Advanced Design and Small-Signal Modeling of ACF Converter for Auxiliary Power Modules Considering Transformer Impedance

Active clamp forward (ACF) converters are being extensively applied to auxiliary power modules (APMs) in electric vehicles (EVs) to minimize the use of components and maximize efficiency. Existing ACF converter designs disregard the parasitic characteristics of the components and the leakage inductance of the transformer, resulting in design inaccuracies. This paper proposes a precise design method that considers the transformer impedance and parasitic characteristics of the components. Furthermore, the input-output relationship of the converter, stress on the switching components, and operational range are analyzed to introduce a design strategy that can minimize design errors. Moreover, this study implements a small-signal model and a controller design method based on the contrived model. The proposed design approach is validated through theoretical analysis, simulation comparison, and experimental verification, which includes the accuracy verification of the controller. This approach focuses on markedly reducing design errors, enhancing the precision of the ACF converter design, and further strengthening the reliability of converters for APM of an EV.