A Novel Four-Switch Non-Isolated DC-DC Converter with Inverted Buck and Non-Inverted Buck-Boost Capability for Electric Vehicle Drivetrain Applications

In this paper, a novel four-switch non-isolated DC-DC converter capable of providing inverted buck and non-inverted buck-boost operation is presented. An intermediate Direct Current (DC) link with non-inverted buck-boost gain from the battery voltage is also exhibited, which aids in the voltage conversion during the Continuous Conduction Mode (CCM) and can also serve as a second output port to cater to a load requiring non-inverted buck-boost operation like an Electric Vehicle (EV) drivetrain. Also, a different switching scheme is explored for the converter with two output ports, demonstrating the versatility of the converter to provide conventional boost catering. Detailed steady-state operation of the converter is analyzed in the CCM mode and the voltage gain is derived in detail. The converter is simulated on MATLAB Simulink simulation platform and the waveforms verify the theoretical results. Closed-loop current controller design is penned down in detail due to the presence of Right Half Plane (RHP) Zero in its voltage-to-duty small signal transfer function, and its efficacy is established using step changes in load. In summary, a novel non-isolated DC-DC converter consisting of four switches and providing buck operation with the inverted polarity and buck-boost operation in the non-inverted polarity is discussed in detail and finds its best fit in EV drivetrain applications.