The research of uninterruptible power supplies with parallel connection of inverters and equivalent control

Telecommunication systems are powered by redundant plants, among which inverters and uninterruptible power supplies occupy the most important position. Converters based on parallelconnected pulse-width inverters allow redundancy without switching. For modeling and research of converters based on pulse-width inverters with equivalent control, a discrete-nonlinear model is proposed that has a higher adequacy in comparison with the linearized one. The model allows increasing the reliability of research results and expanding the number of investigated characteristics of the converter. Among the most important simulation results, it is necessary to highlight the influence of phase delays of the driving signal from the inverters, which lead to an uneven distribution of output currents of the inverters. Thereat the reactive power generated by inverters increases, and their energy efficiency decreases. To reduce the influence of such external action, it is proposed to increase feedback on the difference signal of the average current value of inverters and the actual current value of each inverter. Feedback depth is determined by the level of reactive power acceptable in inverters in practice.