Electronics

Research

16 pages, 16912 KiB

Open AccessCommunication

Generalization of Split DC Link Voltages Behavior in Three-Phase-Level Converters Operating with Arbitrary Power Factor with Restricted Zero-Sequence Component

by Yarden Siton and Alon Kuperman

Electronics 2023, 12(19), 4063; https://doi.org/10.3390/electronics12194063 - 27 Sep 2023

Viewed by 546

Abstract

This article examines the impact of a power factor on the behavior of partial DC link voltages in three-phase three-level AC/DC (or DC/AC) converters operating without additional balancing hardware. We consider the case in which the controller utilizes a bandwidth-restricted (DC in steady [...] Read more.

This article examines the impact of a power factor on the behavior of partial DC link voltages in three-phase three-level AC/DC (or DC/AC) converters operating without additional balancing hardware. We consider the case in which the controller utilizes a bandwidth-restricted (DC in steady state) zero-sequence component to achieve average partial DC link voltage equalization since the injection of high-order zero-sequence components is impossible or forbidden. An assessment of partial split DC-link capacitor voltage behavior (particularly that of ripple magnitudes and phases) is necessary for, e.g., minimizing the values of DC link capacitances and selecting reference voltage values. Previous studies assessed the abovementioned behavior analytically for operation under a unity power factor based on third-harmonic-dominated split partial voltages’ ripple nature. However, it is shown here that deviation from the unity power factor introduces additional (to the third harmonic) non-negligible harmonic content, increasing partial voltage ripple magnitudes and shifting their phase (relative to the mains voltages). As a result, the third-harmonic-only assumption is no longer valid, and it is then nearly impossible to derive corresponding analytical expressions. Consequently, a numerical approach is used in this work to derive a generalized expression of normalized ripple energy as a function of the power factor, which can then easily be utilized for assessments of split DC link voltage behaviors for certain DC link capacitances and reference voltages. Simulations and experimental results validate the proposed methodology applied to a 10 kVA T-type converter prototype. Full article

(This article belongs to the Special Issue Single-Stage DC-AC Power Conversion Systems)

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11 pages, 5694 KiB

Open AccessCommunication

On the Minimum Value of Split DC Link Capacitances in Three-Phase Three-Level Grid-Connected Converters Operating with Unity Power Factor with Limited Zero-Sequence Injection

by Yarden Siton, Moshe Sitbon, Ilan Aharon, Simon Lineykin, Dmitry Baimel and Alon Kuperman

Electronics 2023, 12(9), 1994; https://doi.org/10.3390/electronics12091994 - 25 Apr 2023

Cited by 2 | Viewed by 805

Abstract

This paper introduces an approach to calculating the minimum value of split DC link capacitance in three-phase three-level grid-connected DC-AC converters operating with unity power factor without either active balancing circuits or AC zero sequence injection. Due to the fact that partial DC [...] Read more.

This paper introduces an approach to calculating the minimum value of split DC link capacitance in three-phase three-level grid-connected DC-AC converters operating with unity power factor without either active balancing circuits or AC zero sequence injection. Due to the fact that partial DC link voltages and rectified mains phase voltages reach their maximum and minimum values, respectively, at different time instants, it is feasible to decrease the minimum value of the former below the maximum value of the latter while still maintaining proper functionality of the power stage. The minimum possible split DC link capacitance values are hence derived from the boundary condition where the above-mentioned voltages are tangent to each other. The accuracy of the analytical derivations is confirmed by simulations and experiments carried out on a 10 kVA T-type converter prototype, which show a high degree of agreement. Full article

(This article belongs to the Special Issue Single-Stage DC-AC Power Conversion Systems)

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23 pages, 8951 KiB

Open AccessArticle

Drive System Inverter Modeling Using Symbolic Regression

by Matko Glučina, Nikola Anđelić, Ivan Lorencin and Sandi Baressi Šegota

Electronics 2023, 12(3), 638; https://doi.org/10.3390/electronics12030638 - 27 Jan 2023

Viewed by 1052

Abstract

For accurate and efficient control performance of electrical drives, precise values of phase voltages are required. In order to achieve control of the electric drive, the development of mathematical models of the system and its parts is often approached. Data-driven modeling using artificial [...] Read more.

For accurate and efficient control performance of electrical drives, precise values of phase voltages are required. In order to achieve control of the electric drive, the development of mathematical models of the system and its parts is often approached. Data-driven modeling using artificial intelligence can often be unprofitable due to the large amount of computing resources required. To overcome this problem, the idea is to investigate if a genetic programming–symbolic regressor (GPSR) algorithm could be used to obtain simple symbolic expressions which could estimate the mean phase voltages (black-box inverter model) and duty cycles (black-box compensation scheme) with high accuracy using a publicly available dataset. To obtain the best symbolic expressions using GPSR, a random hyperparameter search method and 5-fold cross-validation were developed. The best symbolic expressions were chosen based on their estimation performance, which was measured using the coefficient of determination (

R^{2}

), mean absolute error (

M A E

), and root mean squared error (

R M S E

). The best symbolic expressions for the estimation of mean phase voltages achieved

R^{2}

,

M A E

, and

R M S E

values of 0.999, 2.5, and 2.8, respectively. The best symbolic expressions for the estimation of duty cycles achieved

R^{2}

,

M A E

, and

R M S E

values of 0.9999, 0.0027, and 0.003, respectively. The originality of this work lies in the application of the GPSR algorithm, which, based on a mathematical equation it generates, can estimate the value of mean phase voltages and duty cycles in a three-phase inverter. Using the obtained model, it is possible to estimate the given aforementioned values. Such high-performing estimation represents an opportunity to replace expensive online equipment with a cheaper, more precise, and faster approach, such as a GPSR-based model. The presented procedure shows that the symbolic expression for the accurate estimation of mean phase voltages and duty cycles can be obtained using the GPSR algorithm. Full article

(This article belongs to the Special Issue Single-Stage DC-AC Power Conversion Systems)

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22 pages, 10225 KiB

Open AccessFeature PaperArticle

DC-AC Converter with Dynamic Voltage Restoring Ability Based on Self-Regulated Phase Estimator-DQ Algorithm: Practical Modeling and Performance Evaluation

by Kamrul Hasan, Muhammad Murtadha Othman, Sheikh Tanzim Meraj, Md. Siddikur Rahman, Molla Shahadat Hossain Lipu and Panos Kotsampopoulos

Electronics 2023, 12(3), 523; https://doi.org/10.3390/electronics12030523 - 19 Jan 2023

Cited by 1 | Viewed by 2137

Abstract

A self-regulated phase estimator (SRPE)-based DQ algorithm for a DC-AC converter with dynamic voltage restoring (DVR) ability is presented in this paper. When compared to the conventional phase-locked loop (PLL), the provided controller can significantly reduce phase distortions and low-order harmonics from the [...] Read more.

A self-regulated phase estimator (SRPE)-based DQ algorithm for a DC-AC converter with dynamic voltage restoring (DVR) ability is presented in this paper. When compared to the conventional phase-locked loop (PLL), the provided controller can significantly reduce phase distortions and low-order harmonics from the load voltage while attaining quicker dynamic response. Furthermore, the fundamental attribute of the load voltage allows the integrated DC-AC converter to operate at a consistent frequency eliminating frequency oscillations. The SRPE is utilized primarily in the DQ control theory as the reference voltage generator which can compensate for the grid voltage. SRPE has good band-pass filtering properties and a mathematically simple structure that can thoroughly attenuate voltage imbalance and has quick dynamic response. The SRPE has been made to be frequency-adaptive using a damping factor and robust grid frequency estimation. The SRPE can maintain the fundamental frequency at 50 Hz and keep the total harmonic distortions (THD) within the 5% limit even during grid disruptions. The DC-AC converter and SRPE-DQ’s stability are thoroughly examined. The experiment is carried out to show the efficacy of the suggested complete control system. There are also comparative simulation studies to show the benefits of the suggested technique. The results reveal that the suggested approach can immediately identify and correct for any grid voltage imbalance while also assisting in maintaining the constant voltage at the load side despite voltage sag/swell and distortions. Full article

(This article belongs to the Special Issue Single-Stage DC-AC Power Conversion Systems)

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19 pages, 4312 KiB

Open AccessArticle

A Single-Stage Bimodal Transformerless Inverter with Common-Ground and Buck-Boost Features

by Dai-Van Vo, Khai M. Nguyen, Young-Cheol Lim and Joon-Ho Choi

Electronics 2023, 12(1), 221; https://doi.org/10.3390/electronics12010221 - 02 Jan 2023

Cited by 3 | Viewed by 1626

Abstract

This paper proposes a single-phase, single-stage common-ground inverter with a non-electrolytic capacitor and buck-boost ability. The proposed single-stage inverter is employed by a boost stage DC-DC converter and bimodal circuit, which makes it satisfactory for PV systems with a wide input voltage range [...] Read more.

This paper proposes a single-phase, single-stage common-ground inverter with a non-electrolytic capacitor and buck-boost ability. The proposed single-stage inverter is employed by a boost stage DC-DC converter and bimodal circuit, which makes it satisfactory for PV systems with a wide input voltage range and lower switch voltage stress. The leakage current of the proposed single-stage inverter can effectively suppress because the parasitic capacitor between the PV panel and the ground is shortened. In addition, the proposed single-stage inverter does not include electrolytic capacitors, which reduces the equivalent series resistance of electrolytic capacitors and also the size of the inverter system. The topology, operating principle, and PWM control method of the proposed single-stage inverter are given. The design guidelines of components and comparative studies of the proposed single-stage inverter are provided. A 500 W laboratory prototype of the proposed single-stage inverter is built to verify the correctness of the simulation and theoretical analysis. Full article

(This article belongs to the Special Issue Single-Stage DC-AC Power Conversion Systems)

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28 pages, 11463 KiB

Open AccessArticle

A Direct Single-Phase to Three-Phase AC/AC Power Converter

by Shuvra Prokash Biswas, Md. Shihab Uddin, Md. Rabiul Islam, Sudipto Mondal and Joysree Nath

Electronics 2022, 11(24), 4213; https://doi.org/10.3390/electronics11244213 - 16 Dec 2022

Cited by 1 | Viewed by 4846

Abstract

The traditional DC-link indirect AC/AC power converters (AC/DC/AC converters) employ two-stage power conversion, which increases the circuit complexity along with gate driving challenges, placing an excessive burden on the processor while implementing complex switching modulation techniques and leads to power conversion losses due [...] Read more.

The traditional DC-link indirect AC/AC power converters (AC/DC/AC converters) employ two-stage power conversion, which increases the circuit complexity along with gate driving challenges, placing an excessive burden on the processor while implementing complex switching modulation techniques and leads to power conversion losses due to the use of a large amount of controlled power semiconductor switches. On the contrary, the traditional direct AC/AC voltage controllers, as well as frequency changers, suffer from high total harmonic distortion (THD) problems. In this paper, a new single-phase to three-phase AC/AC step-down power converter is proposed, which utilizes a multi-linking transformer and bilateral triode thyristors (TRIACs) as power semiconductor switches. The proposed direct AC/AC power converter employs single-stage power conversion, which mitigates the complexity of two-stage DC-link indirect AC/AC converters and traditional single-stage AC/AC frequency changers. Instead of using high-frequency pulse width modulated gate driving signals, line frequency gate pulses are used to trigger the TRIACs of the proposed AC/AC converter, which not only aids in reducing the power loss of the converter but also mitigates the cost and complexity of gate driver circuits. The proposed AC/AC converter reduces the THD of the output voltage significantly as compared to traditional direct AC/AC frequency changers. The performance of the proposed AC/AC converter is validated against RL and induction motor load in terms of overall THD and individual harmonic components through MATLAB/Simulink environment. A reduced-scale laboratory prototype is built and tested to evaluate the performance of the proposed AC/AC power converter. The experimental and simulation outcomes reveal the feasibility and excellent features of the proposed single-phase to three-phase AC/AC converter topology. Full article

(This article belongs to the Special Issue Single-Stage DC-AC Power Conversion Systems)

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10 pages, 3147 KiB

Open AccessArticle

A Common-Ground-Type Five-Level Inverter with Dynamic Voltage Boost

by Saifullah Kakar, Shahrin Md. Ayob, Sze Sing Lee, M. Saad Bin Arif, Norjulia Mohamad Nordin, Reza Barzegarkhoo and Yam P. Siwakoti

Electronics 2022, 11(24), 4174; https://doi.org/10.3390/electronics11244174 - 14 Dec 2022

Cited by 2 | Viewed by 1537

Abstract

Today, transformerless inverters (TIs) are widely applicable in different solar photovoltaic (PV) grid-connected applications owing to their promising features, such as higher efficiency and power density. However, high-frequency common-mode voltage (CMV) in these topologies can result in high leakage current, electromagnetic interference, and [...] Read more.

Today, transformerless inverters (TIs) are widely applicable in different solar photovoltaic (PV) grid-connected applications owing to their promising features, such as higher efficiency and power density. However, high-frequency common-mode voltage (CMV) in these topologies can result in high leakage current, electromagnetic interference, and lack of safety, reducing the whole system’s reliability. To resolve the problems associated with TIs, this paper proposes a novel hybrid switched capacitor (SC)-based common-ground (CG) transformerless inverter (TI) topology, which can be applied in grid-connected photovoltaic (PV) applications. The boost inductor is integrated to achieve continuous input current and dynamic voltage gain. In addition, the proposed circuit comprises nine switches and two SCs with a single input DC source. It can generate five-level AC voltage with voltage boosting within a single-stage DC–AC power conversion. The working principles of the proposed topology, circuit description, and control technique are presented. Furthermore, the proposed inverter is comprehensively compared with other five-level TIs to show its superiority. Finally, a laboratory prototype is developed and tested to validate the practical viability of the proposed configuration. Full article

(This article belongs to the Special Issue Single-Stage DC-AC Power Conversion Systems)

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12 pages, 7904 KiB

Open AccessArticle

A Dual-Buck-Boost DC–DC/AC Universal Converter

by Yao Rong Ong, Shuyu Cao, Sze Sing Lee, Chee Shen Lim, Max M. Chen, Naser Vosoughi Kurdkandi, Reza Barzegarkhoo and Yam P. Siwakoti

Electronics 2022, 11(13), 1973; https://doi.org/10.3390/electronics11131973 - 24 Jun 2022

Viewed by 2127

Abstract

This paper proposes a universal converter that is capable of operating in three modes for generating positive dc voltage, negative dc voltage, and sinusoidal ac voltage. By controlling the duty-cycle of two half-bridges, an inductor is operated at a high frequency to control [...] Read more.

This paper proposes a universal converter that is capable of operating in three modes for generating positive dc voltage, negative dc voltage, and sinusoidal ac voltage. By controlling the duty-cycle of two half-bridges, an inductor is operated at a high frequency to control the voltage across two film capacitors that constitute a dual-buck-boost converter. Two additional half-bridges operating at a fixed state or line frequency are used to select the mode of operation. Compared to the latest universal converter in the recent literature, the proposed topology has the same switch count while reducing the number of conducting switches for inductor current and reducing the number of switches operating at high frequency. The operation of the proposed dual-buck-boost dc–dc/ac universal converter is analyzed. Experimental results are presented for validation. The power conversion efficiency of the 100 W experimental prototype modeled in PLECS is approximately 98%. Full article

(This article belongs to the Special Issue Single-Stage DC-AC Power Conversion Systems)

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