Research

22 pages, 6811 KiB

Open AccessArticle

Analysis and Parameter Design of SiC-Based Current Source Inverter (CSI)

by Xingjian Yang, Zhennan Zhao, Cheng Wang, Jianzhi Xu, Kefu Liu and Jian Qiu

World Electr. Veh. J. 2022, 13(10), 187; https://0-doi-org.brum.beds.ac.uk/10.3390/wevj13100187 - 12 Oct 2022

Cited by 6 | Viewed by 2220

Current source inverters (CSIs) use inductors as the major component to store energy. Compared with voltage source inverters (VSIs), CSIs have two advantages: 1. They can avoid the converter failure caused by capacitor failures, and 2. The load current does not increase with [...] Read more.

Current source inverters (CSIs) use inductors as the major component to store energy. Compared with voltage source inverters (VSIs), CSIs have two advantages: 1. They can avoid the converter failure caused by capacitor failures, and 2. The load current does not increase with load mutation or even short-circuit failure. Therefore, CSIs can be a promising technology for EV charging. However, the waveforms, parameter design procedure, and power efficiency are still unclear. Therefore, it is unclear if CSIs are suitable for EV chargers. This article derives the closed-loop equations of the critical components, including the inductor current waveforms and the voltage ripple. Especially, the load over-voltage phenomenon is derived and verified to further ensure the reliability of the CSI system. Based on the derived equations and reliability requirements, the parameter design procedure is proposed. The power efficiency of both the Si- and SiC-based converters are derived and compared to remove the barrier of applying CSIs in EV chargers in the industry. Our simulations and experiments verify the correctness of the system modeling, over-voltage phenomenon, and power efficiency. All the simulation files (using PLECS) and calculation files (using MATLAB) are attached for the readers to verify and/or further modify. Full article

(This article belongs to the Special Issue Modern Charging Techniques for Electrical Vehicles)

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18 pages, 2953 KiB

Open AccessArticle

Designing and Prototyping of Lithium-Ion Charging System Using Multi-Step Constant Current Method

by Muhammad Nizam, Hari Maghfiroh, Bayhaqi Irfani, Inayati Inayati and Alfian Ma’arif

World Electr. Veh. J. 2022, 13(10), 178; https://0-doi-org.brum.beds.ac.uk/10.3390/wevj13100178 - 25 Sep 2022

Cited by 4 | Viewed by 3234

Abstract

The need for electrical energy means batteries have a critical role in technological developments in the future. One of the most advanced types of batteries is the lithium-ion battery. The conventional charging system has the disadvantage of taking a relatively long time, so [...] Read more.

The need for electrical energy means batteries have a critical role in technological developments in the future. One of the most advanced types of batteries is the lithium-ion battery. The conventional charging system has the disadvantage of taking a relatively long time, so the battery temperature is high. Therefore, a charging method that can shorten the charging time and extend battery life is needed. Some contributions of the paper are the design and prototype of a buck-boost converter for dual-mode lithium-ion battery charging (buck and boost mode) and the implementation of the Multi-Step Constant Current Method (MSCC) algorithm with an optimal charging pattern (OPT) to perform fast charging under voltage, current limit, and temperature monitoring. The test results showed that the proposed charging system prototype has an accuracy of 99.93% for the voltage sensor and 98.86% for the current sensor, whereas the precision of voltage and current sensors are 98.60% and 99.34%, respectively. The proposed method took 45 min to charge the 2-series (2S) and 4-series (4S) batteries. Compared to the CCCV method, the charging time of the MSCC method was 18.18% faster. In terms of battery temperature, MSCC had a lower peak temperature compared to CCCV by 1.5% and 1.25% for 2S and 4S, respectively. Full article

(This article belongs to the Special Issue Modern Charging Techniques for Electrical Vehicles)

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12 pages, 1949 KiB

Open AccessArticle

EV Senseless Orderly Charging Technology for High User Participation Rate in Residential Area

by Ye Yang, Wenjun Duan, Wen Wang, Xiaoqing Zhang, Xiaofeng Peng, Qingwen Han, Yao Li, Shuaihua Li and Shiqiao Gao

World Electr. Veh. J. 2022, 13(7), 126; https://0-doi-org.brum.beds.ac.uk/10.3390/wevj13070126 - 11 Jul 2022

Cited by 2 | Viewed by 1684

Abstract

Private cars are the most active and important incremental factor in the electric vehicle market and are expected to account for 80% of the new energy vehicle sales market by 2030. As the most common charging scenario for private cars, orderly charging in [...] Read more.

Private cars are the most active and important incremental factor in the electric vehicle market and are expected to account for 80% of the new energy vehicle sales market by 2030. As the most common charging scenario for private cars, orderly charging in the community can optimize the distribution load curve by dynamically adjusting charging time and power of electric vehicles, so as to achieve peak-load shaving and turn electric vehicles into a friendly load to the distribution grid. However, after the traditional orderly charging strategy was released, the complexity of the operation on the user’s side was a heavy strike to the user’s willingness to participate in orderly charging, resulting in the quite low participation rate and insufficient demonstration of the characteristics of EV’s elastic power demand. To solve this issue, the paper proposes a senseless orderly charging strategy with user charging demand prediction and substation capacity constraint considered to minimize user charging fee or maximize service provider revenue. After a five-month practical application, the proposed strategy was found to effectively improve the user participation rate in orderly charging and to regulate electric vehicles as an elastic load to meet the grid demand. Full article

(This article belongs to the Special Issue Modern Charging Techniques for Electrical Vehicles)

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19 pages, 1650 KiB

Open AccessArticle

Optimization Model of Electric Vehicles Charging and Discharging Strategy Considering the Safe Operation of Distribution Network

by Mengjiao Zou, Ye Yang, Mingguang Liu, Wen Wang, Heping Jia, Xiaofeng Peng, Shu Su and Dunnan Liu

World Electr. Veh. J. 2022, 13(7), 117; https://0-doi-org.brum.beds.ac.uk/10.3390/wevj13070117 - 29 Jun 2022

Cited by 10 | Viewed by 2477

Abstract

Against the background of carbon neutrality, the power dispatching operation mode has undergone great changes. It not only gradually realizes the coordinated control of source–grid–load–storage, but also strives to realize the multi-level coordination of the transmission network, distribution network and microgrid. Disorderly charging [...] Read more.

Against the background of carbon neutrality, the power dispatching operation mode has undergone great changes. It not only gradually realizes the coordinated control of source–grid–load–storage, but also strives to realize the multi-level coordination of the transmission network, distribution network and microgrid. Disorderly charging and discharging of large-scale electric vehicles (EVs) will have a great negative impact on the distribution network, but aggregating EVs and guiding them to charge and discharge in an orderly manner will play a positive role in delaying investment in the distribution network. Therefore, it is urgent to adopt an effective scheduling control strategy for electric vehicle charging and discharging. First, a variety of indexes were set to analyze the influence of EVs access on distribution network and the correlation between the indexes. Then, by defining the EVs penetration rate and the load simultaneous rate, the charging load planning of EVs was calculated. Based on the simultaneous load rate, the regional electricity load plan was calculated, and a configuration model of distribution capacity suitable for charging loads in different regions was constructed. Finally, an optimal dispatch model for electric vehicles considering the safety of distribution network was proposed and the distribution transformer capacity allocation model was used as the optimization target constraint. Compared with most optimized dispatch models used to maximize aggregator revenues and reduce peak-to-valley differences and load fluctuations in distribution networks, this model could effectively reduce unnecessary investment while meeting regional distribution transformer needs and maintaining distribution network security. Taking the improved IEEE 34-bus systems as an example, the simulation analysis was carried out and the investment demand of distribution network under the condition of disordered and orderly charge and discharge was compared. The results show that the proposed optimal scheduling method can effectively reduce the load fluctuation of distribution network, keep the voltage offset within the allowable voltage deviation range, and can effectively delay the investment of distribution network. Full article

(This article belongs to the Special Issue Modern Charging Techniques for Electrical Vehicles)

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18 pages, 7089 KiB

Open AccessArticle

Analysis of the THD and Common-Mode Voltage of the Three-Phase Boost-Buck EV Traction Inverter

by Yongjie Han, Yuan Zhu and Deliang Wu

World Electr. Veh. J. 2022, 13(7), 114; https://0-doi-org.brum.beds.ac.uk/10.3390/wevj13070114 - 27 Jun 2022

Viewed by 2225

Abstract

A three-phase boost-buck inverter (BBI) comprised of three identical boost-buck DC/DC converter modules is presented for an EV traction inverter application. It allows the step-up and/or step-down of the battery pack voltage according to the operating condition of the traction motor so that [...] Read more.

A three-phase boost-buck inverter (BBI) comprised of three identical boost-buck DC/DC converter modules is presented for an EV traction inverter application. It allows the step-up and/or step-down of the battery pack voltage according to the operating condition of the traction motor so that the overall performance can be optimized, which is essential for EVs with relatively low and varying battery voltages such as a hybrid EV or fuel-cell EV. It also features low switching losses, low harmonic distortion in the output current, and reduced common-mode voltage and/or current. A detailed analysis and performance evaluation of the BBI compared to the conventional technology demonstrate its feasibility in EV traction applications. The functionality and performance of the boost-buck inverter are verified with simulation and experimental results. Full article

(This article belongs to the Special Issue Modern Charging Techniques for Electrical Vehicles)

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19 pages, 5103 KiB

Open AccessArticle

An Inductor-Based and Capacitor-Free Bipolar Pulse Converter with Overvoltage Protection

by Jianzhi Xu, Xingjian Yang, Hui Zhao, Jian Qiu and Kefu Liu

World Electr. Veh. J. 2022, 13(5), 91; https://0-doi-org.brum.beds.ac.uk/10.3390/wevj13050091 - 18 May 2022

Cited by 4 | Viewed by 2295

Abstract

The inductor-based and capacitor-free bipolar pulse converter can be applied to electric vehicle charging and realize an efficient and reliable charging-control strategy. Inductor-based converters can avoid the converter failure caused by the failure of energy storage capacitors and improve the reliability. An overvoltage [...] Read more.

The inductor-based and capacitor-free bipolar pulse converter can be applied to electric vehicle charging and realize an efficient and reliable charging-control strategy. Inductor-based converters can avoid the converter failure caused by the failure of energy storage capacitors and improve the reliability. An overvoltage protection scheme based on active clamping topology is used to protect this converter when the load impedance is too large. This overvoltage protection can take effect in an extremely short time (~50 ns) with little energy wasted. Furthermore, mathematical analyses of the proposed topology are presented and simulations based on LTspice are made, showing the feasibility and reliability of this circuit. Moreover, calculation of the power loss on MOSFETs is presented. A 201 W prototype converter with an efficiency of 83% is presented, and experimental results show that the converter can work reliably. This manuscript also proves the feasibility and application prospect of using this current-source-based converter for EV charging. Full article

(This article belongs to the Special Issue Modern Charging Techniques for Electrical Vehicles)

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13 pages, 5254 KiB

Open AccessArticle

Digital Implementation of LCC Resonant Converters for X-ray Generator with Optimal Trajectory Startup Control

by Zhennan Zhao, Shanlu Zhang, Lei Li, Shengfang Fan and Cheng Wang

World Electr. Veh. J. 2022, 13(5), 71; https://0-doi-org.brum.beds.ac.uk/10.3390/wevj13050071 - 19 Apr 2022

Viewed by 2464

Abstract

High voltage LCC resonant converters have been widely used in X-ray imaging systems in automobile nondestructive testing (NDT) applications. Low ripple voltage waveforms with fast-rising time under no-overshoot response are required for safety in such applications. The optimal state trajectory control (OTC) based [...] Read more.

High voltage LCC resonant converters have been widely used in X-ray imaging systems in automobile nondestructive testing (NDT) applications. Low ripple voltage waveforms with fast-rising time under no-overshoot response are required for safety in such applications. The optimal state trajectory control (OTC) based on the state plane model is one of the most effective control methods to optimize transient response. Dynamic variations of the resonant voltages/currents are described as corresponding trajectories on the state plane. The transient relations can be determined by evaluating the geometric relationships of the trajectories. However, the LCC resonant converter has more state variables, resulting in more complex calculations that make the state trajectory control challenging. Furthermore, the startup duration is the most demanding process of the state trajectory control. In this paper, a digital implementation based on a hybrid controller built in a field-programmable gate array (FPGA) is proposed for LCC resonant converters with optimal trajectory startup control. A coordinated linear compensator is employed to control the switching frequency during steady-state conditions, hence eliminating the steady-state error. The experimental results were conducted on a 140-kV/42-kW LCC resonant converter for an X-ray generator. It achieves a short rising time of output voltage with no additional current or voltage stress in the resonant tank during startup compared to the conventional digital implementation control. Full article

(This article belongs to the Special Issue Modern Charging Techniques for Electrical Vehicles)

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21 pages, 3403 KiB

Open AccessArticle

Techno-Economic Analysis and Feasibility Studies of Electric Vehicle Charging Station

by Muhammad Danial, Fatin Amanina Azis and Pg Emeroylariffion Abas

World Electr. Veh. J. 2021, 12(4), 264; https://0-doi-org.brum.beds.ac.uk/10.3390/wevj12040264 - 15 Dec 2021

Cited by 5 | Viewed by 5885

Abstract

Recent United Nations high-level dialogue on energy, which had emphasized on energy usage and environmental protection, has renewed commitments by different countries on the adoption of electric vehicle (EVs). This paper aims to analyze the economic feasibility of establishing electrical charging stations, which [...] Read more.

Recent United Nations high-level dialogue on energy, which had emphasized on energy usage and environmental protection, has renewed commitments by different countries on the adoption of electric vehicle (EVs). This paper aims to analyze the economic feasibility of establishing electrical charging stations, which is an important factor for the wide adoption of EVs, using life cycle cost analysis. Although local data have been used, the method can be easily adopted to analyze economic feasibility at different markets. The findings have revealed that an electrical charging station is only feasible when the acquisition cost is kept to a minimum to return 1.47 times the initial investment in terms of life cycle cost. An acquisition cost of BND 29,725 on the electrical charging station represents the threshold below which an electrical charging station is more attractive. In order to promote these charging stations, the government needs to provide multiple incentives, including a subsidy to reduce the acquisition cost, relaxing control on the electric selling price, taxing the establishment of conventional filling stations, and minimally reducing the profit margin on the selling price of fossil fuel. It has been shown that a 40% initial subsidy on the purchase of electrical charging stations, coupled with a slight subsidy of BND 0.018/kWh on electricity, would make electrical charging stations economically competitive. To reach its target of 60% electrification of the transportation sector, Brunei would need to implement a structure program to establish between 646 and 3300 electrical charging stations by the year 2035, to cater for its expected number of EVs. Full article

(This article belongs to the Special Issue Modern Charging Techniques for Electrical Vehicles)

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