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22 pages, 9979 KiB

Open AccessArticle

Implementation of a Microgrid Scheme Using a MVDC Connection between Gapado Island and Marado Island in South Korea

by Jinhong Ahn and Eel-Hwan Kim

Energies 2019, 12(1), 187; https://doi.org/10.3390/en12010187 - 8 Jan 2019

Cited by 1 | Viewed by 3654

Abstract

In this paper, we propose a microgrid (MG) implementation method through Medium-Voltage Direct Current (MVDC) connection between Gapado Island and Marado Island in Korea. MVDC is a facility that can be efficiently applied between small power generation complexes. The structure of power generation [...] Read more.

In this paper, we propose a microgrid (MG) implementation method through Medium-Voltage Direct Current (MVDC) connection between Gapado Island and Marado Island in Korea. MVDC is a facility that can be efficiently applied between small power generation complexes. The structure of power generation facilities is mainly supplied by diesel generators, while solar and wind power generators supply additional power. An Energy Storage System (ESS) is also used to reduce the output fluctuations of wind and solar power generation. Since power systems in such areas are low-voltage and low-power distribution systems, problems can arise in terms of power management due to power generators with variable output characteristics such as solar power and wind power generators. In addition, when a major power source such as a diesel generator is dropped, the power system collapses. However, these problems can be solved by interchanging the power between the micro-grids through the connection of MVDCs. With the MVDC connected, we verify the impact of the power system on Marado Island and Gapado Island due to the input and opening of solar, wind and diesel generators. The proposed configuration uses the PSCAD/EMTDC simulation program. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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20 pages, 11051 KiB

Open AccessArticle

Power Factor Corrector with Bridgeless Flyback Converter for DC Loads Applications

by Sheng-Yu Tseng, Po-Jui Huang and Dong-Heng Wu

Energies 2018, 11(11), 3096; https://doi.org/10.3390/en11113096 - 9 Nov 2018

Cited by 10 | Viewed by 4089

Abstract

Since power systems with a DC distribution method has many advantages, such as conversion efficiency increase of about 5–10%, cost reducing by about 15–20% and so on, the AC distribution power system will be replaced by a DC distribution one. This paper presents [...] Read more.

Since power systems with a DC distribution method has many advantages, such as conversion efficiency increase of about 5–10%, cost reducing by about 15–20% and so on, the AC distribution power system will be replaced by a DC distribution one. This paper presents a DC load power system for a DC distribution application. The proposed power system includes two converters: DC/DC converter with battery source and power factor corrector (PFC) with a line source to increase the reliability of the power system when renewable energy or energy storage equipment are adopted. The proposed PFC adopts a bridgeless flyback converter to achieve power factor correction for supplying power to DC loads. When the bridgeless flyback converter is used to achieve PFC, it needs two transformers to process positive and negative half periods, respectively. In order to increase conversion efficiency, the flyback one can add two sets of the active clamp circuit to recover energies stored in leakage inductances of transformers in the converter. Therefore, the proposed bridgeless flyback converter can not only integrate two transformers into a single transformer, but also share a clamp capacitor to achieve energy recovery of leakage inductances and to operate switches with zero-voltage switching (ZVS) at the turn-on transition. With this approach, the proposed converter can increase conversion efficiency and decrease component counts, where it results in a higher conversion efficiency, lower cost, easier design and so on. Finally, a prototype with a universal input voltage source (AC 90–265 V) under output voltage of 48 V and maximum output power of 300 W has been implemented to verify the feasibility of the proposed bridgeless flyback converter. Furthermore, the proposed power system can be operated at different cases among load power P_L, output power P_DC1 of DC/DC converter and output power P_DC2 of the proposed PFC for supplying power to DC loads. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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14 pages, 4717 KiB

Open AccessArticle

Analysis of LC-LC² Compensated Inductive Power Transfer for High Efficiency and Load Independent Voltage Gain

by Md Morshed Alam, Saad Mekhilef, Hussain Bassi and Muhyaddin Jamal Hosin Rawa

Energies 2018, 11(11), 2883; https://doi.org/10.3390/en11112883 - 24 Oct 2018

Cited by 10 | Viewed by 2753

Abstract

A novel LC-LC² compensated resonant converter topology with high efficiency and good controllable voltage gain is presented in this paper. An additional receiving side inductor working together with the receiving coil has the contribution to work with a large range of air [...] Read more.

A novel LC-LC² compensated resonant converter topology with high efficiency and good controllable voltage gain is presented in this paper. An additional receiving side inductor working together with the receiving coil has the contribution to work with a large range of air gap distance. Due to this property, proposed compensation technique is effective for IPT based EV charging application. Voltage gain with independent of load and input impedance having ZPA of the proposed resonant converter are observed by the frequency domain analysis. On the other hand, time domain analysis gives the circuit operation. A 500 W LC-LC² compensated resonant converter prototype is built to testify the theoretical analysis. To observe the efficiency-comparison, an S-SP compensated resonant converter with a similar amount of output power under different air gap is also presented. In order to justify the effectiveness, the proposed compensation method is verified by the laboratory results. The highest efficiency of the proposed compensated resonant converter is 93% with output power of 500 W at 140-mm air gap between the two sides of the IPT (inductive power transfer) transformer. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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13 pages, 5283 KiB

Open AccessArticle

Parallel Control Method Based on the Consensus Algorithm for the Non-Isolated AC/DC Charging Module

by Yixin Zhu, Tao Wang, Liansong Xiong, Gaofeng Zhang and Xin Qian

Energies 2018, 11(10), 2828; https://doi.org/10.3390/en11102828 - 19 Oct 2018

Cited by 2 | Viewed by 2656

Abstract

A high-power charging station for electric vehicles usually adopts a parallel structure of multiple power modules. However, due to the parameter differences among power modules, a parallel system always has circulating current issues. This paper takes a non-isolated AC/DC charging module as the [...] Read more.

A high-power charging station for electric vehicles usually adopts a parallel structure of multiple power modules. However, due to the parameter differences among power modules, a parallel system always has circulating current issues. This paper takes a non-isolated AC/DC charging module as the research object and proposes a current sharing control strategy for multiple power modules based on the consensus algorithm. By constructing a sparse communication network with the CAN (Controller Area Network) protocol and exchanging current information, accurate current sharing among power modules is realized. Firstly, the zero-sequence circulating current issue is analyzed through a parallel model of the three-phase rectifier, with an improved circulating current restraint strategy proposed based on the zero-sequence voltage compensation. Then, the principle of the consensus algorithm is explained, which is applied to the current sharing control of multiple power modules. Finally, the proposal is tested by the designed simulation and experimental cases. From the obtained results, it can be seen that the proposed control strategy can effectively realize accurate current sharing among multiple power modules and well restrain the zero-sequence circulating current at the input side. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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16 pages, 9436 KiB

Open AccessArticle

Power Decoupling of a Single Phase DC-AC Dual Active Bridge Converter Based on an Integrated Bidirectional Buck/Boost Stage

by Jiatu Hong, Mahinda Vilathgamuwa, Jian Yin, Yitao Liu, Jianchun Peng and Hui Jiang

Energies 2018, 11(10), 2746; https://doi.org/10.3390/en11102746 - 13 Oct 2018

Cited by 1 | Viewed by 2942

Abstract

In single phase DC-AC systems, double-line-frequency power ripple appears at the DC side inherently. Normally a large electrolytic capacitor can be used to reduce the power ripple at the DC side. But there are several problems with this method as it decreases the [...] Read more.

In single phase DC-AC systems, double-line-frequency power ripple appears at the DC side inherently. Normally a large electrolytic capacitor can be used to reduce the power ripple at the DC side. But there are several problems with this method as it decreases the power density and reliability of the converter. In addition, a double-line-frequency current ripple appears in case a voltage source serves at the DC side, which is undesired in specific applications. This paper proposes a single phase DC-AC DAB (dual active bridge) converter with an integrated buck/boost stage for power decoupling purpose under low power condition. The proposed active power decoupling method is able to completely eliminate the double-line-frequency power ripple at the DC side. Therefore, a constant DC current can be obtained for requirements in specific DC-AC applications. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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18 pages, 10862 KiB

Open AccessArticle

A Bilateral Zero-Voltage Switching Bidirectional DC-DC Converter with Low Switching Noise

by Chien-Chun Huang, Tsung-Lin Tsai, Yao-Ching Hsieh and Huang-Jen Chiu

Energies 2018, 11(10), 2618; https://doi.org/10.3390/en11102618 - 1 Oct 2018

Cited by 4 | Viewed by 4084

Abstract

This paper proposes a novel bilateral zero-voltage switching (ZVS) bidirectional converter with synchronous rectification. By controlling the direction and timing of excessive current injection, the main power switches can achieve bilateral ZVS under various loads and output voltages. Compared with the common soft-switching [...] Read more.

This paper proposes a novel bilateral zero-voltage switching (ZVS) bidirectional converter with synchronous rectification. By controlling the direction and timing of excessive current injection, the main power switches can achieve bilateral ZVS under various loads and output voltages. Compared with the common soft-switching power converter with only zero-voltage turn-on, the proposed bilateral ZVS bidirectional converter can achieve both zero-voltage switching on and off in every switching cycle. This feature can alleviate the output switching noise due to the controlled rising and falling slope of the switch voltage. Furthermore, the voltage slopes almost remain unchanged over a wide range of output voltages and load levels. The most important feature of bilateral ZVS is to reduce the output switching noise. Experimental results based on a 1 kW prototype are presented to demonstrate the performance of the proposed converter. From experimental results on the proposed scheme, the switching noise reduction is about 75%. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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15 pages, 4865 KiB

Open AccessFeature PaperArticle

Comparative Evaluation of a Permanent Magnet Machine Saliency-Based Drive with Sine-Wave and Square-Wave Voltage Injection

by Jyun-You Chen, Shih-Chin Yang and Kai-Hsiang Tu

Energies 2018, 11(9), 2189; https://doi.org/10.3390/en11092189 - 21 Aug 2018

Cited by 8 | Viewed by 3097

Abstract

This paper improves a permanent magnet (PM) machine saliency-based drive performance based on the selection of a suitable injection signal. For the saliency-based position estimation, a persistently high-frequency (HF) voltage signal is injected to obtain a measurable spatial saliency feedback signal. The injection [...] Read more.

This paper improves a permanent magnet (PM) machine saliency-based drive performance based on the selection of a suitable injection signal. For the saliency-based position estimation, a persistently high-frequency (HF) voltage signal is injected to obtain a measurable spatial saliency feedback signal. The injection signal can be sine-wave or square-wave alternating current (AC) voltage manipulated by the inverter’s pulse width modulation (PWM). Due to the PWM dead-time effect, these HF voltage injection signals might be distorted, leading to secondary harmonics on the saliency signal. In addition, the flux saturation in machine rotors also results in other saliency harmonics. These nonlinear attributes cause position estimation errors on saliency-based drives. In this paper, two different voltage signals are analyzed to find a suited voltage which is less sensitive to these nonlinear attributes. Considering the inverter dead-time, a sine-wave voltage signal reduces its influence on the saliency signal. By contrast, the flux saturation causes the same amount of error on two injection signals. Analytical equations are developed to investigate position errors caused by the dead-time and flux saturation. An interior PM machine with the saliency ratio of 1.41 is tested for the experimental verification. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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14 pages, 5076 KiB

Open AccessArticle

Improvement in Harmonic Compensation of a Smart Charger with a Constant DC-Capacitor Voltage-Control-Based Strategy for Electric Vehicles in Single-Phase Three-Wire Distribution Feeders

by Kei Nishikawa, Fuka Ikeda, Yuki Okamoto, Hiroaki Yamada, Toshihiko Tanaka and Masayuki Okamoto

Energies 2018, 11(6), 1604; https://doi.org/10.3390/en11061604 - 19 Jun 2018

Cited by 3 | Viewed by 3605

Abstract

This paper presents an improvement in harmonic compensation performance of a previously proposed smart charger (SC) with a constant dc-capacitor voltage-control (CDCVC) strategy for electric vehicles (EVs) in single-phase three-wire distribution feeders (SPTWDFs). A controller for 3rd harmonic currents in d-q [...] Read more.

This paper presents an improvement in harmonic compensation performance of a previously proposed smart charger (SC) with a constant dc-capacitor voltage-control (CDCVC) strategy for electric vehicles (EVs) in single-phase three-wire distribution feeders (SPTWDFs). A controller for 3rd harmonic currents in d-q coordinates is added to the previously proposed SC. This addition improves harmonic compensation performance of the source currents. We briefly introduce harmonic current compensation using the previously proposed CDCVC-based algorithm for the SC. Then, the basic principles of the proposed controller for the 3rd harmonic currents in d-q coordinates are discussed in detail. It is shown that synchronization of the current controllers for both the fundamental and 3rd harmonic components is required. The switching frequency of a three-leg pulse-width modulated rectifier with a bidirectional dc–dc converter, which performs the SC, is determined considering the synchronization of the current controllers. Simulation and experimental results demonstrate that balanced and sinusoidal source currents with a unity power factor are achieved during both battery charging and discharging operations in EVs, improving the harmonic compensation performance of the previously proposed SC. Experimental results also demonstrate that the total harmonic distortion values of source currents are improved by 8.4% and 3.6% with the proposed controller for 3rd harmonic currents, when the SC is discharging, for example. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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24 pages, 10439 KiB

Open AccessArticle

A Modularized Discharge-Type Balancing Topology for Series-Connected Super Capacitor String

by Shaogui Fan, Li Sun, Jiandong Duan and Dong Zhang

Energies 2018, 11(6), 1438; https://doi.org/10.3390/en11061438 - 4 Jun 2018

Cited by 2 | Viewed by 3210

Abstract

This paper proposed a modularized discharge-type topology for the voltage balance of series-connected super capacitor (SC) string. The proposed topology consists of cascaded converter modules and a boost converter. The cascaded converter modules discharge the higher voltage SCs directly with the ideal output [...] Read more.

This paper proposed a modularized discharge-type topology for the voltage balance of series-connected super capacitor (SC) string. The proposed topology consists of cascaded converter modules and a boost converter. The cascaded converter modules discharge the higher voltage SCs directly with the ideal output current to realize a fast balancing speed and the boost converter feedbacks the extra energy from the higher voltage SCs to the super capacitor energy storage system (SCESS). The modular design of the cascaded converter modules makes the balancing system suitable for different voltage levels of SCESS. Unlike the charge-type topologies which discharge the higher voltage SCs indirectly, the proposed topology discharges the higher voltage SCs directly with a big current, and the over voltage phenomenon of SCs is then avoided, which means the reliability of the SCESS can be improved. The voltage stress of the switches inside the cascaded converter modules is low, which is different from the existing modularized discharge-type balancing topology. What is more, the control of cascaded converter modules and the boost converter can be implemented by analog devices which will simplify the control of the whole system. The control degree of freedom is high and the voltage of each cell can be controlled. An in-depth comparison analysis with the charge-type balancing topology is performed from the perspective of balancing speed and round-trip energy efficiency. The proposed topology and the balancing performance are confirmed by experimental results. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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12 pages, 2921 KiB

Open AccessArticle

Non-Equal Voltage Cell Balancing for Battery and Super-Capacitor Source Package Management System Using Tapped Inductor Techniques

by Xiaolin Wang, Ka Wai Eric Cheng and Yat Chi Fong

Energies 2018, 11(5), 1037; https://doi.org/10.3390/en11051037 - 24 Apr 2018

Cited by 14 | Viewed by 5506

Abstract

The battery management system (BMS) is the key development for energy storage systems, and battery balancing is an important subsystem of the BMS. However, with rapid development of supercapacitors, future energy storage cells are not constrained by one type, while different types of [...] Read more.

The battery management system (BMS) is the key development for energy storage systems, and battery balancing is an important subsystem of the BMS. However, with rapid development of supercapacitors, future energy storage cells are not constrained by one type, while different types of cells may form a source package (SP). Furthermore, the introduction of second-life batteries from retired electric vehicles promotes the demand of effective balancing systems for SPs with hybrid cells, as well as the requirement that balancing should be extended to any preset ratio rather than 1:1. This paper proposes a novel tapped inductor balancing circuit that allows any ratio of voltage balancing for hybrid energy storage cells. The analysis of the circuit, simulation and experiment results are presented to demonstrate its effectiveness in handling hybrid source balancing. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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17 pages, 9378 KiB

Open AccessArticle

Conducted EMI Prediction and Mitigation Strategy Based on Transfer Function for a High-Low Voltage DC-DC Converter in Electric Vehicle

by Li Zhai, Tao Zhang, Yu Cao, Sipeng Yang, Steven Kavuma and Huiyuan Feng

Energies 2018, 11(5), 1028; https://doi.org/10.3390/en11051028 - 24 Apr 2018

Cited by 19 | Viewed by 6312

Abstract

The high dv/dt and di/dt outputs from power devices in a high-low voltage DC-DC converter on electric vehicles (EVs) can always introduce the unwanted conducted electromagnetic interference (EMI) emissions. A conducted EMI prediction and mitigation strategy that [...] Read more.

The high dv/dt and di/dt outputs from power devices in a high-low voltage DC-DC converter on electric vehicles (EVs) can always introduce the unwanted conducted electromagnetic interference (EMI) emissions. A conducted EMI prediction and mitigation strategy that is based on transfer function for the high-low voltage DC-DC converter in EVs are proposed. A complete test for the DC-DC converter is conducted to obtain the conducted EMI from DC power cables in the frequency band of 150 kHz-108 MHz. The equivalent circuit with high-frequency parasitic parameters of the DC-DC converter is built`1 based on the measurement results to acquire the characteristics of the conducted EMI of the DC power cables. The common mode (CM) and differential mode (DM) propagation coupling paths are determined, and the corresponding transfer functions of the DM interference and CM interference are established. The simulation results of the conducted EMI can be obtained by software Matlab and Computer Simulation Technology (CST). By analyzing the transfer functions and the simulation results, the dominated interference is the CM interference, which is the main factor of the conducted EMI. A mitigation strategy for the design of the CM interference filter based on the dominated CM interference is proposed. Finally, the mitigation strategy of the conducted EMI is verified by performing the conducted voltage experiment. From the experiment results, the conducted voltage of the DC power cables is decreased, respectively, by 58 dBμV, 55 dBμV, 65 dBμV, 53 dBμV, and 54 dBμV at frequency 200 kHz, 400 kHz, 600 kHz, 1.4 MHz, and 50 MHz. The conduced voltage in the frequency band of 150 kHz–108 MHz can be mitigated by adding the CM interference filters, and the values are lower than the limit level-3 of CISPR25 standard (GB/T 18655-2010). Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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19 pages, 14810 KiB

Open AccessArticle

Fault-Tolerant Control for a Flexible Group Battery Energy Storage System Based on Cascaded Multilevel Converters

by Junhong Song, Weige Zhang, Hui Liang, Jiuchun Jiang and Wensong Yu

Energies 2018, 11(1), 171; https://doi.org/10.3390/en11010171 - 11 Jan 2018

Cited by 9 | Viewed by 3780

Abstract

A flexible group battery energy storage system (FGBESS) based on cascaded multilevel converters is attractive for renewable power generation applications because of its high modularity and high power quality. However, reliability is one of the most important issues and the system may suffer [...] Read more.

A flexible group battery energy storage system (FGBESS) based on cascaded multilevel converters is attractive for renewable power generation applications because of its high modularity and high power quality. However, reliability is one of the most important issues and the system may suffer from great financial loss after fault occurs. In this paper, based on conventional fundamental phase shift compensation and third harmonic injection, a hybrid compensation fault-tolerant method is proposed to improve the post-fault performance in the FGBESS. By adjusting initial phase offset and amplitude of injected component, the optimal third harmonic injection is generated in an asymmetric system under each faulty operation. Meanwhile, the optimal redundancy solution under each fault condition is also elaborated comprehensively with a comparison of the presented three fault-tolerant strategies. This takes full advantage of battery utilization and minimizes the loss of energy capacity. Finally, the effectiveness and feasibility of the proposed methods are verified by results obtained from simulations and a 10 kW experimental platform. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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Review

Jump to: Research

21 pages, 12609 KiB

Open AccessReview

A Review of the Design and Control of Free-Piston Linear Generator

by Xuezhen Wang, Feixue Chen, Renfeng Zhu, Guilin Yang and Chi Zhang

Energies 2018, 11(8), 2179; https://doi.org/10.3390/en11082179 - 20 Aug 2018

Cited by 30 | Viewed by 7744

Abstract

The Free-piston linear generator (FPLG) is a novel energy converter which can generate electrical energy and is regarded as a potential technology for solving the restriction of the short driving range of electric vehicles. Getting rid of the crank and flywheel mechanism, FPLG [...] Read more.

The Free-piston linear generator (FPLG) is a novel energy converter which can generate electrical energy and is regarded as a potential technology for solving the restriction of the short driving range of electric vehicles. Getting rid of the crank and flywheel mechanism, FPLG obtains some advantages of a variable compression ratio, compact size, and highly-efficient power generation. Linear electric machine (LEM) design and piston motion control are two key technologies of FPLG. However, they are currently the main obstacles to the favorable performance of FPLG. LEM being used to drive the piston motion or generate electric energy is an integrated design including a motor/generator. Various types of LEMs are investigated, and suitable application scenarios based on advantages and disadvantages are discussed. The FPLG’s controller is used to ensure stable operation and highly-efficient output. However, cycle-to-cycle variations of the combustion process and motor/generator switching make it difficult to improve the performance of the piston motion control. Comments on the advantages and disadvantages of different piston motion control methods are also given in this paper. Full article

(This article belongs to the Special Issue Power Electronics for Energy Storage)

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