Time-Varying Capacitors as Lossless Two-Port Devices

TL;DR

This paper challenges classical views on time-varying capacitors, proposing a complete two-port model grounded in energetic and system-theoretic principles that aligns with thermodynamics.

Contribution

It introduces a new two-port device model for time-varying capacitors based on dissipativity and passivity theory, correcting previous incomplete models.

Findings

The classical one-port model is incomplete and inconsistent with thermodynamics.

A new two-port model is derived that is energetically consistent.

The approach clarifies the physical interpretation of time-varying capacitors.

Abstract

Inspired by recent assertions that imply incorrectness of the classical constitutive relationship of time-varying capacitance, energetic and system-theoretic perspectives are invoked that, instead of incorrectness, show incompleteness of the associated one-port device model. Based on dissipativity and passivity theory, an energetic analysis is presented that naturally leads to a complete two-port device model that is consistent with the laws of thermodynamics.