JournalTOCs

IET Electrical Systems in Transportation
Journal Prestige (SJR): 0.406

Citation Impact (citeScore): 3
Number of Followers: 11

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2042-9738 - ISSN (Online) 2042-9746
Published by IET

[46 journals]

PFC-SEPIC converter-fed half-bridge LLC resonant converter for e-bike
charging applications
- Pages: 225 - 233
  Abstract: In today's market, electric bikes (e-bikes) are becoming exceedingly popular due to their smaller size, ease of domestic charging and cost-friendly alternative in the category of electric vehicles. So, there is a need for the development of a power factor corrected (PFC) private off-board charger (OBC) to cater to the need of the domestic charging of e-bikes. Traditionally, e-bike chargers powered by a domestic meter are realised by a non-PFC OBC with a power rating of 500-700 W. Such converters draw harmonic currents at very high crest factor and affect the life and performance of other domestic appliances. A private OBC which derives its power from the domestic supply for charging the battery of an e-bike is proposed. The charger has two stages, i.e. the PFC stage for input current shaping and the DC-DC stage for regulating the battery charging voltage and charging current. The PFC stage is based on the single-ended primary inductance converter and the DC-DC stage is based on the inductor inductor capacitor (LLC) resonant converter. A 570 W, 57.6V, 10 A prototype is built using digital signal processor (TMS320F28035) to evaluate and validate its performance for charging a lithium-ion battery pack.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
High-efficiency design method of LLC resonant converter for PHEV battery
chargers ( based on time-domain model)
- Pages: 234 - 242
  Abstract: High efficiency, high power density and wide output voltage are required for on-board charger (OBC) applications. LLC resonant converter has the advantage of achieving zero-voltage switching for variable frequency and different load conditions. Compared with conventional fundamental harmonic approximation method, operation-mode analysis based on the time domain model provides an accurate description of resonant current, voltage and DC gain. In this study, the efficiency-oriented modified method is proposed based on the operation-mode analysis. The converter inductance ratio, characteristic impedance and transformer turns ratio are optimised and both-side soft switching can be achieved in the high output voltage region. Conduction loss can be minimised by optimising resonant parameters. Finally, a high-efficiency design method is proposed and validated through experiments on a 3.3 kW prototype applied in OBC. The prototype of the LLC resonant converter has been tested for dynamic charging voltage (230-430 V) with a peak efficiency value of 98.5%.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
Thermal characteristics of a lithium-ion battery used in a hybrid electric
vehicle under various driving cycles
- Pages: 243 - 248
  Abstract: Lithium-ion battery is the most preferable type for hybrid electric vehicle due to their superior performance. The battery performances and safety factors are influenced by its operating temperature, hence it needs to be controlled carefully. Battery has a good performance at high temperature but this put it at risks of thermal runaway and explosion. This study presents a simulation model to predict battery's thermal behaviours during discharging and charging through regenerative braking in a series hybrid electric vehicle under various driving cycles. In total, five driving cycles are covered namely New European Driving Cycle (NEDC), Artemis cycle, Japanese 10-15 Mode cycle, FTP-75 cycle and worldwide harmonised light vehicles test procedure cycle. Validation of the model is performed using experimental results for NEDC cycle. Important results presented in this study focus on the battery temperature under different driving cycles and the impacts by considering thermal generation during charging process. Even though the temperature increase is relatively small, but the contribution of heat generation during charging is significant especially in an aggressive driving cycle. These results are very important in providing better understanding on the battery thermal behaviours so that a more effective battery management system can be developed (199/200).
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
Method for EV charging in stochastic smart microgrid operation with fuel
cell and renewable energy source (RES) units
- Pages: 249 - 258
  Abstract: Nowadays, running out of fossil fuels and more attention to reduce environmental pollutions are essential factors for the growing use of electric vehicles (EVs). Owing to these factors, it is important to present a method, which schedules charging or discharging of EVs and simultaneously considers economic and environmental aspects of the problem. This study proposes a multi-objective optimisation programme for charging or discharging of EVs in a smart distribution system by taking advantage of advanced metering infrastructure and uses a ε-constraint method for minimising operational costs and (CO2) emissions. Simulating stochastic patterns of EV owner driving behaviour as well as considering different models and types of EVs with the help of trip planning algorithm are the main advantages of this study. Investigating the multi-objective problem in two cases shows the effectiveness and flexibility of this algorithm in real cases. Besides, vehicle-to-grid capability of EVs was also considered. This method was tested on a 33-bus distribution test system for over 24 h. As the results show, the total amount of scheduled power, the peak-to-valley difference of daily load, transmission power loss, CO2 emission, and the total operational cost are reduced by the trip planning programme and EV owner revenue is increased.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
Salp swarm algorithm-based fractional-order PID controller for LFC systems
in the presence of delayed EV aggregators
- Pages: 259 - 267
  Abstract: Electric vehicles (EVs) battery has the ability to enhance the balance between the load demand and power generation units. Random behaviour of owners and EVs low capacity are some factors that develop the EV aggregator notion to increase the EV participation in the ancillary services market. In the presence of EVs aggregator, the frequency control service is capable of causing time-varying delay in load frequency control (LFC) systems. Owing to the dependency of controller effectiveness on its parameters, these parameters should be designed optimally in order to have a better result in an LFC system in the presence of time-varying delay. Therefore, a salp swarm algorithm (SSA) is utilised to adjust the fractional-order proportional integral derivative (PID) (FOPID) controller coefficients. Also, some evaluations are performed about the proposed LFC performance by an integral absolute error, integral time absolute error and mean absolute error indicators. In this study, both single and two-area LFC systems containing EVs aggregator with time-varying delay are simulated and analysed. The results indicate that the proposed controller has fewer frequency variations in contrast to other controllers presented in the case studies. Moreover, it is concluded that the FOPID controller could significantly decrease the overshoot and settling time of the frequency variation signal.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
Multi-frequency averaging (MFA) model of a generic electric vehicle
powertrain suitable under variable frequency of averaging developed for
remote operability
- Pages: 268 - 274
  Abstract: Geographically distributed hardware-in-the-loop (HIL) testing has the potential to allow hybrid vehicle powertrain components (battery, motor drive, and engine) to be developed at geographically remote locations but tested concurrently and coupled. Inter-location internet communication links can allow non-ideal behaviour observed in a physical component in one location (e.g. an electrical drive) to be imposed on another physical component elsewhere (e.g. an ICE), and vice-versa. A key challenge is how to represent the behaviour of a remote, physical component under testing in a local HIL environment. Internet communications are too slow and unreliable to transmit waveforms in real-time and so one solution is to use a local `slave' model whose behaviour and parameters are tuned based on observations at the remote location. This study proposes a multi-frequency averaging (MFA) slave model of an electric motor drive system for use in this application; it addresses a weakness in previously published work by extending the MFA model to variable frequency operation. The model was benchmarked against experimental operation (and its equivalent simulation model) in open-loop and closed-loop space vector pulse-width modulation control strategy, fixed and variable frequency operation. Results show significant reconciliation of model and experiment.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
Energy flow control and sizing of a hybrid battery/supercapacitor storage
in MVDC shipboard power systems
- Pages: 275 - 284
  Abstract: The propulsion system of a medium-voltage dc (MVDC) ship is subject to large thrust/torque variations due to interactions of the ship and the propeller with sea waves. These variations induce steep power fluctuations on the MVDC bus, adversely impacting the stability, efficiency and power quality. Hybrid energy storage system (HESS) is a promising solution for mitigating these power fluctuations. Dictating the energy that the HESS components must deliver/absorb, the energy management strategy (EMS) impacts the size/capacity of the energy storage system (ESS). Based on this consideration, sizing and EMS of a battery/supercapacitor (SC) HESS are jointly optimised by using a deep reinforcement learning-based method. The proposed method splits the power between the HESS components such that while the operational constraints are satisfied, energy storage size and losses are minimised. Its features are adaptability to varying sea states, real-time implementation feasibility, while obviating the requirement for knowledge of the ship propulsion power profile. The efficacy of the joint sizing/EMS on reducing the ESS size is validated by comparing the sizes when battery-only, SC-only and HESS are employed in the MVDC shipboard power system. Real-time implementation feasibility and adaptability to various ship propulsion power profiles is confirmed through real-time simulations.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
Studying the electromechanical system of a series/parallel HEV with
planetary gearbox dynamics
- Pages: 285 - 290
  Abstract: This study presents a complex electromechanical model for the simulation of a hybrid electric vehicle which is the Toyota Prius THS-II. The electromechanical model comprises the electrical subsystem, as it is developed and adopted in the past in several research activities, however, the interest in this study is focused on the application of a mathematical model for the power split device (planetary gearbox) of the mechanical subsystem in order to take into account full dynamic interaction between the subsystems by taking into account gear dynamics, in comparison with previous studies which implement simple algebraic models. The differential equations of the mechanical subsystem are solved with the aid of a dimensionless system in order to deal with the `stiffness' problem. The relevant simulations which have been performed considered two cases. In the first case, the power split device is modelled with a simple algebraic model, while in the second case, the mathematical model for the power split device is the model discussed in this study. The developed source code is compiled by employing the MPI module in order to render the relevant simulations capable of running very fast. Finally, a comparison between the results of the two cases is demonstrated.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
Off-board electric vehicle battery charger using PV array
- Pages: 291 - 300
  Abstract: During the recent decade, the automobile industry is booming with the evolution of electric vehicle (EV). Battery charging system plays a major role in the development of EVs. Charging of EV battery from the grid increases its load demand. This leads to propose a photovoltaic (PV) array-based off-board EV battery charging system in this study. Irrespective of solar irradiations, the EV battery is to be charged constantly which is achieved by employing a backup battery bank in addition to the PV array. Using the sepic converter and three-phase bidirectional DC-DC converter, the proposed system is capable of charging the EV battery during both sunshine hours and non-sunshine hours. During peak sunshine hours, the backup battery gets charged along with the EV battery and during non-sunshine hours, the backup battery supports the charging of EV battery. The proposed charging system is simulated using Simulink in the MATLAB software and an experimental prototype is fabricated and tested in the laboratory and the results are furnished in this study.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
Power optimisation scheme of induction motor using FLC for electric
vehicle
- Pages: 301 - 309
  Abstract: In electric vehicles (EVs) and hybrid EVs, energy efficiency is essential where the energy storage is limited. Adding to its high stability and low cost, the induction motor efficiency improves with loss minimisation. Also, it can consume more power than the actual need to perform its working when it is operating in less than full load condition. This study proposes a control strategy based on the fuzzy logic control (FLC) for EV applications. FLC controller can improve the starting current amplitude and saves more power. Through the MATLAB/SIMULINK software package, the performance of this control was verified through simulation. As compared with the conventional proportional integral derivative controller, the simulation schemes show good, high-performance results in time-domain response and rapid rejection of system-affected disturbance. Therefore, the core losses of the induction motor are greatly reduced, and in this way improves the efficiency of the driving system. Finally, the suggested control system is validated by the experimental results obtained in the authors' laboratory, which are in good agreement with the simulation results.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
In-depth study of the application of solid-state transformer in design of
high-power electric vehicle charging stations
- Pages: 310 - 319
  Abstract: Solid-state transformers (SST) will play an important role in future electric power distribution. The SST usually used for traction and transportation systems. However, it can be employed for other applications. For example, electric vehicles (EVs) are confronting the increased demand now, and the service provider must expand the infrastructures such as the high-power EV charging stations in urban areas. One solution for designing a high-power charging station is the SST-based charging stations, which can be connected to the distribution network. This study proposes an SST-based EV charging station, which is connected to the 20 kV catenary without any low-frequency transformer and provides the necessary power for connected EVs without affecting the grid power quality. The proposed EV charging station has high flexibility such that it can be integrated with distributed generation. It also provides vehicle-to-grid, grid-to-vehicle and sun-to-vehicle features. Besides, it can inject reactive power to the grid based on its free capacity. This study also proposes an advance virtual flux predictive power controller to improve the immunity of this structure against voltage harmonics. Exact simulations have been done for a three-phase 20 kV/600 V/360 kVA station with different scenarios. Results verify the performance of this infrastructure.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)
Hierarchical control architecture for resilient interconnected microgrids
for mass transit systems
- Pages: 320 - 327
  Abstract: Railway transit is relied on every day to transport millions of passengers and bring billions worth of economic goods to market. However, electrified railway infrastructures are dependent on the electric grid, which is vulnerable to extreme weather, changing supply and demand patterns, and cyber-terrorism. A hierarchical control system that uses a resiliency metric and applies game theory techniques to handle the exchange of energy between interconnected microgrids is presented. The proposed designs are modelled and simulated in Simulink, for a proposed high-speed railway in the UK. Interconnected microgrids for railway infrastructures demonstrate a reduced dependence on the electric grid by at least 95%. The results are both extremely impressive and promising towards a more resilient and stable energy future both for railway and for other critical infrastructures.
  PubDate: 9 2020
  Issue No: Vol. 10, No. 3 (2020)