Current sharing control strategy in CRM mode for multi-module parallel Boost converter

Abstract

The critical conduction mode (CRM) of boost topology can realize the zero-voltage switch of the power MOSFET. Maintaining the negative inductor current within a certain range through variable frequency control, which can make the converter have high efficiency in a large load range. The application of gallium nitride (GaN) devices can further increase the switching frequency of the converter, which is very critical in the application of CRM mode. Parallel converters must solve the problem of uneven current distribution. This paper proposes a new digital current sharing control strategy without adding auxiliary circuits. On the one hand, this control strategy achieves accurate current sharing among different modules through reasonable current sharing control. On the other hand, it uses formula calculations to change the switching frequency in real time to maintain the CRM mode to improve efficiency. Finally, a two-channel parallel boost experimental prototype was built based on the modular idea to verify the feasibility and superiority of the proposed control strategy.