Application of DC/DC Cuk converter as a soft starter for battery chargers based on double-loop control strategy

摘要

This study presents a new soft starter based on a Cuk converter for output-current trajectory-tracking task in a battery-charger system. For this purpose, a double-loop current controller is developed, which is able to control the input current of the converter as well as its output current. The reference value of the input current is modified using a proportional-integral-derivative (PID) controller through an outer loop, which works to reduce the steady-state error of the output current. Also, sliding-mode theory and equivalent-control method are used to establish the closed-loop-system stability and investigate the dynamic performance of the switching regulator. The system robustness is studied in depth taking into account the parametric variations associated with various operating points of the battery charger. The utilization of a hysteresis modulator in the control loop removes the risk of control-signal saturation and guarantees the converter operation. The developed system not only has the merits of simplicity of the current control and smooth response but also ensures a wide current-regulation range. The proposed cascade controller is tested using simulations in powersim (PSIM) software. Finally, the system effectiveness is validated via the experimental results.