Abstract:
At present, the single stage inverters are popular in
integrating large-scale solar farms with distribution networks that
demand higher dc bus voltage. The elevated dc potentials would
degrade the reliability of the solar panels and inverter modules. In
this work, the multiboost solar inverter topologies of three variants
are presented for grid-connected applications. Since the proposed
topologies aim to achieve higher voltage boost at ac side with
reduced dc bus potential, it is required to use asynchronous switching strategies, unlike parallel inverter configurations. Although
the proposed topologies are advantageous in-terms of improved
reliability of solar panels and inverter modules, but instantaneous
characteristic impedance imbalance due to asynchronous switching
provokes circulating current within the inverter modules. Since
the circulating current is undesirable concerning power quality
and thermal aspects, in this work, the method of instantaneous
impedance balance is ensured with the specially designed switching
algorithm for proposed topologies. The eliminated instantaneous
circulating current provides the flexibility of operating all inverter
modules with the common dc bus. The proposed high gain boost
configurations and switching methodologies are demonstrated on
hardware prototype by pumping 2.4-kW power to the grid.
