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4 pages, 188 KiB

Open AccessEditorial

Power Converters in Power Electronics: Current Research Trends

by Minh-Khai Nguyen

Electronics 2020, 9(4), 654; https://doi.org/10.3390/electronics9040654 - 16 Apr 2020

Cited by 8 | Viewed by 7450

Abstract

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical [...] Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

Research

Jump to: Editorial, Review

10 pages, 3662 KiB

Open AccessArticle

A Novel RPWN Selective Harmonic Elimination Method for Single-Phase Inverter

by Guohua Li, Chunwu Liu, Zhenfang Fu and Yufeng Wang

Electronics 2020, 9(3), 489; https://doi.org/10.3390/electronics9030489 - 16 Mar 2020

Cited by 5 | Viewed by 2990

Abstract

In the existing random pule width modulation (RPWM) selective harmonic elimination methods, the formula of switching cycle T_N+1 is complex, and the duty ratio D_N+1 of the next switching cycle needs to be calculated in advance. However, in the case of [...] Read more.

In the existing random pule width modulation (RPWM) selective harmonic elimination methods, the formula of switching cycle T_N+1 is complex, and the duty ratio D_N+1 of the next switching cycle needs to be calculated in advance. However, in the case of unknown T_N+1, D_N+1 is also difficult to calculate accurately, and the two parameters are based on each other. A novel selective harmonic elimination method in RPWM is proposed in this paper. The PWM voltage pulse is placed at the back of the switch cycle, which simplifies the formula of the switch cycle T_N+1 and eliminates the need to calculate the duty ratio D_N+1. Two kinds of RPWM selective harmonic elimination ideas are summarized. The general formulas of the switch cycle, the effective random number k, and the upper and lower limits of switch frequency corresponding to k are derived. The spectrum shaping of inverter output voltage can be realized without using digital filter in this method. Simple algorithm, small calculation and easy implementation are characteristics of the proposed method. The simulation and experimental results confirm the ability of the proposed method for reducing harmonics at the specific frequency in power spectral density (PSD). Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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16 pages, 1839 KiB

Open AccessArticle

Multiport Isolated link with Current-Fed Z-Source Converters to Manage Power Imbalance in PV Applications

by Jose M. Sandoval, Victor Cardenas, Manuel A. Barrios, Mario Gonzalez Garcia and Janeth Alcala

Electronics 2020, 9(2), 280; https://doi.org/10.3390/electronics9020280 - 6 Feb 2020

Cited by 3 | Viewed by 2387

Abstract

In order to address power imbalance in large-scale PV systems, this paper presents a multiport isolated medium-frequency (MF) link to process different power levels from PV arrays, using current-fed Z-source inverters (CZSI) modules to drive the energy from the PV array to the [...] Read more.

In order to address power imbalance in large-scale PV systems, this paper presents a multiport isolated medium-frequency (MF) link to process different power levels from PV arrays, using current-fed Z-source inverters (CZSI) modules to drive the energy from the PV array to the MF link in a single power stage. The MF link provides the galvanic isolation required by many codes and standards to integrate a system to the grid. The multiport configuration of the MF link allows the system to process different power levels on each primary port and, being all ports magnetically coupled, provide balanced power levels on secondary ports which can be used for multilevel converters applications. Additionally, the current-fed version of the Z-source topology offers natural protection against short-circuit damage enhancing reliability of the system. The analysis of CZSI cells and the study of asymmetrical power levels transference, as well as simulation and experimental results are presented. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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22 pages, 3843 KiB

Open AccessArticle

Comparative Evaluation of Wide-Range Soft-Switching PWM Full-Bridge Modular Multilevel DC–DC Converters

by Jingwen Chen, Xiaofei Li, Hongshe Dang and Yong Shi

Electronics 2020, 9(2), 231; https://doi.org/10.3390/electronics9020231 - 31 Jan 2020

Cited by 1 | Viewed by 3122

Abstract

This paper discusses some wide-range soft-switching full-bridge (FB) modular multilevel dc–dc converters (MMDCs), and a comparative evaluation of these FB MMDCs is also presented. The discussed topologies have all merits belonging to conventional FB MMDCs, e.g., smaller voltage stress on the primary switches, [...] Read more.

This paper discusses some wide-range soft-switching full-bridge (FB) modular multilevel dc–dc converters (MMDCs), and a comparative evaluation of these FB MMDCs is also presented. The discussed topologies have all merits belonging to conventional FB MMDCs, e.g., smaller voltage stress on the primary switches, no added primary clamping devices and modular primary structure. In addition, the primary switches in each converter can obtain zero-voltage switching (ZVS) or zero-current switching (ZCS) in a wide load range. Two presented topologies are selected as examples to discuss in detail. The proposed FB MMDCs are assessed and evaluated based on performance, components and topology structure indices, such as soft switching characteristics, current stress, power loss distribution, number of added devices, complexity of structure and added cost. Experimental results are also included to verify the feasibility and advantages of the new topologies. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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14 pages, 6032 KiB

Open AccessArticle

Add-On Type Pulse Charger for Quick Charging Li-Ion Batteries

by Bongwoo Kwak, Myungbok Kim and Jonghoon Kim

Electronics 2020, 9(2), 227; https://doi.org/10.3390/electronics9020227 - 30 Jan 2020

Cited by 13 | Viewed by 6795

Abstract

In this paper, an add-on type pulse charger is proposed to shorten the charging time of a lithium ion battery. To evaluate the performance of the proposed pulse charge method, an add-on type pulse charger prototype is designed and implemented. Pulse charging is [...] Read more.

In this paper, an add-on type pulse charger is proposed to shorten the charging time of a lithium ion battery. To evaluate the performance of the proposed pulse charge method, an add-on type pulse charger prototype is designed and implemented. Pulse charging is applied to 18650 cylindrical lithium ion battery packs with 10 series and 2 parallel structures. The proposed pulse charger is controlled by pulse duty, frequency and magnitude. Various experimental conditions are applied to optimize the charging parameters of the pulse charging technique. Battery charging data are analyzed according to the current magnitude and duty at 500 Hz and 1000 Hz and 2000 Hz frequency conditions. The proposed system is similar to the charging speed of the constant current method under new battery conditions. However, it was confirmed that as the battery performance is degraded, the charging speed due to pulse charging increases. Thus, in applications where battery charging/discharging occurs frequently, the proposed pulse charger has the advantage of fast charging in the long run over conventional constant current (CC) chargers. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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16 pages, 3904 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Common Mode Voltage Elimination for Quasi-Switch Boost T-Type Inverter Based on SVM Technique

by Duc-Tri Do, Minh-Khai Nguyen, Van-Thuyen Ngo, Thanh-Hai Quach and Vinh-Thanh Tran

Electronics 2020, 9(1), 76; https://doi.org/10.3390/electronics9010076 - 1 Jan 2020

Cited by 15 | Viewed by 3511

Abstract

In this paper, the effect of common-mode voltage generated in the three-level quasi-switched boost T-type inverter is minimized by applying the proposed space-vector modulation technique, which uses only medium vectors and zero vector to synthesize the reference vector. The switching sequence is selected [...] Read more.

In this paper, the effect of common-mode voltage generated in the three-level quasi-switched boost T-type inverter is minimized by applying the proposed space-vector modulation technique, which uses only medium vectors and zero vector to synthesize the reference vector. The switching sequence is selected smoothly for inserting the shoot-through state for the inverter branch. The shoot-through vector is added within the zero vector in order to not affect the active vectors as well as the output voltage. In addition, the shoot-through control signal of active switches of the impedance network is generated to ensure that its phase is shifted 90 degrees compared to shoot through the signal of the inverter leg, which provides an improvement in reducing the inductor current ripple and enhancing the voltage gain. The effectiveness of the proposed method is verified through simulation and experimental results. In addition, the superiority of the proposed scheme is demonstrated by comparing it to the conventional pulse-width modulation technique. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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14 pages, 7046 KiB

Open AccessArticle

Improvement of Stability in a PCM-Controlled Boost Converter with the Target Period Orbit-Tracking Method

by Yanfeng Chen, Fan Xie, Bo Zhang, Dongyuan Qiu, Xi Chen, Zi Li and Guidong Zhang

Electronics 2019, 8(12), 1432; https://doi.org/10.3390/electronics8121432 - 30 Nov 2019

Cited by 4 | Viewed by 5756

Abstract

Thee peak-current-mode (PCM) control strategy is widely adopted in pulse width-modulated (PWM) DC-DC converters. However, the converters always involve a sub-harmonic oscillating state or chaotic state if the active duty ratio is beyond a certain range. Hence, an extra slope signal in the [...] Read more.

Thee peak-current-mode (PCM) control strategy is widely adopted in pulse width-modulated (PWM) DC-DC converters. However, the converters always involve a sub-harmonic oscillating state or chaotic state if the active duty ratio is beyond a certain range. Hence, an extra slope signal in the inductor-current loop is used to stabilize the operation of the converter. This paper presents a new technique for enlarging the stable range of PCM-controlled DC-DC converters, in which the concept of utilizing unstable period-1 orbit (UPO-1) of DC-DC converters is proposed and an implementation scenario based on the parameter-perturbation method is presented. With the proposed technique, perturbations are introduced to the reference current of the control loop, and the converters operating in a chaotic state can be tracked, and thus be stabilized to the target UPO-1. Therefore, the stable operating range of the converters is extended. Based on an example of a PCM-controlled boost converter, simulations are presented as a guide to a detailed implementation process of the proposed technique, and comparisons between the proposed technique and techniques in terms of ramp compensation are provided to show the differentiation in the performance of the converter. Experimental results in the work confirm the effectiveness of the proposed technique. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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13 pages, 6687 KiB

Open AccessArticle

Direct Power-Based Three-Phase Matrix Rectifier Control with Input Power Factor Adjustment

by Jae-Chang Kim, Dongyeon Kim and Sang-Shin Kwak

Electronics 2019, 8(12), 1427; https://doi.org/10.3390/electronics8121427 - 29 Nov 2019

Cited by 5 | Viewed by 3202

Abstract

In a current source rectifier such as a matrix rectifier, input voltage and current cannot be in phase unless an additional input power factor control technique is implemented. This paper proposes such a technique for a matrix rectifier using power-based space vector modulation [...] Read more.

In a current source rectifier such as a matrix rectifier, input voltage and current cannot be in phase unless an additional input power factor control technique is implemented. This paper proposes such a technique for a matrix rectifier using power-based space vector modulation (SVM). In the proposed method, the modulation index and phase required in order to apply the SVM are calculated based on the active and reactive power of the rectifier for intuitive power factor control. The active power that the rectifier should generate for the regulation of the output inductor current is obtained by the PI (proportional-integral) controller. The reactive power, which is supplied by the rectifier for adjustment of the power factor, is assigned differently depending on the output condition: for the output condition capable of unity power factor, it is set to a negative value of reactive power of the input capacitor, and when the unity power factor is not achievable, it is set with the maximum reactive power the rectifier can generate under the given condition to attain the maximum possible input power factor. It is determined whether the given condition is the light load condition by comparing the absolute value of the reactive power supplied by the input capacitor with the maximum rectifier reactive power that can be produced under the given condition. The SVM based on the active and reactive power of the rectifier in this technique allows the input power factor control to be intuitive and simple. The performance and feasibility of the technique were proved by simulation and experimentation. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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15 pages, 2981 KiB

Open AccessArticle

Robust Two-Layer Model Predictive Control for Full-Bridge NPC Inverter-Based Class-D Voltage Mode Amplifier

by Xinwei Wei, Hongliang Wang, Kangliang Wang, Kui Li, Minying Li and An Luo

Electronics 2019, 8(11), 1346; https://doi.org/10.3390/electronics8111346 - 14 Nov 2019

Cited by 2 | Viewed by 2889

Abstract

Finite control set model predictive control (FCS-MPC) is able to handle multiple control objectives and constraints simultaneously with good dynamic performance. However, its industrial application is limited by its high dependence on system model and the huge computational effort. In this paper, a [...] Read more.

Finite control set model predictive control (FCS-MPC) is able to handle multiple control objectives and constraints simultaneously with good dynamic performance. However, its industrial application is limited by its high dependence on system model and the huge computational effort. In this paper, a novel robust two-layer MPC (RM-MPC) with strong robustness is proposed for the full-bridge neutral-point clamped (NPC) voltage mode Class-D amplifier (CDA) aiming at this problem. The errors caused by the parameter mismatches or uncertainties of the LC filter and the load current are regarded as lumped disturbance and estimated by the designed Luenberger observer. The robust control can be achieved by compensating the estimated disturbance to the used predictive model. In order to reduce computation of the controller, a two-layer MPC is proposed for the full-bridge NPC inverter with an LC filter. The first layer is used to calculate the optimal output level which minimizes the tracking error of the output voltage. The second layer is used to determine the switching state for the purpose of capacitor voltage balancing. The experimental results show that the lumped model error is observed centrally through only one observer with low complexity. The two-layer MPC further reduced the computation without affecting the dynamic performance. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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11 pages, 5024 KiB

Open AccessArticle

Current Source AC-Side Clamped Inverter for Leakage Current Reduction in Grid-Connected PV System

by Xiangli Li, Na Wang, Guocheng San and Xiaoqiang Guo

Electronics 2019, 8(11), 1296; https://doi.org/10.3390/electronics8111296 - 6 Nov 2019

Cited by 7 | Viewed by 3461

Abstract

For the grid-connected photovoltaic inverters, the switching-frequency common-mode voltage brings the leakage current, which should be eliminated. So far, many kinds of single-phase inverters have been published for this purpose, but most of them are the conventional voltage-type ones, which have the disadvantages [...] Read more.

For the grid-connected photovoltaic inverters, the switching-frequency common-mode voltage brings the leakage current, which should be eliminated. So far, many kinds of single-phase inverters have been published for this purpose, but most of them are the conventional voltage-type ones, which have the disadvantages of poor reliability due to the DC-link electrolytic capacitor and the risk of short-through of the bridge switches. To solve this technical issue, a novel current source inverter with AC-side clamping is proposed to mitigate the switching-frequency common-mode voltage. Meanwhile, a novel modulation method is proposed for the new single-phase inverter to achieve low-frequency operation of the main switches, which reduces the switching losses. Finally, the proposed method is implemented on the TMS320F28335DSP + XC6SLX9FPGA digital hardware platform. Also, the performance comparisons are done with the traditional solution. The results prove the proposed solution. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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19 pages, 2413 KiB

Open AccessArticle

New “Full-Bridge Buck Inverter–DC Motor” System: Steady-State and Dynamic Analysis and Experimental Validation

by Eduardo Hernández-Márquez, Carlos Alejandro Avila-Rea, José Rafael García-Sánchez, Ramón Silva-Ortigoza, Magdalena Marciano-Melchor, Mariana Marcelino-Aranda, Alfredo Roldán-Caballero and Celso Márquez-Sánchez

Electronics 2019, 8(11), 1216; https://doi.org/10.3390/electronics8111216 - 24 Oct 2019

Cited by 11 | Viewed by 4189

Abstract

A mathematical model of a new “full-bridge Buck inverter–DC motor” system is developed and experimentally validated. First, using circuit theory and the mathematical model of a DC motor, the dynamic behavior of the system under study is deduced. Later, the steady-state, stability, controllability, [...] Read more.

A mathematical model of a new “full-bridge Buck inverter–DC motor” system is developed and experimentally validated. First, using circuit theory and the mathematical model of a DC motor, the dynamic behavior of the system under study is deduced. Later, the steady-state, stability, controllability, and flatness properties of the deduced model are described. The flatness property, associated with the mathematical model, is then exploited so that all system variables and the input can be differentially parameterized in terms of the flat output, which is determined by the angular velocity. Then, when a desired trajectory is proposed for the flat output, the input signal is calculated offline and is introduced into the system. In consequence, the validation of the mathematical model for constant and time-varying duty cycles is possible. Such a validation of this mathematical model is tackled from two directions: (1) by circuit simulation through the SimPowerSystems toolbox of Matlab-Simulink and (2) via a prototype of the system built by using Matlab-Simulink and a DS1104 board. The good similarities between the circuit simulation and the experimental results allow satisfactorily validating the mathematical model. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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16 pages, 7637 KiB

Open AccessArticle

A Fast Charging Balancing Circuit for LiFePO₄ Battery

by Sen-Tung Wu, Yong-Nong Chang, Chih-Yuan Chang and Yu-Ting Cheng

Electronics 2019, 8(10), 1144; https://doi.org/10.3390/electronics8101144 - 10 Oct 2019

Cited by 14 | Viewed by 9439

Abstract

In this paper, a fast charging balancing circuit for LiFePO₄ battery is proposed to address the voltage imbalanced problem of a lithium battery string. During the lithium battery string charging process, the occurrence of voltage imbalance will activate the fast balancing mechanism. [...] Read more.

In this paper, a fast charging balancing circuit for LiFePO₄ battery is proposed to address the voltage imbalanced problem of a lithium battery string. During the lithium battery string charging process, the occurrence of voltage imbalance will activate the fast balancing mechanism. The proposed balancing circuit is composed of a bi-directional converter and the switch network. The purpose of bi-directional is that the energy can be delivered to the lowest voltage cell for charging mode. On the other hand, the energy stored in the magnetizing inductors of the transformer can be charged back to the higher voltage cell in recycling mode. This novel scheme includes the following features: (1) The odd-numbered and even-numbered cells in the string with the maximum differential voltage will be chosen for balancing process directly. In this topology, there is no need to store and deliver the energy through any intermediate or the extra storing components. That is, the energy loss can be saved to improve the efficiency, and the fast balancing technique can be achieved. (2) There is only one converter to complete the energy transfer for voltage balancing process. The concept makes the circuit structure much simpler. (3) The structure has bi-directional power flow and good electrical isolation features. (4) A single chip controller is applied to measure the voltage of each cell to achieve the fast balancing process effectively. At the end of the paper, the practical test of the proposed balancing method on LiFePO₄ battery pack (28.8 V/2.5 Ah) is verified and implemented by the experimental results. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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14 pages, 2692 KiB

Open AccessArticle

A Fractional-Order Element (FOE)-Based Approach to Wireless Power Transmission for Frequency Reduction and Output Power Quality Improvement

by Guidong Zhang, Zuhong Ou and Lili Qu

Electronics 2019, 8(9), 1029; https://doi.org/10.3390/electronics8091029 - 13 Sep 2019

Cited by 10 | Viewed by 3852

Abstract

A wireless power transmission (WPT) requires high switching frequency to achieve energy transmission; however, existing switching devices cannot satisfy the requirements of high-frequency switching, and the efficiency of current WPT is too low. Compared with the traditional power inductors and capacitors, fractional-order elements [...] Read more.

A wireless power transmission (WPT) requires high switching frequency to achieve energy transmission; however, existing switching devices cannot satisfy the requirements of high-frequency switching, and the efficiency of current WPT is too low. Compared with the traditional power inductors and capacitors, fractional-order elements (FOEs) in WPT can realize necessary functions though requiring a lower switching frequency, which leads to a more favorable high-frequency switching performance with a higher efficiency. In this study, a generalized fractional-order WPT (FO-WPT) is established, followed by a comprehensive analysis on its WPT performance and power efficiency. Through extensive simulations of typical FO wireless power domino-resonators (FO-WPDRS), the functionality of the proposed FO-WPT for medium and long-range WPT is demonstrated. The numerical results show that the proposed FOE-based WPT solution has a higher power efficiency and lower switching frequency than conventional methods. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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12 pages, 6046 KiB

Open AccessArticle

A Three-Bridge IPT System for Different Power Levels Conversion under CC/CV Transmission Mode

by Bingyang Luo, Yatao Shou, Jianghua Lu, Ming Li, Xiangtian Deng and Guorong Zhu

Electronics 2019, 8(8), 884; https://doi.org/10.3390/electronics8080884 - 9 Aug 2019

Cited by 3 | Viewed by 4106

Abstract

This paper proposes an inductive power transfer (IPT) system with three-bridge switching compensation topology. With the proposed IPT topology, the equivalent circuit and the resonant condition are analyzed to achieve the load-independent constant current (CC) and load-independent constant voltage (CV) outputs. On this [...] Read more.

This paper proposes an inductive power transfer (IPT) system with three-bridge switching compensation topology. With the proposed IPT topology, the equivalent circuit and the resonant condition are analyzed to achieve the load-independent constant current (CC) and load-independent constant voltage (CV) outputs. On this basis, multiple power levels can be achieved under CC/CV conditions by bridge arm switching, which makes it possible to complete charging tasks for multiple power level electric vehicles (EV) without switching the IPT system. A circuit simulation was built to verify the different power level switching effects of the structure. A 3.3 kW IPT system was designed to verify the proposed structure. At the rated output power, the experimental efficiency was up to 92.04% and 91.21% in CC and CV output modes, respectively. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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15 pages, 5489 KiB

Open AccessArticle

Control Design of LCL Type Grid-Connected Inverter Based on State Feedback Linearization

by Longyue Yang, Chunchun Feng and Jianhua Liu

Electronics 2019, 8(8), 877; https://doi.org/10.3390/electronics8080877 - 7 Aug 2019

Cited by 8 | Viewed by 3679

Abstract

Control strategy is the key technology of power electronic converter equipment. In order to solve the problem of controller design, a general design method is presented in this paper, which is more convenient to use computer machine learning and provides design rules for [...] Read more.

Control strategy is the key technology of power electronic converter equipment. In order to solve the problem of controller design, a general design method is presented in this paper, which is more convenient to use computer machine learning and provides design rules for high-order power electronic system. With the higher order system Lie derivative, the nonlinear system is mapped to a controllable standard type, and then classical linear system control method is adopted to design the controller. The simulation and experimental results show that the two controllers have good steady-state control performance and dynamic response performance. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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20 pages, 7228 KiB

Open AccessArticle

Application of the Lyapunov Algorithm to Optimize the Control Strategy of Low-Voltage and High-Current Synchronous DC Generator Systems

by Jinfeng Liu, Xiaohai Tan, Xudong Wang and Herbert Ho-Ching IU

Electronics 2019, 8(8), 871; https://doi.org/10.3390/electronics8080871 - 6 Aug 2019

Cited by 1 | Viewed by 3389

Abstract

In the present study, a novel multiple three-phase low-voltage and high-current permanent magnet synchronous generation system is proposed, which has only half-turn coils per phase. The proposed system is composed of a generator and two confluence plates with 108 rectifier modules. The output [...] Read more.

In the present study, a novel multiple three-phase low-voltage and high-current permanent magnet synchronous generation system is proposed, which has only half-turn coils per phase. The proposed system is composed of a generator and two confluence plates with 108 rectifier modules. The output can reach up to 10,000 A continuous DC power supply, which is suitable for the outdoors and non-commercial power supply. The application of the Lyapunov algorithm in the synchronous rectification control was optimized. A current sharing loop control was added to the closed-loop control to ensure a stable output voltage and the output current sharing of each rectifier module. Since the two control variables solved by the Lyapunov algorithm were coupled and the negative definite function of the Lyapunov algorithm could not be guaranteed in this system, a simple decoupling method was used to decouple the control variables. Compared to the conventional control, the proposed strategy highly improved the dynamic performance of the system. The effectiveness of the proposed strategy was verified by the simulation. The 5 V/10,000 A hardware experiment platform was built, which proved the feasibility and validity of the proposed strategy for a high-power generation system. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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15 pages, 4347 KiB

Open AccessArticle

Multiple Modulation Strategy of Flying Capacitor DC/DC Converter

by Pengcheng Li, Chunjiang Zhang, Sanjeevikumar Padmanaban and Leonowicz Zbigniew

Electronics 2019, 8(7), 774; https://doi.org/10.3390/electronics8070774 - 11 Jul 2019

Cited by 4 | Viewed by 4047

Abstract

Flying-capacitor multiplexed modulation technology is suitable for bipolar DC microgrids with higher voltage levels and higher current levels. The module combination and corresponding modulation method can be flexibly selected according to the voltage level and capacity level. This paper proposes a bipolar bidirectional [...] Read more.

Flying-capacitor multiplexed modulation technology is suitable for bipolar DC microgrids with higher voltage levels and higher current levels. The module combination and corresponding modulation method can be flexibly selected according to the voltage level and capacity level. This paper proposes a bipolar bidirectional DC/DC converter and its interleaved-complementary modulation strategy that is suitable for bipolar DC microgrids. The converter consists of two flying-capacitor three-level bidirectional DC/DC converters that are interleaved in parallel 90°, and then cascaded with another module to form a symmetrical structure of the upper and lower arms; the complementary modulation of the upper and lower half bridges constitutes an interleaved complementary multilevel bidirectional DC/DC converter. If the bidirectional converter needs to provide a stronger overcurrent capability, more bridge arms can be interleaved in parallel. Once n bridge arms are connected in parallel, the bridge arms should be interleaved 180°/n in parallel. In bipolar DC microgrids, the upper and lower arms should be complementarily modulated, and the input and output are isolated by the inductance. To solve the current difference, caused by the inconsistent parasitic, the voltage-current double closed-loop-control is used, and the dynamic response is faster during bidirectional operation. This paper proposes theoretical analysis and experiments that verify bipolar bidirectional DC/DC converter for high-power energy storage. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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15 pages, 2242 KiB

Open AccessArticle

Individual Phase Full-Power Testing Method for High-Power STATCOM

by Qingjun Huang, Bo Li, Yanjun Tan, Xinguo Mao, Siguo Zhu and Yuan Zhu

Electronics 2019, 8(7), 754; https://doi.org/10.3390/electronics8070754 - 4 Jul 2019

Cited by 2 | Viewed by 3075

Abstract

For a high-power static synchronous compensator (STATCOM), a full-power pre-operation test in the factory is necessary to ensure the product quality of a newly manufactured one. But owing to the hardware limitation and cost of test platform, such test is currently too difficult [...] Read more.

For a high-power static synchronous compensator (STATCOM), a full-power pre-operation test in the factory is necessary to ensure the product quality of a newly manufactured one. But owing to the hardware limitation and cost of test platform, such test is currently too difficult to conduct in the factory, thus it poses great risk to the on-site operation and commissioning. To address this issue, this paper proposes an individual phase full-power testing method for STATCOM. By changing the port connection, three-phase STATCOM was reconstructed into a structure that two phases are in parallel and then in series with the third-phase, and then connected to two phases of the rated voltage grid. Then by rationally matching the voltage and current of three phases, the parallel phases can get a reactive current hedging under both the rated voltage and rated current, meanwhile three phases maintain their active power balance. As a result, STATCOM gets a phase full-power tested phase by phase. The simulation results in Matlab/Simulink show that, under the proposed test system, both the voltage and current of the parallel two phases get their rated values while the grid current is only about 3% of the rated current, meanwhile the DC-link voltage of each phase converter is stabilized. Compared with other testing methods for STATCOM, this method requires neither extra hardware nor high-capacity power supply to construct the test platform, but it can simultaneously examine both the entire main circuit and a large part of the control system in STATCOM. Therefore, it provides a cost-effective engineering method for the factory test of high-power STATCOM. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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23 pages, 11939 KiB

Open AccessArticle

A Parametric Conducted Emission Modeling Method of a Switching Model Power Supply (SMPS) Chip by a Developed Vector Fitting Algorithm

by Xuchun Hao, Shuguo Xie and Ziyao Chen

Electronics 2019, 8(7), 725; https://doi.org/10.3390/electronics8070725 - 26 Jun 2019

Cited by 5 | Viewed by 3927

Abstract

This paper proposes a modeling method to establish a parametric-conducted emission model of a switching model power supply (SMPS) chip through a developed vector fitting algorithm. A common SMPS chip LTM8025 was taken as an example to explain the modeling process. According to [...] Read more.

This paper proposes a modeling method to establish a parametric-conducted emission model of a switching model power supply (SMPS) chip through a developed vector fitting algorithm. A common SMPS chip LTM8025 was taken as an example to explain the modeling process. According to the integrated circuit (IC) electromagnetic modeling (ICEM) standard, the parametric conducted emission model is divided into two parts: IC internal activity (ICIA) and IC passive distribution network (ICPDN). The parameters of ICIA are identified by measured data and correlated with key components; an improved vector-fitting algorithm is proposed to solve the fitting problem of ICPDN without phase information. This parametric model can be used with commercial simulation software together to achieve predictions of conducted emissions from power modules. The experiment results show that the maximum and 90% confidence interval of the forecast errors are 9.677 dB and (−4.56 dB, 6.52 dB) respectively, which achieve the international standard requirements and have sufficient accuracy and effectiveness. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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17 pages, 3265 KiB

Open AccessArticle

A PWM Scheme for Five-Level H-Bridge T-Type Inverter with Switching Loss Reduction

by Thanh-Hai Quach, Duc-Tri Do and Minh-Khai Nguyen

Electronics 2019, 8(6), 702; https://doi.org/10.3390/electronics8060702 - 21 Jun 2019

Cited by 4 | Viewed by 5248

Abstract

In this paper, a new pulse width modulation (PWM) scheme using an offset function to reduce switching loss in the five-level H-bridge T-type inverter (5L-HBT²I) is proposed. The proposed modulation technique is implemented with a third harmonic offset voltage function. A [...] Read more.

In this paper, a new pulse width modulation (PWM) scheme using an offset function to reduce switching loss in the five-level H-bridge T-type inverter (5L-HBT²I) is proposed. The proposed modulation technique is implemented with a third harmonic offset voltage function. A new control voltage, that is adding the offset voltage into the initial control, is shifted to the top or bottom position of the carrier, simultaneously—where the absolute value of its load current is high or medium in comparison to other phase load currents. Due to reducing the intersection between a control voltage and the carriers, the number of switch commutations of the inverter is reduced. As a result of reducing the number of commutation count with a high current at the non-switching position, the switching losses of the inverter are decreased. Analysis and comparison of switching losses on the two-level and three-level inverters, which are components of 5L-HBT²I are presented. The power loss analysis on the 5L-HBT²I is performed. The proposed technique implements the switching loss reduction strategy based on setting the operation of the two-level inverter in six-step mode. PSIM software is used to clarify the proposed technique. The simulation results show that the total switching losses of the proposed technique in 5L-HBT2I reduce in comparison to the conventional sine PWM technique. A prototype is built to validate the proposed scheme. Simulation and experimental results match the analysis. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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17 pages, 7105 KiB

Open AccessArticle

Shaping SiC MOSFET Voltage and Current Transitions by Intelligent Control for Reduced EMI Generation

by Congwen Xu, Qishuang Ma, Ping Xu and Tongkai Cui

Electronics 2019, 8(5), 508; https://doi.org/10.3390/electronics8050508 - 8 May 2019

Cited by 6 | Viewed by 5045

Abstract

In power converters, the fast switching of the power conversion components results in rapid changes in voltage and current, which results in oscillations and high-level electromagnetic interference (EMI), so the power components become a source of internal electromagnetic interference. Taking SiC Metal-Oxide-Semiconductor Field-Effect [...] Read more.

In power converters, the fast switching of the power conversion components results in rapid changes in voltage and current, which results in oscillations and high-level electromagnetic interference (EMI), so the power components become a source of internal electromagnetic interference. Taking SiC Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) as an example, an intelligent control method to suppressing interference sources is proposed in this paper. The combination of open-loop and closed-loop methods can simultaneously reduce the electromagnetic interference generated by voltage and current. Firstly, this paper analyzes how to select a reference signal. The relationship between the time domain and the frequency domain of the noise signal is analyzed. The convolution of the trapezoidal signal and the Gaussian signal is selected as the reference signal, which is named S-shaped signal in this paper. The S-shaped signal has continuous infinitely conductive characteristics, so its spectrum has a large attenuation in the high frequency region. Secondly, a new topology is proposed. Based on the closed-loop gate control, a current control signal is added, which can simultaneously shape the output voltage and control the output current slope. Both the simulation results and the experimental results show that the output voltage can follow the reference signal, S-shaped signal, and the slope and overshoot of output current can be changed. Compared with classical gate driver method, the spectrum of output voltage and output current obtained by the method proposed in this paper has a large attenuation, in other words, the electromagnetic interference is significantly reduced. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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17 pages, 7213 KiB

Open AccessFeature PaperArticle

Modulation Strategy with a Minimal Number of Commutations for a Five-Level H-Bridge NPC Inverter

by Florent Becker, Ehsan Jamshidpour, Philippe Poure and Shahrokh Saadate

Electronics 2019, 8(4), 454; https://doi.org/10.3390/electronics8040454 - 23 Apr 2019

Cited by 3 | Viewed by 7217

Abstract

In this paper, a so-called OPTimized Pulse Width Modulation (OPT-PWM) strategy with a minimal number of commutations for a multilevel converter (MC) is proposed. The principle is based on the reduction of the number of switch commutations by removing the unnecessary ones for [...] Read more.

In this paper, a so-called OPTimized Pulse Width Modulation (OPT-PWM) strategy with a minimal number of commutations for a multilevel converter (MC) is proposed. The principle is based on the reduction of the number of switch commutations by removing the unnecessary ones for each voltage level transition. The OPT-PWM strategy is applied to a five-level H-Bridge Neutral Point Clamped (HB-5L-NPC) inverter. A specific block based on a state machine is added to conventional modulation techniques to perform the transitions from a given voltage level to another one via the best trajectory with a minimal number of commutations. The principle of this additional block can be applied to any modulation technique. In this paper, the proposed strategy is validated first by simulation and then through experimental tests. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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15 pages, 6391 KiB

Open AccessArticle

Analysis of a DC Converter with Low Primary Current Loss and Balance Voltage and Current

by Bor-Ren Lin

Electronics 2019, 8(4), 439; https://doi.org/10.3390/electronics8040439 - 17 Apr 2019

Cited by 11 | Viewed by 3068

Abstract

A dc/dc pulse width modulation (PWM) circuit was investigated to realize the functions of reduced primary current loss and balanced voltage and current distribution. In the presented dc/dc converter, two full bridge pulse width modulation circuits were used with the series/parallel connection on [...] Read more.

A dc/dc pulse width modulation (PWM) circuit was investigated to realize the functions of reduced primary current loss and balanced voltage and current distribution. In the presented dc/dc converter, two full bridge pulse width modulation circuits were used with the series/parallel connection on the high-voltage/low-voltage side. The flying capacitor was adopted on the input side to achieve voltage balance on input split capacitors. The magnetic coupling element was employed to achieve current sharing between two parallel circuits. A capacitor-diode passive circuit was adopted to lessen the primary current at the commutated interval. The phase-shifted duty cycle control approach was employed to regulate load voltage and implement soft switching characteristics of power metal-oxide-semiconductor field-effect transistors (MOSFETs). Finally, the experimental results using a 1.68 kW prototype converter were obtained to confirm the performance and feasibility of the studied circuit topology. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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16 pages, 5921 KiB

Open AccessArticle

Enhancement of System Stability Based on PWFM

by K. I. Hwu, C. W. Wang and Y. T. Yau

Electronics 2019, 8(4), 399; https://doi.org/10.3390/electronics8040399 - 3 Apr 2019

Cited by 2 | Viewed by 3447

Abstract

In this paper, a pulse width and frequency modulation (PWFM) control strategy is presented, which combines the one-comparator counter-based pulse width modulation (PWM) control with pulse frequency modulation (PFM) control to increase pseudo-1-bit resolution under constant-frequency operation. Accordingly, system stability will be enhanced [...] Read more.

In this paper, a pulse width and frequency modulation (PWFM) control strategy is presented, which combines the one-comparator counter-based pulse width modulation (PWM) control with pulse frequency modulation (PFM) control to increase pseudo-1-bit resolution under constant-frequency operation. Accordingly, system stability will be enhanced significantly. As compared with the traditional counter-based PWM control, there is no difference in off-chip circuit complexity except a slight change in on-chip hardware. Finally, a prototype circuit is used to verify the proposed control concept by some experimental results with no limit cycle oscillation. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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14 pages, 3234 KiB

Open AccessArticle

Transformerless Quasi-Z-Source Inverter to Reduce Leakage Current for Single-Phase Grid-Tied Applications

by Woo-Young Choi and Min-Kwon Yang

Electronics 2019, 8(3), 312; https://doi.org/10.3390/electronics8030312 - 12 Mar 2019

Cited by 13 | Viewed by 4363

Abstract

The conventional single-phase quasi-Z-source (QZS) inverter has a high leakage current as it is connected to the grid. To address this problem, this paper proposes a transformerless QZS inverter, which can reduce the leakage current for single-phase grid-tied applications. The proposed inverter effectively [...] Read more.

The conventional single-phase quasi-Z-source (QZS) inverter has a high leakage current as it is connected to the grid. To address this problem, this paper proposes a transformerless QZS inverter, which can reduce the leakage current for single-phase grid-tied applications. The proposed inverter effectively alleviates the leakage current problem by removing high-frequency components for the common-mode voltage. The operation principle of the proposed inverter is described together with its control strategy. A control scheme is presented for regulating the DC-link voltage and the grid current. A 1.0 kW prototype inverter was designed and tested to verify the performance of the proposed inverter. Silicon carbide (SiC) power devices were applied to the proposed inverter to increase the power efficiency. The experimental results showed that the proposed inverter achieved high performance for leakage current reduction and power efficiency improvement. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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16 pages, 4495 KiB

Open AccessArticle

Three-Phase Five-Level Cascade Quasi-Switched Boost Inverter

by Van-Thuan Tran, Minh-Khai Nguyen, Cao-Cuong Ngo and Youn-Ok Choi

Electronics 2019, 8(3), 296; https://doi.org/10.3390/electronics8030296 - 6 Mar 2019

Cited by 8 | Viewed by 4759

Abstract

This paper presents a three-phase cascaded five-level H-bridge quasi-switched boost inverter (CHB-qSBI). The merits of the CHB-qSBI are as follows: single-stage conversion, shoot-through immunity, buck-boost voltage, and reduced passive components. Furthermore, a PWM control method is applied to the CHB-qSBI topology to improve [...] Read more.

This paper presents a three-phase cascaded five-level H-bridge quasi-switched boost inverter (CHB-qSBI). The merits of the CHB-qSBI are as follows: single-stage conversion, shoot-through immunity, buck-boost voltage, and reduced passive components. Furthermore, a PWM control method is applied to the CHB-qSBI topology to improve the modulation index. The voltage stress across power semiconductor devices and the capacitor are significantly lower using improved pulse-width modulation (PWM) control. Additionally, by controlling individual shoot-through duty cycle, the DC-link voltage of each module can achieve the same values. As a result, the imbalance problem of the DC-link voltage can be solved. A detailed analysis and operating principle with the modulation scheme and comprehensive comparison for the CHB-qSBI are illustrated. The experimental and simulation results are presented to validate the operating principle of the three-phase CHB-qSBI. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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19 pages, 3726 KiB

Open AccessArticle

A Novel Three-Switch Z-Source SEPIC Inverter

by Baocheng Wang and Wei Tang

Electronics 2019, 8(2), 247; https://doi.org/10.3390/electronics8020247 - 21 Feb 2019

Cited by 10 | Viewed by 3858

Abstract

In this paper, a novel single-phase transformerless Z-source inverter (ZSI) derived from the basic SEPIC topology, which is named SEPIC-based ZSI, is proposed. The negative end of the input DC voltage of this topology is directly connected to the load and grounded, which [...] Read more.

In this paper, a novel single-phase transformerless Z-source inverter (ZSI) derived from the basic SEPIC topology, which is named SEPIC-based ZSI, is proposed. The negative end of the input DC voltage of this topology is directly connected to the load and grounded, which can completely eliminate leakage current. Furthermore, this topology has some attractive characteristics such as buck–boost capability, impressive voltage gain, linear voltage gain is realized by a simple control method, and so on. The theoretical design and simulation results are demonstrated by corresponding experiments carried out on a 500 W laboratory prototype controlled by using a DSP TMS320F28335 controller combined with a FPGA SPARTAN-6. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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18 pages, 4328 KiB

Open AccessArticle

Voltage Multiplier Cell-Based Quasi-Switched Boost Inverter with Low Input Current Ripple

by Minh-Khai Nguyen and Youn-Ok Choi

Electronics 2019, 8(2), 227; https://doi.org/10.3390/electronics8020227 - 18 Feb 2019

Cited by 16 | Viewed by 5501

Abstract

A novel single-phase single-stage voltage multiplier cell-based quasi-switched boost inverter (VMC-qSBI) is proposed in this paper. By adding the voltage multiplier cell to the qSBI, the proposed VMC-qSBI has the following merits; a decreased voltage stress on an additional switch, a high voltage [...] Read more.

A novel single-phase single-stage voltage multiplier cell-based quasi-switched boost inverter (VMC-qSBI) is proposed in this paper. By adding the voltage multiplier cell to the qSBI, the proposed VMC-qSBI has the following merits; a decreased voltage stress on an additional switch, a high voltage gain, a continuous input current, shoot through immunity, and a high modulation index. A new pulse-width modulation (PWM) control strategy is presented for the proposed inverter to reduce the input current ripple. To improve the voltage gain of the proposed inverter, an extension is addressed by adding the VMCs. The operating principle, steady-state analysis, and impedance parameter design guideline of the proposed inverter are presented. A comparison between the proposed inverter and other impedance source-based high-voltage gain inverters is shown. Simulation and experimental results are provided to confirm the theoretical analysis. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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19 pages, 5284 KiB

Open AccessArticle

A Modified Model Predictive Power Control for Grid-Connected T-Type Inverter with Reduced Computational Complexity

by Van-Quang-Binh Ngo, Minh-Khai Nguyen, Tan-Tai Tran, Joon-Ho Choi and Young-Cheol Lim

Electronics 2019, 8(2), 217; https://doi.org/10.3390/electronics8020217 - 15 Feb 2019

Cited by 16 | Viewed by 4361

Abstract

This study proposed a modified power strategy based on model predictive control for a grid-connected three-level T-type inverter. The controller utilizes the mathematical model to forecast the performance of the grid current, the balance of DC-bus capacitor voltages and switching frequency. The proposed [...] Read more.

This study proposed a modified power strategy based on model predictive control for a grid-connected three-level T-type inverter. The controller utilizes the mathematical model to forecast the performance of the grid current, the balance of DC-bus capacitor voltages and switching frequency. The proposed method outlines a new technique to formulate a control objective. The control objective includes the absolute error of the inverter voltage reference and its possible values instead of the grid current error. By using the modified equivalent transformations in the cost function, the execution time was reduced 22% compared to the traditional model predictive control while maintaining the high dynamic performances of the power and low total harmonic distortion of the current. A comparative investigation showed that the proposed method obtains a high-performance control compared with the classical power control scheme with linear PI controllers and space vector modulation. The feasibility of the proposed method was verified by the simulation and experimental results. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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Review

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37 pages, 10744 KiB

Open AccessReview

Review of Multilevel Voltage Source Inverter Topologies and Analysis of Harmonics Distortions in FC-MLI

by Ronak A. Rana, Sujal A. Patel, Anand Muthusamy, Chee woo Lee and Hee-Je Kim

Electronics 2019, 8(11), 1329; https://doi.org/10.3390/electronics8111329 - 11 Nov 2019

Cited by 58 | Viewed by 13747

Abstract

We review the most common topology of multi-level inverters. As is known, the conventional inverters are utilized to create an alternating current (AC) source from a direct current (DC) source. The two-level inverter provides various output voltages [(Vdc/2) and (−Vdc/2)] of the load. [...] Read more.

We review the most common topology of multi-level inverters. As is known, the conventional inverters are utilized to create an alternating current (AC) source from a direct current (DC) source. The two-level inverter provides various output voltages [(Vdc/2) and (−Vdc/2)] of the load. It is a successive method, but it makes the harmonic distortion of the output side, Electromagnetic interference (EMI), and high dv/dt. We solve this problem by constructing the sinusoidal voltage waveform. This is achieved by a “multilevel inverter” (MLI). The multilevel inverter creates the output voltage with multiple DC voltages as inputs. Many voltage levels are combined to produce a smoother waveform. During the last decade, the multilevel inverter has become very popular in medium and high-power applications with some advantages, such as the reduced power dissipation of switching elements, low harmonics, and low EMIs. We introduce the information about several multilevel inverters such as the diode-clamped multilevel inverter (DC-MLI), cascaded H-bridge multilevel inverter (CHB-MLI), and flying-capacitor multilevel inverter (FC-MLI) with Power systems CAD (PSCAD) simulation. It is shown that THD is 28.88% in three level FC-MLI while THD is 18.56% in five level topology. Therefore, we can decrease the total harmonic distortion adopting the higher-level topology. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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15 pages, 5119 KiB

Open AccessReview

Active Power Decoupling for Current Source Converters: An Overview Scenario

by Jianhua Zhang, Hao Ding, Baocheng Wang, Xiaoqiang Guo and Sanjeevikumar Padmanaban

Electronics 2019, 8(2), 197; https://doi.org/10.3390/electronics8020197 - 8 Feb 2019

Cited by 21 | Viewed by 4773

Abstract

For single-phase current source converters, there is an inherent limitation in DC-side low-frequency power oscillation, which is twice the grid fundamental frequency. In practice, it transfers to the DC side and results in the low-frequency DC-link ripple. One possible solution is to install [...] Read more.

For single-phase current source converters, there is an inherent limitation in DC-side low-frequency power oscillation, which is twice the grid fundamental frequency. In practice, it transfers to the DC side and results in the low-frequency DC-link ripple. One possible solution is to install excessively large DC-link inductance for attenuating the ripple. However, it is of bulky size and not cost-effective. Another method is to use the passive LC branch for bypassing the power decoupling, but this is still not cost-effective due to the low-frequency LC circuit. Recently, active power decoupling techniques for the current source converters have been sparsely reported in literature. However, there has been no attempt to classify and understand them in a systematic way so far. In order to fill this gap, an overview of the active power decoupling for single-phase current source converters is presented in this paper. Systematic classification and comparison are provided for researchers and engineers to select the appropriate solutions for their specific applications. Full article

(This article belongs to the Special Issue Power Converters in Power Electronics)

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