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Based on the newly designed planetary gear gearbox with reciprocating linear motion of its output shaft, research on its dynamic characteristics was conducted. The "kinematic mechanism method" was used to calculate the system's transmission ratio, revealing its characteristic of having a relatively large transmission ratio. Combined with the calculation of transmission efficiency, the characteristic of high transmission efficiency was verified. The "velocity vector method" was used to calculate the relationship between the angular velocities of various components of the gearbox. By conducting a stress analysis on the planetary gear transmission system, the forces and torques acting on each component, as well as the meshing forces of the gears were calculated. The "central parameter method" was adopted to simulate the meshing contact between the gears in the planetary gear transmission system as undamped springs. Considering the two translational vibrations along the radial direction and the rotational twisting along the circumferential direction of each component, a translational-torsional coupled dynamic theoretical model of the system was constructed. Dynamic differential equations of the planetary gear transmission system were derived and solved to obtain the support forces and torques of each component at the bearing support positions, enhancing the research on the dynamic characteristics of the planetary gear transmission system. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The expert assessment method underlies most decision-making methods in the technical field of activity, from the search for rational design solutions to issues of industrial safety of hazardous production facilities, which is embodied in the form of regulatory documents governing the implementation of a risk-oriented approach to problem solving in the specified areas. The subjectivity of the expert assessment method can often lead to decisions that are objectively not rational in a specific design situation. This article considers a modification of the superstructure of the criteria weight assessment level of the hierarchy analysis method based on statistical processing of a set of possible combinations of criteria priorities using the example of choosing a rational option for a belt conveyor drive system, which is a direct replacement for the expert assessment method and paired comparisons at this hierarchy level. It is shown that when taking into account the proposed modification and paired comparison at the first level of the hierarchy of clearly defined values of options within each criterion (characteristics of technical objects), the method of paired comparisons is excluded from the structure of the methodological apparatus of the hierarchy analysis method, which makes it possible to single out the obtained set of results into a separate decision-making method.

The traditional mechanical wheel has high carbon emission, complex drive system structure, serious power reduction in high altitude and low temperature environment, and high operating cost. Aiming at the driving system of a 100t mechanical transmission dump truck, the composition and characteristics of the driving system are studied. A scheme of drive system and control system including main traction transmission and auxiliary system was proposed. The main traction system used 793 kWh power battery as the power source, to drive a 680 kW main traction motor combining with DTC algorithm. The two inverter modules, DC/DC module and battery cooling unit of the auxiliary system respectively drove the hydraulic pump motor steering and lifting, provided power for the vehicle air conditioning and cooling fan, and provided heat dissipation power for the battery. Mine loading test such as braking and traction conversion, heavy-load uphill starting, heavy-load uphill driving, and heavy-load downhill electric braking, etc. were carried out under full load condition at an altitude of 5500 m and-30 °C. The operation performance was reliable and stable, the operating cost was reduced by 93%, the total running time was 4230 h, and the total running mileage was 4238 km. The structure of the driving system is simple, recovery of braking energy improves the energy efficiency of the system, reduces carbon emissions and promotes the development of green mines. [ABSTRACT FROM AUTHOR]

The issue of power supply to electric rail vehicles leads to a separation of the rail network into electrified and unelectrified portions, where the sections lacking electrification exclude the operation of electric rail vehicles powered from the overhead lines. The potential solution to this problem was found in adding energy storage systems to electric rail vehicles to allow them some range of travel beyond the electrified lines. A simulation analysis of a special-purpose rail vehicle traveling across a non-electrified section of a railway line was conducted to assess the energy consumption rate and the necessary energy storage capacity. Three energy storage solutions were simulated, showing the travel range they can provide, with the aim of finding the lowest battery capacity solution that would still allow the vehicle to safely complete the simulated drive. The final selection of energy storage system capacity was done based on the assumed expected range outside the electrified railway weighed against the mass and cost of the extra energy storage system added to the vehicle. For a vehicle with a mass of 65 tons, a battery system with a capacity of 600 Ah was found to be sufficient. [ABSTRACT FROM AUTHOR]

The creation of new and improvement of existing machines and mechanisms requires the development of drive engineering and the creation of new drive systems capable of competing with currently known circuit solutions. Under these conditions, the creation of combined pneumatic-mechanical drives is an important scientific and technical task. The purpose of this work is to increase the speed at a given accuracy of auxiliary movements of the target mechanisms of technological machines by creating a pneumatic-mechanical drive with improved energy and dynamic characteristics. The technical solution of a positioning pneumatic-mechanical drive of executive movements of technological equipment is presented, mathematical and computer models are developed. In this case, the method of solving the differential equation in the SimInTech program is used. As a result, an oscillogram of transients is obtained. The developed models allow for dynamic analysis of pneumatic-mechanical systems.

Abstract To address the low efficiency and high labor demands of manual Codonopsis pilosula cultivation, as well as the limitations of existing flat-type transplanting machines that create trenches of inconsistent depth hindering root growth and seedling emergence, a C. pilosula film-covered outcrop tilted transplanting machine was developed. Based on theoretical analysis of the prototype's key components and agronomic requirements for oblique C. pilosula transplanting, the structure and working parameters of the rotary tiller soil throwing device, soil lifting device, track-type soil conveying device, seedling throwing device, and film covering device were determined. The core components' working principles were analyzed, and the soil throwing process of the rotary tiller device was simulated using the discrete element method (DEM). A calculation domain was established, and the results showed that the average mass of the rotary tiller device was 49.44 kg, while the required soil lifting amount for the scraper-type soil lifting device was 21.84 kg, meeting the soil throwing requirements. Field experiments in 10 test areas demonstrated an average qualified rate of 89.50% for planting depth, 84.00% for planting posture, 90% for exposed plant spacing, 4.51 cm for plant spacing, and 8.67% coefficient of variation for planting spacing. These results meet industry standards for planting depth and planting spacing, confirming the machine's effectiveness in achieving high-quality tilted transplanting of C. pilosula seedlings.

The computer numerical control swivel head drive system has a number of states from ideal operation to complete failure, and dividing these states into success and failure is not rational and may even lead to fatal errors. Given this problem, this study proposed a method of building a multistate reliability evaluation model based on a Bayesian network (BN). First, BN was built in accordance with the mechanism of the drive system and in consideration of the interaction between different failure modes. Second, stable working data were used to determine the failure probabilities in the different life cycles of nodes. Last, a probability distribution table was employed to describe the multistate characteristics of nodes, and a BN model of the multistate system was built. The ranking of the importance of risks that may lead to drive system failure was determined using the posterior probability calculation method of BN. [ABSTRACT FROM AUTHOR]

Manual wheelchairs, which are the basic means of transport for people with disabilities, are usually characterized by an inefficient adaptation to the physical capabilities of their users. For this reason, it is advisable to search for solutions that will allow us to change the parameters of the mechanical power generated by human muscles. For this purpose, mechanical gearing known from other solutions, for example, from bicycles, can be used. The paper describes the design methodology and a number of issues related to the construction of an innovative wheelchair prototype using a chain transmission in its drive system. This solution allows for the implementation of a variable ratio between the wheels and the pushrims. Thus, it effectively allows for matching the demand for driving torque to the movement conditions and the physical capabilities of its user. The use of such a system provides the basis for increasing the efficiency of the manual propulsion process. Initial studies show that changing the gear ratio allows for different speeds of the wheelchair wheel. In the tests conducted, the root mean square of this value varied from 15.2 RPM to 35.5 RPM, which resulted in a change in power from 15.8 W to 40.1 W. Of course, the values of rotational speed and torque show a cyclically changing character, which results from the intermittent nature of generating drive by the wheelchair user. The average peak values of rotational speed were 31.4 ± 1.7 RPM, 44.3 ± 3.4 RPM and 57.9 ± 3.4 RPM, while the torque was 12.1 ± 0.5 Nm, 12.4 ± 0.4 Nm and 14.1 ± 0.6 Nm for Gears 1, 4 and 6, respectively. [ABSTRACT FROM AUTHOR]

To address the low efficiency and high labor demands of manual Codonopsis pilosula cultivation, as well as the limitations of existing flat-type transplanting machines that create trenches of inconsistent depth hindering root growth and seedling emergence, a C. pilosula film-covered outcrop tilted transplanting machine was developed. Based on theoretical analysis of the prototype's key components and agronomic requirements for oblique C. pilosula transplanting, the structure and working parameters of the rotary tiller soil throwing device, soil lifting device, track-type soil conveying device, seedling throwing device, and film covering device were determined. The core components' working principles were analyzed, and the soil throwing process of the rotary tiller device was simulated using the discrete element method (DEM). A calculation domain was established, and the results showed that the average mass of the rotary tiller device was 49.44 kg, while the required soil lifting amount for the scraper-type soil lifting device was 21.84 kg, meeting the soil throwing requirements. Field experiments in 10 test areas demonstrated an average qualified rate of 89.50% for planting depth, 84.00% for planting posture, 90% for exposed plant spacing, 4.51 cm for plant spacing, and 8.67% coefficient of variation for planting spacing. These results meet industry standards for planting depth and planting spacing, confirming the machine's effectiveness in achieving high-quality tilted transplanting of C. pilosula seedlings. [ABSTRACT FROM AUTHOR]

To bridge the gap in the research on the control and drive methods of the key equipment of the new subsea production control system, all-electric subsea gate valve actuator, and to solve the problems of the valve control and drive system in the traditional subsea production system, this paper proposed a full-featured and feasible electrical system of the all-electric subsea gate valve actuator containing the control system and the drive system. The key functions were realized, including status monitoring, redundant communication, redundant power supply, redundant drive, and low-power open-position holding. The electrical system is suitable for monitoring and controlling all-electric subsea gate valve actuators with various specifications and is highly integrated, open, efficient, and real-time. The electrical system prototype was developed and successfully tested for several functions. The results showed that the all-electric subsea gate valve actuator electrical system was capable of controlling and driving the actuator, monitoring the status information of the internal and external environment of the system, as well as the power output information of the drive system, and having redundancy features. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a software framework is presented through an application that is able to jointly optimize an electric motor and a gearbox for the design of a drive system for electric vehicles. The framework employs a global optimization method and uses both analytical and finite element method (FEM) models to evaluate the objective functions. The optimization process is supported by a statistical surrogate model, which allows a large reduction of runtime. An earlier version of this framework was only suitable for electric motor optimization. In the application presented in a previous paper, the motor of a belt-driven electric drive system was optimized. In this paper, the optimization of the same drive system is shown, but now with a combined optimization of a gear drive and motor. The objective functions of optimization are minimizing the total loss energy and the weight of the drive system. The optimization results are compared with previous results to demonstrate the further potential of joint optimization. [ABSTRACT FROM AUTHOR]

Monorail crane, as one of the important equipment forms of underground auxiliary transportation, has a generally low running speed (full load < 2 m/s), and the traditional single power drive is difficult to meet the power and environmental requirements of monorail crane. In order to improve the driving performance of monorail crane and achieve the goal of green mine, a new distributed hybrid power drive system is proposed based on the traditional monorail crane structure. Its control strategy is established based on the deterministic rules and its modeling and simulation tests are carried out. First of all, combined with the multi section of the monorail crane structure, different power sources are set at different drive ends, and a distributed architecture is adopted as the hybrid power architecture of the high-speed monorail crane. Different working modes under the architecture are formulated to determine the energy flow direction under different modes; Secondly, in order to improve the power performance of the monorail crane and the working range of the explosion-proof diesel engine, the working mode switching logic strategy and torque distribution strategy are formulated in the face of conventional working conditions. On this basis, the deterministic rule control strategy based on the logic threshold value is designed, and the overall switching logic simulation strategy is built using MATLAB; Then, according to the actual running situation of the high-speed monorail crane, three complete machine cycle conditions are established, namely, small slope heavy load, small slope light load and large slope light load; Finally, the control strategy is imported into AMESim simulation software, and the physical model of the high-speed monorail crane distributed hybrid power system is jointly simulated. The simulation results show that the designed control strategy based on the deterministic rules can make the working points of the explosion-proof diesel engine and explosion-proof motor of the monorail crane in the high efficiency range, and make the whole machine have a good speed following performance; Under the condition of small slope and heavy load, the state of charge (SOC) consumption of the battery pack is only 17.6%, the maximum operating speed under full load reaches 3.01 m/s, and the emissions of CO, HC and NOx are reduced by 67.3%, 36.4%, 49.4% and 13.1% respectively compared with the emissions of traditional monorail cranes; Under the working condition of large slope and light load, the consumption of SOC value of the battery pack is only 13.1%, the maximum operating speed under full load reaches 2.29m/s, and the emissions of CO, HC and NOx are 70.2%, 58.1% and 41.7% lower than those of traditional monorail cranes respectively. The research results are of great significance and practical value to improve the running speed of monorail crane, enhance its transportation efficiency, and reduce exhaust emissions to improve the downhole working environment.

To bridge the gap in the research on the control and drive methods of the key equipment of the new subsea production control system, all-electric subsea gate valve actuator, and to solve the problems of the valve control and drive system in the traditional subsea production system, this paper proposed a full-featured and feasible electrical system of the all-electric subsea gate valve actuator containing the control system and the drive system. The key functions were realized, including status monitoring, redundant communication, redundant power supply, redundant drive, and low-power open-position holding. The electrical system is suitable for monitoring and controlling all-electric subsea gate valve actuators with various specifications and is highly integrated, open, efficient, and real-time. The electrical system prototype was developed and successfully tested for several functions. The results showed that the all-electric subsea gate valve actuator electrical system was capable of controlling and driving the actuator, monitoring the status information of the internal and external environment of the system, as well as the power output information of the drive system, and having redundancy features.

Manual wheelchairs, which are the basic means of transport for people with disabilities, are usually characterized by an inefficient adaptation to the physical capabilities of their users. For this reason, it is advisable to search for solutions that will allow us to change the parameters of the mechanical power generated by human muscles. For this purpose, mechanical gearing known from other solutions, for example, from bicycles, can be used. The paper describes the design methodology and a number of issues related to the construction of an innovative wheelchair prototype using a chain transmission in its drive system. This solution allows for the implementation of a variable ratio between the wheels and the pushrims. Thus, it effectively allows for matching the demand for driving torque to the movement conditions and the physical capabilities of its user. The use of such a system provides the basis for increasing the efficiency of the manual propulsion process. Initial studies show that changing the gear ratio allows for different speeds of the wheelchair wheel. In the tests conducted, the root mean square of this value varied from 15.2 RPM to 35.5 RPM, which resulted in a change in power from 15.8 W to 40.1 W. Of course, the values of rotational speed and torque show a cyclically changing character, which results from the intermittent nature of generating drive by the wheelchair user. The average peak values of rotational speed were 31.4 ± 1.7 RPM, 44.3 ± 3.4 RPM and 57.9 ± 3.4 RPM, while the torque was 12.1 ± 0.5 Nm, 12.4 ± 0.4 Nm and 14.1 ± 0.6 Nm for Gears 1, 4 and 6, respectively.

Some autistic adults experience repeated adverse events, including rejection, victimization and stigmatization. They also describe others being critical and negatively judging them, such as for how they socially interact or for expressing passion for particular interests. The impact of these adverse events can be substantial, including increasing vulnerability for poorer mental health, and contributing to development of negative self beliefs (such as "I am different" or "I do not fit in") and shame-based difficulties. Not all evidence-based psychological therapies are well-received by autistic people, or effective. Given high rates of self-harm and suicidality, finding acceptable and effective therapies for autistic adults is paramount. Here, writing as autistic and non-autistic clinicians and researchers, we outline the theoretical principles of compassion-focused theory and therapy (CFT). We propose that: (1) compassion-focused theory can provide a useful framework for conceptualizing shame-based difficulties some autistic adults experience; (2) CFT can be appropriate for addressing these; and (3) there is an impetus for practitioners to adopt compassion-focused approaches when supporting autistic adults. [ABSTRACT FROM AUTHOR]

Many industrial rotating machines driven by asynchronous motors are often affected by detrimental torsional vibrations. In this paper, a method of attenuation of torsional vibrations in such objects is proposed. Here, an asynchronous motor under proper control can simultaneously operate as a source of drive and actuator. Namely, by means of the proper control of motor operation, it is possible to suppress torsional vibrations in the object under study. Using this approach, both transient and steady-state torsional vibrations of the rotating machine drive system can be effectively attenuated, and its precise operational motions can be assured. The theoretical investigations are conducted by means of a structural mechanical model of the drive system and an advanced circuit model of the asynchronous motor controlled using two methods: the direct torque control - space vector modulation (DTC-SVM) and the rotational velocity-controlled torque (RVCT) based on the momentary rotational velocity of the driven machine working tool. From the obtained results it follows that by means of the RVCT technique steady-state torsional vibrations induced harmonically and transient torsional vibrations excited by switching various types of control on and off can be suppressed as effectively as using the advanced vector method DTC-SVM. [ABSTRACT FROM AUTHOR]

The paper is focused on presenting a methodology for measuring power and torque based on diagnostic equipment available in most diagnostic workshops, such as OBD interfaces or the CAN Bus on-board data transmission network, under real-world road conditions. The publication presents an algorithm for calculating the powertrain's torque and power based on measurements of changes in vehicle speed or acceleration recording during a two-phase road test. The results presented, based on the method described, apply to both the internal combustion and electric vehicle. Common powertrain operating parameters, such as maximum power, maximum torque and the powertrain's flexibility parameters described in the literature, are proposed for the final evaluation of the vehicle's traction system. [ABSTRACT FROM AUTHOR]

Copyright of Steel Pipe is the property of Steel Pipe Magazine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the significant share of the induction motors (IMs) in global electricity consumption, the study of the IM in different power supply regimes is the aim of this work. In practice, these electrical receivers are not supplied from ideal voltage systems, therefore the power quality (PQ) is an important aspect in analysing the operation of this type of motors. We proposed a methodology for analysing the effects of unbalanced distorted voltages not only on the technical parameters of the IM but also on the power supply as well as on the driven mechanical system. We identified some dependencies, in analytical forms, between the sizes of interest and the considered PQ disturbances. The results showed that the supply voltage disturbances have significant effects on the induction motor, both electrically and mechanically. These effects are amplified if the IM is running at loads below 50% of the rated load.

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Zhejiang University: Science A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Some autistic adults experience repeated adverse events, including rejection, victimization and stigmatization. They also describe others being critical and negatively judging them, such as for how they socially interact or for expressing passion for particular interests. The impact of these adverse events can be substantial, including increasing vulnerability for poorer mental health, and contributing to development of negative self beliefs (such as “I am different” or “I do not fit in”) and shame-based difficulties. Not all evidence-based psychological therapies are well-received by autistic people, or effective. Given high rates of self-harm and suicidality, finding acceptable and effective therapies for autistic adults is paramount. Here, writing as autistic and non-autistic clinicians and researchers, we outline the theoretical principles of compassion-focused theory and therapy (CFT). We propose that: (1) compassion-focused theory can provide a useful framework for conceptualizing shame-based difficulties some autistic adults experience; (2) CFT can be appropriate for addressing these; and (3) there is an impetus for practitioners to adopt compassion-focused approaches when supporting autistic adults.

Hybrid electric vehicles (HEVs) have certain advantages over internal combustion engines in terms of energy consumption and emission performance. However, the transmission system parameters are uncertain. The low matching between the engine and the power transmission system makes it a big problem to improve the efficiency of hybrid vehicles. Therefore, the multi-objective optimization design of hybrid vehicles is studied. The transmission system parameters of hybrid vehicles are analyzed from the objective function, decision variables, and constraints. The NSGA-II algorithm with elite strategy is introduced to realize the optimal selection of parameters and formulation of energy consumption optimization strategy. The results showed that the multi-objective optimization algorithm could adjust the position of the working point of the engine and improve the efficiency by more than 10%. There was an average difference of 2.15% after the improvement in the fuel consumption of four-gear vehicles. The fuel consumption per 100 km decreases by more than 3%. The maximum climbing gradient of the whole vehicle was 33.9%. The power factor of the direct gear of the maximum power factor increases by 15% after the improvement. The multi-objective energy consumption optimization design of hybrid vehicles proposed in the study can effectively improve the economic and dynamic performance of the whole vehicle and reduce fuel consumption. It provides a reference for the optimization of the hybrid vehicle transmission system. [ABSTRACT FROM AUTHOR]

Heavy machinery is critical to agriculture, construction, mining, and other sectors of a country's economy. However, such vehicles consume a high amount of fuel, increasing production costs and the emission of polluting gases into the atmosphere. One of the alternatives to reduce fuel consumption is the electrification of these vehicles, but the definition of an optimal topology for the electrification of heavy vehicles is still under study, and works with electric drive systems projects for these machines are scarce. This paper presents the main characteristics of the design of an electric drive system for the electrification of a backhoe, including the control and simulation of the motor drive system, and presents a prototype bench and experimental tests carried out in the context of the hybridization topology presented. Based in these results, improvements are proposed and discussed with aid of computational simulation. [ABSTRACT FROM AUTHOR]

In order to ensure the stability of battery management power system, improve the reliability of on-board electronic products, and ensure the stability of thermal energy recovery power system, the author proposes an electromagnetic compatibility optimization scheme based on wiring harness, power module, and PCB noise, taking the battery management system of vehicle electronic components as an example, the role of electromagnetic compatibility on products is described, the hardware circuit is analyzed and designed by electromagnetic compatibility design theory to ensure the reliability of vehicle components. The electromagnetic stability of the power battery is guaranteed through the electromagnetic compatibility optimization analysis of the battery management system, so as to achieve more stable battery management. The experimental results show that each module of the battery management system works stably, and the disturbance degree test shows that the resonant noise of the battery management system disappears, and there is no obvious narrowband electromagnetic disturbance, and the overall value is below the limit of 20 dB. In conclusion the electomagnetic compatibility optimization scheme can effectively ensure the stability of the battery management power system, and indirectly ensure the stability of the heat recovery power system. [ABSTRACT FROM AUTHOR]

We propose a method for rapid prototyping of a three-phase AC drive system for educational purposes. The proposed method allows college students to design and manufacture a drive system comprising three-phase inverters, a permanent-magnet (PM) machine, a controller, and sensors within a semester. The rapid prototyping process, which requires less than a day, enables efficient iteration and testing during the development process. In addition to addressing the electrical design considerations, this study also addresses the mechanical aspects of the drive system, including the use of coreless PM machines fabricated, using additive manufacturing technology, and the inverter manufacturing process, utilizing an auto-milling machine. Finally, we provide details of the rapid prototyping of closed-loop control, based on sensor feedback to regulate the rotating magnetic fields and output torque. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increasing interest in employing wide-bandgap (WBG) drive systems has brought about very high power, high-frequency inverters enjoying switching frequencies up to hundreds of kilohertz. However, voltage surges with steep fronts, caused by turning semiconductor switches on/off in inverters, travel through the cable and are reflected at interfaces due to impedance mismatches, giving rise to overvoltages at motor terminals and in motor windings. The phenomena typically associated with these repetitive overvoltages are partial discharges and heating in the insulation system, both of which contribute to insulation system degradation and may lead to premature failures. In this article, taking the mentioned challenges into account, the repetitive transient overvoltage phenomenon in WBG drive systems is evaluated at motor terminals and in motor windings by implementing a precise multiconductor transmission line (MCTL) model in the time domain considering skin and proximity effects. In this regard, first, a finite element method (FEM) analysis is conducted in COMSOL Multiphysics to calculate parasitic elements of the motor; next, the vector fitting approach is employed to properly account for the frequency dependency of calculated elements, and, finally, the model is developed in EMTP-RV to assess the transient overvoltages at motor terminals and in motor windings. As shown, the harshest situation occurs in turns closer to motor terminals and/or turns closer to the neutral point depending on whether the neutral point is grounded or floating, how different phases are connected, and how motor phases are excited by pulse width modulation (PWM) voltages.

ABSTRACT An electric orchard tractor with a power battery and transmission driven by dual motors was developed. The output shafts of the walking and power take-off (PTO) motors are connected by a wet clutch, which controls whether the two motors are coupled or independent. When the load of the walking or PTO motor exceeds its output torque, the two motors are driven by power coupled by the wet clutch to meet the power demand. According to the heavy-load working conditions of ploughing and rototilling, the power battery capacity and working duration targets of 15 kW and 4 hours/charge were set. A prototype 15 kW electric orchard tractor was manufactured and assembled, and its performance was assessed. A bench test showed that the tractor’s maximum PTO output power was 13.9 kW and a field rototilling test showed that its maximum continuous working time was 4.5 hours. Thus, the prototype electric orchard tractor met the design goals and requirements of for orchard operations.

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Permanent magnetization of electric windlass and mooring winch (EWMW) has become a research trend in the development of new generation deck machinery. The paper investigates the development of a low-speed and high-efficiency permanent magnet synchronous motor (PMSM) and its drive system based on the load characteristics and special requirements of an EWMW. Firstly, the design specifications and key points of the motor drive system are analyzed. Secondly, a design method of parameter matching is proposed to design a 110 kW 75 r/min PMSM based on finite element method, field circuit coupling, and co-simulation. Finally, a prototype is developed and applied to a 45 T EWMW. The test results show that the PMSM can attain an efficiency of 94.3% at the rated operation, good traction characteristics with high torque at low speed, and 3 times wide flux-weakening region at constant power. Therefore, the matching design method is effective in the design of PMSM and drive system for EWMW.

Given the need to reduce greenhouse gas emissions, new energy-efficient solutions can be adopted for construction and agricultural machinery. Such a solution is a digital hydraulic cylinder that uses several active areas and a constant pressure supply with which a gradual variation of the driving force can be obtained. Traditional hydraulic systems have high energy losses due to the need to direct and throttle the flow through different valves. The article presents simulations in the AMESim environment and laboratory experiments of a digital hydraulic cylinder with three active areas. Through numerical simulations, the authors aim to highlight the energy efficiency of a digital hydraulic cylinder compared to a hydraulic cylinder in a conventional drive. [ABSTRACT FROM AUTHOR]

In this paper, a proposed electric drive system for a three-phase induction motor is presented. The proposed drive system is suggested for a golf car as one type of electric vehicle. The suggested system consists of three similar single-phase buck–boost converters. Hence, each single-phase buck–boost converter is used as a buck–boost inverter and is used to energize only one phase of the induction motor. The suggested system has the advantage of high reliability, as it can deal with different fault conditions such as battery and motor winding faults. The suggested electric drive system depends on a buck–boost converter which gives variable voltages as well as variable frequencies. Thus, variable speeds of the electric vehicles can be easily achieved. A variable DC voltage (positive or negative) can be achieved at the output of the adopted buck–boost converter, which is considered another advantage of the proposed drive system. This DC voltage can be used to achieve braking of the induction motor used to drive the electric vehicle. Therefore, this advantage can be used instead of ordinary mechanical braking to increase vehicle reliability. To demonstrate our proposed idea, a simulation study is presented. The simulation is carried out using Power Simulation Program (PSIM) software. The simulation study takes into consideration the performance of the adopted buck–boost converter under different conditions to present its advantages. Furthermore, a performance study of the suggested induction motor drive system is carried out under different conditions ranging from healthy to faulty conditions to test system reliability. For more illustration, an experimental prototype of the adopted buck–boost converter is built, and its performance is studied. From all the obtained results, the efficacy of the proposed system is demonstrated. [ABSTRACT FROM AUTHOR]

The increasing interest in employing wide-bandgap (WBG) drive systems has brought about very high power, high-frequency inverters enjoying switching frequencies up to hundreds of kilohertz. However, voltage surges with steep fronts, caused by turning semiconductor switches on/off in inverters, travel through the cable and are reflected at interfaces due to impedance mismatches, giving rise to overvoltages at motor terminals and in motor windings. The phenomena typically associated with these repetitive overvoltages are partial discharges and heating in the insulation system, both of which contribute to insulation system degradation and may lead to premature failures. In this article, taking the mentioned challenges into account, the repetitive transient overvoltage phenomenon in WBG drive systems is evaluated at motor terminals and in motor windings by implementing a precise multiconductor transmission line (MCTL) model in the time domain considering skin and proximity effects. In this regard, first, a finite element method (FEM) analysis is conducted in COMSOL Multiphysics to calculate parasitic elements of the motor; next, the vector fitting approach is employed to properly account for the frequency dependency of calculated elements, and, finally, the model is developed in EMTP-RV to assess the transient overvoltages at motor terminals and in motor windings. As shown, the harshest situation occurs in turns closer to motor terminals and/or turns closer to the neutral point depending on whether the neutral point is grounded or floating, how different phases are connected, and how motor phases are excited by pulse width modulation (PWM) voltages. [ABSTRACT FROM AUTHOR]

Introduction. The problem of the load on an electric drive system in a parallel kinematic structure is considered. The task of developing a fault-tolerant system that provides performing a given process in case of a failure of one or more drives is described. The work objective is to create a method for estimating the current and additional load on each drive of the mechanism of a parallel kinematic structure. The solution enables to correct the operating mode when performing a given process without compromising serviceable drives.Materials and Methods. Previously, a diagnostic method was developed. It is based on the calculation and analysis of the coefficients of straight lines that approximate the envelopes of the values of the wavelet transform coefficients of electric motor current signals, taking into account the characteristic scales. This makes it possible to determine the current technical condition of the electric motor and find malfunctions. The logical continuation of this approach is the proposed method for assessing the current and additional load. It provides finding the current load on the drive based on the coefficients of the lines approximating the envelopes of the wavelet coefficients of the current signal. To calculate the additional load, the number and location of faulty drives are taken into account.Results. For each scale of the wavelet coefficients, the relative coefficients and the current load on each drive are determined. The possibility of redistributing the load to two adjacent jacks was checked; the behavior of the system in this case was investigated. The load moved by the faulty jack is redistributed to two adjacent jacks in equal shares — 14.76 % each. The total load on the drives is 44.28 %, which is safe for the servo. The load on the drive of the fourth jack does not change (29.52 %). The drives have a sufficient safety margin. It is established that all three operating modes are acceptable for the studied servo drive, and they do not cause dynamic overloads and premature failure.Discussion and Conclusions. The experimental studies on the method of assessing the current and additional load have shown its adequacy and high efficiency. It was found that when the drives were disconnected from one of the racks of the mechanism, the system performed a load redistribution on the drives. Thus, it was possible to avoid their dynamic overloads and premature failure. This means that the solution is able to ensure the reliable functioning of the complex at the time of renovation work.

Manipulators are multi-part constructions whose members are connected by joints. The most common kinematic structure is the series structure. The effector at the end of the structure is a process head or a gripper. The most commonly used kinematic structure is a series structure, and the effector at the end of it is a technological head or a gripper. The area of application of manipulators is very wide and it de-termines the type of tools used, the kinematic structure, the drive system, and the base platform ‒ sta-tionary or mobile one. As industrial, medical, and research robots there are used the manipulators built on a stationary platform. A construction of this type requires a high degree of repeatability and preci-sion in the movements performed. A multi-part structure with a large number of degrees of freedom provides the manipulators with a large working capacity, but at the same time makes it difficult to use them effectively for manual operation. This is why they are most commonly used for robots in which some or all movements are controlled automatically. Manipulators, mounted on mobile platforms, are a special group, called in short mobile robots. They are most often used for special tasks, such as military and rescue operations, as well as for the exploration of hard-to-reach research areas. Manipulators used there must be able to carry heavy loads, have a wide range of workspace and the ability to generate large lifting forces. Their use for dangerous activities protects people from the risk of loss of their life or health, and thus it increases the efficiency of the work. In recent years, there has been observed an intensive development in constructions of this type.