Modeling of PWM DC/DC Converters Using the Graft Scheme

Summary

The pulse‐width modulated (PWM) converters and their derived QRCs and MRCs are reconfigured into basic converter units (BCUs) and linear devices, resulting in simplified modelling and analysis processes. This chapter presents a systematic and unified approach to modeling transformerless PWM converters based on the graft scheme. One of the most important advances in characterizing PWM DC/DC converters has been the development of accurate small‐signal models for them. The PWM converters can be generated from the BCUs connected in cascade. Converters are usually connected in cascade to achieve multiple functions. The graft scheme can be used to integrate multiple converters to form a single‐stage converter (SSC). For instance, the buck‐boost, Cuk, sepic, and Zeta converters can be derived from the two BCUs, buck and boost. The chapter also presents derivation of the small‐signal models.