Irina Semykina

The shift to autonomous electric transport in mining is essential for reducing costs, enhancing productivity, and improving labour safety. The paper assesses the rate of traction battery fade in an electric mining dump truck charged using wireless charging stations under different scenarios and charging infrastructure options. The research was conducted using lithium iron phosphate batteries and the BelAZ-7558E dump truck as a case study. A review of battery lifetime assessment methods was conducted, and mathematical and scenario modeling methods were applied. To mathematically represent wireless charging stations, traction batteries, the powertrain of dump trucks, and the processes that occur within them, a dynamic model was developed using MatLab Simulink. To study the battery fade process, the mathematical model based on the Arrhenius equation was used. The capacity loss of the traction battery was determined for the considered charging infrastructure options. The wireless charging scenario delivers optimal results when charging stations are placed at the loading points. The simulation results are useful for estimating and predicting the fade of traction batteries. They also aid in designing the lifecycle of wireless charging infrastructure for autonomous electric dump trucks at specific mining enterprises.

One of the key problems in the construction of wireless charging systems is to increase the efficiency of wireless energy transfer, especially with limited dimensions of devices and changing mutual position of coils. Traditional design methods are often insufficiently accurate for multilayer coils, which requires the development of new approaches. The study is based on a mathematical model of a wireless energy transfer system with a series LC topology, built on the basis of equivalent circuits, while the parameters of the transmitting and receiving coils are determined using the vector potential method. An approach is proposed that allows reducing the number of variable parameters that determine the efficiency of wireless energy transfer. A technique for optimizing the considered wireless charging systems at the design stage is developed, according to the criteria of wireless energy transfer efficiency, the value of the transmitted power and over-voltage on the capacitors of the resonant circuit. The technique is based on multi-criteria analysis using relative im-portance coefficients. For specific conditions, the optimal parameters of the transmitting and receiving coils are determined, namely the number of turns and layers of the winding under given dimensional constraints, ensuring maximum efficiency. Experimental testing on a model confirmed the correspondence of the calculated and real characteristics with sufficient reliability. It is shown that the proposed approach allows one to effectively take into account geometric constraints and minimize losses in the resonant circuit. The proposed optimization method demonstrates high efficiency in the design of wireless charging systems with multilayer coils and series LC topology under conditions of possible coil displacements.

Belt conveyors are a critical element of production capacity in mining and manufacturing industries. The reliability, smoothness, and trouble-free operation of belt conveyor equipment directly impact the production performance and economic efficiency of the enterprise. In this paper, a belt conveyor is considered as a single electromechanical system. A mathematical model for this system was developed by decomposing the belt conveyor mechanism, identifying individual mechanical components most susceptible to failure. The resulting model represents an eight-mass system. Based on the resulting equations, a model of the conveyor's electromechanical drive system was created in the MATLAB Simulink environment. The modeling yielded diagnostic indicators of belt conveyor failure modes, such as roller jamming, receiving hopper blockage, and others. The results of a model-based study showed that the stator current of an asynchronous motor changes characteristically during emergency situations. The period, frequency, and shape of the current oscillations depend on the specific type of fault in the mechanical component of the belt conveyor. To confirm these results, field studies were conducted on a real-world object—a type HE-K belt conveyor. During the experiments, the RMS value of the motor stator current, the frequency and voltage of the power supply network, and the output frequency and voltage of the frequency converter were recorded. The results of the study confirm the feasibility of using changes in the stator current of an asynchronous motor to diagnose emergency operating conditions of a belt conveyor. This allows for increased reliability and efficiency of equipment operation, as well as a reduction in economic losses associated with emergency situations.

Belt conveyors are a critical element of production capacity in mining and manufacturing industries. The reliability, smoothness, and trouble-free operation of belt conveyor equipment directly impact the production performance and economic efficiency of the enterprise. In this paper, a belt conveyor is considered as a single electromechanical system. A mathematical model for this system was developed by decomposing the belt conveyor mechanism, identifying individual mechanical components most susceptible to failure. The resulting model represents an eight-mass system. Based on the resulting equations, a model of the conveyor's electromechanical drive system was created in the MATLAB Simulink environment. The modeling yielded diagnostic indicators of belt conveyor failure modes, such as roller jamming, receiving hopper blockage, and others. The results of a model-based study showed that the stator current of an asynchronous motor changes characteristically during emergency situations. The period, frequency, and shape of the current oscillations depend on the specific type of fault in the mechanical component of the belt conveyor. To confirm these results, field studies were conducted on a real-world object—a type HE-K belt conveyor. During the experiments, the RMS value of the motor stator current, the frequency and voltage of the power supply network, and the output frequency and voltage of the frequency converter were recorded. The results of the study confirm the feasibility of using changes in the stator current of an asynchronous motor to diagnose emergency operating conditions of a belt conveyor. This allows for increased reliability and efficiency of equipment operation, as well as a reduction in economic losses associated with emergency situations.

Relevance. Aluminum production is one of the most important industries all over the world. It has a high environmental load, resource and energy intensity. To reduce the negative impact of aluminum production, efforts are underway to improve its technological processes, aimed at increasing aluminum recovery rates, reducing waste volumes, and lowering energy consumption. The reduction of energy consumption can be achieved, among others, through implementing control systems that provide energy management. Due to the complexity and multiplicity of technological processes in aluminum production, the use of traditional linear approaches for such control systems is ineffective, and adequate mathematical models are required. At the same time, for the production level, the use of mathematical models based on a phenomenological description of the ongoing physical processes overly complicates the control task. As a result, the use of intelligent and adaptive approaches to both the mathematical description of technological processes and the optimal energy consumption management is relevant. Objects. Technological complexes of aluminum production, which have the properties of inertia, nonlinearity, and closedness; and the control system based on artificial intelligence methods. Alumina production is chosen as an illustration. Aim. To develop mathematical models capable of adequately describing the interrelated processes in the technological complexes under consideration, as well as the control system that allows optimal energy consumption management. Methods. For the mathematical model based on balance equations under uncertainty, the fuzzy-set theory was used along with the gradient descent method to identify the model parameters; for the optimization task, the genetic algorithm method was used. Results. The mass balance model and the process conditions changing model have been developed to determine the energy consumption for the technological complexes of aluminum production with continuous inertial nonlinear closed production. Based on these models, the dynamic characteristics of energy consumption and the parameters of technological processes were determined depending on the main controlled parameters, allowing us to predict emergencies. Considering technological parameters and cost factors, the optimization task for energy consumption management was solved.

The article outlines wireless battery charging as a promising direction for electric vehicles. There is the question raised of this technology applicability in the gaseous-and-dusty mine, and for such systems, the method for ignition risk evaluation is described. It is shown that the only potential ignition source is the charging area between the coils of the wireless charger. The authors formulate the objectives for studying the electromagnetic field in the charging area and propose variants of the mathematical description for this field. The research stages are listed which are necessary to substantiate the parameters and operating modes of wireless chargers that are safe for operating in the conditions of the gaseous-and-dusty mine.

The article discusses an approach based on the analysis of the drive motor currents to create an additional means of protection against emergency situations during the operation of bridge cranes associated with lifting a load with a mass exceeding the permissible one. A mathematical model of an overhead crane drive is described, as well as the results of computer simulation. It is shown that in the process of lifting up, before the stage of lifting the load, the stator current of the drive electric motor does not depend of the load mass, but when the load is detached, already for several periods of the mains voltage after the rope is pulled, when the mass of the load is exceeded, a measurable excess of the amplitude value of the current is recorded. This pattern has been confirmed for a number of cranes of various lifting capacities used at metallurgical enterprises. The possibility of diagnosing excess weight of the lifted load with a higher speed than existing mechanical methods of overload control is demonstrated, at the same time it is not required to make changes to the structural elements of overhead cranes.

The paper considers conditions of mining machinery electric drives operation and analyzes the causes of insufficient reliability. To improve the reliability and efficiency of induction motors the authors propose the computer system designed for dynamic identification of electric motors to monitor their parameters and variables, which are estimated on operating equipment in real time. Operation of the system allows calculating unmeasurable quantities and is based on the mathematical model of the induction motor as well as mathematical methods of estimation and the information contained in the measured phase voltages and currents of the stator. For dynamic mode the mathematical model of the motor’s state and the measurement part were developed and certain results were obtained. Real-time information can be used for both control and management of electric motors, function testing, protection, forecasting as well as acceptance testing of electric motors in mining machinery electric drives to identify their individual data and quality control of the industrial processes in the manufacture or repair of motors.

Regarding the current tendency of replacing the geared electric drives with gearless drum motor and substitution of the obsolete induction motors with energy-efficient synchronous motors, the authors consider the difficulties of the high-power permanent magnet synchronous motor and present its model with parameters corresponding to the real belt conveyor electric drive parameters. This paper describes the questions of the vector control system simulation for the synchronous gearless drum-motor of an underground belt conveyor. The control of permanent magnet synchronous motor is realized having regard to rotor angle and random traffic flow. The mechanical system of an underground belt conveyor is represented by the multimass system with the viscoelastic bar. As a conclusion, the article presents the results of the direct torque control system simulation in the speed adjustment mode.

The possibility of carrying out monitoring of parameters and variables of the induction electric motor (IM) working as a part of the electric mining machinery drive is considered. Monitoring is carried out on the working inventory in real time by means of the computer system on the basis of the IM mathematical model, mathematical estimation methods and also information which is contained in easily measured phase tension and IM stator currents. As a result IM indicators are defined difficult or cannot be measured in the mining machinery operation course. These are the active and induced windings resistances of a stator and a rotor, a magnetic linkage, an angular frequency of a rotor rotation and the electromagnetic moment. Algorithms of dynamic IM identification and the software are developed for carrying out monitoring. Theoretical provisions and conclusions are confirmed with results of the pilot studies. Information received during monitoring can be used for perfecting of the electric drive.