Constant-Power Constant-Voltage Charging Protocol Based on a Four-Phase Interleaved Buck Converter for Electric Vehicle Batteries

In this paper, a control strategy is proposed to implement the constant power (CP)-constant voltage (CV) charging protocol for the ultrafast charging of electric vehicles (EV). The battery charger consists in a four-phase interleaved buck converter, with a multiple-loop controller in cascade configuration. Each of the three loops has its dedicated proportional integral (PI) controller for the control of a specific variable of the system. Namely, i) an inner loop to control the inductor current of each leg, ensuring equal distribution of the current between the four phases, ii) a first outer loop regulating the output voltage and providing the reference of the inner loop, and iii) a most outer loop to regulate the battery power by modifying the reference of the voltage loop. The correct operation of the system is validated by means of numerical simulation performed using the switched model implemented in PSIM<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">©</sup> software.