World Electr. Veh. J., Volume 11, Issue 2 (June 2020) – 18 articles

A two-motor power-split dedicated hybrid transmission (DHT) with two planetary gears is proposed for the applications of a hybrid electric vehicle (HEV) and plug-in HEV (PHEV). The proposed DHT can provide electronically controlled continuous variable transmission (eCVT) with two different gear ratios. One of two electric motors is employed to act as a speeder for splitting the input power of internal combustion engine (ICE) and the other acts as a torquer to assist ICE for boosting. Assisted by an electric motor, ICE can always be enhanced to operate at its efficient area for the benefits of fuel economy improvement. The maximum ICE torque is viable to be mechanically transmitted to vehicle wheels from standstill with two different gear ratios. This feature can help reduce the traction motor torque and power sizing significantly. The paper presents detailed theoretical analyses of the proposed eCVT. Comprehensive simulation demonstrations for a pickup truck HEV application are given to address that the vehicle fuel consumption can be considerably reduced without compromising acceleration performance. Full article

This paper presents a braking strategy analysis for a Formula SAE electric race car. The proposed braking strategy aims to increase the recovery energy by a relevant distribution of the braking forces between the rear and front wheels. A mathematical model of the car is presented, and a simulation is performed in Matlab-Simulink. The model is organized using the energetic macroscopic representation graphical formalism. A real racetrack driving cycle is considered. Three braking strategies are compared considering the energy recovery and the vehicle stability. The simulation results show that the proposed strategy enables higher energy recovery while avoiding locking on both rear and front wheels. As in such a race the driving range is fixed, the reduction in energy consumption can be used to reduce the battery size. The battery weight can thus be decreased to improve the vehicle performance during competition. Full article

During the high-power charging process, the heat generated by the power battery is significantly increased, resulting in a significant temperature rise, which will bring safety hazards and worsens capacity degradation. In this study, we focus on the energy storage system composed of LiFePO₄ pouch battery cells whose capacity is 30Ah. The coupling calculation between the one-dimensional electro-chemical model and the 3D heat generation model is realized. The accuracy of the model is verified by charging the battery at different rates. The results show that the inlet flow rate and the cooling channel size within a certain range has a great influence on the cooling effect of the battery pack during high power charging process. Comparing the temperature distribution of the battery pack under different charging rates, the electrochemical-heating coupling model established in this study can truly reflect the heat generation of the battery. Through the calculation of the heat generation of the battery pack, the boundary conditions of the cooling system design can be found, which provides a basis for the optimal design of the conditional cooling system for battery high-power charging. Full article

In the literature, many optimization algorithms were developed to control electrical loads, especially Electric Vehicles (EVs) in buildings. Despite the success of the existing algorithms in improving the power profile of charging EVs and reducing the total electricity bill of the end-users, these algorithms didn’t show significant contribution in improving the voltage profile on the network, especially with the existence of highly inductive loads. The control of the active power may not be sufficient to regulate the voltage, even if sophisticated optimization algorithms and control strategies are used. To fill the gap in the literature, we propose a new algorithm that is able to control both the active and reactive power flows using electric vehicles in buildings and homes. The algorithm is composed of two parts; the first part uses optimization to control the active power and minimize the electricity bill, while the second part controls the reactive power using the bidirectional converter in the EV in a way that the voltage profile on the distribution transformer respects its limits. The new approach is validated through a comparative study of four different scenarios, (i) without EV, (ii) with EV using uncoordinated charging, (iii) with EV using coordinated charging, (iv) with EV using our proposed algorithm. Results show that our algorithm has maintained the voltage within the recommended limits, and it has minimized the peak load, the electricity cost, and the techno-economic losses on the network. Full article

In this paper, a new control strategy for hybrid excited salient permanent-magnet synchronous motor (HEPMSM) is proposed, where both armature winding and DC field windings are located in the stator. The developed control strategy fulfills the required characteristics of the electric vehicles (EVs) and hybrid electric vehicles (HEVs) motors. A detailed mathematical model of the HEPMSM is presented. The field current (FC) is kept constant near its rated value for the high acceleration constant torque (CT) region. The conventional control usable method of reducing FC and reversing it on the motor performance characteristics through the constant power (CP) region is examined and evaluated. A proposed FC pattern is applied to three deferent operating modes of EV. High acceleration and wide stable constant power speed range without overdesign is the main target of this work. Based on the deduced optimum control pattern, the required EV-HEPMSM performance characteristics are developed. The required d–q control armature, field currents as well as d–q stator voltage components are provided for either current or voltage control technique availabilities. Simulation work is carried out on the commonly used method and on the proposed method. The obtained simulated characteristics effectively validate the target of the proposed steady-state presented analysis and pattern. Full article

One of the decisive reasons for the slow market penetration of electric vehicles is their short driving range, especially in cold temperatures. The goal of this paper was to increase the driving range in cold temperatures. Electric vehicles recover kinetic energy by recuperation and storage in the battery. However, if the battery is fully charged or cold, the option of recuperation is severely limited. Braking energy is dissipated into the environment via the mechanical brake, and the range thus decreases. Electrothermal recuperation (ETR) enables the braking power to be used in heater systems and thus saves energy in the overall system. In this paper, ETR was investigated with a highly responsive serial layer heater. An overall model consisting of the electric powertrain, the heating circuit, and the vehicle interior was developed and validated. The limitations of recuperation capability were determined from driving tests. The factors state of charge and battery temperature were varied in the conducted simulations in order to quantify the range increase through ETR. The results showed that the range could be increased via electrothermal recuperation by up to 8% at −10 °C in a real driving cycle, using a serial heater. A control strategy of the heating circuit enabled the coolant circuit to function as buffer storage. The interior temperature—and consequently user comfort—remained unchanged. Full article

The smart grid concept enables demand-side management, including electric vehicles (EVs). Thus way, some ancillary services can be provided in order to improve the power system stability, reliability, and security. The high penetration level of renewable energy resources causes some problems to independent system operators, such as lack of primary reserve and active power balance problems. Nowadays, many countries are encouraging the use of EVs which provide a good chance to utilize them as a virtual power plant (VPP) in order to contribute to frequency event. This paper proposes a new control method to use EV as VPP for providing primary reserve in smart grids. The primary frequency reserve helps the power system operator to intercept the frequency decline and to improve the frequency response of the whole system. The proposed method calculates the electric vehicles’ primary reserve based on EVs’ information, such as the state of charge (SOC), the arriving time and the vehicle’s departure time. The effectiveness of the proposed scheme is verified by several simulation scenarios on a real-world modern power system with different generating units, such as conventional power plants, renewable energy resources, and electric vehicles. Full article

Dimensional chains are the basis for testing the feasibility of vehicle architectures in the early development phase since they allow for parametrical vehicle modeling. Parametrical modeling is employed in the early development of the vehicle in order to enable the estimation of the space available for powertrain components. For battery electric vehicles (BEVs), new dimensional chains have increased relevance because of the geometrical interdependencies between the traction battery and the passenger compartment. The passenger compartment and traction battery share the same position in the vehicle, i.e., between the axles, which leads to a conflict between these two components. Furthermore, the passenger compartment dimensions are needed to size components like heating, ventilation, and air conditioning (HVAC), the energy consumption of which in turn influences the required battery capacity. In order to describe these interdependencies, we identify a set of dimensional chains and derive a passenger compartment volume estimation model that can be employed in the early development phase of the vehicle design. We further analyze the single elements of the dimensional chain and present typical values for each element. Full article

Norway is the largest Battery Electric Vehicle (BEV) market in the world per capita. The share of the passenger vehicle fleet passed 9.4% at the end of 2019, and users have access to 1500 Combined Charging System (CCS)/Chademo standard fast chargers located in more than 500 different locations. This paper analyses the usage pattern of these fast chargers using a dataset from two large operators covering most of their charging events between Q1 2016 and Q1 2018. The target of the analysis was to understand the fundamental factors that drive the demand for fast charging and influences the user experience, so that they can be taken into account when dimensioning charge facilities, and when designing vehicles. The data displays clear variations in charge power, charge time and charged energy between winter and summer, and a large spread of results due to the BEV models different technical characteristics. The charge power is clearly reduced in the winter compared to the summer, while the charge time is longer. Some charge events have a particularly low charge power which may be due to users fast charging a cold battery at a high State of Charge (SOC) in a vehicle with passive battery thermal management. Full article

Power electronics play a fundamental role for electric transportation, renewable energy conversion and many other industrial applications. They have the ability to help achieve high efficiency and performance in power systems. However, traditional inverters such as voltage source and current source inverters present some limitations. Consequently, many research efforts have been focused on developing new power electronics converters suitable for many applications. Compared with the conventional two-stage inverter, Z-source inverter (ZSI) is a single-stage converter with lower design cost and high efficiency. It is a power electronics circuit of which the function is to convert DC input voltage to a symmetrical AC output voltage of desired magnitude and frequency. Recently, ZSIs have been widely used as a replacement for conventional two-stage inverters in the distributed generation systems. Several modifications have been carried out on ZSI to improve its performance and efficiency. This paper reviews the-state-of-art impedance source inverter main topologies and points out their applications for multisource electric vehicles. A concise review of main existing topologies is presented. The basic structural differences, advantages and limitations of each topology are illustrated. From this state-of-the-art review of impedance source inverters, the embedded quasi-Z-source inverter presents one of the promising architectures which can be used in multisource electric vehicles, with better performance and reliability. The utilization of this new topology will open the door to several development axes, with great impact on electric vehicles (EVs). Full article

To counteract climate change, electric vehicles are replacing vehicles with internal combustion engine on the automotive market. Therefore, electric vehicles must be accepted and used like conventional vehicles. This study aims to investigate to which extent electric vehicles are already being used like conventional vehicles. To do this, we present a supervised method where we combine usage data from conventional vehicles (from car use model based on survey data) and electric vehicles (from sensor data) in Germany and California. Based on conventional vehicles, eight car usage profiles were defined by hierarchical clustering in a previous study. Using a softmax regression, we estimate for each electric vehicle a probability of assignment for every car usage profile. Comparison of conventional and electric vehicles with a high probability reveals that electric vehicles are used similar for long-distance travel (>100 km) and different for short-distance travel (<10 km) to conventional vehicles. This implies that electric vehicles are indeed used for long-distance travel but are still not entirely used for everyday mobility. This could be because electric vehicles are not yet suitable for all trip purposes (e.g., transport of larger items). Full article

Dependence on energy-intense transportation systems could escalate the chances of environmental degradation. A shift of transportation modes from conventional vehicles to energy-efficient vehicles is a viable method of mitigating the rate of carbon emissions; however, the adoption rate of environment-friendly vehicles is still low globally and vital to explore. This study aims to investigate the determinants that influence individuals’ intention to purchase hybrid vehicles, through the development of a research model based on the Theory of Planned Behavior, integrated with environmental knowledge as an additional variable. Data were collected from 256 car users across Malaysia’s metropolitan city. The findings augment the rich theoretical basis of the Theory of Planned Behavior by incorporating environmental knowledge as a supplementary variable in assessing individuals’ behaviour in the sustainable transportation domain, which constitutes the novelty value of this study. The outcomes imply the need for governments and practitioners to execute appropriate approaches in nurturing public’s motivation in adopting energy-efficient cars, so that the adoption rate of pro-environmental vehicles can be increased. Overall, this study infers that the adoption of hybrid vehicles is viable if individuals are properly provided with sufficient awareness and education, which subsequently builds trust, empowerment, and confidence in owning these vehicles. Full article

The research presented in this paper documents the implementation of an active hybrid energy storage system that combined a battery pack and an ultracapacitor bank. The implemented hybrid energy storage system was used to reduce the peak-power that the battery needs to provide to the load. An active topology utilising two direct current/direct current (DC/DC) converters and a switch was used to implement the hybrid energy storage system. Fuzzy logic was used as a close-loop control structure to control the DC/DC converters in the topology, whilst a rule-based control strategy was used to control the operating states of the hybrid energy storage system. Experimental implementation of the system showed that the system was able to actively control the energy flow throughout the hybrid energy storage system in order to limit the power drawn from the battery to a user-defined limit. The performance of the fuzzy logic controllers was also experimentally found to be sufficient when used in conjunction with the rule-based control strategy. The system allows one to utilize batteries that are optimized for energy density seeing that the system was able to actively limit the power drawn from the battery, whilst providing the required power to the load by utilising the ultracapacitor bank. Full article

This paper presents a novel inductive link for wireless power transfer (WPT) system of electric vehicles (EVs). The WPT technology uses an alternating magnetic field to transfer electric power through space. The use of the WPT technology for charging electric vehicle provides an excellent alternative to the existing plug-in charging technology. It has been reported that the inductive link using planar coils such as the circular and rectangular coil are capable of transferring a high power with high efficiency. However, they have a poor tolerance for lateral misalignment, thus their power transfer efficiency decreases significantly with the misalignment. Due to the poor misalignment performance of the planar coil topology, extensive studies have been carried out on the flux pipe topology due to their excellent misalignment tolerance. To address this, in this paper, a novel inductive link using double helix flux pipe topology is proposed. The performances of the inductive link using the proposed double helix flux pipe are analyzed and compared with inductive links using conventional flux pipe. The proposed model has excellent characteristics in terms of the power transfer efficiency and tolerance against misalignments. The proposed model is capable of transferring over 1.6 kW of power with a coil-to-coil efficiency of over 98.5% at a load resistance of 20 Ω. Full article

This work explores the impact of the rapid growth of plug-in electric vehicles on wholesale electricity pricing. Understanding electric vehicle impacts on the grid is important for the mid- and long-range planning of transmission owners, distribution utilities, and regional system operators. Current research in electric vehicles considers technology adoption projections and the infrastructure needed to support electric vehicle growth. This work considers how projected electric vehicle growth in the State of Wisconsin would impact the transmission congestion and wholesale electricity pricing in the year 2030. We find minimal impacts on electricity prices (<2%) even under rapid growth assumptions, in which EVs comprise 5% of all vehicles in 2030. The increases seen in hourly locational marginal prices (LMPs) due to projected electric vehicle growth are, on average, less than those seen in annual changes of historic electricity prices in Wisconsin. We do find moderate, relative increases in congestion prices (+16–32%), which could provide an opportunity to align electric vehicle charging schedules with times of low transmission congestion. Full article

Hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) are evolving rapidly since the introduction of Toyota Prius into the market in 1997. As the world needs more fuel-efficient vehicles to mitigate climate change, the role of HEVs and PHEVs are becoming ever more important. While fuel economies of HEVs and PHEVs are superior to those of internal combustion engine (ICE) powered vehicles, they are partially powered by batteries and therefore they resemble characteristics of battery electric vehicles (BEVs) such as dependence of fuel economy on ambient temperatures. It is also important to understand how different extent of hybridization (a.k.a., hybridization ratio) affects fuel economy under various driving conditions. In addition, it is of interest to understand how HEVs and PHEVs compare with BEVs at a similar vehicle weight. This study investigated the relationship between vehicle mass and vehicle performance parameters, mainly fuel economy and driving range of PHEVs focused on 2018 and 2019 model years using the test data available from fuel economy website of the US Environmental Protection Agency (EPA). Previous studies relied on modeling to understand mass impact on fuel economy for HEV as there were not enough number of HEVs in the market to draw a trendline at the time. The study also investigated the effect of ambient temperature for HEVs and PHEVs and kinetic energy recovery of the regenerative braking using the vehicle testing data for model year 2013 and 2015 from Idaho National Lab (INL). The current study assesses current state-of-art for PHEVs. It also provides analysis of experimental results for validation of vehicle dynamic and other models for PHEVs and HEVs. Full article

Battery Electric Vehicles (BEVs) have increasingly become prevalent over the past years. BEVs can be regarded as a grid load and as a way to support the grid (energy buffering), provided this extensive battery usage does not affect the BEV’s performance. Data from both the vehicle and the grid are required for effective Vehicle-to-Grid (V2G) implementation. As such, a cloud-based big data platform is proposed in this paper to exploit these data. Additionally, this study aims to develop smart algorithms, which optimise different factors, including BEV cost of ownership and battery degradation. Dashboards are developed to provide key information to different V2G stakeholders. Full article

In this paper, a 15 KW in-wheel motor (IWM) is taken as the research object, and the coupling factors among the electromagnetic field, temperature field and flow field are analyzed, and the strong and weak coupling factors between the three fields are clarified, and by identifying the strong and weak coupling factors between the three fields, a three-field coupling analysis model for IWM with appropriate complexity is established, and the validity of the model is verified. In a certain driving condition, the electromagnetic field, temperature field and flow field characteristics of IWM are analyzed with the multi-field coupling model. The result shows that, after the IWM runs 8440 s under driving conditions, in this paper, the IWM electromagnetic torque of the rated working condition is 134.2 Nm, and IWM the electromagnetic torque of the peak working condition is 451.36 Nm, and the power requirement of the motor can be guaranteed. The highest temperature of the IWM is 150 °C, which does not exceed the insulation grade requirements of the motor (155 °C), the highest temperature of the permanent magnet (PM) is 65.6 °C, and it does not exceed the highest operating temperature of the PM, and ensures the accurate calculation of components loss and the temperature of the motor. It can be found, through research, that the electromagnetic torque difference between unidirectional coupling and bidirectional coupling is 3.2%, the maximum temperature difference is 7.98% in the three-field coupling analysis of IWM under rated working conditions. Therefore, it is necessary to consider the influence of coupling factors on the properties of motor materials when analyzing the electromagnetic field, temperature field and flow field of IWM; it also provides some reference value for the simulation analysis of IWM in the future. Full article