Download Abstract - JPInfotech

OPERATION MODES ANALYSIS AND LIMITATION FOR
DIODE-ASSISTED BUCK–BOOST VOLTAGE SOURCE
INVERTER WITH SMALL VOLTAGE VECTOR
ABSTRACT:
Diode-assisted buck–boost voltage source inverter (VSI) boosts the dc source
voltage by introducing diode-assisted capacitor network. With parallel capacitive
charging and series capacitive discharging, the new topology extends voltage regulation
range and avoids extreme duty ratio of switching devices in the front boost circuit.
As for the unique structure, various novel pulse-widthmodulation strategies are
provided to obtain the linear voltage gain with regard to the chopped intermediate dclink voltage of the inverter bridge in one switching time period. It provides a
competitive solution for high voltage gain applications.
However,when the inverter supplies inductive or capacitive load with extreme
low load power factor, the unidirectional current flow of the diode may limit the
application of the converter utilizing small voltage vectors for ac output voltage
extension. As a result, diode-assisted buck–boost VSI exhibits new operation mode that
has not been discussed before.
This project makes a detailed circuit analysis of the relationship between the
undesired operation condition and load power factor. Then, a simple approach to totally
eliminate the undesired limitation by replacing the diodes with controlled switching
devices is provided.
BLOCK DIAGRAM:
Dc source
Diode-assisted buck–
boost converter
Driver section
Pic controller
VSI
Output
TOOLS AND SOFTWARE USED:
 MP LAB
 ORCAD/PSPICE
 MATLAB/SIMULINK
OUTPUT:
 HARDWARE
 SIMULATION