Abstract:
The Buck-Boost dc-dc converter has a series switch with the source and a series diode with the load. The series switch makes the input current discontinuous. Filtering out the high frequency switching component from the discontinuous input current of the buck boost dc-dc converter is difficult. In a recent research the one quadrant buck-boost has been modified with additional diode-capacitors to have continuous input current which is easy to filter. There are applications where two quadrant dc-dc converters with boost-buck voltage gain/attenuation are necessary. DC motors and battery chargers are the examples of such applications. In this thesis the modified one quadrant buck-boost dc-dc converter has further been topologically changed to operate the converter in two quadrant mode and yet maintain the continuous input current during whichever side is being used as the input of the converter. The proposed two quadrant buck-boost dc-dc converter with continuous input current has been investigated with R, R-L and R-L-Emf loads by interchanging the positions of source and load of the converter. The simulation results indicate the proposed buck-boost converter performs two quadrant operations (i.e.-ve voltage - ve current and -ve voltage +ve current with the change of duty cycle of control pulse of the switches of the dc-dc converter). In the proposed two quadrant buck-boost dc-dc converter additional switch, diodes, capacitors and inductors are used as per requirement. Number of switches used in the proposed circuit is two and the gate pulses provided to the switches are compliment of each other.
