Multi-loop controller for wide operating range single-ended primary inductor DC/DC converter

A novel controller based on the decoupling of single-ended primary inductor converter (SEPIC) state-space averaging model to four simple first-order systems is proposed. Instead of designing a single controller for a fourth-order SEPIC converter, four PI controllers are designed for the four decoupled systems. Combining the four PI controllers with the four decoupled systems forms a multi-loop feedback control system which is able to work at a wider operating condition. Circuit implementation of the proposed controller is presented and experimental results are included to demonstrate the effectiveness of the proposed design scheme.