This paper presents the three-phase version of the isolated dc-dc Weinberg converter. The main characteristics of the proposed converter are as follows: small volume, low weight, reduced number of components, buck operation for a duty cycle of less than 1/3, and input and output current ripple cancellation for a duty cycle of 1/3 or 2/3. Typical applications include telecommunication, electric vehicles, renewable energy conversion systems, and batteries. This paper gives theoretical analysis, design example, and experimental data on a 735-W 120-Vdc-input 75-Vdc-output 42-kHz switching frequency laboratory prototype. The prototype performance shows good agreement with the theoretical predictions. © 2011 IEEE.