In conventional arrangements of three-phase LLC converters, there are at least three magnetic components that occupy a considerable volume and mass of the power converter. Although, the three-phase ...LLC topology has many advantages over the single-phase one, circuit designers tend to select the single-phase topology because it has the minimal number of magnetic components. The purpose of this study is to reduce the number of the magnetic components of the three-phase topology, by integrating the three-discrete transformers into a single magnetic core, based on a theoretical framework. Lagrangian dynamics is applied to theoretically prove that it is possible to replace the three-discrete transformers by a single integrated transformer. The Lagrangian dynamics theory allowed us to derive a physically motivated model for the integrated transformer, in which each component of the integrated transformer has its own Lagrangian parameter. The Lagrangian model reveals that in a symmetrical design, there is no interphase coupling, and as a result the magnetic components can be downsized owing to the ac flux cancellation. Along with the theoretical discussion, the practical merits of implementing the integrated transformer is reported. Furthermore, the experimental tests are conducted utilizing a 500 W–390 V/12 V–200 kHz prototype.
Polymer electrolyte membrane fuel cells (PEMFCs) are prone to membrane dehydration and liquid water flooding, negatively impacting their performance and lifetime. Therefore, PEMFCs require ...appropriate water management, which makes accurate water modeling indispensable. Unfortunately, available control-oriented models only replicate individual water-related aspects or use oversimplistic approximations. This paper resolves this challenge by proposing, for the first time, a control-oriented PEMFC stack model focusing on physically motivated water modeling, which covers phase change, liquid water removal, membrane water uptake, and water flooding effects on the electrochemical reaction. Parametrizing the resulting model with measurement data yielded the fitted model. The parameterized model delivers valuable insight into the water mechanisms, which were thoroughly analyzed. In summary, the proposed model enables the derivation of advanced control strategies for efficient water management and mitigation of the degradation phenomena of PEMFCs. Additionally, the model provides the required accuracy for control applications while maintaining the necessary computational efficiency.
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