TITLE:
THD Analysis of Cascaded H-Bridge Inverter with Fuzzy Logic Controller
AUTHORS:
Sivakumar N., Sumathi A.
KEYWORDS:
Cascaded H-Bridge Multilevel Inverter, THD, Photo Voltaic Modules, SPWM, Fuzzy Logic Controller, MPPT Technique
JOURNAL NAME:
Circuits and Systems,
Vol.8 No.7,
July
18,
2017
ABSTRACT: In recent days, the multilevel inverter technology is widely applied to domestic
and industrial applications for medium voltage conversion. But, the power
quality issues of the multilevel inverter limit the usage of much sensitive
equipment like medical instruments. The lower distortion level of the output
voltage and current can generate a quality sinusoidal output voltage in inverters
and they can be used for many applications. The harmonics can cause
major problems in equipments due to the nonlinear loads connected with the
power system. So, it is necessary to minimize the losses to raise its overall efficiency.
In this paper, a new topology of seven level asymmetrical cascaded
H-bridge multilevel inverter with a Fuzzy logic controller had been implemented
to reduce the Total Harmonic Distortion (THD) and to improve the
overall performance of the inverter. The proposed model is well suited for use
with a solar PV application. In this topology, only six IGBT switches are used
with three different voltage ratings of PV modules (1:2:4). The lower number
of semiconductor switches leads to minimizing overall di/dt ratings and voltage
stress on each switches and switching losses. The gate pulses generated by
Sinusoidal Pulse Width Modulation (SPWM) technique with a Fuzzy logic
controller are also introduced. A buck-boost converter is used to maintain the
constant PV voltage level integrated by an MPPT technique followed by Perturb
and Observer algorithm is also implemented. The MPPT is used to harness
the maximum power of solar radiations under its various climatic conditions.
The new topology is evaluated by a Matlab/Simulink model and compared
with a hardware model. The results proved that the THD achieved by
this topology is 1.66% and realized that it meets the IEEE harmonic standards.