Design and implementation of a single phase modified Z-source inverter topology for photovoltaic/grid interconnected DC charging applications
Date
2018-03-01
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Abstract
Solar energy has been the most popular sources of renewable energy for residential and
semi-commercial applications. Solar energy sources alone cannot be used to charge an
electric vehicle (EV). Solar/Grid interconnected charging stations are used to charge
EV batteries to reduce the dependency on the grid and enable charging at convenient
locations such as a residential garage or a parking lot right next to an office or a shopping
mall.
The Z-source inverter (ZSI) topology achieves voltage boost and DC-AC power conversion
in a single stage. In this thesis, the design and implementation of a modified
ZSI (MZSI) based charging topology for PV/EV/Grid interconnected application has been
presented. The operation of the proposed topology was verified. The proposed topology
reduces the number of conversion stages to charge EVs from a Smart Grid/PV interface
(high efficiency).
A 3.3 kW MZSI has been designed and simulated using PLECS. Detailed loss modeling
was done using PLECS. The peak efficiency of 94% was observed under irradiation
and temperature changes. A scaled-down version of the proposed topology has been
implemented for proof of concept.
In a single-phase 60 Hz inverter, the 120 Hz component has to be suppressed. One
way is to size the capacitance in the system to absorb the 120 Hz component which may
result in a bulky system. The design of Active Power Filters (APF) for the ZSI topology
can be tricky because of the shoot-through state. A new DC side active power filter has
been proposed for ZSI topology which suppresses the 120 Hz component completely
thereby eliminating the need to use electrolytic capacitors in ZSI systems. The proposed
APF can reduce the capacitance by 100 times. Simulation studies have been presented
for the proposed topology.
Description
Keywords
Electric vehicles, Solar inverter, Residential DC charging, Plug-in, Z-source