Three-Level Boost Converter With CRM Operation

This paper presents implementation of triangular critical conduction mode (CRM) modulation scheme to three-level boost (TLB) converter and proposes a three-level CRM modulation scheme for the topology. Compared to conventional triangular method, the proposed one performs full-utilization of three-level capability and synthesizes quadrangular inductor current waveform. By adjusting a designable period of the proposed scheme in a switching cycle, several variables including operating frequency, inductor current peak and component rms currents can be decreased. As a result, converter efficiency can be improved and current stresses of circuit components can be mitigated. In this paper, details of TLB operation principle, analysis of the proposed scheme and effects of adjustable design parameter are provided. A 700-W TLB converter prototype has been set up in order to verify the effectiveness of proposed CRM modulation scheme.