Vehicle and electronics. Innovative technologies

Increasing the efficiency of the automotive generator due to active rectification

2024-05-01T16:45:51+03:00

Problem. Increasing fuel economy requirements for modern vehicles lead to an increase in their electrification. The rise in the number of electrical systems leads to a higher load on the electrical power supply system, with the vehicle's power load reaching 2-3 kW. Leading automobile companies have begun serial production of vehicles with the new 12/48 V power supply voltage standard. The traditional alternator used today is a synchronous alternator, and rectifier diodes are used to convert the generated AC to DC to charge the battery, which is inefficient. A study of losses in an automobile alternator shows that the diode rectifier creates a significant portion of the machine's losses at low speeds, resulting in increased fuel consumption. The solution to this problem is to use a synchronous rectifier to replace traditional rectifier diodes, thus improving the efficiency of the AC/DC rectifier. Goal: To improve the economic and environmental characteristics of a mild hybrid vehicle through the use of a synchronous two-semi-periodic rectifier with a midpoint in the car generator. Methodology: Analytical methods are used to calculate energy losses on diodes and in the phase windings of the generator when employing a two-semiperiod rectifier with a midpoint, compared to a bridge rectifier. Results: The structure, functions, and operation modes of the synchronous rectification system are considered. The effect of synchronous rectification on the generator efficiency of a mild hybrid vehicle is analyzed. It was determined which configurations of synchronous rectification are more effective from the standpoint of energy saving and under which operating conditions. It was determined that in a two-semiperiod rectifier with a midpoint, compared to a bridge rectifier, there will be the same heating of the phase windings and 2 times fewer losses on the diodes. Practical value: A version of the bridge synchronous rectification system of the 48 V generator for a mild hybrid vehicle using MOSFET transistors and specialized control IC is proposed. A synchronous rectification system and its circuit implementation for a 12 V generator based on a two-semi-periodic rectifier scheme with a midpoint is proposed, which allows increasing the energy efficiency and economy of the automobile generator.

Analysis and development of criteria for the operational efficiency of urban electric buses

2024-04-17T15:24:06+03:00

Problem. Currently, manufacturers and research specialists primarily utilize the amount of autonomous mileage and/or the specific electricity consumption of autonomous DEEs per unit of mileage to describe the general characteristics of urban electric buses. However, the structural mass and the key operational parameter, the nominal passenger capacity, are often disregarded. Therefore, comparing electric buses of the same type with identical dimensional parameters based solely on these criteria is illogical and incorrect. Goal. This study aims to establish criteria for the operational efficiency of urban low-floor electric buses of various types, considering autonomous DEE and their charging or replacement systems. These criteria should account for structural mass and nominal passenger capacity, facilitating a proper comparative assessment and the selection of the most optimal options for use in urban passenger transportation systems. Methodology. Criteria for the operational efficiency of city electric buses of various types are proposed based on an analysis of electricity consumption required for both movement and the operation of heating, ventilation, and air conditioning systems. The criteria consider the mass in the equipped state and the main parameter - nominal passenger capacity. Results. Several operational efficiency criteria for urban electric buses, incorporating mass parameters and passenger capacity, are suggested. The feasibility of their application is demonstrated through a comparison of five sketch projects of electric buses of various types with modern models. Originality. The proposed criteria for the operational efficiency of urban electric buses offer a method for adequately comparing any selected models, regardless of their types and technical specifications. Practical value. The proposed criteria for the operational efficiency of urban electric buses of various types can be beneficial for transport company specialists in selecting suitable rolling stock for specific routes. Additionally, design bureau and scientific and technical center specialists can utilize these criteria during the design process of new urban electric transport models.

Calculation of the parameters of an axial flux motor as an actuator of automotive systems

2024-04-30T10:56:18+03:00

Problem. Axial flux electric motors offer several significant advantages compared to electric motors of traditional design. Currently, scientific periodicals contain numerous publications regarding the development and use of axial flux electric motors with printed windings across various fields. These include applications such as HDD-drives in computer technology, fans and pumps of various capacities, propulsion systems for bicycles and motorcycles, including in-wheel motors, manipulator drives for machine tools and industrial robots, and even within space technologies. Research confirms the high efficiency and size-to-weight ratios of axial flux motors when modern technologies are employed. However, there is little information available regarding the application of such motors in automotive electromechanical equipment. A distinctive feature of automotive electrical systems is their predominantly 12 V onboard power supply, along with high demands on size-to-weight ratios and reliability in conditions of elevated vibrations and wide temperature ranges. In this context, the development of an axial flux motor for automotive applications becomes relevant, particularly as an actuating mechanism for auxiliary systems such as window lifters, windshield wipers, air conditioning, and cooling fans, etc. Goal. The goal of the article is to determine the feasibility of using an axial flux electric motor as an actuator for automotive auxiliary systems by comparing its calculated parameters with the parameters of motors of traditional design using modern technologies and materials. Methodology. The methods and algorithms used for the calculation of electric machines take into account the characteristics and physical processes specific to axial flux machines with printed windings and permanent magnet arrays. Results. A comparison of the obtained characteristics of the designed motor with the characteristics of a modern prototype of traditional design was conducted. Based on the comparison, it was determined that the designed motor has better size-to-weight ratios while maintaining energy performance. Consequently, a conclusion was drawn about the feasibility of using electric motors with axial flux as actuators for automotive auxiliary systems. Originality. The prototype of the designed motor is considered to be a 250 W DC motor with a supply voltage of 12 V. The imposed constraint on the external diameter of the designed motor is set to 100 mm. Practical value. At the same output power and nearly identical torque, the calculated motor exhibits higher size-to-weight ratios. The weight of the calculated motor is 46% of the weight of the prototype. With an external diameter 54% larger than the prototype, the axial length of the calculated motor is 73% smaller. The mass of the calculated motor is 2.34 times smaller than the mass of the prototype.

Development of an electric drive for personal light electric vehicles

2024-04-30T10:47:10+03:00

Problem. The article addresses the challenge of enhancing inclusive mobility and environmental cleanliness by developing a traction electric drive for personal light electric vehicles. A study was conducted on modern electric drive systems for personal light electric vehicles. Goal. The aim is to boost inclusive mobility and environmental cleanliness through the development of a traction electric drive for a personal light electric vehicle, specifically based on a tricycle. Methodology. The methodology involves scientific analysis and synthesis of traction electric drives for electric vehicles. An assessment of the nominal capacity of the battery module from the Nissan Leaf electric car was conducted using both partial discharge procedures and the Leaf Spy Pro program. Results. Based on an analysis of existing electric drive systems, a traction electric drive for a tricycle was developed. A functional diagram of the electric bicycle drive was generated. A control system for a sensorless brushless motor was developed, determining rotor position by measuring EMF in the free phase. This led to the creation of a stable voltage electrical circuit with a virtual midpoint. The tricycle's electric drive utilizes two 10-inch motor wheels on the rear wheels, enabling high speed and efficiency. Controllers specifically designed for electric wheel motors with a power of 350 W were selected to control the traction electric drive. Modules from the 2015 Nissan Leaf electric car's battery, which had depleted 20% of their capacity, were chosen to power the electric drive. The battery health status is 77.95%. A model of the battery's electrical equivalent circuit was constructed, and partial discharge graphs of the Nissan Leaf battery module were analyzed. Originality. The results provide a comprehensive insight into the development of a traction electric drive for personal light electric vehicles, using a tricycle as an example. Practical value. The research led to the development of an electric drive for a three-wheeled vehicle, with two motor wheels of 350 W nominal power each. The power supply voltage ranges from 36 V to 48 V, powered by six battery modules from the Nissan Leaf electric car, totaling 48 V. The energy capacity of one battery module is 0.3898 kWh, resulting in a total energy capacity of 2.3388 kWh for the vehicle's battery. However, the realizable capacity does not exceed 1.871 kWh, providing a travel distance of approximately 75 km on one battery charge. These findings demonstrate the feasibility of reusing batteries from electric cars with diminished capacity to power light electric vehicles. The results are relevant for scientific and technical professionals involved in electric vehicle development.

Method for expert evaluation of the technical con-dition of the cylinder-piston group of automotive engines after hydrolock

2024-03-26T16:17:03+02:00

Problem: The study examines the thermogasdynamic process within an internal combustion engine cylinder during cold cranking mode while measuring compression. Analysis of various models and comparison of known data revealed unresolved challenges in constructing mathematical models of the engine operating cycle. The vast majority of practical data and recommendations for compression measurement in a cylinder are based on empirical knowledge, numerous experiments, and tests. Consequently, there arises a need for computational models of the compression measurement process and their theoretical justification, particularly in cases where engine damage occurs during hydrolock in a cylinder. Methodology. To address the identified issues, a mathematical model of the thermogasdynamic process within the cylinder during cold cranking while measuring compression was developed. Originality. Unlike existing models, this model describes the processes in the cylinder step by step, considering the real nature of intake-exhaust processes, air leakage through part interfaces, and heat exchange with the walls. Through modeling, the main patterns of compression changes depending on the modes and the nature of damage to associated parts of the valve mechanism and the cylinder-piston group were identified, including deformation of the connecting rod during hydraulic lock due to liquid entering the cylinder. Practical value. Based on the study results, it was concluded that the model's properties make it effectively applicable in diagnosing and monitoring the technical condition of automotive engines during operation.

Efficiency of energy-generating tiles with different types of multipliers

2024-03-26T14:37:01+02:00

Problem. With the urgent need for sustainable and renewable energy solutions, the integration of energy-harvesting technologies in urban infrastructure has become a focal point of innovation. Energy-generating tiles, transforming pedestrian movement into electricity, offer a viable path forward. Yet, their efficiency hinges on the internal design, particularly the type of multipliers used. Goal. This study aims to assess and compare the efficiency of energy-generating tiles equipped with helical and straight-cut gear multipliers, to identify the optimal design for maximizing energy conversion in urban environments. Methodology. An experimental setup was created to test prototypes of the energy-generating tiles under controlled foot traffic conditions. The study measured and analyzed the electrical output and efficiency of tiles with both types of gear multipliers, simulating real pedestrian traffic scenarios. Results. Energy-generating tiles featuring straight-cut gears outperformed those with helical gears in energy output and conversion efficiency. The research also illuminated the influence of pedestrian dynamics, like step force and frequency, on tile performance. Originality. This research advances renewable energy technology by offering a comprehensive analysis of energy-generating tile efficiency with different gear multipliers. It introduces an innovative method for evaluating tile performance, underscoring the significance of gear design in energy conversion.

Practical value. The findings have considerable implications for sustainable urban development, suggesting that implementing energy-generating tiles in areas with high foot traffic could significantly enhance urban renewable energy sources. This study not only guides the design of more efficient energy-harvesting tiles but also encourages their broader adoption, supporting urban sustainability goals and the reduction of carbon emissions.

Enhancing electromagnetic compatibility and energy efficiency of electric vehicle charging stations

2024-04-30T10:43:46+03:00

Problem. The article proposes a single-link structure for an electric vehicle charging station utilizing an active four-square rectifier with power factor correction. A Matlab model of the proposed charging station is developed, taking into account parameters such as the power network, the switches of the active rectifier, its automatic control system, and an equivalent model of the battery compartment. Additionally, a mathematical model for calculating static and dynamic losses is created based on polynomial approximation of the energy dependencies of IGBT modules. The analysis investigates power quality parameters, components of energy losses, and efficiency of the charging station across various charge currents and PWM frequencies during a full battery charge interval. Goal. The aim of this study is to propose a single-link structure for an electric vehicle charging station using an active four-square rectifier with power factor correction. It includes an analysis of power quality parameters, components of energy losses, and efficiency of the charging station at different charge currents and PWM frequencies during a full battery charge interval. Methodology. To achieve the goal, several key steps are considered. These include theoretical substantiation of the scheme of the electric microgrid charging station for electric vehicles with one-stage energy conversion, analysis of the battery connection scheme in the Tesla Model S electric car, research and calculation of efficiency, modeling of the charging station, development of a Matlab model of a microgrid system for the charging station, SAC analysis of battery charge voltage and current of a three-phase AV with PWM, modeling of losses in IGBT modules by polynomial approximation of dependencies, distribution of losses in the charging station system, and analysis of energy efficiency parameters. Results. The study presents the energy efficiency parameters of an external DC EV charging station using an active rectifier. It reveals that maximum efficiency of the system is achieved at minimum charge current. However, decreasing the charge current prolongs the charge process and slightly affects power quality parameters. Originality. A mathematical model for calculating static and dynamic losses was developed based on polynomial approximation of the energy dependencies of IGBT modules. The analysis encompasses power quality parameters, components of energy losses, and efficiency of the charging station across various charge currents and PWM frequencies during a full battery charge interval. Practical value. This study contributes to the further development of electric vehicles by improving the energy indicators of electric vehicle batteries and converters of electric vehicle charging stations, enabling fast charging modes. Active development is observed in each of these directions.