Investigation On Wireless-Parallel Technology Of Single-phase Inverters

In order to ensure redundancy, expandability and good reliability of a power supply system, a parallel-inverter power supply system is required. Generally, there are two kinds of parallel-inverter power supply system: parallel-inverter system with control interconnections and parallel-inverter system without control interconnections. As the latter is more flexible and easier to expand, it is studied more and more nowadays.In this thesis, an inverter controller composed of voltage-loop and current-loop was introduced, then the principle of power distribution (P-Q droop method) was analyzed and the function to control the output power was presented. Influence of cable impedance's deviation on the power distribution was studied in theory and validated by simulation. In order to weaken this influence, two improved droop method, harmonic injection method and output impedance regulation method, was introduced. And a novel improved droop method, P-Q droop coefficient regulation method, was proposed. Simulation results validated this proposed method. As methods mentioned above could only distribute Alternating Current, a DC circum current attenuator was designed.In the following part of this paper, a generalized small-signal model for parallel-inverter power supply system was presented. With the small-signal model, the stability of the system could be studied and the droop coefficients be chosen properly.Finally, experiment results were showed, which proved what had studied in theory and in simulation.