ABSTRACT:
In this paper
a new mode of operation has been introduced for Packed U-Cell (PUC) inverter. A
sensor-less voltage control based on redundant switching states is designed for
the PUC5 inverter which is integrated into switching process. The sensor-less
voltage control is in charge of fixing the DC capacitor voltage at half of the
DC source value results in generating symmetric five-level voltage waveform at
the output with low harmonic distortion. The sensor-less voltage regulator reduces
the complexity of the control system which makes the proposed converter
appealing for industrial applications. An external current controller has been
applied for grid-connected application of the introduced sensor-less PUC5 to
inject active and reactive power from inverter to the grid with arbitrary power
factor while the PUC auxiliary DC bus is regulated only by sensor-less
controller combined with new switching pattern. Experimental results obtained
in stand-alone and grid-connected operating modes of proposed PUC5 inverter
prove the fast response and good dynamic performance of the designed sensorless
voltage control in balancing the DC capacitor voltage at desired level.
KEYWORDS:
1.
Multilevel
Inverter
2.
Packed U-Cell
3.
Sensor-Less Voltage
Regulator
4.
PUC5
5.
5-Level
Inverter
6.
Power Quality
SOFTWARE: MATLAB/SIMULINK
CONCLUSION:
The PUC5 inverter has been proposed in
this paper while the capacitor voltage is balanced without involving any external
controller and voltage feedback sensors. The proposed sensor-less voltage
controller has been integrated into switching technique to work as open-loop system
with reliable results. Moreover, another controller has been designed for the
PUC5 inverter to work as unity power factor grid-connected inverter. Low
harmonics components in both voltage and current waveforms generated by PUC5,
no need to bulky output filters, reliable and good dynamic performance in variable
conditions (including change in DC source, load, power amount injected to the
grid), requiring no voltage/current sensor in stand-alone mode, low manufacturing
costs and miniaturized package due to using less components and etc are
interesting advantages of the introduced
PUC5 topology which have been proved by experimental results in both
stand-alone and grid-connected modes. The presented PUC5 inverter can be a
challenging candidate for conventional photovoltaic application inverters.
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