Composite Control Scheme for Input Capacitors Voltage Dynamic Regulation of I-RSCC

In DC applications with wide input voltage range, hard switching and high current stress hinder the efficiency improvement. To broaden the soft switching range, a composite control scheme with voltage dynamic regulation of input capacitors is proposed for isolated resonant switched capacitor converter (I-RSCC). In the proposed composite control scheme, there are two phase shift time to regulate the output voltage jointly. And the phase shift time inside the resonant switched capacitor unit is used to adjust the input capacitor voltage. And the phase shift time between the primary and secondary side is used to control the voltage conversion ratio between the voltage of input and output capacitors. Therefore, the operation efficiency is improved. Firstly, the I-RSCC topology and operation principle under the proposed composite control are introduced. Secondly, soft switching conditions of the switching devices are discussed. Moreover, to achieve optimal control, power loss of switching devices, including switching loss and conduction loss, root mean square (RMS) current and peak current are also considered in the selection of optimization targets. Then the objective functions and constraints are deduced, and the crayfish optimization algorithm (COA) is employed to obtain the optimal operating point. Therefore, the power loss of the switching devices is reduced by optimizing the control. Finally, the simulation and experimental platforms are also built to verify the proposed control. The experimental results shows that the soft switching range is expanded under the proposed composite control. Moreover, the RMS and peak current of the switching devices are reduced under the proposed control. And a maximum efficiency improvement of up to 4.54% is achieved under the proposed control.