A Novel Three-Active-Switch Isolated Bridgeless Inverter for Renewable Energy Applications

Module-integrated converters (MICs) have attracted attention as efficient distributed renewable energy systems due to their high flexibility, reliability, and scalability. Given that MICs are installed for each energy module, it is crucial to design circuits with minimal active switches for high power density and low cost. This article proposes a novel three-active-switch isolated bridgeless inverter for MICs. By adopting an asymmetrical operation and bridgeless structure, the proposed inverter utilizes only three active switch components, considerably reducing the cost of space requirements for additional power supplies and gate drivers. Moreover, galvanic isolation is achieved by using one transformer without any modification, allowing simple production and low cost. Additionally, the inverter has a dual-mode operation, i.e., discontinuous conduction mode (DCM) and continuous conduction mode (CCM) at low and high instantaneous power ranges, respectively, to reduce input and output current/voltage ripples and ensure optimal power component values. Consequently, the proposed inverter can easily achieve low cost, small size, and high power density, which are the requirements of MIC. Circuit operation and design guidelines of a novel isolated bridgeless inverter are presented in detail. The effectiveness and performance of the proposed inverter were verified using a 300-W prototype, achieving a peak efficiency of 95.2%.