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 article is analytical. It considers the construction principles of the automation system structure which realize the concept of «unmanned mine». All of these principles intend to deal with problems caused by a continuous complication of mining-and-geological conditions at coalmine such as the labor safety and health protection, the weak integration of different mining automation subsystems and the deficiency of optimal balance between a quantity of resource and energy consumed by mining machines and their throughput. The authors describe the main problems and neck stage of mining machines autonomation and automation subsystem. The article makes a general survey of the applied «unmanned technology» in the field of mining such as the remotely operated autonomous complexes, the underground positioning systems of mining machines using infrared radiation in mine workings etc. The concept of «unmanned mine» is considered with an example of the robotic road heading machine. In the final, the authors analyze the techniques and methods that could solve the task of underground mining without human labor.

In the recent decades there has been a tendency for simplifying gears construction, furthermore a lot of manufacturers design gearless electric drives for traction and power mechanisms. Rejection of mechanical transmission and replacing obsolete induction motor with energy-efficient permanent magnet synchronous machine (PMSM) allow to increase electric drive reliability, reduce repair and maintenance costs, also improve the technological process and industrial safety.This article is devoted to questions of permanent magnet synchronous motor control for underground belt conveyor gearless drum-motor. The model of PMSM with special construction was created by finite elements method in Infolytica MagNet and MotorSolve environments, simulation was provided with to regard due special nature of high-torque slow-moving power machines. The last section of article contains comparison of methods for high-torque slow-moving PMSM control and simulation results of vector control system.

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.