Advanced Energy and Propulsion Technology for Electric and Intelligent Transportation

A disruptive Electric Propulsion system is proposed for next-generation Low-Earth-Orbit (LEO) small satellite constellations, utilizing an RF-powered Helicon Plasma Thruster (HPT). This system is built around a Magnetically Enhanced Inductively Coupled Plasma (MEICP) reactor, which enables acceleration of quasi-neutral plasma through a magnetic nozzle. The MEICP reactor features an innovative design with a multi-dipole magnetic confinement system, generated by neodymium iron boron (NdFeB) permanent magnets, combined with an azimuthally asymmetric half-wavelength right (HWRH) antenna and a variable-section ionization chamber. The plasma reactor is followed by a solenoid-free magnetic nozzle (MN), which facilitates the formation of an ambipolar potential drop, enabling the conversion of electron thermal energy into ion beam energy. This study explores the impact of an inhomogeneous magnetic field on the heating mechanism of the HPT and highlights its multi-mode operation within a pulsed power range of 200 to 500 W of RF. The discharge state, characterized by high-energy electron-excited ions and low-energy excited neutral particles in the plasma plume, was analyzed using optical emission spectroscopy (OES). The experimental testing campaign, conducted under pulsed power excitation, reveals that, as RF input power increases, the MEICP reactor transitions from inductive (H-mode) to wave coupling (W-mode) discharge modes. Spectrograms, electron temperature, and plasma density measurements were obtained for the Helicon Plasma Thruster within its operational envelope. Based on OES data, the ideal specific impulse was estimated to exceed 1000 s, highlighting the significant potential of this technology for future LEO/VLEO space missions. Full article

During the modulation process of the VSI motor drive system, the nonlinear errors caused by the dead-time and conduction voltage drop will increase the phase current harmonic distortion and the torque ripple. To solve this problem, a novel dead-time free modulation scheme is proposed in this paper. In the non-zero crossing region of the phase current, the switching tube, whose body diode can provide a continuation path, is set as off-state, the driving signal is only implemented on another switching tube with the same bridge arm, and the errors caused by the conduction voltage drop and switching delay are compensated to the pulse duration. At the same time, to suppress the zero current clamp effect that exists near the zero crossing point of the phase current, another modulation scheme for the phase current crossing zero in advance is proposed, which avoids the complicated determination and calculation of the current polarity near the zero crossing point of the current. Both of the above modulation schemes eliminate the dead-time, and the switching principle is presented. In addition, to suppress the impact of the current ripple and high-frequency noise on the accuracy of the phase current detection, a second-order resonance digital filter without phase shift is introduced. Finally, compared to two deadtime compensation methods, the effectiveness and superiority of the proposed dead-time free modulation scheme are verified by the experimental results. Full article

Different from the voltage source inverter (VSI), the current source inverter (CSI) can boost the voltage and eliminate the additional passive filter and dead time. However, the DC-side inductor current is not a real current source and is generated by a DC voltage supply and an inductor. Under different switching states, the DC-side inductor will be charged or discharged, which leads to the DC-side inductor current being discontinuous or increasing. To solve the control problem of the DC-side inductor current of the CSI, a novel single-phase CSI topology with five switching tubes for grid-connected applications is proposed. Firstly, the reference calculation method and the hysteresis loop control scheme for the DC-side inductor current are proposed, and the adjustable and constant DC-side inductor current are obtained. Since the PWM signals cannot be directly implemented to the switching tubes, the modulation strategy for the single-phase CSI is proposed in this paper. Then, an active damping method based on the feedback capacitor voltage is presented to suppress the resonance peak caused by the LC filter on the grid side. Finally, the math model of the AC-side structure is established, and the optimal proportional-resonant controller parameters’ design method is explored by the amplitude–frequency characteristic curves. The simulation and experiment are implemented for the proposed CSI topology. The results show that a high-quality power with a good control performance can be obtained with the proposed CSI topology. Full article

Common-mode voltage (CMV) leads to the shaft voltage and shaft current by coupling the capacitor network in the permanent magnet synchronous machine (PMSM), which affects the reliability of the whole motor drive system. Based on the low-CMV modulation strategy for the PMSM drive system, this paper proposed an improved near-state pulse-width modulation (NSPWM) on switching loss. First, the generation mechanism for the switching signals of NSPWM was analyzed, and it was observed that there exists one phase of switches in an inactive state for every sector. Then, to reduce the switching loss of the NSPWM, this paper proposed an improved NSPWM modulation strategy based on power factor angle to adjust switching action, which ensures the switching tubes that have the biggest conduction current have no switching action. In addition, the switching loss analytic formula of the NSPWM was derived to prove the correctness of the proposed method for optimizing switching loss. Finally, the proposed modulation strategy was carried out in the simulation and experimental platform. Under the premise of good steady and dynamic performance, the results show that the proposed modulation strategy has less switching loss. Full article

Common-mode voltage (CMV) brings shaft voltage and shaft current, and corrodes the bearings of the permanent-magnet synchronous machine (PMSM), which affects the reliability of the whole PMSM drive system. Since the CMV applied by the zero voltage vectors (ZVVs) is three times that applied by the active voltage vectors (AVVs), a modulation scheme achieving minimum CMV without ZVV is proposed and introduced into the model predictive control structure for the PMSM drive system. Firstly, the whole modulation range is divided into three regions, including the low voltage modulation region (LVMR), high voltage modulation region (HVMR), and over-voltage modulation region (OVMR). Meanwhile, the regional boundary expression is derived. Then, the active zero-state pulse width modulation (AZSPWM) is adopted in LVMR. To improve the steady-state performance, near-state pulse width modulation (NSPWM) without opposite ZVVs is applied to the HVMR. Furthermore, when the reference voltage vector (VV) is located in OVMR, an optimal scheme is proposed to improve the dynamic response. Under the premise of no ZVV existing in the whole modulation region, simulation and experimental results show that the proposed hybrid modulation method can improve the steady-state and dynamic performance of the PMSM drive system. Full article

Due to the influence of parasitic internal parameters and junction capacitance, the silicon carbide (SiC) power devices are frequently marred by significant overshoots in current and voltage, as well as high-frequency oscillations during the switching process. These phenomena can severely compromise the reliability of SiC-based power electronic converters during operation. This study delves into the switching transient of the SiC MOSFET with the goal of establishing a quantitative correlation between the gate driving current and the overshoot in both the drain-source voltage and the drain current. In light of these findings, the innovative active gate drive (AGD) circuit, which features an adjustable gate current, is introduced. Throughout the switching process, the AGD circuit employs a dynamic monitoring and feedback mechanism that is responsive to the gate voltage and rate of change in the drain-source voltage and drain current of the SiC MOSFET. This adjustment enables gate driving current to be actively modified, thereby effectively mitigating the occurrence of overshoots and oscillations. To empirically validate the efficacy of the proposed AGD circuit in curbing voltage and current overshoots and oscillations, a double-pulse experimental setup was meticulously constructed and tested. Full article

We present an innovative cooperative driving strategy known as Dynamic Resequencing and Platooning (DRP) designed to ensure the safe and efficient traversal of Connected and Automated Vehicles (CAVs) through signal-free intersections. By employing a Resequencing and Platooning Algorithm (RPA) grounded in state transition networks and CAV platooning, the optimal crossing sequence for CAVs is ascertained within a finite time. Through the utilization of a decentralized energy-optimal control framework, optimal trajectories are devised for CAVs, thereby facilitating optimal coordination among them. Simulation results underscore the substantial performance benefits of the DRP strategy compared to traffic light, First-In-First-Out (FIFO), and Local Dynamic Resequencing (LDR) strategies, with notable reductions observed in both travel delay and fuel consumption. Full article

In the current source photovoltaic grid-connected system, to prevent the DC-link inductor from incurring an opening circuit fault, it is necessary to include the overlap time in the switching signals. However, current error and serious harmonic distortion in the inverter-side and grid-side currents are generated, which will cause additional losses and reduce the power quality of the grid, so it is important to compensate for the current error caused by the overlap time. In this paper, the relationship between the nonlinear current errors caused by the overlap time and the AC-side voltage is analyzed. Then, the mathematical expression of the low-order harmonics with losses caused by the overlap time is derived. On this basis, a current error compensation method with a discrete filter of AC-side voltage is proposed. Finally, a simulation and experiment are carried out to verify the correctness and effectiveness of the theoretical analysis and compensation scheme presented in this paper. With an overlap time of 3 μs, the THD of the grid-side current decreases from 5.93% to 1.59% after compensation. Full article

Variable flux reluctance machines (VFRMs) are increasingly attracting research interest due to their magnetless and robust brushless structure. Under the modulation effect of the airgap permeance, the VFRM operates with a series of field harmonics, distinguishing it from conventional AC synchronous machines. This paper deals with the analysis and preliminary design of the VFRM from the perspective of multiple working airgap field harmonics. Firstly, the spatial and temporal order of the working field harmonics are defined. The systematic winding theory, including the unified star of slots and winding factor calculation method, is established to consider all these working harmonics. Then, an average torque model is built and simplified. The key role of 1st-order rotor permeance, 1st- and 3rd-order polarized stator permeance is deduced. The relationship between key parameters and average torque is computed, providing a guideline for the preliminary design of the VFRM. Full article

In recent years, there has been increasing interest in integrating the smart grid concept into railway networks, which has been driven by the need to enhance energy efficiency and reduce air pollution in such energy-intensive systems. Consequently, experts have actively sought innovative solutions with which to tackle these challenges. One promising strategy involves integrating renewable energy sources (RESs), energy storage systems (ESSs), and electric vehicle charging stations (EVCSs) into current electric railway systems (ERSs). This study begins by examining the concept of implementing smart grids in railway systems through bibliometric analysis. It then delves into the realization of a hybrid railway microgrid (H-RMG) designed to enhance power flow capacities, improve energy efficiency, and address power quality issues in traditional AC railway networks. This paper introduces various future AC–DC-coupled hybrid railway microgrid (ADH-RMG) architectures centered around a shared DC bus acting as a DC hub for upgrading conventional AC railway systems utilizing interfacing static converters. Through an exploration of different possible ADH-RMG configurations, this research aims to offer valuable insights and a roadmap for the modernization and reconstruction of existing railway networks using smart grid technologies. The integration of RESs and EV charging infrastructures within the ADH-RMG concept presents a promising pathway toward establishing more sustainable and environmentally friendly railway systems. Full article

Due to the regular influence of human activities, traffic flow data usually exhibit significant periodicity, which provides a foundation for further research on traffic flow data. However, the temporal dependencies in traffic flow data are often obscured by entangled temporal regularities, making it challenging for general models to capture the intrinsic functional relationships within the data accurately. In recent years, a plethora of methods based on statistics, machine learning, and deep learning have been proposed to tackle these problems of traffic flow forecasting. In this paper, the Transformer is improved from two aspects: (1) an Efficient Attention mechanism is proposed, which reduces the time and memory complexity of the Scaled Dot Product Attention; (2) a Generative Decoding mechanism instead of a Dynamic Decoding operation, which accelerates the inference speed of the model. The model is named EGFormer in this paper. Through a lot of experiments and comparative analysis, the authors found that the EGFormer has better ability in the traffic flow forecasting task. The new model has higher prediction accuracy and shorter running time compared with the traditional model. Full article

This study investigates the CO₂ reduction potential of powertrain hybridisation on heavy-duty lorries and city buses. The analysis considers modern parallel and serial hybrid architectures, assessing their efficiency and limits in CO₂ emission reduction through vehicle simulation in VECTO, which is the official tool of the European Commission for calculating heavy-duty vehicle fuel and energy consumption. The results reveal distinct trends for each vehicle type and architecture. In lorries, more significant improvements are observed in urban delivery profiles, reaching up to ~16%, indicating the benefits of hybridisation in transient conditions with energy recuperation opportunities. City buses, particularly those with serial architectures, exhibit significant emission reductions that reach 36%, making them suitable for urban environments. The optimisation of electric motor size and performance plays a crucial role in achieving emission reductions, while battery capacity must be carefully considered to avoid adverse effects. For lorries in urban delivery use, further improvements of 17.5% can be achieved by utilising a 160 kW engine motor and 30 kWh battery. Buses are already quite well optimised, with serial architecture presenting the highest benefits with a 120 kW electric motor and a battery of 11 kWh. Future research should focus on supercapacitors and gearboxes to improve efficiency at higher vehicle speeds and assess hybridisation potential in interurban coach travel. The heavy-duty vehicle sector can make significant strides towards low-carbon transport by maximising hybrid powertrain efficiency and emission reductions. Full article

The large majority of electric cars have a single-speed gearbox, because electrified powertrains provide maximal power across a wide operating range, and single-speed simplifies construction and reduces capital costs. Nevertheless, multi-speed transmissions have also been developed for electric cars, and some of them have recently appeared as commercial products. This paper aims to compare, through some practical examples, solutions with single-speed and dual-speed transmissions. In particular, given the very smooth driving of electric cars, for dual-speed solutions, a dual-clutch gearbox was considered. Finally, a continuously variable transmission (CVT) was also used. Different solutions were analyzed from a technical–economic point of view, based on a simulation of the vehicle under standardized driving cycles, thus evaluating the capital and running electricity costs. The obtained results show that the comparison between the two solutions is very open, and in the majority of cases, the advantages in terms of efficiency overcome the disadvantages due to the additional capital costs. For a rather low battery cost of 150 €/kWh, the total cost reduction moves from about 100–150 € up to 1500–2000 €, depending on the electricity cost, along the whole vehicle lifespan. Full article

International trade is continuously rising, leading to an increase in the flow of goods passing through transportation hubs, including air and sea. In addition, the aging fleet of inland vessels necessitates renewal through the construction of new vessels, presenting opportunities for the adoption of modern transport technologies. Autonomous barges can transport bulk and containerized cargo between the central port of a specific region and smaller satellite ports, enabling the dispersal of goods over a wider area. Equipping autonomous barges with advanced sensors, such as LIDAR, computer vision systems that operate in visible light and thermal infrared, and incorporating advanced path finding and cooperation algorithms may enable them to operate autonomously, subject only to remote supervision. The purpose of this study is to explore the potential of autonomous electric propulsion barges in inland waterway transport. Given the increasing demand for efficient and sustainable transport solutions as a result of various new policies, which have set new ambitious goals in clean transportation, this study aims to develop a proposition of an electric propulsion hybrid drive inland waterway barge, and compare it to a conventional diesel-powered barge. The methodology involves the creation of a simulation model of an inland waterway class IV electric barge, equipped with advanced sensors and autonomous control systems. The barge’s navigation is managed through a multi-agent system, with evolutionary algorithms determining a safe passage route. This research also utilizes a proprietary networked ship traffic simulator, based on real inland vessel recorded routes, to conduct the autonomous navigation study. The energy consumption of the barge on a route resulting from the ship traffic simulation is then examined using the mathematical model using the OpenModelica package. As a result of the study, the proposed hybrid propulsion system achieved a 16% reduction in fuel consumption and CO₂ emissions, while cutting engine operation time by more than 71%. The findings could provide valuable insights into the feasibility and efficiency of autonomous electric propulsion barges, potentially helping future developments in inland waterway transport. Full article

As the electrification process of aircrafts continues to advance, the propulsion motor system, as its core component, has received more attention and research. This paper summarizes and analyzes the development status, research focus and typical cases in this field in recent years. Firstly, it analyzes the basic structure and principle of five common motors, summarizes the current status of their respective applications in electric aircrafts, and compares them to determine the most suitable type of motor for use as a propulsion motor, focusing on various performance indexes. Then, the optimized design of propulsion motors is generally divided into two categories, namely high power density and fault tolerance. Starting from the basic relationship equation of motor design, the basic method to improve the power density of motors is pointed out; at the same time, according to the basic principles and objectives of the fault tolerance of motors, the fault tolerance design is divided into two aspects, namely the redundant design and the design to improve the fault tolerance capability. Finally, this paper summarizes the current development status of the propulsion motor system and the existing problems and points out the main development direction of this field in the future, so as to provide reference for the further development of the electric propulsion system of aircraft. Full article

Automotive drive cycles have existed since the 1960s. They started as requirements as being solely used for emissions testing. During the past decade, they became popular with scientists and researchers in the testing of electrochemical vehicles and power devices. They help simulate realistic driving scenarios anywhere from system to component-level design. This paper aims to discuss the complete history of these drive cycles and their validity when used in an electrochemical propulsion scenario, namely with the use of proton exchange membrane fuel cells (PEMFC) and lithium-ion batteries. The differences between two categories of drive cycles, modal and transient, were compared; and further discussion was provided on why electrochemical vehicles need to be designed and engineered with transient drive cycles instead of modal. Road-going passenger vehicles are the main focus of this piece. Similarities and differences between aviation and marine drive cycles are briefly mentioned and compared and contrasted with road cycles. The construction of drive cycles and how they can be transformed into a ‘power cycle’ for electrochemical device sizing purposes for electrochemical vehicles are outlined; in addition, how one can use power cycles to size electrochemical vehicles of various vehicle architectures are suggested, with detailed explanations and comparisons of these architectures. A concern with using conventional drive cycles for electrochemical vehicles is that these types of vehicles behave differently compared to combustion-powered vehicles, due to the use of electrical motors rather than internal combustion engines, causing different vehicle behaviours and dynamics. The challenges, concerns, and validity of utilising ‘general use’ drive cycles for electrochemical purposes are discussed and critiqued. Full article

Mobile robots can perform tasks on the move, including exploring terrain, discovering landmark features, or moving a load from one place to another. This group of robots is characterized by a certain level of intelligence, allowing the making of decisions and responding to stimuli received from the environment. As part of Industry 5.0, such mobile robots and humans are expected to co-exist and work together in a shared environment to make human work less tiring, quicker, and safer. This can only be realized when clean, dense, and economical energy sources are available. The aim of the study is to analyze the state of the art and to identify the most important directions for future developments in energy sources of robotic power systems based mainly on batteries. The efficiency and performance of the battery depends on the design using different materials. Work environments and performance requirements are considered in this systematic review to classify solutions that help developers choose the best-suited power system for specific application. Indirectly, the aim of the work is to generate discussion within the scientific and engineering community. A narrative review of publications from six major bibliographic databases according to preset inclusion criteria is combined with a critical analysis of current and future technologies. The main findings of the review allow answering the question of what is the role of modern power source technologies, artificial intelligence, and ground-breaking research work in global policies related to energy saving, green policies, and sustainable development. The main opportunities and threats are discussed, and a brief feasibility analysis is carried out. The novelty of the article relates not only to the analysis of technologies, but also to approaches and their use under conditions of limited resource availability, when resource usage must be minimized. The article provides an overview of batteries, their specifications, classifications, and their advantages and disadvantages. In addition, we propose (1) an algorithm for selecting the main energy source for robot application, and (2) an algorithm for selecting an electrical system power supply. Current mobile robot batteries are, in most cases, the robot’s biggest limitation. Progress in battery development is currently too slow to catch up with the demand for robot autonomy and range requirements, limiting the development of mobile robots. Further intensive research and implementation work is needed to avoid years of delay in this area. Full article

The following research focuses on the analytical and numerical study of an arcjet constrictor. In order to perform these analyses, a geometric design of the constrictor was proposed. The analytical study considers mathematical models proposed by Stine and Watson, related to the properties of air propellants, such as the specific enthalpy, electric conductivity, thermal conductivity, and specific heat. The numerical study considered the equations for mass, momentum, energy, and electricity that describe the interaction between the electric arc and the fluid flow. These equations were solved in ANSYS FLUENT software, in which the $\kappa$-$ϵ$ turbulence and the magnetohydrodynamic (MHD) models were used. The external routines, including user-defined functions, user-defined scalars, and user-defined memory were implemented in C++ language for source terms and linked to ANSYS FLUENT. The velocity profiles were obtained analytically for the electric arc temperatures of 9000 K, 10,000 K, and 11,000 K with peak magnitudes of 2960 m/s, 3350 m/s, and 3100 m/s, respectively, at the outlet of the constrictor. It was observed from the numerical results that the velocity magnitude of the air-based plasma inside the constrictor increases as the temperature of the electric arc rises up to 10,000 K However, above 10,000 K, the velocity magnitude decreases because at this temperature level, the air particles become completely ionized, and the specific heat of the air-based plasma decreases. The numerical simulation produced velocity profile magnitudes at two different electric arc temperatures (9000 K and 10,000 K) with peak magnitudes of 2400 m/s and 2900 m/s, respectively, at the outlet of the constrictor. The numerical and analytical results were very close with an error of 16.327%. Full article

This paper proposes an economic adaptive cruise controller (EACC) that considers battery aging characteristics based on adaptive model predictive control (AMPC). By establishing a battery capacity decay model based on experimental data, the capacity loss during vehicle operation is determined, and the parameters in the equivalent circuit model are updated according to the actual capacity of the battery. The controller uses indicators that characterize driving safety, tracking performance, comfort, and economy. The economic indicator is the decrease in the value of the battery capacity. Fuzzy weight allocation is designed based on the host vehicle’s speed and the workshop’s relative distance to adjust the weight between different indicators under different working conditions. Additionally, the proposed controller is compared with other traditional controllers under different working conditions, cycle times, and battery state of health (SOH). The simulation results indicate that, under various battery SOH conditions, the performance of the controller which considers battery capacity degradation characteristics is better than that of traditional controllers. Moreover, the fixed-weight controller performs better when following a vehicle at medium and low speeds. Finally, the proposed strategy was validated through hardware-in-the-loop testing, demonstrating its ability to meet the real-time requirements of the system. Full article