In this paper we analyze an optical receiver (OR) for the optical time domain reflectometer (OTDR). Using optical receiver's model, which consists of shunt-shunt feedback transimpedance amplifier (TIA) and InGaAs avalanche photodiode (APD), we discuss and give equations for all important noise sources, which are amplifiers input transistor channel thermal and flicker noises, avalanche photodiode noise and feedback resistors noise. Than in terms of OTDR parameters, we explain the need of TIA variable gain, define the range of bandwidths, and introduce optimal values for OR dynamic range, APD multiplication and feedback resistance. Using these values we give an OR reference design and analyze received results.

The modification of the proportional–integral (PI) controller with the variable proportional constant for tracking of the grid-connected photovoltaic microinverter output current has been proposed. The obtained results show that in the case when the proportional constant of the PI controller varies in time according to the appropriate law, the microinverter output current sinus shape distortions decrease as compared to the case when the ordinary PI controller is used. The operation of the microinverter with the proposed controller was investigated for the cases when the electrical grid voltage sinus shape is not distorted and when it is distorted by the higher harmonics.

The single stage photovoltaic microinverter based on couple of two-switch DC-DC flyback converters has been suggested. The results of simulation and experimental investigation for the case when photovoltaic microinverter operates in off-grid and grid-tied modes are presented. The proposed single stage microinverter is characterized by simple design and high efficiency.

In this paper, a six-phase voltage source inverter with a single-neutral star connected load is investigated. A space vector PWM (SVPWM), which uses largest magnitude vectors is proposed and implemented. Simulation results of the six-phase voltage source inverter (VSI), which uses the proposed SVPWM method, are compared to the results when a standard sinusoidal PWM scheme is used. Analysis of the results shows that proposed SVPWM scheme is suitable to form a six-phase sinusoidal output voltage. The main advantage of proposed SVPWM scheme is that it requires the same computational resources as the three-phase SVPWM.