Low-speed Mode Research Articles

Electric vehicle charger energy management by considering several sources and equalizing battery charging

This article proposes a novel energy management structure for electric vehicles, consisting of a supercapacitor and two types of batteries, to improve efficiency and navigable distance. The key features of a suitable energy storage system include high power and energy density, low cost and weight, minimal maintenance, and long life. Although batteries are the primary power storage source in electric vehicles, they have power limitations. Therefore, a high-power-density supercapacitor is added to the battery to create a hybrid energy storage system, reducing stress on the battery and increasing its lifespan. The article presents a new structure for hybrid storage systems based on the existence of a main battery, a replaceable battery, a supercapacitor, and a DC-DC converter. An active charge equalizer circuit for the main battery in standby mode and its control system are also introduced. A control method for dividing power between different sources under different conditions is presented, and the design parameters of the energy storage system are optimized using a genetic algorithm to minimize mass and losses. The performance of the proposed system is evaluated through simulation in MATLAB software and tested in a small-scale laboratory sample. The article also provides a detailed analysis of different working modes, including electric motor acceleration, low-speed mode, high-speed mode, and electric regenerative braking mode. Additionally, a control method for energy management between batteries and supercapacitors is introduced, aiming to increase efficiency. The results show that the proposed hybrid energy storage system can effectively improve the efficiency of electric vehicles.

Aggressive flight control of quadrotors using incremental nonlinear dynamic inversion with a high-fidelity thrust unit model

The application of quadrotors has been expanded into aggressive tasks such as military confrontation and aerobatics shows, making it crucial to enhance flight maneuverability to adapt to rapid and large-scale command changes. Unlike hovering or low-speed modes, aggressive flight exacerbates quadrotor model uncertainty, making it challenging for controllers to balance response speed and robustness. This paper proposes an INDI control method that integrates a high-fidelity thrust model unit to address this practical need. First, based on the pole distribution theory and the application of INDI on quadrotors, it is concluded that the dynamic response of quadrotor flight is impacted by the accuracy of the thrust model. Second, consider the airflow velocity and angles, the high-fidelity modeling approach, and the aerodynamic forces and torque expression validated through wind tunnel experiments are provided. Then the flight controller for the quadrotor is designed with the established high-fidelity thrust unit model. Finally, aggressive trajectory-tracking flight tests are set to evaluate the improvement of our work. The results demonstrate that our proposed method indeed enhances the response speed and tracking accuracy, as well as the flight stability of the quadrotor.

Thermal Analysis and Test of Axial Flux Permanent Magnet Synchronous Motor Performances

The axial flux permanent-magnet synchronous motor with amorphous alloy stators has the advantages of high power density, high efficiency, large starting torque. But the PMSM has poor performance in heat resistant and radiation. And the electromagnetic loss has a significant impact on in-wheel motor’s heat generation. To demonstrate the influence of electromagnetic loss on winding coils of the PMSM, the mathematical model of the thermal transformation was founded to illustrate the progress of temperature rising. The mathematical model and experimental test were verified mutually. The experimental prototype was manufactured and tested, including the output power model and braking energy recovery model. And the experimental prototype performed working in low rotation speed mode and middle rotation speed mode separately, when the revolving speed increased by 50% the thermal of winding raise approximately 23.5%. Further, the analytic formulas and experimental results consistent with each other approximately, in which the mathematical analysis method was verified by test value.

TRACTION MOTOR FOR FRONT LOADER CHASSIS

The purpose of the work is the import substitution of traction electric drives as part of the project to create in the Chuvash Republic a serial production of a family of front loaders with a hybrid electric drive.
 
 For most transport electric motors, operation in the high-torque electric motor mode is not the main operating mode, since the vehicle acceleration is carried out in a short time with overcoming low-efficiency low-speed modes. A distinctive feature of the traction motor for the chassis of a front loader is the rearrangement of priorities in favor of operating technological modes.
 
 The analytical results of the stage of the preliminary design of the traction electric motor of each wheel for a front loader with a hybrid electric transmission are presented. Based on the results of calculations, it was found that for the given traction-dynamic, temperature and overall characteristics, the most efficient type of engine is NdFeB magnet motor, the phase ratio is 6, the magnetic system is radial with magnetic supports, the non-magnetic gap is 3 mm, the shroud is based on a carbon filament, cooling is forced liquid, the highest efficiency of 92% falls on the cycle of heavy operating modes of the front loader. The cost of manufacturing a motor with an axial magnetic system is higher compared to cylindrical type motors provided the electromagnetic power is equal.
 
 The choice of a magnetic system based on the ratio of magnetic fluxes of different combinations of rotor poles and stator teeth is substantiated. The materials of the article illustrate diagrams of magnetic fields and temperature distribution of the traction motor, calculated at the stage of preliminary design by the finite element method, as well as a dimensional drawing of a sketch of an electric motor for given performance characteristics, transferred to the stage of technical design.

Development of the technical solution to prevent a single-rotor helicopter from entering uncontrolled rotation

The phenomenon of a single-rotor helicopter entering an unintended left rotation with the further development of an uncontrolled turn periodically arises while operating this type of helicopter, both in Russia and abroad. This phenomenon can lead to serious aviation incidents and even disasters. Currently, there is no unambiguous justification for the phenomenon of "uncontrolled" U-turn and the causes of occurrence, since the operating conditions of the tail rotor (TR), especially at low-speed modes, depend on many factors. These factors include, firstly, wind direction and speed, T/R “vortex ring", as well as the impact of the main rotor vortex trace. One of the explanations for this phenomenon lies in the special specifics of the yaw trim of a singlerotor helicopter, which is provided by the tail rotor. These papers emphasize that the change in wind speed and direction which affects the helicopter, and the TR is the main cause of the unintentional left turn. Currently, there are no tools and methods for determining the wind effect on the TR in order to develop a warning signal for a pilot about a change in the nature of the TR flow and an alert about the occurrence of uncontrolled rotation. This paper proposes the system for measuring the TR air flow using a special sensor that allows us to measure the inductive air flow velocity of a small value in an aerodynamic way without additional various electronic transformations that are inherent in conventional Pitot tube probes. The use of such a measurement system makes it possible to identify the probability of a dangerous situation, to inform the pilot and help him take the proper actions.

Форсирование четырехтактного двигателя путем перевода на работу по двухтактному циклу в режимах с низкими частотами вращения

Improving the dynamic qualities of internal combustion engines and the throttle response of vehicles equipped with them is an urgent problem in engine building. To solve it, we suggest switching a four-stroke engine to a two-stroke cycle at low-speed modes. Within the study, we found that the worst indicators of fuel efficiency of two-stroke engines are partially compensated by the best indicators of their power density. We took a close look at the switching of the 2 / 4SIGHT gasoline engine of the British company Ricardo from a four-stroke cycle to a two-stroke cycle. To implement the switching, we used a two-stage intercooled supercharging and a gas distribution valve switching system. The method proved to be applicable to diesel engines as well. Hence, we studied a diesel engine D-245 (4 CHN 11.0 / 12.5) mounted on a tracked vehicle. At a speed of 1600… 2400 min – 1, such a diesel engine operates in a four-stroke cycle, at lower speeds it operates in a two-stroke cycle. Finally, we did computational studies of the working process of this diesel engine. The study showed the expediency of switching the engine to a two-stroke cycle at low-speed modes.

Research on vehicle adaptive cruise control based on BP neural network working condition recognition

To solve the problems of the vehicle following model mismatch under different driving conditions and poor vehicle following performance, this paper proposes an adaptive cruise control system based on BP neural network to identify different driving conditions. Firstly, eight typical driving cycles are selected as samples, which are redivided into low-speed mode and medium high-speed mode. According to the selected characteristic parameters and re-division of driving mode, a new BP neural network structure is designed. Secondly, the characteristic parameter values are calculated by using the characteristic parameters, and the characteristic parameters are normalized. The working condition recognition model is obtained by training the normalized data values. Finally, according to the classification of working conditions, the fuzzy control upper control algorithm and the MPC upper control algorithm for medium-high speed conditions are designed respectively. Based on the above control algorithms, the joint simulation is carried out with Car-Sim and MATLAB/Simulink. The simulation results show that the low-speed fuzzy logic algorithm and the medium high-speed MPC algorithm proposed in this paper can make the vehicle have a better following performance and comfort.

Optical pulses generation of single-cycle and dual-UWB using square and Gaussian electric pulses

- In this paper, a method for generating transverse band (UWB) pulses, the basis of which is a large-scale interferometer with a resonator of small silicone rings capable of changing paired configuration, is reported. Single-cycle, dual-bandwidth signals are generated at the time of the Picosecond pulse, and the small ring amplifier is modulated with square and Gaussian electric pulses, respectively. Microwave photonic systems that work with large optical components suffer from large size, high energy consumption, high cost, and vulnerability to environmental disturbances. Therefore, it is highly desirable to assemble the microwave photonic system on a single chip to make it more compact, cheap, and low-consumption. They have a low spectrum. One of its applications is in short-range wireless telecommunications and high power for wireless transmission of large multimedia data. It can also be used in low speed and power mode for IoT applications such as precision internal positioning. Unlike the WiFi or Bluetooth distance estimation, which is based on signal intensity, the bandwidth signal has a very narrow pulse width, similar to the radar pulse, which enables it to estimate the position using pulse forward time and 10 cm accuracy. With an intensified modulator based on silicon photonics, one can very hopefully generate an adjustable microwave signal on the chip.

Study on Evaluation of Urban and Rural High-quality Living Space Based on Accessibility Analysis——Taking Shahe City, Hebei Province as an example

The change of planning thought from “taking things as the center” to “taking people as the center” requires that the allocation mode of supporting public service facilities in urban and rural residential areas should also change from simple service radius to accessibility analysis. In this study, Dijkstra algorithm is used to analyze the spatial network with the help of the spatial data of urban transportation network and six types of public service facilities. Based on the concept of equalization of urban and rural public service facilities, this paper constructs an evaluation index system of high-quality living space of urban and rural residents based on accessibility, determines the weight by calculating the information entropy of each index, and compares and analyzes the accessibility evaluation results on the scale of urban and rural residential areas. Try to construct the full coverage and partial coverage of the 15-minute living circle of various facilities under four modes of driving at higher or lower speeds and walking for adults or the elderly. The research results show that the hardware construction of the city’s transportation network system and public service facilities is efficient and convenient, with high accessibility and accessibility, showing the characteristics of urban-rural equivalence. However, under the low speed and walking mode, there is still room for layout optimization and improvement of some road systems and facilities.

A low power reconfigurable ADC for bioimpedance monitroing system

This article introduces a re-configurable pipeline analog-to-digital converter (ADC) deliberated for implantable surveillance devices for bio-impedance monitoring systems. To improve the efficiency of the bio-impedance method, an automatic adaptation circuit is introduced. This adaptive unit is responsible for setting the resolution and sampling rate on the basis of amplitude and frequency of the signal. Using a new, low-power automatic adaptation circuit low power consumption is achieved by using Dynamic Threshold metal oxide semiconductor (DTMOS) technique, it can automatically determine its setup. The converter has two modes of operations. In high-resolution mode, the converter has a 12-bit resolution and at low resolution mode, 8-bit resolution is used. The ADC bandwidth of low-speed mode is 100 kHz and high-speed mode is 1 GHz. The architecture is designed using 180 nm technology and simulated using Cadence virtuoso tool. The results achieved, low power consumption i.e. 0.844 mw, and it is operated with 1 V power supply. For signal to noise and distortion ratio (SNDR), effective number of bits (ENOB), the converter utilizes 71.06 dB, 11.45 in 12-bit and 72.3 dB, 7.41 in 8-bit mode respectively. By using proposed method around 20% of power consumption is reduced and 40% power supply is decreased. The proposed design is also used for mixed signal circuit testing.

Numerical study of the dependence of the wave velocity of filtration gas combustion on the process parameters

When solving problems in the field of filtration combustion of gases, numerical methods are often used to analyze the wave structure depending on changes in the hydrogen content in the mixture and other physical and chemical parameters. This work analyzes the stationary structure of the wave of filtration combustion of incompressible gas in the low-speed mode when the parameters of the gas flow and the porous medium change, as well as when the hydrogen content in the mixture changes. The problem is solved by the numerical Runge-Kutta method of the fourth order of accuracy, tested on a system of differential equations. Reduced to a dimensionless form, the system of equations is written in vector format. Programming is performed in Delphi 7. The results presented show agreement with the known experimental data and also allow us to obtain new conclusions about the structure of the filtration combustion wave of gases.

Low-Speed Stability Optimization of Full-Order Observer for Induction Motor

In terms of the instability of the full-order observer for the induction motor in the low-speed regenerative mode, the low-speed unstable region which leads to the extension of the commissioning cycle cannot be eliminated by the traditional adaptive law which aims at good system performance. It is proposed that the feedback gain matrix can control both the unstable region and the system performance both. To make a trade-off between the stability and performance by designing the feedback gain matrix is still an open problem. To solve this problem, first we analyze the cause of instability and derive constraints to ensure system stability by establishing a transfer function of the adaptive observing system for the speed. Then, with the derived constraints as the design criteria for the feedback gain matrix, a control strategy combining the weighted adaptive law with the improved feedback gain matrix is proposed to improve the stability at low speed. Finally, by comparing the traditional control strategy with the proposed control strategy through simulations and experiments, we show that the proposed control strategy achieves better performance with higher stability.

Sound level study of a hybrid car

One of the main reasons for the urban noise are the cars. When the hybrid cars are moved in low-speed mode, reduced noise is supposed. In the presented paper have been made comparative analysis according to standard methods of the external and internal sound levels of a hybrid car. The experiment at different speeds in two modes – using ICE and using electric traction were carried out. The results of the measurements are visualized in graphs and tables. They show variation of external and internal sound levels at different speeds in separate octave bands. Spectral analysis at each speed is done. The results show changing of sound level vs speed and noise predominant maximums at respective frequencies.

Hardware simulation of lane keeping assist based on sensor fusion

PurposeSafety is one of the most crucial factors in transportation due to so many factors, including human-error, that might result in various small to fatal accidents. This is why lane keeping assist (LKA) is an important system that needs to be developed. LKA will prevent the vehicle from moving to another lane because the driver is negligent to maintain the direction of the vehicle.Design/methodology/approachIn this study, LKA works using camera and ultrasonic sensors. The data coming from these two types of sensors are then fused to determine how should the car reacts to some certain situation so that it stays on the lane. The sensor fusion method was used to further ensure the car's safety.FindingsThe results of the hardware simulation show that LKA can successfully avoid the car from getting off the lane with safety index of 95% for high-speed mode and 100% for medium and low-speed mode; meanwhile on the use of ultrasonic sensor, the speed of the car is adjusted to the distance of the car's side disturbance.Originality/valueThis research has succeeded in simulating a sensor fusion–based LKA system.

Micromobility evolution and expansion: Understanding how docked and dockless bikesharing models complement and compete – A case study of San Francisco

Shared micromobility – the shared use of bicycles, scooters, or other low-speed modes – is an innovative transportation strategy growing across the United States that includes various service models such as docked, dockless, and e-bike service models. This research focuses on understanding how docked bikesharing and dockless e-bikesharing models complement and compete with respect to user travel behaviors. To inform our analysis, we used two datasets from February 2018 of Ford GoBike (docked) and JUMP (dockless electric) bikesharing trips in San Francisco. We employed three methodological approaches: 1) travel behavior analysis, 2) discrete choice analysis with a destination choice model, and 3) geospatial suitability analysis based on the Spatial Temporal Economic Physiological Social (STEPS) to Transportation Equity framework. We found that dockless e-bikesharing trips were longer in distance and duration than docked trips. The average JUMP trip was about a third longer in distance and about twice as long in duration than the average GoBike trip. JUMP users were far less sensitive to estimated total elevation gain than were GoBike users, making trips with total elevation gain about three times larger than those of GoBike users, on average. The JUMP system achieved greater usage rates than GoBike, with 0.8 more daily trips per bike and 2.3 more miles traveled on each bike per day, on average. The destination choice model results suggest that JUMP users traveled to lower-density destinations, and GoBike users were largely traveling to dense employment areas. Bike rack density was a significant positive factor for JUMP users. The location of GoBike docking stations may attract users and/or be well-placed to the destination preferences of users. The STEPS-based bikeability analysis revealed opportunities for the expansion of both bikesharing systems in areas of the city where high-job density and bike facility availability converge with older resident populations.

Design and analysis of a novel variable flux spoke-type motor for washing machines

This paper deals with the design and analysis of a novel variable flux spoke-type motor (VFSM) for washing machines by focally considering the performance at the laundry and spin-drying operating modes. The key design goal is to obtain the high efficiency for the two operating modes. At the laundry mode, the ferrite and AlNiCo magnets are utilized together as the excitations to obtain a high magnetic loading, thus to obtain high torque and efficiency. At the spin-drying mode, the AlNiCo magnets are demagnetized by a pulse negative d-axis current to reduce magnetic flux density, thus to obtain low iron loss and high efficiency. The outer rotor structure with the spoke-type magnet configuration is utilized to enhance the high output performances. The D2L method is utilized to design the key parameters of the VFSM. To demonstrate the superiority of the designed VFSM, the electromagnetic characteristics are predicted by the finite element method (FEM). As a result, the volume size of the proposed VFSM is decreased by 19.4%, and the efficiency at the low-speed laundry mode is increased by 25.4%, when compared to the referenced commercial washing machine motor.

Спосіб приготування та добір компонентного складу спінених вибухових композицій для ущільнення просадних ґрунтів

A device for the preparation of a water-filled foamed explosive composition is proposed, which can be used in field conditions for compacting subsidence of unstable soils. Foamed water-filled explosive composition consists of ammonium nitrate, surfactants and water. The method of preparation of foamed explosive composition, which consists in mixing surfactants with water and then with ammonium nitrate mechanically in a low-speed mode without foaming the mixture, applying this suspension under pressure to the object of blasting and metered aeration by ejection mixtures with instantaneous delivery of the foamed explosive composition to the application site. The selection of the component composition of low-density water-filled foamed explosive compositions is proposed, and their physical, technical and dynamic characteristics are given. Dynamic and physico-technical characteristics of low-density foamed explosive compositions were investigated and it was found that the minimum detonation velocity of these explosives in open charges and in charges in the hard shell is less than the minimum detonation velocity of standard ammonite № 6ZHV; the brisance of foamed explosive compositions does not exceed (10–11)*10-3m, which is almost twice less than that of igdanite and three times that of ammonite № 6ZHV; slightly higher pulse pressure rise time to maximum in foamed blast compositions compared to igdanitor; the pressure at the wavefront of foamed explosive compositions is 6–7 times lower than that of ammonite № 6ZHV, respectively, and the velocity of pressure pulse growth is much lower. Such parameters of the pulsesive explosiv of the explosives make it possible to use foamed explosive compositions for uniform compaction of subsidence loess soils at the required power and in the mine clearance of fields.

Evolution of subsonic and supersonic corner vortices in a supersonic cascade

Numerical investigations on a supersonic cascade are conducted at the flow-through, high-backpressure, and low-speed modes to obtain a deeper understanding of the generation, development, and transformation of the subsonic and supersonic corner vortices. The geometry considered is the SAV21 supersonic cascade designed by the German Aerospace Centre operating under incoming Mach number of 2.4 and flow turning angle equal to 45 degrees. The corner vortex is generated by the impinging and glancing of shock waves on the boundary layer and drives the low-kinetic energy fluid moving spanwise. The cross-flow topology of the supersonic corner vortex follows Zhang's theory that considers flow with high Reynolds number and excludes the incorrect solutions generated by the expression of the velocity gradient along the vortex axis. The Hopf bifurcation position of the subsonic corner vortex can be accurately predicted by describing the velocity gradient along the vortex axis, while deviation occurs when using Zhang's theory. By observing the development process of corner vortices, the reason for the limitations in the range of application of Zhang's theory is analyzed. In general, the key factors for the evolution of the subsonic and supersonic corner vortices are the velocity gradient and pressure gradient along the vortex axis, respectively. The bifurcation processes of the corner vortex can be classified into four types. And the bifurcation principle can be summarized, the appearance of limit cycle does not immediately change the rotating direction of the vortex and the bifurcation process is gradual.

Ignition characteristics in a thin strut-equipped dual mode combustor fueled with liquid kerosene

Ignition characteristics in a strut-equipped dual mode combustor fueled with liquid kerosene were observed and discussed in this paper. A series of experiments and numerical simulations were carried out in the combustor both at the high-speed mode (Ma = 2.8) and at the low-speed mode (Ma = 2.0). Combustion establishment process and flame characteristics were captured and analyzed with the method of high-speed photography. Results indicated that two flammable regions, namely the recirculation region and the shear layer, generated in the combustor with the assistance of strut. Then, the optimization of ignitor parameters, including installation location of ignitor and ignitor power, had been conducted to achieve a stable flame successfully in these two flammable regions. During the flame establishment process, the ignition delay characteristics and the fluctuation energy of flame, adopted as the main parameters to estimate the ignition characteristics, were analyzed and discussed in different experimental conditions, which were mainly affected by operating Mach number, equivalence ratio of fuel, and mass flow of oxygen. The analysis results of these impacts on ignition process in this paper was beneficial to the optimization of ignition scheme in dual mode combustor for future investigations.

Smart Speed Imaging in Digital Image Correlation: Application to Seismotectonic Scale Modeling

Analogue models of earthquakes and seismic cycles are characterized by strong variations in strain rate: from slow interseismic loading to fast coseismic release of elastic energy. Deformation rates vary accordingly from micrometer per second (e.g. plate tectonic motion) to meter per second (e.g. rupture propagation). Deformation values are very small over one seismic cycle, in the order of a few tens of micrometer, because of the scaled nature of such models. This cross-scale behaviour poses a major challenge to effectively monitor the experiments by means of digital image correlation techniques, i.e. at high resolution ($>$100 Hz) during the coseismic period but without dramatically oversampling the interseismic period. We developed a smart speed imaging tool which allows on-the-fly scaling of imaging frequency with strain rate, based on an external trigger signal and a buffer. The external trigger signal comes from a force sensor that independently detects stress drops associated with analogue earthquakes which triggers storage of a short high frequency image sequence from the buffer. After the event has passed, the system returns to a low speed mode in which image data is downsampled until the next event trigger. Here we introduce the concept of smart speed imaging and document the necessary hard- and software. We test the algorithms in generic and real applications. A new analogue earthquake setup based on a modification of the Schulze ring-shear tester is used to verify the technique and discuss alternative trigger systems.