Two-Inductor CPM Control in Interleaved Bidirectional High-Gain DC-DC Converter

This article proposes an improved control strategy for an existing interleaved bidirectional high-gain dc-dc converter. The converter provides excellent steady-state performance. It uses an intermediate voltage-lift capacitor to achieve a high-voltage conversion ratio, whereas interleaving between its two inductor currents results in low ripple in low-voltage side high current. However, it suffers from poor transient performance in its step-up mode due to the fourth-order duty-to-output voltage transfer function with one right-half-plane zero (RHPZ). The article proposes a two-inductor current program mode (CPM) control in the step-up mode of the converter, which modifies the control-to- output voltage transfer function to a second-order system. It enhances the controller's bandwidth and results in a faster dynamic response. The proposed two-inductor CPM control relies on the feedback of both the inductor currents. A method is developed to estimate the average inductor currents from the intermediate capacitor current, reducing the required number of current sensors to one. A 200 W, 30/300 V, and 50 kHz laboratory prototype is developed to validate all the theoretical inferences and demonstrate the enhanced dynamic response resultant from the proposed two-inductor CPM control.