Variable Inductor Based Bidirectional DC-DC Converter for Electric Vehicles

This paper presents the feasibility study of variable inductor (VI)-based bidirectional dc-dc converter for applications with a wide range of load variations such as electric vehicles. An additional winding is introduced to the conventional power inductor to inject a control current for adjusting the permeability of magnetic cores. This has significant merits in controlling the current ripple and enhancing the current handling capability of power inductors, thereby reducing the size of magnetic components and improving the performance. For current values, twice and three times the rated current, the current ripple is reduced by 40.90 % and 36.10 %, respectively. Nonetheless, this device requires a precisely controlled dc-current. As such, a small current controlled, low-power and low-cost buck converter is built to power up the auxiliary winding. To improve the reliability and robustness of the VI, an integrated closed loop control that enables the control of the main converter and the auxiliary converter is also implemented and tested in real time to test the viability of the VI.