World Electr. Veh. J., Volume 13, Issue 5 (May 2022) – 23 articles

Brushless stator-mounted traction motors, which are new and emerging, have many potential applications in the electrified transport industry. Brushless stator-mounted machines (BSSMs), with the so-called flux modulation (FM) effects, use asynchronous field harmonics to realize energy conversion by altering the basic principle for conventional machine design which requires the stator and rotor to have the same pole number. The machines show promise of meeting the challenging requirements of electric vehicle (EV) traction motors. Therefore, in this paper, a review is undertaken on the state-of-the-art and potentials of the BSSMs for EV drives. The focus on BSSMs is due to their suitability for high-speed high torque density performance, as well as possessing suitable heat dissipation and flux weakening capabilities. The study is used to first rehash and discuss the design and excitation topologies, operating principles, and some emerging trends based on the basic BSSM variants, e.g., the doubly salient machine, flux reversal machine, and flux switching machine, while also undertaking a bibliometric synthesis on relevant studies highlighting the design and performance candidature of these niche BSSMs in EV applications, especially when compared to the well-developed Prius–IPM motor. Full article

The increasing demand for electric vehicles (EVs) in the transportation industry, especially for efficient battery–electric trucks, has led to an increase in studies on the efficiency or energy consumption of commercial vehicles. In this paper, average energy consumption was investigated in terms of the effect of different transmission types in vehicle models considering three routes, and the effect of the number of gears on energy consumption for each transmission type was analyzed. Target performance specifications and packaging were also evaluated. The optimal design could be identified in terms of transmission type, the number of gears, vehicle performance, and packaging. Vehicle models with two types of electric drive units (EDUs) were developed in a MATLAB/Simulink environment. Driving cycles were obtained from collected road load data of municipal, intercity, and regional areas operated by heavy-duty trucks using nCode software. The battery model was developed based on the electric circuit network (ECN) modeling technique. The main research purpose of this study was to investigate the effect of multispeed and multimodal EDUs and the number of gears on the energy consumption of heavy commercial electric vehicles from actual road conditions in Turkey. The three-speed EDU was the optimal design, providing 7.83, 7.26, and 7.21% less energy consumption on the three routes, compared with three-mode electric drive units. Consequently, the energy consumption difference was 7.5% for combined real road conditions. Full article

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

The dual-credit policy advances the process of vehicle electrification; however, few studies have reviewed the policy preferences and development trends of the Chinese new energy vehicle industrial policy at different stages from the development angle of the dual-credit policy. This article reviews the policy evolution of the Chinese new energy vehicle industrial policy based on the 2T model (time and types) and evaluates the policy intensity of different industrial policies by PI index. The results find that the Chinese new energy vehicle industry policy is divided into three development periods: 2004–2008—promotion policy and technological policy; 2009–2013—financial policy; and 2014–2020—charging infrastructure policy. The early policy preference for new energy vehicles was not found to be significant. Financial policies have significantly stimulated the development of the new energy vehicle industry, and the implementation of the charging infrastructure policy is late. The policy intensity of the promotion policy is the strongest, followed by the technological policy, and the policy intensity of the charging infrastructure is the weakest. The policy intensity of the financial policy will weaken in the later period. The promulgation of the dual-credit policy reflects the continuity and synergy of policy development. Full article

In the development of actual vehicles, manufacturers usually adopt a simplified control strategy to ensure the reliability of the control strategy based on the application scenarios. There are two main working modes for the fuel cell system in fuel cell electric vehicles in China. One is the stepped power type, and the other is the following power type. Therefore, the analysis and comparison of these two typical working modes in the power test of fuel cell electric vehicles helps determine how the fuel cell system works in the actual vehicle and how to choose energy management strategies in different application scenarios. We do the actual tests to explore how the two typical control strategies perform in actual vehicles. These two typical control strategies show different characteristics in the same test. It shows that the energy management strategies should be adopted according to the application scenarios and optimization goals. In the stepped power control strategy, the fluctuation of the fuel cell system and the frequency of starting and stopping are significantly reduced, which is beneficial to the durability of the fuel cell system. Compared with the stepped control strategy, the fluctuation of the output power of fuel cell electric vehicles with the following power control strategy increased significantly. At the same time, a simplified state of charge (SOC) test method is proposed. Due to the particularity of the stepped power control strategy, the change of capacity can be used to replace the change of SOC. For the following power control strategy, the change of electric energy can be used instead of SOC changes. Full article

The excessive use of fossil fuels has caused great concern due to modern environmental problems, particularly air pollution. The above situation demands that different areas of research aim at a sustainable movement to reduce CO${}_2$ emissions caused by non-renewable organic fuels. A solution to this problem is the use of Electric Vehicles (EV) for mass transportation of people. However, these systems require high-power DC/DC converters capable of handling high current levels and should feature high efficiencies to charge their batteries. For this application, a single-stage converter is not viable for these applications due to the high current stress in a switch, the low power density, and its low efficiency due to higher switching losses. One solution to this problem is Multiphase Converters, which offer high efficiency, high power density, and low current ripple on the battery side. However, these characteristics are affected by the current imbalance in the phases. This paper is focused on the study of the effects of the current imbalance in a Multiphase Buck Converter, used as an intermediate cover between a power supply and the battery of an EV. Analyzing the efficiency and thermal stress parameters in different scenarios of current balance and current imbalance in each phase. Full article

Nowadays, technology is developed rapidly in communication technology. Several new technologies have been introduced due to the evolution of wireless communication and this provided the way to communicate among vehicles, using a Vehicular Ad-Hoc Network (VANETs). Routing in VANETs becomes most challenging because of the huge mobility and dynamical topology changes, which lead to reduced efficiency in the network. The core idea of this network is to increase the efficiency during the process of the communication. The most suited routing protocol for VANETs is Geographic routing, for the reason that it provides higher scalability and low overheads. The major challenges in VANETs are the selection of best neighbor in dynamically changing VANET topology. Furthermore, to provide better QoS needful actions are essential. In this paper, we introduced a new MAC/NET with Updated Genetic Algorithm—A Cross Layer Approach, (MNUG-CLA) based on a MAC layer and network layer to overcome the drawbacks of the network. In the network layer, a new neighbor discovery protocol is developed to select the best next hop for the dynamically varying network. In the MAC layer, in order to improve the quality, multi-channel MAC model is introduced for instantaneous transmission from various service channels. For overall optimal path selection, we used an updated GA algorithm. The performance was demonstrated through the use of an extensive simulation environment, NS-2. The simulation results prove that this protocol provides better results, in terms of energy efficiency, energy consumption and successive packet transmission, when compared with the earlier approaches. Full article

Lithium-ion capacitors (LiC) are hybrid energy storage systems (ESS) combining the advantages of lithium-ion batteries and electric double-layer capacitors, including longer lifetime, high power, and energy densities. LiCs are popular for high-power applications where fast charge and discharge driving profiles are demanded from electric vehicles (EV). However, LiCs generate excess heat when they are exposed to fast charging/discharging profiles. Therefore, a robust thermal management system (TMS) is crucial, in order to ensure reliable operation. In this study, a novel hybrid TMS based on air-cooling system assisted phase change materials (PCM), heat pipes, and a heat sink is proposed for an LiC module under a 150 A continuous current profile. A very thin aluminum heat sink and flat copper heat pipes were added to the PCM to increase its thermal conductivity. An experimental test bench of the proposed TMS was developed, and the temperature distribution of the module for each of the individual LiC cells was studied. The maximum temperature of the module under natural convection, when there was not any cooling system, reached almost 59.8 °C. The experimental results showed that after using the proposed hybrid TMS, the hottest cell reached 36.18 °C while the coldest cell reached 35.54 °C. Therefore, 39.5% improvement could be seen during the whole charge and discharge process after 3000 s. Moreover, the temperature difference within the module, of four LiCs, was around 0.64 °C, which was exceptional. Full article

The use of drones is very extended for multiple applications. Some of them impose attitude and navigation requirements that need appropriate measurements. Pixhawk is an open-source autopilot used on board drones that includes a magnetometer as part of its inertial measurement unit. A testing facility based on a Helmholtz cage is used to evaluate the metrological features of different magnetometer units. The first test induces a magnetic field rotation around six different Pixhawk magnetometers, simulating changes in attitude and course for a drone. The data show a standard deviation higher than 250 mG, in comparison with the standard deviation of 30 mG in the standard gaussmeter model HMR2300. The second test is focused on the stability of the magnetometer, where the Helmholtz cage simulates a certain flight altitude and course. Values obtained from Pixhawk magnetometers range between 25 mG and 116 mG for the highest peak-to-peak magnetic field amplitude, while the standard gaussmeter range is only between 1.3 mG to 5.4 mG. Considering these results, it is possible to determine the limitations of the Pixhawk autopilot magnetometer, both in terms of manufacturing tolerances and measuring stability. Therefore, users should be very careful when using this type of autopilot in professional applications that require precision and safety. Full article

The demand for electricity in Saudi Arabia has grown in the last few years due to the growth in the economy and the population. The country has invested in many solutions such as promoting renewable energy and shifting to generation mix to respond to this growing demand. However, Electric Vehicles (EVs) are used as an important factor in achieving the Saudi Vision 2030 in its environmental and economical parts. This work gives an overview on the Saudi electrical energy system and then investigates the impact EVs technology in the electricity sector in Saudi Arabia and its relevant consequences. A statistical analysis is used to quantify the number of EVs, travelled distance and traffic congestions, and State of Charge (SOC). The data were used to implement a daily load profile for EVs for a large population of vehicles. The obtained results show that the EVs peak loads occur during the late evening and early morning at different means. Interestingly, the work shows that the peak periods of EVs occur during the off-peak times of the daily load curve. This means that a large population of EVs can offer more flexibility and improvement to the electric grid, and the summative EV load of a large population of vehicles has a smooth pattern and will not affect the national electric system. Full article

A method for real-time estimation of rotor flux linkage of permanent-magnet synchronous machines (PMSMs) under both steady state and free-running conditions is proposed in this paper. At steady state, a method for the estimation of rotor flux linkage is proposed based on the injection of variable-period zero-voltage perturbation, of which the accuracy is irrespective of the influence of voltage-source inverter (VSI) nonlinearity. Moreover, for the estimation of rotor flux linkage under free-running condition, due to system inertia after shutdown or fault in the motor driver, an effective approach using history data recorded at different transients of rotor speeds is developed, which has eliminated the influence of VSI nonlinearity during the modeling process. The proposed two methods are experimentally validated on a down-sized PMSM prototyped for electric vehicle application, which shows good performance for the estimation of rotor flux linkage under both steady state and free-running conditions. Full article

The electromagnetic suspension high-speed maglev train system uses long-stator linear synchronous motors (LLSMs) as levitation and traction mechanisms. In this paper, the modeling and simulation of the traction power supply system for the maglev train are performed. The simulation models include transformers, converters, variable-length cables and LLSMs of both two sides and two ends; meanwhile, the corresponding control and segmented power supply strategies, including the two-step method and three-step method, are implemented. Based on the system model, the operational performance of the high-speed maglev power supply control system is verified, and the fault performances under open circuit and short circuit are also analyzed. The whole simulation modeling and results have important reference significance for the research of high-speed maglev technology. Full article

The premise of the large-scale operation of electric buses corresponds to efficient charging service guarantees. Recent research on charging stations mainly aims to obtain the construction location and construction sequence through optimization methods or decision-making methods. This research has considered the aspects of geography, charging efficiency, economic efficiency, and emergency response capacity. The increase of charging stations will lead to competition among charging stations, unbalanced use of charging facilities, and unnecessary loss of electricity to the power grid. In fact, few studies pay attention to the actual operation of existing charging stations. Therefore, it is necessary to establish a scientific, comprehensive, and efficient charging services evaluation framework to support the actual operation of charging stations. Based on the analytic hierarchy process (AHP), this paper designs a multi-level indicator evaluation framework, which includes 6 first-level indicators and 20 s-level indicators. The first-level indicators are cutting peak and filling valley (A1), location and scale (A2), intelligent technology (A3), equipment efficiency (A4), operating income (A5), and reliability (A6). Through the questionnaire survey of ten experts in related fields, we understood the importance and attention of these indicators. The results show that the weights of indicators of location and scale index (A2) and reliability (A6) are high, which are 0.2875 and 0.2957, respectively. The least concerned indicator is equipment utilization efficiency (A4), at a weight of 0.0531. According to the actual data of charging stations in Zhengzhou, China, the comprehensive competitiveness of several charging stations is evaluated by the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS). The result shows that station 1 has the highest comprehensive competitiveness, followed by station 2 and station 7. The evaluation framework proposed in this paper comprehensively considers a variety of factors. The combination of AHP and TOPSIS can reduce the uncertainty in experts’ evaluation of the service of the charging station. Full article

The growing oil demand and serious environmental concerns have promoted the concept of the usage of electric vehicles (EVs) across the globe. EVs can be integrated into the grid for power transaction and to support the grid requirements, thereby drawing the attention of researchers, policy makers and industries. EVs are not only a transportation tool but also act as a distributed source or load. The EV battery plays a prominent role in grid integration and sustainable transportation. The monitoring and control aspect of the battery management system (BMS) plays a vital role in the successful deployment and usage of EVs. In this paper, an equivalent circuit model (ECM) of battery is proposed and analyzed that describes the battery behavior at various temperatures, considering the internal resistance of the battery. A stochastic model was developed for the battery ageing and replacement to ensure that systematic replacement of batteries based on the calendar ageing was performed. A reliability assessment of EV accessibility and availability was carried out by using Markov chain. A case study of a Diesel-renewable powered Electric Vehicle Charging Station (EVCS) in a micro-grid was carried out that suits the requirement of large-scale EV fleet integration to the grid for power transaction. The holistic approach of BMS was considered for the sustainable transportation and grid integration Full article

Unmanned aerial vehicles (UAVs) are a promising means of optimizing existing and developing new technological processes at modern airports. At present, in most countries of the world, airports are still closed to UAVs. To allow UAVs to operate at the airport, it is necessary to solve the problem of ensuring the safety of their movement. In this paper, we consider modern methods for ensuring the safety of the movement of electric multicopters (EMs), which are a type of UAV that, according to its technical characteristics, can be operated at the airport in various applications, including for transportation or monitoring on the territory of the airport. To allow EMs to work at the airport, this paper proposes the joint use of two methods of ensuring traffic safety developed in recent years. The results of the conducted expert evaluation show that such a solution can be considered as the key to the approval of EMs for operation at airports. Full article

Due to its advantages, the Proportional Integral Derivative (PID) controller has been the most widely used controller in the industrial sector. It allows linear systems to have good performance, but if the system is subjected to physical variation conditions, the system’s behavior becomes non-linear, in which case the PID controller is insufficient. The use of the PID controller for speed control in rotating machines, such as the doubly fed induction motor (DFIM) is widely used, but the non-linearity of the machine parameters allows for undesirable behaviors, resulting in overshoots and torque ripples. For this reason, several techniques have been adopted to increase the DTC’s robustness. One finds the integration of artificial intelligence as optimization algorithms. These algorithms are used to generate gains close to the optimum, converging the behavior of the DFIM to its optimum. In this work, an Ant Colony Optimization (ACO) algorithm was proposed to adjust the PID controller gains of the DTC control to control the DFIM, using a combined weighting cost function, to obtain efficient torque and speed control. This paper presents a new hybrid structure resulting from the intelligent ACO-DTC control implemented on Matlab-Simulink. The performance results extracted from the simulation showed the effectiveness of the intelligent ACO-DTC control, which provides satisfactory performance in terms of rapidity, stability, precision, and torque ripples compared to the conventional DTC. Full article

Electric vehicles are rapidly popping up in the market as a new alternative to fossil fuels, in order to reduce carbon emissions in urban areas. However, the improper placement of charging piles has impeded the development of electric vehicles. In this paper, 12 indicators from 4 categories, namely economy, environment, cost, and service quality are selected to form an index system for evaluating the location of electric vehicle charging piles. The entropy weight-TOPSIS method is also applied for the same purpose. On the basis of the evaluation, this paper proposes a set coverage model and adopts a greedy heuristic algorithm to find out the optimal location of charging piles. Finally, the paper verifies the reasonability and feasibility of this model by studying the existing location of electric vehicle charging piles in northeast China. The evaluation is based on the Liaoning Province Electric Vehicle Big Data Supervision Platform, which has data that are official and scientifically based. The set coverage model proposed, based on the evaluation, is a new solution to finding out the optimal location of electric vehicle charging piles across China. This study aims to provide a theoretical basis for the development of this new energy industry. Full article

Cold orbital forging (COF) as an advanced incremental metal-forming technology has been widely used in processing vehicle parts. During the COF process, the vibration on the COF machine injures the service life of the machine and the quality of the forged part. The study of the vibration control of the COF machine is therefore necessary. In this study, the dynamic model of the COF machine is established, and the vibration performances of some key positions are obtained using Matlab&Simulink software. Subsequently, the vibration performances are effectively verified by conducting a vibration test experiment. Based on the dynamics model of the COF machine and Matlab&Simulink software, least-mean-squares (LMS), recursive least-squares (RLS) and OCTAVE vibration-control algorithms are applied to reduce the vibration. Comparing the vibration performances of the COF machine, these vibration-control algorithms are useful for reducing the vibration of the machine, which improves the service life of the machine and the quality of the forged part. Based on the vibration performances of the COF machine, the effects of LMS and RLS vibration controls are better than the OCTAVE, and they also obviously reduce the vibration of the COF machine. The vibration-control algorithms are first to be applied to reduce the vibration of the COF machines in this study, which will be beneficial to future research on the vibration controls of metal-forming machines and other mechanical systems. Full article

Excessive temperature is detrimental to the operation stability of the automobile drive axle. It is necessary to judge whether the highest temperature exceeds the limited dangerous temperature and study the effects of key factors on reducing the temperature. In this study, the temperature field distribution (TFD) of the automobile drive axle is revealed using the thermal network method (TNM). Compared with the experimentation and finite element analysis (FEA), the TNM is more convenient for obtaining the temperature. Subsequently, the highest temperature of the automobile drive axle is clear and applied to judge whether the highest temperature exceeds the limited dangerous temperature. On the basis of the TNM, the structure and parameter effects of the automobile drive axle on reducing the temperature are studied, which improves the operation stability and working life. Several conclusions can be drawn. The highest temperatures of two-axle and planetary automobile drive axles are both located in the motor. Compared with the two-axle drive axle, the highest temperature of the planetary drive axle is obviously lower. Therefore, in terms of the planetary drive axle, the possibility of exceeding the limited dangerous temperature is lower. In addition, on the premise of ensuring the normal operation, the motor output power, the friction coefficient among teeth, the helical angle of the gear, and the thermal transfer coefficient of the lubricating oil can be optimized to be lower for reducing the temperature of the automobile drive axle. Full article

A modal shift to electric pedal-assisted cycles (EPACs) can help with reaching the transport emission goals of the European Green Deal. With the rising sales of EPACs in Europe, a lack of appropriate (electric) cycling infrastructure remains a major barrier for many potential users. This paper discusses the results of a survey about the requirements of (potential) cyclists to design a better cycling infrastructure. The differences in requirements for non-cyclists vs. cyclists and electric cyclists vs. conventional cyclists are discussed using statistical analysis. The key findings are that cyclists and non-cyclists both require wide quality cycling infrastructure with safe crossing points, secure bicycle parking and smart traffic lights. Non-cyclists’ requirements significantly differ from cyclists’ on 12 items, of which rain cover while cycling and parking spots for the car are the most noteworthy. There is (but) one significant difference between the requirements of EPAC users and conventional cyclists: the need for charging points for EPACs along the cycle route. Full article

With the increase of fire problems of new energy vehicles (EVs), more and more attention has been paid to charging safety. Firstly, the charging safety problems and protection strategies in the power grid are summarized from the grid side, the charging equipment side, the vehicle side, and the operation platform side, and a solution for the vehicle side charging safety protection is proposed. Secondly, with regards to building a charging early warning protection system architecture, a real-time protection strategy for EV charging is proposed; a battery temperature difference, battery voltage ramp rate, and current ramp rate are proposed; and a double-layer protection model of an active protection layer and a big data protection layer is established based on the real-time monitoring of 27 parameters. Finally, by building a physical simulation platform of the early warning system, the simulation and verification are carried out based on the BYD Han model. The system was demonstrated in the State Grid Tianjin Electric Power Company of China. The results show that the system can realize the charging real-time early warning and deal with it in time when the battery charging is abnormal, which has practical application value for the popularization and development of EVs. Full article

In the mid-low speed Maglev train, the levitation force produced by end electromagnets is influenced by the train speed due to the eddy current effect, especially the front-end electromagnets at high speed. In this paper, the eddy current effect of front-end electromagnets is calculated by an analytical method, which is validated by the Finite Element method (FEM). To compensate a decrease of levitation force, two improved structures of end electromagnet modules are designed and compared. One is the permanent magnet compensation structure, designed by inserting a piece of permanent magnet (PM), and called the PM hybrid structure, and the other is an additional electromagnet compensation structure, which adopts five electromagnets, and called the five-coil structure. In terms of comparison, the five-coil structure can not only produce a high enough levitation force, but can also be easily manufactured. Its effectiveness is verified by the prototype application. Full article

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