Performance optimization of BKYC topology with closed-loop regulation for DC bus voltage in EV applications

Abstract This study presents the development of a Bidirectional KY (BKY) converter tailored for integration into electric vehicle (EV) drivetrain systems. The converter operates in continuous conduction mode (CCM), supplying power from a battery pack to a BLDC motor via the DC bus. Voltage gain analysis is conducted with consideration of non-idealities in semiconductor devices and passive components. System stability is validated through Bode and phase margin plots. Due to frequent dynamic variations in EV drivetrain operation, the DC bus voltage tends to fluctuate, necessitating robust regulation. To address this, an Average Current Mode Control (ACMC) strategy is employed, utilizing state-space modelling to derive realistic loop gain transfer functions for both current and voltage control loops. Furthermore, a passivity-based control (PBC) scheme integrated with a nonlinear disturbance observer (NDO) is proposed to reduce steady-state error and improve voltage regulation. Comparative analysis reveals that the PBC+NDO approach offers superior transient response and sustained voltage stability across varying operating conditions. The proposed converter and control strategies are implemented and evaluated using MATLAB/Simulink and dSpace under diverse driving scenarios.