The paper presents the influence of signal stationarity on digital stochastic measurement method implementation. The implementation method is based on stochastic voltage generators, analog adders, low resolution A/D converter, and multipliers and accumulators implemented by Field-Programmable Gate Array (FPGA). The characteristic of first implementations of digital stochastic measurement was the measurement of stationary signal harmonics over the constant measurement period. Later, digital stochastic measurement was extended and used also when it was necessary to measure timeseries of non-stationary signal over the variable measurement time. The result of measurement is the set of harmonics, which is, in the case of non-stationary signals, the input for calculating digital values of signal in time domain. A theoretical approach to determine measurement uncertainty is presented and the accuracy trends with varying signal-to-noise ratio (SNR) are analyzed. Noisy brain potentials (spontaneous and nonspontaneous) are selected as an example of real non-stationary signal and its digital stochastic measurement is tested by simulations and experiments. Tests were performed without noise and with adding noise with SNR values of 10dB, 0dB and - 10dB. The results of simulations and experiments are compared versus theory calculations, and comparasion confirms the theory

The presence of a low DC voltage in a power grid produces an excitation asymmetry for the distribution transformers, resulting in unwanted half-cycle saturation that may impair transformer safety, reliability and efficiency, especially in increasing the reactive power, stray losses and iron losses. This paper highlights a diagnostic method based on the phase value of the particular even harmonics of a transformer excitation current as the basic marker of an excitation asymmetry. In order to achieve a straightforward insight into the nature of even harmonics behaviour, a novel method of decomposition an excitation current waveform into its unhysteretic (pure magnetization) and hysteretic components has been included in the harmonic analysis.

In modern industry power consumption is becoming one of the most important constraints during the development phase of the product. In motor industry, significant part of the power consumption improvement can be done in motor control. Brushless dc (BLDC) motor drives are penetrating the market rapidly. Heating, ventilation and air conditioning (HVAC) systems use conventional motor drive technology and the machines found in these devices are characterized by low efficiency and high maintenance. BLDC motor drives are characterized by higher efficiency, lower maintenance and higher cost. This paper presents the analysis, design, and implementation of a cost-effective control technique for a low cost solution, six switch threephase inverter brushless dc motor drive using single current sensor for current control. Various parameters defined optimization path for target drive solution. Also, basic framework for low cost BLDC control IC is presented. The controller is modeled and the concept is proven using simulator. Then the verification and feasibility study are done by using field-programmable gate array prototyping on the custom board made for this research. Final simulation results along with prototype operation measurements are presented as well.

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