In the paper, induction machine (IM) torque control is studied as an example of a three-dimensional non-holonomic integrator including drift terms. By expanding Brockett's controller derived for the driftless systems, a control structure is proposed that provides simultaneous modulation of both the amplitude and the frequency of the sinusoidal stator current vector. The proposed control assures high dynamics in the torque response, maximal torque per amp ratio during transients and in steady-state and global asymptotic stability, which is confirmed by experimentally.
COBISS.SI-ID: 14609174
This paper analyzes the impact of magnetic saturation on the steady-state operation of the induction motor (IM) drive in regard to rotor field-oriented control (RFOC). The aim of the presented two methods is to obtain the required steady-state torque with minimal stator current, which thus reduces stator coper losses considerably. The second method directly searches the minimal stator current for the required load torque. Experiments completely confirm the efficiency of the proposed selection of a magnetizing current.
COBISS.SI-ID: 14247446
This paper deals with the detection of saturation in the magnetic core of a welding transformer. During normal operation welding transformer’s magnetic core can become saturated, which causes current spikes and over-current protection switch-off of the entire system. The aim of this paper is to present a reliable method, based on the artificial neural network, for detection of magnetic core saturation that does not require an additional sensor.
COBISS.SI-ID: 13844502
This paper deals with the parameter determination procedure of a gas-discharge arrester’s (GDA) model. In order to achieve good results, differential evolution (DE), a stochastic optimization algorithm, is included in the determination process. The main task of the DE algorithm is to vary the model’s parameters during the optimization process, thus minimizing the difference between the measured and model-calculated current and voltage time behavior. An accurate GDA model has been obtained on the basis of measurements on a single GDA test object.
COBISS.SI-ID: 13994774
This paper deals with the analytical determination of a middle frequency resistance spot welding transformer iron core model. The model considers eddy currents, hysteresis, and the saturation effect of a magnetic field in a laminated iron core. The proposed model is simple, based on parameters that can be easily obtained from a data sheet, and is easy to implement. It is applicable for the design of control algorithms as well as a rough optimisation of blade thickness, air gap width, and the dimensions of the transformer’s core.
COBISS.SI-ID: 13845014