03-05-2012, 11:21 AM
Selective Harmonic Elimination Technique for a Multilevel Inverter
[attachment=21123]
INTRODUCTION
multilevel inverter is more recent and popular type of
power electronic converter that synthesizes a desired
output voltage from several levels of dc voltages as inputs. If
sufficient number of dc sources is used, a nearly sinusoidal
voltage waveform can be synthesized.
In comparison with the hard-switched two-level pulse
width modulation inverter, multilevel inverter offers several
advantages such as, its capabilities to operate at high voltage
with lower dv/dt per switching, high efficiency and low
electromagnetic interference [1]-[4].
CASCADE MULTILEVEL INVERTER
Cascade Multilevel Inverter (CMLI) is one of the most
important topology in the family of multilevel and multipulse
inverters. It requires least number of components with
compare to diode-clamped and flying capacitors type
multilevel inverters and no specially designed transformer is
needed as compared to multipulse inverter. It has modular
structure with simple switching strategy and occupies less
Selective Harmonic Elimination Technique for a
Multilevel Inverter
Jagdish Kumar, Biswarup Das, Senior Member, IEEE, and Pramod Agarwal, Member, IEEE
Fifteenth National Power Systems Conference (NPSC), IIT Bombay, December 2008
space [1], [3].
NEWTON-RAPHSON METHOD
The Newton-Raphson (N-R) method is one of the fastest
iterative methods. This method begins with an initial
approximation and generally converges at a zero of a given
system of nonlinear equations [10].
The N-R method is to be implemented to compute the
switching angles for the system given by (4). The Switching
angles which are in the range of 0 to /2 producing desired
fundamental voltage along with elimination of 5th ,7th, 11th,
and 13th harmonic components for a given modulation index
are feasible solutions of (4). The N-R method implemented
previously in [4]-[6] was based on trial and error method for
estimation of initial guess and for which solutions exist.
Once a solution set was obtained, successive solutions were
computed by using previous solution set as initial guess for the
next one;
[attachment=21123]
INTRODUCTION
multilevel inverter is more recent and popular type of
power electronic converter that synthesizes a desired
output voltage from several levels of dc voltages as inputs. If
sufficient number of dc sources is used, a nearly sinusoidal
voltage waveform can be synthesized.
In comparison with the hard-switched two-level pulse
width modulation inverter, multilevel inverter offers several
advantages such as, its capabilities to operate at high voltage
with lower dv/dt per switching, high efficiency and low
electromagnetic interference [1]-[4].
CASCADE MULTILEVEL INVERTER
Cascade Multilevel Inverter (CMLI) is one of the most
important topology in the family of multilevel and multipulse
inverters. It requires least number of components with
compare to diode-clamped and flying capacitors type
multilevel inverters and no specially designed transformer is
needed as compared to multipulse inverter. It has modular
structure with simple switching strategy and occupies less
Selective Harmonic Elimination Technique for a
Multilevel Inverter
Jagdish Kumar, Biswarup Das, Senior Member, IEEE, and Pramod Agarwal, Member, IEEE
Fifteenth National Power Systems Conference (NPSC), IIT Bombay, December 2008
space [1], [3].
NEWTON-RAPHSON METHOD
The Newton-Raphson (N-R) method is one of the fastest
iterative methods. This method begins with an initial
approximation and generally converges at a zero of a given
system of nonlinear equations [10].
The N-R method is to be implemented to compute the
switching angles for the system given by (4). The Switching
angles which are in the range of 0 to /2 producing desired
fundamental voltage along with elimination of 5th ,7th, 11th,
and 13th harmonic components for a given modulation index
are feasible solutions of (4). The N-R method implemented
previously in [4]-[6] was based on trial and error method for
estimation of initial guess and for which solutions exist.
Once a solution set was obtained, successive solutions were
computed by using previous solution set as initial guess for the
next one;