Multimode Sequence Modeling Method for Accurate Description of VHF Resonant Converters Based on Mixed Logical Inequalities

Due to the high operating frequency and the fact that they usually work in resonant soft-switching mode, very-high-frequency (VHF) converters are characterized by multiple modes and significant influence of parasitic parameters, and usually suffer from mode-skipping. These characteristics make the modeling and analysis of such systems more difficult. Therefore, taking a VHF resonant boost converter as an example, this article proposes a multimode sequence (MMS) modeling method based on mixed logical inequalities for accurately describing VHF converters. First, according to the mode analysis of the converter, the mode switching sequence is determined. Then, the simplified constraints of each mode are derived. After that, by combining mixed logical inequalities with simplified constraints, the MMS model of the VHF converter is established, and the corresponding calculation process is given. In addition, by a simple derivation, the proposed method can also consider the nonlinear parasitic capacitance and does not affect the computational complexity. It is worth mentioning that the MMS modeling method does not need to obtain analytical expressions for the state variables, so it is not limited by the order and topology of the converter and can provide a basis for the design, analysis, and control of VHF converters. Finally, a prototype with an operating frequency of 10 MHz is built to verify the feasibility of the method.