linearization techniques are employed to transform the bi-level problem into a single-level mixed-integer linear programming (MILP) optimization problem....
Energies
A new structure of switched capacitor multilevel inverter (SCMLI) capable of voltage boosting and... more A new structure of switched capacitor multilevel inverter (SCMLI) capable of voltage boosting and with self-balancing ability is introduced in this article. This advantage is the result of a step by step rise of capacitor voltages in each module, supplied by just one DC voltage source. The proposed topology generates a sinusoidal output waveform with a magnitude several times greater than the input one. Higher output staircase AC voltage is obtained by applying a nearest level control (NLC) modulation technique. The most significant features of this configuration can be mentioned as: fewer semiconductor devices, remarkably low total harmonic distortion (THD), desirable operating under high /low frequency, high efficiency, inherent bipolar voltage production, easy circuit expansion, ease of control and size reduction of the circuit thanks to utilizing neither bulky transformer nor inductor. Moreover, the proposed SCMLI is comprehensively surveyed through theoretical investigation and...
Electronics
This paper aims to present a novel switched-capacitor multi-level inverter. The presented structu... more This paper aims to present a novel switched-capacitor multi-level inverter. The presented structure generates a staircase near sinusoidal AC voltage by using a single DC source and a few capacitors to step-up the input voltage. The nearest level control (NLC) strategy is used to control the operation of the converter. These switching states are designed in a way that they always ensure the self-voltage balancing of the capacitors. Low switching frequency, simple control, and inherent bipolar output are some of the advantages of the presented inverter. Compared to other existing topologies, the structure requires fewer circuit elements. Bi-directional power flow ability of the proposed topology, facilitates the operation of the circuit under wide range of load behaviors which makes it applicable in most industries. Besides, a 13-level laboratory prototype is implemented to realize and affirm the efficacy of the MATLAB Simulink model under different load conditions. The simulation and...