Problems of Bucket-Wheel Excavators Body in Hardly-Workable Grounds in Polish Open Pit Mines

Correction Mechanism for Balancing Driving Torques in an Opencast Mining Stacker with an Induction Motor and Converter Drive System

“…Models and simulations of the transient electromagnetic processes are useful tools [4,15]. When the system is working with the chosen control algorithms (scalar or vector) and manually set parameters in the inverter control system, special attention should be paid to avoid dangerous settings (e.g., frequencies, torques, electric power) that may cause the whole mechanical structure to vibrate, possibly leading to resonance [8,13,20]. All curves (marked with numbers from 1 to 8) in Figure 5 are on the same percentage scale related to the defined inverter parameter system, the rated nominal values, and the quantity values.…”

“…The problem of resonance vibrations in opencast mining machines has been the subject of many studies [2,21]. According to the commonly known formula, we can define the general external excitation [8]:…”

“…The intensity will depend on the selection of parameters and limits. There are several ways to move the system and the machine out of the resonance area [8]:…”

“…The machine belongs to a group of the selfpropelled stackers used in global opencast mining [6]. The technical and technological parameters of the stacker, its scope of work, and details of its performance, as well as assessments its safety level, stability, and operationality, have been discussed in numerous publications e.g., [7,8].…”

Analysis of the Dynamic Response as a Basis for the Efficient Protection of Large Structure Health Using Controllable Frequency-Controlled Drives

“…The key idea that led to the studies presented in this paper is to appropriately control the frequency controller of the bucket-wheel drive in a way that passes over certain numbers of bucketwheel revolutions. Therefore, it avoids not only the potential resonant states of the slewing superstructure but also the states that are in their close proximity (resonance-affected states: RASs), which, over the multidecadal exploitation, inevitably lead to the appearance of fatigue cracks [3,[49][50][51]. The device for the semiautomation of control of the frequency controller of the bucket-wheel drive, whose software is based on the study presented in this paper, prevents the slewing superstructure from entering these undesired states based on the predetermined working regimes, while preserving all of the existing protection systems of a bucket-wheel excavator.…”